SYSTEMS FOR DELIVERING IMPLAINTABLE DEVICES ACROSS AN ATRIAL SEPTUM

[0001] This application claims the benefit of priority of U.S. patent application Ser. No. 16/374,698, filed Apr. 3, 2019, the entire contents of which are incorporated herein by reference.

[0002] This application generally relates to devices and methods for delivering implantable devices to the atrial septum, particularly in subjects with heart pathologies such as pulmonary arterial hypertension (PAH), congestive heart failure (CHF) or myocardial infarction (MI).

[0003] Pulmonary arterial hypertension occurs when the pressure within the blood vessels and lungs becomes too high. PAH may be caused by obstruction in the arties in the lung such as the development of scar tissue in the blood vessels of the lungs, but in many cases, the cause is unknown. Under normal conditions, the pressure within the right side of the heart and the blood vessels of the lungs is lower than the rest of the body which maximizes oxygenation of the blood in the lungs. With PAH, the heart must work harder under greater pressure to pump blood through the arteries in the lungs, weakening the heart muscles over time. As a result, the heart may be unable to sufficiently pump blood to the lungs to be oxygenated to keep the body functioning normally.

[0004] Heart failure is the physiological state in which cardiac output is insufficient to meet the needs of the body or to do so only at a higher filling pressure. There are many underlying causes of HF, including myocardial infarction, coronary artery disease, valvular disease, hypertension, and myocarditis. Chronic heart failure is associated with neurohormonal activation and alterations in autonomic control. Although these compensatory neurohormonal mechanisms provide valuable support for the heart under normal physiological circumstances, they also play a fundamental role in the development and subsequent progression of HF.

[0005] For example, one of the body's main compensatory mechanisms for reduced blood flow in HF is to increase the amount of salt and water retained by the kidneys. Retaining salt and water, instead of excreting it via urine, increases the volume of blood in the bloodstream and helps to maintain blood pressure. However, the larger volumes of blood also cause the heart muscle, particularly the ventricles, to become enlarged. As the heart chambers become enlarged, the wall thickness decreases and the heart's contractions weaken, causing a downward spiral in cardiac function. Another compensatory mechanism is vasoconstriction of the arterial system, which raises the blood pressure to help maintain adequate perfusion, thus increasing the load that the heart must pump against.

[0006] In low ejection fraction (EF) heart failure, high pressures in the heart result from the body's attempt to maintain the high pressures needed for adequate peripheral perfusion. However, as the heart weakens as a result of such high pressures, the disorder becomes exacerbated. Pressure in the left atrium may exceed 25 mmHg, at which stage fluids from the blood flowing through the pulmonary circulatory system transudate or flow out of the pulmonary capillaries into the pulmonary interstitial spaces and into the alveoli, causing lung congestion and, if untreated, the syndrome of acute pulmonary edema and death.

[0007] Table 1 lists typical ranges of right atrial pressure (RAP), right ventricular pressure (RVP), left atrial pressure (LAP), left ventricular pressure (LVP), cardiac output (CO), and stroke volume (SV) for a normal heart and for a heart suffering from HF. In a normal heart beating at around 70 beats/minute, the stroke volume needed to maintain normal cardiac output is about 60 to 100 milliliters. When the preload, after-load, and contractility of the heart are normal, the pressures required to achieve normal cardiac output are listed in Table 1. In a heart suffering from HF, the hemodynamic parameters change (as shown in Table 1) to maintain peripheral perfusion.

	TABLE 1
	Parameter	Normal Range	HF Range
	RAP (mmHg)	2-6	6-20
	RVSP (mmHg)	15-25	20-80
	LAP (mmHg)	6-12	15-50
	LVEDP (mmHg)	6-12	15-50
	CO (liters/minute)	4-8	2-6
	SV (milliliters/beat)	60-100	30-80

[0008] HF is generally classified as either systolic heart failure (SHF) or diastolic heart failure (DHF). In SHF, the pumping action of the heart is reduced or weakened. A common clinical measurement is the ejection fraction, which is a function of the blood ejected out of the left ventricle (stroke volume) divided by the maximum volume in the left ventricle at the end of diastole or relaxation phase. A normal ejection fraction is greater than 50%. Systolic heart failure generally causes a decreased ejection fraction of less than 40%. Such patients have heart failure with reduced ejection fraction (HFrEF). A patient with HFrEF may usually have a larger left ventricle because of a phenomenon called “cardiac remodeling” that occurs secondary to the higher ventricular pressures.

[0009] In DHF, the heart generally contracts normally, with a normal ejection fraction, but is stiffer, or less compliant, than a healthy heart would be when relaxing and filling with blood. Such patients are said to have heart failure with preserved ejection fraction (HFpEF). This stiffness may impede blood from filling the heart and produce backup into the lungs, which may result in pulmonary venous hypertension and lung edema. HFpEF is more common in patients older than 75 years, especially in women with high blood pressure.

[0010] Both variants of HF have been treated using pharmacological approaches, which typically involve the use of vasodilators for reducing the workload of the heart by reducing systemic vascular resistance, as well as diuretics, which inhibit fluid accumulation and edema formation, and reduce cardiac filling pressure. No pharmacological therapies have been shown to improve morbidity or mortality in HFpEF whereas several classes of drugs have made an important impact on the management of patients with HFrEF, including renin-angiotensin antagonists, beta blockers, and mineralocorticoid antagonists. Nonetheless, in general, HF remains a progressive disease and most patients have deteriorating cardiac function and symptoms over time. In the U.S., there are over 1 million hospitalizations annually for acutely worsening HF and mortality is higher than for most forms of cancer.

[0011] In more severe cases of HFrEF, assist devices such as mechanical pumps are used to reduce the load on the heart by performing all or part of the pumping function normally done by the heart. Chronic left ventricular assist devices (LVAD), and cardiac transplantation, often are used as measures of last resort. However, such assist devices typically are intended to improve the pumping capacity of the heart, to increase cardiac output to levels compatible with normal life, and to sustain the patient until a donor heart for transplantation becomes available. Such mechanical devices enable propulsion of significant volumes of blood (liters/min), but are limited by a need for a power supply, relatively large pumps, and pose a risk of hemolysis, thrombus formation, and infection. Temporary assist devices, intra-aortic balloons, and pacing devices have also been used.

[0012] Various devices have been developed using stents to modify blood pressure and flow within a given vessel, or between chambers of the heart Implantable interatrial shunt devices have been successfully used in patients with severe symptomatic heart failure. By diverting or shunting blood from the left atrium (LA) to the right atrium (RA), the pressure in the left atrium is lowered or prevented from elevating as high as it would otherwise (left atrial decompression). Such an accomplishment would be expected to prevent, relieve, or limit the symptoms, signs, and syndromes associated of pulmonary congestion. These include severe shortness of breath, pulmonary edema, hypoxia, the need for acute hospitalization, mechanical ventilation, and death.

[0013] Percutaneous implantation of interatrial shunts generally requires transseptal catheterization immediately preceding shunt device insertion. The transseptal catheterization system is placed from an entrance site in the femoral vein, across the interatrial septum in the region of fossa ovalis (FO), which is the central and thinnest region of the interatrial septum. The FO in adults is typically 15-20 mm in its major axis dimension and <3 mm in thickness, but in certain circumstances may be up to 10 mm thick. LA chamber access may be achieved using a host of different techniques familiar to those skilled in the art, including but not limited to: needle puncture, stylet puncture, screw needle puncture, and radiofrequency ablation. The passageway between the two atria is dilated to facilitate passage of a shunt device having a desired orifice size. Dilation generally is accomplished by advancing a tapered sheath/dilator catheter system or inflation of an angioplasty type balloon across the FO. This is the same general location where a congenital secundum atrial septal defect (ASD) would be located.

[0014] Moreover, devices such as those described in U.S. Pat. No. 5,312,341 to Turi, have been theorized for transseptal catheterization. Specifically, these devices have a retaining means such as an inflatable balloon that is inflated within the left atrium of the patient to prevent inadvertent retraction of the distal tip of the sheath from the left atrium during subsequent portions of the catheterization procedure.

[0015] In view of the foregoing, it would be desirable to provide devices for delivering implantable devices to the atrial septum of the heart to reduce left atrial pressure.

[0016] It would further be desirable to provide devices and methods for controlled positioning and delivery of atrial shunt devices.

[0017] The present invention overcomes the drawbacks of previously-known devices by providing apparatus for delivering a device for regulating blood pressure between a patient's left atrium and right atrium. The delivery apparatus includes a sheath having a distal region sized and shaped for percutaneous advancement to the atrial septum, a proximal region, and a sheath lumen extending therethrough, the sheath lumen sized and shaped to receive the shunt in a contracted delivery state. The apparatus also includes a first, outer catheter moveably disposed within the sheath lumen, wherein the first catheter has a first catheter lumen extending therethrough, and a hub moveably disposed within the sheath lumen distal to the first catheter.

[0018] The hub has a hub lumen extending therethrough and one or more engagers sized and shaped to releaseably engage the shunt in the contracted delivery state within the sheath lumen. The hub may include an engagement portion and a ring portion, wherein the engagement portion of the hub has a diameter smaller than a diameter of the ring portion, and wherein the one or more engagers are disposed circumferentially around the engagement portion of the hub. For example, a first expandable end of the shunt may be positioned between the one or more engagers and the ring portion and between an outer surface of the engagement portion and an inner wall of the sheath in the contracted delivery state within the sheath lumen. The hub further may include a proximal portion, such that the first catheter has a cavity sized and shaped to receive at least a portion of the proximal portion to limit movement of the hub relative to the first catheter.

[0019] In addition, the apparatus further includes a second, inner catheter moveably disposed within the first catheter lumen and the hub lumen, and wherein the first catheter and the hub are movable which the second catheter remains in place. The second catheter may include a stop, e.g., a lock ring, disposed at a distal end of the second catheter, such that the hub has a cavity sized and shaped to receive at least a portion of the stop to limit movement of the hub relative to the second catheter. In addition, the second catheter may include a guidewire lumen extending therethrough sized and shaped to receive a guidewire.

[0020] The apparatus also includes a handle disposed at the proximal region of the sheath. The first catheter, the hub, and the second catheter are independently movable relative to the sheath responsive to actuation at the handle to facilitate transition of the shunt from the contracted delivery state to an expanded deployed state at the atrial septum. In addition, the handle includes a knob that when actuated facilitates deployment of and/or halfway retrieval of the shunt at the atrial septum by adjusting a length of the delivery apparatus relative to the sheath. For example, the knob may be actuated to gradually adjust the length of the delivery apparatus relative to the sheath to assist in halfway retrieval of the shunt.

[0021] The handle may include a first actuator, the first actuator coupled to the sheath such that actuation of the first actuator causes the sheath to move relative to the hub, the first catheter, and the second catheter. The handle also may include a second actuator, the second actuator coupled to the second catheter such that actuation of the second actuator causes the second catheter to move relative to the sheath, the hub, and the first catheter. For example, the second actuator may be coupled to the second catheter via one or more guiderails and a pusher plate. Accordingly, the first actuator may move along the one or more guiderails within a housing of the handle.

[0022] The apparatus also includes a locking mechanism for releasably coupling the hub and the first catheter. Thus, the handle further includes a third actuator operatively coupled to the locking mechanism such that actuation of the third actuator causes the locking mechanism to couple or decouple the hub and the first catheter. The handle further may include an actuation ring positioned between the second actuator and the third actuator, wherein the actuation ring has an indented distal edge sized and shaped to engage with a toothed proximal edge of the third actuator, and a grooved proximal edge sized and shaped to engage with an indented distal edge of the second actuator. For example, actuation of the third actuator may orient the actuation ring such that actuation of the second actuator is inhibited.

[0023] In accordance with another aspect of the invention, a method for delivering a shunt at an atrial septum of a patient is provided. The method includes selecting a sheath and a delivery apparatus including a first, outer catheter, a hub distal to and releasably coupled to the first catheter, the hub having one or more engagers disposed thereon, the one or more engagers sized and shaped to releasably engage with the shunt in a contracted delivery state within a lumen of the sheath, and a second, inner catheter extending through a center lumen of the first catheter and the hub. The first catheter, the hub, and the second catheter are independently moveable relative to the sheath upon actuation of a handle operatively coupled to the sheath and the delivery apparatus.

[0024] The method further includes advancing a distal end of the sheath through the atrial septum into a first atrium, and then advancing the delivery apparatus within the lumen of the sheath, and actuating the handle to move the delivery apparatus distally relative to the sheath such that a first expandable end of the shunt extends distally out the distal end of the sheath and transitions from a contracted state within the lumen of the sheath to an expanded state in the first atrium. The method then includes (1) actuating the handle to move the second catheter distally relative to the sheath, the first catheter, and the hub; (2) moving the delivery apparatus and the sheath proximally until the first expandable end of the shunt rests against the atrial septum from within the first atrium; and (3) actuating the handle to decouple the hub and the first catheter. The method further includes moving the first catheter and the sheath proximally relative to the hub to disengage a second expandable end of the shunt with the one or more engagers of the hub and expose the second expandable end of the shunt from the sheath to transition from the contracted state within the lumen of the sheath to an expanded state in a second atrium. Finally, the method includes removing the sheath and the delivery apparatus from the patient such that a neck region of the shunt is positioned within the atrial septum to permit blood to flow through an opening in the neck region of the shunt and thereby through the atrial septum.

[0025] In accordance with one aspect of the invention, the method further includes actuating the handle to adjust a length of the delivery apparatus relative to a length of the sheath prior to disengaging the second expandable end of the shunt with the one or more engagers of the hub to assist in halfway retrieval of the shunt. For example, the handle may be actuated to gradually adjust the length of the delivery apparatus relative to the length of the sheath to facilitate retrieving the shunt in a partially deployed state. In accordance with yet another aspect of the invention, the second catheter includes a guidewire lumen extending therethrough sized and shaped to receive a guidewire, such that the method also includes inserting a guidewire percutaneously through the atrial septum into the first atrium. Thus, advancing the delivery apparatus through the sheath includes advancing the delivery apparatus over the guidewire. As will be understood by a person ordinarily skilled in the art, a dilator may be advanced over the guidewire through the fossa ovalis to enlarge the opening within the atrial septum, and removed prior to advancing the sheath and the delivery apparatus within the lumen of the sheath over the guidewire.

[0026] In accordance with another aspect of the present invention, a system for retrieving a shunt implanted in an atrial septum of a patient is provided. The system includes a sheath having a proximal end, a distal end, and a lumen extending therebetween. The system further includes one or more grappling hooks slidably movable through the lumen of the sheath. The one or more grappling hooks are transitionable between a contracted delivery state within the lumen of the sheath and an expanded deployed state when exposed from the distal end of the sheath. In addition, the one or more grappling hooks each have a hook portion that may be coupled to a proximal end of the shunt in the expanded deployed state. Accordingly, when the one or more grappling hooks are coupled to the shunt, transition of the one or more grappling hooks from the expanded deployed state to the contracted delivery state causes the proximal end of the shunt to transition from an expanded deployed state to a collapsed retrieval state. Moreover, the sheath is sized and shaped to receive the proximal end of the shunt in the collapsed retrieval state and may be moved over the shunt to transition a distal end of the shunt from an expanded deployed state to a collapsed retrieval state, to thereby retrieve the shunt from the atrial septum.

[0027] In one embodiment, the one or more grappling hooks are biased toward the expanded deployed state. Accordingly, the system further may include a restraint slidably movable over the one or more grappling hooks to transition the one or more grappling hooks between the contracted delivery state and the expanded deployed state. For example, the one or more grappling hooks may have a non-expandable catheter portion proximal to the hook portion, such that movement of the restraint towards the non-expandable catheter portion causes the one or more grappling hooks to transition from the contracted delivery state to the expanded deployed state, and movement of the restraint towards the hook portion causes the one or more grappling hooks to transition from the expanded deployed state to the contracted delivery state.

[0028] In another embodiment, the one or more grappling hooks are biased toward the contracted delivery state. Accordingly, the system further may include a balloon catheter slidably movable within the lumen of the sheath. The balloon catheter includes a balloon transitionable from a deflated state to an inflated state adjacent the proximal end of the shunt, thereby creating a ramp in the inflated state such that movement of the one or more grappling hooks over the balloon in the inflated state causes the one or more grappling hooks to transition from the contracted delivery state to the expanded deployed state.

[0029] In accordance with another aspect of the present invention, a system for loading a shunt for intravascular delivery to an atrial septum of a patient is provided. The system may include a proximal loader having proximal end, a distal end, and a lumen extending therebetween. For example, a proximal portion of the lumen may be sized and shaped to receive a proximal end of the shunt in a collapsed delivery state, and a distal portion of the lumen may be sized and shaped to transition the proximal end of the shunt from an expanded deployed state to the collapsed delivery state when the proximal end of the shunt is received through the distal portion of the lumen. In addition, the system further may include a distal loader having a cavity sized and shaped to receive the proximal loader therein. For example, movement of the proximal loader distally within the cavity of the distal loader may cause the proximal end of the shunt positioned within the cavity of the distal loader to transition from the expanded deployed state to the collapsed delivery state within the proximal portion of the lumen of the proximal loader. Moreover, the proximal portion of the lumen further may be sized and shaped to slidably receive a delivery apparatus therethrough, such that the delivery apparatus may engage with the proximal end of the shunt in the collapsed delivery state.

[0030] In accordance with yet another aspect of the present invention, an alternative method for delivering a shunt to an atrial septum of a patient is provided. For example, the method may include: advancing a distal end of a sheath having a cap removably disposed thereon from a first atrium, through the atrial septum into a second atrium, the sheath having a shunt disposed therein in a collapsed delivery state, the shunt coupled to a delivery apparatus within the sheath; decoupling the cap from the distal end of the sheath; retracting the sheath relative to the cap and the shunt to partially deploy the shunt within the second atrium; moving the sheath and the shunt together proximally to align a radiopaque marker disposed on the distal end of the sheath with the atrial septum; decoupling the shunt from the delivery apparatus; retracting the sheath until the shunt is fully deployed within the atrial septum; and removing the sheath and delivery apparatus from the patient. The method further may include advancing the sheath distally prior to decoupling the shunt from the delivery apparatus to transition the partially deployed shunt to the collapsed delivery state within the sheath, e.g., for half-way retrieval of the shunt.

[0031] In accordance with another aspect of the present invention, a guidewire loading device for loading a guidewire into an atrial shunt delivery cartridge, e.g., a cartridge for loading a shunt for intravascular delivery to the atrial septum of a patient, is provided. The loading device may include a proximal portion having a lumen sized and shaped to receive the atrial shunt delivery cartridge therein and a distal portion having an adjustable lumen. In addition, the loading device may include a pair of flexible wings extending radially from the distal portion. The pair of flexible wings, when a force is applied thereon, may cause a diameter of the adjustable lumen of the distal portion to increase to a size sufficient to receive the atrial shunt delivery cartridge therein. For example, the diameter of the adjustable lumen of the distal portion may be biased toward a size smaller than when the force is applied on the pair of flexible wings. Thus, upon release of the force on the pair of flexible wings, the adjustable lumen of the distal portion will squeeze against the atrial shunt delivery cartridge, thereby holding the cartridge in position to receive the guidewire. Moreover, a free end of the pair of flexible wings may include a flat edge extending parallel to a longitudinal axis of the distal portion.

[0066] Embodiments of the present invention are directed to devices for delivering implantable devices to the atrial septum of the heart, and thus may be useful in treating subjects suffering from heart failure or other disorders associated with elevated left atrial pressure. For example, the inventive device may be designed to deliver an hourglass or “diabolo” shaped stent, preferably formed of a shape memory metal as described in U.S. Pat. No. 9,629,715 to Nitzan, assigned to the assignee of the present invention, the entire contents of which are incorporated herein by reference. The delivery device is configured to lodge the stent securely in the atrial septum, preferably the fossa ovalis, to function as an interatrial shunt, allowing blood flow from the left atrium to the right atrium.

[0067] Referring to FIGS. 1A and 1B, apparatus 100 is provided for delivering interatrial shunt devices, e.g., devices described in U.S. Pat. No. 9,629,715 to Nitzan and U.S. Pat. No. 9,713,696 to Yacoby, assigned to the assignee of the present invention, the entire contents of each of which are incorporated herein by reference. Apparatus 100 may include distal end 102, catheter 104, and proximal end 106 having handle 108. Distal end 102 comprises components suitable for coupling apparatus 100 to devices of the present invention, as described in detail below. Catheter 104 comprises a biocompatible tube shaft of suitable size, e.g., approximately 14 Fr., and suitable length, e.g., approximately 75-100 cm and preferably 85 cm. Proximal end 106 comprises handle 108 that is configured to be manipulated, e.g., by a human hand, to transition components in distal end 102 from an engaged position shown in FIG. 1A to a disengaged position shown in FIG. 1B. Handle 108 may be manipulated, for example, by moving finger grips 110 proximally from a locked position shown in FIG. 1A to an unlocked position shown in FIG. 1B. In addition, handle 108 may be manipulated by moving finger grips 110 distally from the locked position to the unlocked position so as to transition components in distal end 102 from the disengaged position to the engaged position to load devices of the present invention.

[0068] FIGS. 2A and 2B illustrate distal end 102 in the engaged position of FIG. 1A and the disengaged position of FIG. 1B, respectively. At distal end 102, apparatus 100 may include latching legs 112, 114, and 116 having hook portions 118, 120, and 122, respectively. Latching legs 112, 114, and 116 comprise a biocompatible material such as a biocompatible metal or polymer, and are positioned longitudinally and radially so as to firmly secure devices of the present invention for delivery. Hook portions 118, 120, and 122 extend outwardly from the distal end of latching legs 112, 114, and 116, respectively, and are configured to fit securely between struts and rings of the devices of the present invention. Preferably, hook portions 118, 120, and 122 hook outwardly away from center axis 123 of catheter 104 in both the engaged and disengaged positions as shown in FIGS. 1A and 1B. Center axis 123 is centered relative to catheter 104 on both a longitudinal and cross-sectional basis. By facing outwardly from center axis 123, hook portions 118, 120, and 122 may engage the inner surface of the device, e.g., within a lumen of a shunt. In one embodiment, hook portions 118, 120, and 122 hook generally perpendicularly away from center axis 123 from a radial perspective. As will be readily understood by one of ordinary skill in the art, while three latching legs are illustrated, more or fewer latching legs may be used without departing from the scope of the present invention. For example, one, two, four, five, six, or more latching legs may be used. Catheter 104 may include cover tube 124 which may have a larger diameter than the remaining shaft of catheter 104. Cover tube 124 comprises a biocompatible material such as a biocompatible metal or polymer, and may be the same or different material than the remaining shaft of catheter 104. Components at distal end 102, such as latching legs 112, 114, and 116, may be at least partially disposed within cover tube 124. For example, the proximal ends of latching legs 112, 114, and 116 may be coupled to annular member 148 and cover tube 124 by laser welding.

[0069] Referring now to FIGS. 3A to 3D, the inner components at distal end 102 of apparatus 100 are illustrated. FIGS. 3A and 3B respectively illustrate distal end 102 in the engaged position of FIGS. 1A and 2A and the disengaged position of FIGS. 1B and 2B. As shown in FIG. 3A, catheter 104 and cover tube 124 comprise lumens 126 and 128, respectively, for housing the inner components. Latching legs 112 and 114 share common ramp portion 130 having inner section 132 and outer section 134 while latching leg 116 has separate ramp portion 136 having inner section 138 and outer section 140. Inner sections 132 and 138 are angled so as to be positioned closer to the central axis of catheter 104 and cover tube 124 relative to the positions of outer sections 134 and 140. Latching legs may also include jogs and protrusions. For example, latching leg 116 illustratively includes protrusion 142 proximal to ramp portion 136, and jog 144 between hook portion 122 and ramp portion 136. Protrusion 142 is configured to contact the distal surface of annular member 148 to maintain suitable positioning of latching leg 116. Jog 144 is shaped to prevent release ring 146 from moving too distally.

[0070] Release ring 146 is coupled to latching legs 112, 114, and 116. For example, latching legs 112, 114, and 116 may be partially disposed within release ring 146 as illustrated in FIGS. 3A to 3D. Release ring 146 is moveable within cover tube 124. Release ring 146 may be located in a first position, e.g., an engaged position, where release ring 146 contacts inner sections 132 and 138 of ramp portions 130 and 136 such that latching legs 112, 114, and 116 extend radially outward as shown in FIGS. 3A and 3C. Release ring 146 may be moved to a second position, e.g., a disengaged position, where release ring 146 contacts outer sections 134 and 140 of ramp portions 130 and 136 such that latching legs 112, 114, and 116 move radially inward as shown in FIGS. 3B and 3D. In one embodiment, release ring 146 is configured to move from the second position to the first position to load a device of the present invention and to move from the first position to the second position to release the device.

[0071] Annular member 148 may be partially disposed in the proximal end of cover tube 124 and configured to couple cover tube 124 to catheter 104 via a suitable coupling mechanism, e.g., teeth 150, ribs. Annular member 148 includes lumen 152 sized to accept pull-cord 154 therethrough.

[0072] Pull-cord 154 is coupled to release ring 146 and actuation of pull-cord 154 moves release ring 146 from the first position shown in FIG. 3A to the second position shown in FIG. 3B, and vice versa. In a preferred embodiment, pull-cord 154 is coupled to handle 108 such that pull-cord 154 is actuated by moving finger grips 110 from a locked position shown in FIG. 1A to an unlocked position shown in FIG. 1B, and vice versa.

[0073] Pull-cord 154 may be coupled to release ring 146 via release ring base 156. In this embodiment, release ring base 156 is directly coupled to release ring 146 and pull-cord 154 such that actuation of pull-cord 154 moves release ring base 156 to move release ring 146 from the first position the second position, and vice versa.

[0074] Spring 158 may be coupled to the proximal surface of release ring base 156 and the distal surface of annular member 148 such that release ring base 156 and annular member 148 maintain spring 158 therebetween. Spring 158 is configured to bias release ring 146 towards a particular position such as towards the first position as shown in FIG. 3A.

[0075] FIGS. 3A and 3C illustrate the components at distal end 102 in an engaged position, where FIG. 3C omits cover tube 124 for clarity. As pull-cord 154 is actuated, e.g., via handle 108, release ring 146 is moved, e.g., via release ring base 156, from the engaged position to the disengaged position shown in FIGS. 3B and 3D, where FIG. 3D omits cover tube 124 for clarity. Release ring 146 slides along ramp portions 130 and 136 from inner sections 132 and 138 to outer sections 134 and 140 such that latching legs 112, 114, and 116 move from being extended radially outward to being positioned radially inward. As release ring 146 moves from the engaged position to the disengaged position, spring 158 is compressed and as release ring 146 moves from the disengaged position to the engaged position, spring 158 is decompressed.

[0076] FIG. 4A illustrates the components at distal end 102 of apparatus 100 engaged to an exemplary device of the present invention and FIG. 4B illustrates the components disengaged from the exemplary device. Device 400 includes rings 402 and struts 404 and may be constructed similar to devices described in U.S. Pat. No. 9,629,715 to Nitzan, U.S. Pat. No. 9,713,696 to Yacoby, and U.S. Pat. No. 10,076,403 to Eigler, assigned to the assignee of the present invention, the entire contents of each of which are incorporated herein by reference. As shown in FIG. 4A, latching legs 112, 114, and 116 are sized, shaped, angled, and spaced apart from one another so as to engage device 400 in openings between rings 402 and struts 404 when device 400 is in a contracted, delivery state. Hook portions 118, 120, and 122 are sized, shaped, and angled to fit between rings 402 and struts 404. Hook portions 118, 120, 122 also hook outwardly away from the center axis at the distal end of the delivery apparatus. Accordingly, hook portions 118, 120, 122 may be disposed in the lumen of device 400 in the engaged position of FIG. 4A and engage device 400 from within the inner surface of device 400 such that hook portions 118, 120, 122 extend radially beyond the inner surface of device 400. For example, hook portions 118, 120, 122 may extend radially to the outer surface of device 400 or beyond the outer surface of device 400. As shown in FIG. 4B, latching legs 112, 114, and 116 are configured to move radially inward a sufficient distance to decouple hook portions 118, 120, and 122 from device 400 in the disengaged position, thereby releasing device 400 for implantation.

[0077] FIG. 5 is a flowchart of exemplary method 500 of delivering device 400 illustrated in FIGS. 4A and 4B to reduce left atrial pressure in a subject, for example, a human having CHF, using apparatus 100 illustrated in FIGS. 1A-1B. Some of the steps of method 500 may be further elaborated by referring to FIGS. 6A-6Q.

[0078] Referring to FIG. 5, first, a device and apparatus for delivering the device are provided (step 501). The device may be an hourglass-shaped device having a plurality of sinusoidal rings connected by longitudinally extending struts that define first and second flared end regions and a neck disposed therebetween, as well as an optional tissue valve coupled to the second flared end region.

[0079] Then, the device is collapsed radially to a contracted, delivery state and coupled to the delivery apparatus (step 502). For example, as illustrated in FIGS. 6A-6C, device 400 may be loaded into tapered loading tube 600 by first placing device 400 within wide diameter end 602 of loading tube 600 as shown in FIG. 6A. Then, using loading tool 604, device 400 is crimped down within loading tube 600. Loading tool 604 includes thin leg end 606 having two thin legs and wide leg end 608 having two wide legs. Device 400 may be pushed into loading tube 600 first by thin leg end 606 as illustrated in FIG. 6B and then pushed further into loading tube 600 by wide leg end 608 as illustrated in FIG. 6C. As will be understood by a person ordinarily skilled in the art, thin leg end 606 may have more than two thin legs, e.g., three, four, or more thin legs, and accordingly, wide leg end 608 may have more than two wide legs, e.g., three, four, or more wide legs.

[0080] In FIG. 6D, device 400 is disposed within thin diameter end 610 of loading tube 600. Thin diameter end 610 has a suitable internal diameter for contracting the device, e.g., approximately 14 Fr. Loading tube 600 includes tapered section 612 between wide diameter end 602 and thin diameter end 610. Tapered section 612 facilitates radial compression of device 400 into thin diameter end 610. Loading tube 600 is coupled to loading cartridge 614 via coupling section 616 having a suitable coupling mechanism, e.g., threads, ribs. Loading cartridge 614 may be transparent and has a suitable internal diameter, e.g., approximately 14 Fr.

[0081] Referring to FIG. 6E, device 400 is pushed into loading cartridge 614 using pusher 618. Pusher 618 has a suitable diameter, e.g., approximately 14 Fr., and may have a “star”-shaped end (not shown). In accordance with one aspect of the invention, the thin leg end of loading tool 604 is long enough to serve as pusher 618. Loading cartridge 614 is disconnected from loading tube 600 and connected to hemostasis valve section 620, which may be a Tuohy-Borst valve, as shown in FIG. 6F. Valve section 620 includes knob 622 and Y-connector 624. Distal end 102 of apparatus 100 is inserted through knob 622 of valve section 620. Knob 622 and Y-connector 624 are adjusted to permit movement of apparatus 100 while maintaining a seal to prevent fluid leakage, e.g., air leakage, blood leakage. The steps shown in FIGS. 6A-6F may be performed while device 400 is immersed in an anticoagulant such as heparinized saline.

[0082] FIGS. 6G and 6H illustrate coupling device 400 to apparatus 100 at distal end 102. Distal end 102 is advanced within loading cartridge 614 toward device 400. The components of distal end 102 may be in the disengaged position as illustrated in FIG. 6G. For example, the release ring at distal end 102 may contact an outer section of the ramp portions of the latching legs such that the latching legs are disposed radially inward. Next, distal end 102 is moved longitudinally toward device 400 and rotated to align the latching legs with suitable portions of device 400, e.g., at openings between struts and rings of device 400. Once suitable position is achieved, the components of distal end 102 may move to the engaged position as illustrated in FIG. 6H. For example, the release ring may be moved via a pull-cord and handle such that the release ring contacts an inner section of the ramp portions of the latching legs so the latching legs extend radially outward. In accordance with another aspect of the invention, the release ring may be moved via a PEEK tube as described in further detail below. A medical professional, e.g., a clinician, may verify that device 400 is engaged to apparatus 100 by slowing advancing and retracting apparatus 100 a distance, e.g., approximately 5 mm, while device 400 remains in loading cartridge 614. In addition, a clinician may verify that apparatus 100 is capable of disengaging from device 400 within loading cartridge 614 by pressing handle to cause the components at distal end 102 to disengage and then moving distal end 102 away from device 400. After such verification, the clinician may reengage apparatus 100 to device 400. Preferably, device 400 is loaded into loading cartridge 614 shortly before implantation, so as to avoid unnecessarily compressing device 400 or re-setting of the optional closed shape of leaflets, which may interfere with later deployment or operation of the device.

[0083] Referring back to FIG. 5, the device then is implanted, first by identifying the fossa ovalis of the heart septum, across which device 400 is to be deployed (step 503). Specifically, a trans-septal puncture device, e.g., a mechanical needle such as a BROCKENBROUGH needle or a radiofrequency trans-septal puncture device, may be percutaneously introduced into the right atrium via the subject's venous vasculature, for example, via the femoral artery. Then, under fluoroscopic and/or echocardiographic visualization, the needle is pressed against the fossa ovalis, at a pressure insufficient to puncture the fossa ovalis. The pressure from the needle causes “tenting” of the fossa ovalis, i.e., causes the fossa ovalis to stretch into the left atrium. Other portions of the atrial septum are thick and muscular, and so do not stretch to the same extent as the fossa ovalis. Thus, by visualizing the extent to which different portions of the atrial septum tents under pressure from the needle, the fossa ovalis may be identified, and in particular, the central portion of the fossa ovalis may be located.

[0084] The fossa ovalis (particularly its central region) may be punctured with the trans-septal puncture device, and a guidewire may be inserted through the puncture by threading the guidewire through the needle into the left atrium, and then removing the needle (step 504). The puncture through the fossa ovalis then may be expanded by advancing a dilator over the guidewire through the puncture (step 505). Alternatively, a dilator may be advanced over the trans-septal puncture device, without the need for a guidewire. The dilator is used to further dilate the puncture and a sheath then is advanced over the dilator and through the fossa ovalis; the dilator and guidewire or needle then are removed. The sheath, which may be 14 Fr., is then flushed.

[0085] Distal end 102 of apparatus 100, with device 400 coupled thereto in a contracted, delivery state, then is advanced into the sheath (step 506). For example, the delivery system may be flushed, e.g., via fluid connected to fluid tube 630, and then loading cartridge 614 may be coupled to sheath 626, e.g., via port 628, as illustrated in FIG. 6I. The clinician should verify that loading cartridge contains no air therein. In accordance with another aspect of the invention, a Tuohy Borst adapter having a Luer fitting may be used which allows for continuous flushing of the loading cartridge during connection of the loading cartridge to the hemostasis valve of the delivery sheath. Next, while holding sheath 626 in place, loading cartridge 614 is advanced distally within port 628 as illustrated in FIG. 6J. The device and delivery apparatus are advanced distally in sheath 626 until proximal end 106 of apparatus 100 is a predetermined distance X, e.g., approximately 1 cm, from knob 622 as illustrated in FIG. 6K. The delivery system again may be flushed, e.g., via fluid connected to fluid tube 630. The engagement of the latching legs of apparatus 100 with device 400 permit movement of device 400 longitudinally forward and longitudinally backward through sheath 626.

[0086] Then, under fluoroscopic and/or echocardiographic visualization, sheath 626 may be repositioned such that the distal tip of sheath 626 is disposed a predetermined distance, e.g., approximately 1-2 cm, distal to the fossa ovalis within the left atrium. Next, device 400 and apparatus 100 are advanced distally such that the device is partially advanced out of the sheath so the first flared end of the device protrudes out of the sheath and into the left atrium, and expands to its deployed state (step 507). For example, device 400 and apparatus 100 may be advanced distally until the handle at proximal end 106 contacts knob 622 as shown in FIG. 6L. In a preferred embodiment, the distance between proximal end 106 and distal end 102 of delivery device 100 is adjustable such that only the first flared end of shunt device 400 protrudes out of the sheath when the handle at proximal end 106 contacts knob 622. Such advancement causes device 400 to partially protrude out of sheath 626 and into left atrium LA, which causes the first flared end region to expand in the left atrium LA, as shown in FIG. 6M. The first flared end region of device 400 may protrude beyond the atrial septum AS into left atrium LA such that the angle θ between center axis 628 of device 400, sheath 626, apparatus 100, and/or catheter 104 and the outer surface of the atrial septum at the left atrial side below device 400 is generally perpendicular, e.g., between about 80 and about 100 degrees, between about 85 and about 95 degrees, or about 90 degrees, as shown in FIG. 6M. Alternatively, device 400 may be positioned across the atrial septum AS, e.g., across a puncture through the fossa ovalis, at a non-perpendicular angle between center axis 628 and the outer wall of the atrial septum at the left atrial side below device 400. For example, the angle θ′ may be substantially greater than 90 degrees as shown in FIG. 6N. Such an angle may be appropriate when device 400, sheath 626, apparatus 100, and/or catheter 104 are advanced toward the atrial septum transapically or through the inferior vena cava. Exemplary angles θ′ between center axis 628 and the outer surface of the atrial septum below device 400 include between about 110 and about 170 degrees, between about 120 and about 50 degrees, between about 130 and about 150 degrees about 120 degrees, about 125 degrees, about 130 degrees, about 135 degrees, about 140 degrees, about 145 degrees, about 150 degrees, about 155 degrees, about 160 degrees, about 165 degrees, and about 170 degrees.

[0087] As another example, the angle θ″ may be substantially less than 90 degrees as shown in FIG. 6O. Such an angle may be appropriate when device 400, sheath 626, apparatus 100, and/or catheter 104 are advanced toward the atrial septum through the superior vena cava. Exemplary angles θ″ between center axis 628 and the outer surface of the atrial septum at the left atrial side below device 400 include between about 10 and about 70 degrees, between about 20 and about 60 degrees, between about 30 and about 50 degrees, about 10 degrees, about 15 degrees, about 20 degrees, about 25 degrees, about 30 degrees, about 35 degrees, about 40 degrees, about 45 degrees, about 50 degrees, about 55 degrees, about 60 degrees, about 65 degrees, and about 70 degrees.

[0088] An hourglass shape may aid in non-perpendicular deployment because the flared ends of the device engage the atrial septum, even when positioned at an angle relative to the central axis of the puncture through the atrial septum.

[0089] Next, under fluoroscopic and/or echocardiographic visualization, it is verified that the first flared end of the device protrudes from sheath 626 and then knob 622 of Tuohy-Borst connector 620 is used to lock the delivery system in place within the sheath 626. Sheath 626, along with the delivery system 100 are pulled proximally causing the first flared end region of device 400 to engage the left side of the atrial septum AS as shown in FIG. 6M. For example, as the latching legs of apparatus 100 are engaged with device 400 within sheath 626, device 400 is prevented from accidental deployment wholly within the left atrium LA, which may also assist in positioning the device when advanced at non-perpendicular angles as described in FIGS. 6N and 60.

[0090] Using fluoroscopic and/or echocardiographic visualization, the clinician next verifies that the device is positioned across the fossa ovalis. The clinician then reduces the pulling force of the sheath and allows the fossa ovalis to straighten. Then, while holding sheath 626 in place, knob 622 is released and the components at distal end 102 of apparatus 100 are moved from an engaged position to a disengaged position, e.g., by actuating handle 108 as shown in FIG. 6P. Then, apparatus 100 is pulled proximally with the sheath 626 a predetermined distance, e.g., approximately 5-6 cm.

[0091] The shunt device then may be fully deployed by pulling the sheath proximally causing the first flared end region to engage the left side of the atrial septum and the neck of the device to lodge in the puncture through the fossa ovalis, and allowing expansion of the second flared end of the device into the right atrium as shown in FIG. 6Q (step 508). Any remaining components of the delivery system then may be removed, e.g., sheath and distal end of delivery apparatus (step 509). Once positioned in the fossa ovalis, the device shunts blood from the left atrium to the right atrium when the left atrial pressure exceeds the right atrial pressure (step 510), thus facilitating treatment and/or the amelioration of symptoms associated with CHF.

[0092] Referring to FIGS. 7A and 7B, an alternative exemplary apparatus is provided for delivering interatrial shunt devices, e.g., device 400 of FIGS. 4A and 4B, and/or devices described in U.S. Pat. No. 9,629,715 to Nitzan, U.S. Pat. No. 9,713,696 to Yacoby, and U.S. Pat. No. 10,076,403 to Eigler. Apparatus 700 includes distal end 702, catheter 704, proximal end 706, and knob system 703. Distal end 702 comprises components suitable for coupling apparatus 700 to devices of the present invention, as described in detail below. Catheter 704 comprises a biocompatible tube shaft of suitable size, e.g., approximately 14 Fr., and suitable length, e.g., approximately 75-100 cm and preferably 85 cm. Proximal end 706 includes handle 708 that is designed to be manipulated, e.g., by a human hand, to transition components in distal end 702 from an engaged position to a disengaged position. In addition, apparatus 700 includes Luer connector 705 in communication with control tube 707 extending from proximal end 706 to distal end 702 of apparatus 100. For example, control tube 707 may extend through catheter 704 and through handle 708 for over-the-wire flushing, e.g., via a Tuohy Borst adapter connected to apparatus 700. Control tube 707 has a lumen extending therethrough sized to receive a guidewire.

[0093] Like handle 108, handle 708 may be manipulated, for example, by moving finger grips 710 proximally from a locked position shown to an unlocked position. In addition, handle 708 may be manipulated by moving finger grips 710 distally from the locked position to the unlocked position so as to transition components in distal end 702 from the disengaged position to the engaged position to load devices of the present invention. Handle 708 also may include securement mechanism 709 coupled to handle safety lock 711 such that finger grips 710 cannot be moved until handle safety lock 711 is released. Upon activation, handle 708 is retained in position, enabling a single user to perform the procedure.

[0094] FIGS. 8A and 8B illustrate distal end 702 in the engaged position and the disengaged position, respectively. At distal end 702, apparatus 700 may include latching legs 712, 714, and 716 having hook portions 718, 720, and 722, respectively. Latching legs 712, 714, and 716 comprise a biocompatible material such as a biocompatible metal or polymer, and are positioned longitudinally and radially so as to firmly secure devices of the present invention for delivery. Hook portions 718, 720, and 722 extend outwardly from the distal end of latching legs 712, 714, and 716, respectively, and are configured to fit securely between struts and rings of the devices of the present invention. Preferably, hook portions 718, 720, and 722 hook outwardly away from center axis 723 of catheter 704 in both the engaged and disengaged positions as shown in FIGS. 8A and 8B. Center axis 723 is centered relative to catheter 704 on both a longitudinal and cross-sectional basis. By facing outwardly from center axis 723, hook portions 718, 720, and 722 may engage the inner surface of the device, e.g., within a lumen of a shunt.

[0095] In one embodiment, hook portions 718, 720, and 722 move generally radially away from center axis 723. The angle between the lower surface of the hook portion and the longitudinal axis of the latching leg is preferably less than 90 degrees and greater than 75 degrees, e.g., 87 degrees, as shown in FIG. 8C to enable a more secure engagement with the shunt. For example, an angle less than 75 degrees could result in failure to disengage the shunt from the delivery device after deployment, whereas an angle greater than 90 degrees could result in failure to achieve half-way retrieval of the shunt by the delivery device. Such improved engagement allows the delivery device to pull the distal flange of a half-deployed shunt back into the sheath (“halfway-retrieval”) in the event the shunt's distal flange is deployed in an undesired location. As will be readily understood by one of ordinary skill in the art, while three latching legs are illustrated, more or fewer latching legs may be used without departing from the scope of the present invention. For example, one, two, four, five, six, or more latching legs may be used.

[0096] Catheter 704 may include cover tube 724 which may have a larger diameter than the remaining shaft of catheter 704. Cover tube 724 comprises a biocompatible material such as a biocompatible metal or polymer, and may be the same or different material than the remaining shaft of catheter 704. Components at distal end 702, such as latching legs 712, 714, and 716, may be at least partially disposed within cover tube 724. Referring back to FIGS. 8A and 8B, distal end 702 includes control tube 707, e.g., a polyether ether ketone (PEEK) tube, having a lumen extending therethrough sized to receive a guidewire, as described in more detail below. Control tube 707 is moveable between an engaged position, where the distal end of control tube 707 extends past the distal end of cover tube 724 as shown in FIG. 8A, and a disengaged position, where the distal end of control tube 707 is moved proximally, but still extends past the distal end of cover tube 724 as shown in FIG. 8B.

[0097] Referring now to FIGS. 9A to 9D, the inner components at distal end 702 of apparatus 700 are described. FIGS. 9A and 9B respectively illustrate distal end 702 in the engaged position of FIG. 8A and the disengaged position of FIG. 8B, respectively. As shown in FIG. 9A, catheter 704 and cover tube 724 comprise lumens 726 and 728, respectively, for housing the inner components. Latching legs 712 and 714 share common ramp portion 730 having inner section 732 and outer section 734 while latching leg 716 has separate ramp portion 736 having inner section 738 and outer section 740. Inner sections 732 and 738 are angled so as to be positioned closer to central axis 723 of catheter 704 and cover tube 724 relative to the positions of outer sections 734 and 740. Latching legs may also include jogs and protrusions. For example, latching leg 716 illustratively includes protrusion 742 proximal to ramp portion 736, and jog 744 between hook portion 722 and ramp portion 736. Protrusion 742 is configured to contact the distal surface of annular member 748 to maintain suitable positioning of latching leg 716. Jog 744 is shaped to prevent release ring 746 from moving too far distally.

[0098] Release ring 746 is coupled to latching legs 712, 714, and 716. For example, latching legs 712, 714, and 716 may be partially disposed within release ring 746 as illustrated in FIGS. 9A to 9D. Release ring 746 is moveable within cover tube 724. Release ring 746 may be located in a first position, e.g., an engaged position, where release ring 746 contacts inner sections 732 and 738 of ramp portions 730 and 736 such that latching legs 712, 714, and 716 extend radially outward as shown in FIGS. 9A and 9C. Release ring 746 may be moved to a second position, e.g., a disengaged position, where release ring 746 contacts outer sections 734 and 740 of ramp portions 730 and 736 such that latching legs 712, 714, and 716 move radially inward as shown in FIGS. 9B and 9D. In one embodiment, release ring 746 is configured to move from the second position to the first position to load a device of the present invention and to move from the first position to the second position to release the device.

[0099] Annular member 748 may be partially disposed in the proximal end of cover tube 724 and configured to couple cover tube 724 to catheter 704 via a suitable coupling mechanism, e.g., teeth 750, ribs. Annular member 748 includes lumen 752 sized to accept control tube 707 therethrough.

[0100] Control tube 707 is coupled to release ring 746 and actuation of control tube 707 moves release ring 746 from the first position shown in FIG. 9A to the second position shown in FIG. 9B, and vice versa. In a preferred embodiment, control tube 707 is coupled to handle 708 such that control tube 707 is actuated by moving finger grips 710 from a locked position to an unlocked position, and vice versa. In addition, control tube 707 includes lumen 755 extending therethrough sized to receive a guidewire such that distal end 702 of apparatus 700 may be advanced over a guidewire to the desired device deployment location. The over-the-wire capability enables safe retrieval of a fully embolized device.

[0101] Control tube 707 may be coupled to release ring 746 via release ring base 756. In this embodiment, release ring base 756 is directly coupled to release ring 746 and control tube 707 such that actuation of control tube 707 moves release ring base 756 to move release ring 746 from the first position the second position, and vice versa.

[0102] Spring 758 may be coupled to the proximal surface of release ring base 756 and the distal surface of annular member 748 such that release ring base 756 and annular member 748 maintain spring 758 therebetween. Spring 758 is configured to bias release ring 746 towards a particular position such as towards the first position as shown in FIG. 9A.

[0103] FIGS. 9A and 9C illustrate the components at distal end 702 in an engaged position, where FIG. 9C omits cover tube 724 for clarity. As control tube 707 is actuated, e.g., via handle 708, release ring 746 is moved, e.g., via release ring base 756, from the engaged position to the disengaged position shown in FIGS. 9B and 9D, where FIG. 9D omits cover tube 724 for clarity. Release ring 746 slides along ramp portions 730 and 736 from inner sections 732 and 738 to outer sections 734 and 740 such that latching legs 712, 714, and 716 move from being extended radially outward to being positioned radially inward. As release ring 746 moves from the engaged position to the disengaged position, spring 758 is compressed and as release ring 746 moves from the disengaged position to the engaged position, spring 758 is decompressed.

[0104] FIG. 10A illustrates the components at distal end 702 of apparatus 700 engaged to an exemplary interatrial shunt device and FIG. 10B illustrates the components disengaged from the exemplary device. Device 400 includes rings 402 and struts 404 and may be constructed similar to devices described in U.S. Pat. No. 9,629,715 to Nitzan, U.S. Pat. No. 9,713,696 to Yacoby, and U.S. Pat. No. 10,076,403 to Eigler. As shown in FIG. 10A, latching legs 712, 714, and 716 are sized, shaped, angled, and spaced apart from one another so as to engage device 400 in openings between rings 402 and struts 404 when device 400 is in a contracted, delivery state. Hook portions 718, 720, and 722 also are sized, shaped, and angled to fit between rings 402 and struts 404 and hook portions 718, 720, 722 hook outwardly away from the center axis at the distal end of the delivery apparatus such that hook portions 718, 720, 722 are disposed in the lumen of device 400 in the engaged position of FIG. 10A and engage at the inner surface of device 400. Preferably, hook portions 718, 720, and 722 move radially away from center axis 723 at an angle less than 90 degrees, e.g., 87 degrees, toward proximal end 706 of apparatus 700 as shown in FIG. 8C to enable halfway retrieval of a partially deployed device. As shown in FIG. 10B, latching legs 712, 714, and 716 are configured to move radially inward a sufficient distance to decouple hook portions 718, 720, and 722 from device 400 in the disengaged position, thereby releasing device 400 for implantation.

[0105] FIG. 11 is a flowchart of exemplary method 1100 of delivering device 400 to reduce left atrial pressure in a subject, for example, a human having a heart condition, using apparatus 700 illustrated in FIGS. 7A and 7B. Steps 1101-1104 are similar to steps 501-504 described in FIG. 5, except that apparatus 700 is used instead of apparatus 100, and for brevity are not discussed again here. At step 1105, a dilator having a guidewire lumen sized and shaped to receive the guidewire therethrough is advanced over the guidewire across the atrial septum through the fossa ovalis into the left atrium. A sheath is then advanced over the dilator across the atrial septum through the fossa ovalis into the left atrium. The dilator is then removed. In accordance with another aspect of the present invention, a sheath having a dilator disposed therein may be advanced together over the guidewire across the atrial septum through the fossa ovalis into the left atrium.

[0106] At step 1106, distal end 702 of apparatus 700, with device 400 coupled thereto, is advanced through the sheath over the guidewire until proximal end 706 of apparatus 700 is a predetermined distance from the proximal end of the sheath such that distal end 702 of apparatus 700 is a predetermined distance from the distal end of the sheath. The guidewire is received from the Luer connector 705 via lumen 755 of control tube 707. Steps 1107-1110 are similar to steps 507-510 described in FIG. 5, except that apparatus 700 is used instead of apparatus 100 and the guidewire may be removed through Luer connector 705 at step 1109, and for brevity are not described again herein. Thus, for example, the components at distal end 702 of apparatus 700, e.g., latching legs 712, 714, and 716, are moved from an engaged position to a disengaged position, e.g., by actuating the handle at proximal end 706 to decouple hook portions 718, 720, and 722 from device 400 in the disengaged position, before the sheath is retracted to deploy device 400 within the atrial septum.

[0107] In accordance with another aspect of the present invention, knob system 703 may be used for length adjustment of apparatus 700 relative to the sheath during deployment of device 400 at the atrial septum, e.g., to assist in halfway retrieval of device 400. For example, referring now to FIGS. 12A-12C, knob system 703 includes proximal knob 1202, distal knob 1204, and optional lock nut 1206. Referring to FIG. 12A, proximal knob 1202 may be pulled proximally to enable rotating distal knob 1204 clockwise to assist in “halfway retrieval” of device 400 as described here. Distal knob 1204 is rotatable to shorten the distance between the knob 1204 and the distal end 702 of apparatus 700, thus pulling distal end 702 proximally within the sheath. For example, in the event that the first flared end region of device 400 is deployed and the second flared end region is still in a collapsed state within the sheath and coupled to distal end 702 of apparatus 700, distal knob 1204 may be rotated clockwise to retract distal end 702, and thus device 400, within the sheath. As distal end 702 is retracted within the sheath, device 400 is also retracted, thus causing the first flared end region to collapse into the sheath.

[0108] Referring now to FIGS. 12B and 12C, lock nut 1206 is moveable between an open and closed position to permit retraction of proximal knob 1202, and thereby rotation of distal knob 1204. Referring to FIG. 12B, lock nut 1206 is in an open position such that proximal knob 1202 may be pulled proximally and distal knob 1204 may be rotated to the adjust the length of catheter 704 relative to the length of the sheath. When the length of catheter 704 relative to the length of the sheath is at the desired amount, lock nut 1206 may be moved to the closed position as shown in FIG. 12C to fix the set length.

[0109] Referring to FIG. 13A, an alternative distal end of an apparatus for delivering devices of the present invention is provided. Distal end 1302 is constructed similar to distal end 102 described in FIGS. 2A to 3D, or distal end 702 described in FIGS. 8A to 9D, except that distal end 1302 includes tube 1304 extending distally from cover tube 1306. Thus, distal end 1302 includes hook portions 1308 and 1310 that move away from a center axis of the catheter as described above, and tube 1304 includes windows 1312 and 1314 sized for hook portions 1308 and 1310 to protrude through in the engaged position as described in FIGS. 2A, 3A, 3C, 8A, 9A, and 9C to engage device 400 in a collapsed state within sheath 1316. As shown in FIG. 13A, when hook portions 1308 and 1310 are in the disengaged position as described in FIGS. 2B, 3B, 3D, 8B, 9B, and 9D, hook portions 1308 and 1310 do not extend beyond the diameter of tube 1304 which prevents the risk of entanglement. As will be readily understood by one of ordinary skill in the art, while two latching legs are illustrated, more or fewer latching legs may be used without departing from the scope of the present invention. For example, one, three, four, five, six, or more latching legs may be used, and accordingly, tube 1304 may include a corresponding number of windows.

[0110] Referring to FIGS. 13B-13D, an alternative distal end of an apparatus for delivering devices of the present invention is provided. Distal end 1301 is constructed similar to distal end 1302 described in FIG. 13A, and accordingly, distal end 102 described in FIGS. 2A to 3D and/or distal end 702 described in FIGS. 8A to 9D, except that instead of tube 1304, distal end 1301 includes cap 1303 extending distally from cover tube 1305. Thus, distal end 1301 includes one or more hook portions 1307 that move away from a center axis of the catheter as described above, and cap 1303 includes one or more windows 1309 sized for hook portions 1307 to protrude through in the engaged position as described above to engage device 400 in a collapsed state within the sheath. Cap 1303 has a rounded surface and is sized and shaped such that when hooks portions 1307 are retracted, cap 1303 prevents the shunt from being dragged inward along with hooks portions 1307, insuring that the shunt is released. As will be understood by a person having ordinary skill in the art, tube 1304 and cap 1303 may be two separate components coupled together or may be formed as a single unitary component.

[0111] As described above with regard to, e.g., distal end 102 of FIGS. 2A to 3D, hook portions 1307 is coupled to ramp portion 1311 that interacts with release ring 1313 to cause hook portions 1307 to move radially inward/outward responsive to the longitudinal position of release ring 1313 relative to ramp portion 1311. For example, as shown in FIGS. 13C and 13D, release ring 1313 is positioned along ramp portion 1311 such that hook portions 1307 protrudes out through windows 1309 of cap 1303. As shown in FIG. 13D, the inner surface of cover tube 1305 may include ridge 1317 sized and shaped to prevent release ring 1313 from moving too far distally within cover tube 1305. Moreover, spring 1317 may cause release ring 1313 to be pushed against ridge 1317, thereby biasing hook portions 1307 in the engaged positioned, unless actuated by the user.

[0112] For example, to engage hook portions 1307 from the shunt device, release ring 1313 may be moved proximally via pull-chord 1315. As release ring 1313 slides proximally along ramp portion 1311, hook portions 1317 move radially inward toward the central axis of the catheter within window 1309, to thereby disengage with the shunt device without dragging the shunt device inward and insure that the shunt device is released.

[0113] Referring to FIG. 14, an alternative exemplary apparatus is provided for delivering interatrial shunt devices, e.g., device 400 of FIG. 4A, 4B or 6Q, and/or devices described in U.S. Pat. No. 9,629,715 to Nitzan, U.S. Pat. No. 9,713,696 to Yacoby, and U.S. Pat. No. 10,076,403 to Eigler. Apparatus 1400 includes distal end 1402, catheter 1404, and proximal end 1406 having handle 1408 for actuating distal end 1402. Distal end 1402 is sized and shaped to be advanced through sheath 1410, which is sized to extend between distal end 1402 and proximal end 1406 over catheter 1404. Apparatus 1400 may include inner catheter 1411 extending from distal end 1402 through catheter 1404 and through proximal end 1406, e.g., past the proximal most part as shown. Inner catheter 1411 has a lumen sized to receive a guidewire therethrough.

[0114] Exemplary method 1500 of delivering device 400 to reduce left atrial pressure in a subject, for example, a human having a heart pathology, using apparatus 1400 illustrated in FIG. 14 will now be described with reference to FIG. 15. Some of the steps of method 1500 may be further elaborated by referring to FIGS. 16A-16T. Steps 1501-1507 are similar to steps 1101-1107 described in FIG. 11, except that apparatus 1400 is used instead of apparatus 700, and thus for brevity these steps are not discussed again here. FIG. 16A is a perspective view of proximal end 1406 of apparatus 1400 and FIG. 16B is a partial cross-sectional view illustrating internal components. FIGS. 16A and 16B illustrate handle 1408 at proximal end 1406 of apparatus 1400 when distal end 1402 having device 400 coupled thereto, and catheter 1404 are advanced over the guidewire and through sheath 1410 across the fossa ovalis (step 1506). Handle 1408 includes first actuator 1422, second actuator 1423, and third actuator 1424 for actuating the components within the distal region of sheath 1410 such that the shunt transitions between a contracted delivery state, to a partially expanded state, and then to a fully expanded deployed state. First, second, and third actuators 1422, 1423, and 1424 may be buttons, switches, levers, touchscreens, or the like. First, second, and third actuators 1422, 1423, and 1424 may be combined into a single component, two components, or may be more than three components.

[0115] In addition, handle 1408 includes knob 1401. The inner components of knob 1401 includes a threaded portion that corresponds with a threaded portion coupled to sheath 1410. Accordingly, as knob 1401 is rotated about the longitudinal axis of handle 1408, rotational movement of knob 1401 is converted to translational movement of the threaded portion coupled to sheath 1410 along the longitudinal axis of handle 1408, thereby causing movement of sheath 1410 relative to catheter 1404. This permits gradual adjustment of the length of sheath 1410 relative to catheter 1404, and accordingly halfway-retrieval of device 400 when device is halfway deployed as will be described in further detail below. Knob 1401 may not be rotated until third actuator 1424 is moved from a locked position to an unlocked position.

[0116] As illustrated in FIG. 16B, third actuator 1424 may be coupled to third actuator component 1413 rotatable about the longitudinal axis of handle 1408, parallel to inner catheter 1411, between a first, second, and third position. For example, FIGS. 16A and 16B illustrate third actuator 1424 in the first position, such that third actuator 1424 is centered within opening 1433 of the housing of handle 1408. Third actuator component 1413 may include a toothed pattern along its proximal end for engaging with a corresponding indent along the distal end of actuator ring 1415, wherein actuator ring 1415 is freely rotatable about the longitudinal axis of handle 1408. As shown in FIG. 16B, there is a defined space between an edge of the tooth of third actuator component 1413 and an edge of the indent of actuator ring 1415 when third actuator 1424 is in the first position. When third actuator 1424 is moved to the third position, such that third actuator component 1413 is rotated, e.g., clockwise, about the longitudinal axis of handle 1408, the edge of the tooth of third actuator component 1413 engages with the edge of the indent of actuator ring 1415. This prevents actuator ring 1415 from rotating in an opposite direction, e.g., counter-clockwise, about the longitudinal axis of handle 1408. Thus, second actuator 1423 and second actuator component 1417 are also prevented from moving distally within opening 1435 along the longitudinal axis of handle 1408.

[0117] When third actuator 1424 is moved to the second position, such that third actuator component 1413 is rotated, e.g., counter-clockwise, about the longitudinal axis of handle 1408, the space between the edge of the tooth of third actuator component 1413 and the edge of the indent of actuator ring 1415 increases such that actuator ring 1415 is free to rotate in the same direction, e.g., counter-clockwise until the edge of the indent of actuator ring 1415 engages with the edge of the tooth of third actuator component 1413. In addition, third actuator component 1413 is operatively coupled to a locking mechanism between inner catheter 1411 and a hub disposed within the distal region of sheath 1410 as described in further detail below.

[0118] Actuator ring 1415 also may include a grooved pattern along its proximal end for engaging with a corresponding indent along the distal end of second actuator component 1417 coupled to second actuator 1423. Accordingly, the edge of the tooth of third actuator component 1413 may further engage with the indent of actuator ring 1415, to thereby rotate actuator ring 1415 until the groove of actuator ring 1415 engages with the indent of second actuator component 1417. Second actuator 1423 may be moveable between a first and second position. For example, FIGS. 16A and 16B illustrate second actuator 1423 in the first position, such that first actuator 1423 is positioned proximally relative to opening 1435 of the housing of handle 1408. Third actuator component 1413, actuator ring 1415, and second actuator component 1423 include a lumen sized and shaped to receive first actuator component 1419 coupled to first actuator 1422. In addition, the lumens of third actuator component 1413 and actuator ring 1415 are sized and shaped to permit rotation about first actuator component 1419, whereas the lumen of second actuator component 1417 may be sized and shaped such that second actuator component 1417 is only permitted to move longitudinally along first actuator component 1419.

[0119] First actuator component 1419 is moveable along the longitudinal axis of handle 1408, parallel to inner catheter 1411, between a first and second position. For example, FIGS. 16A and 16B illustrate first actuator 1422 in the first position, such that first actuator 1422 is positioned distally relative to opening 1437 of the housing of handle 1408. As illustrated in FIG. 16B, first actuator component 1419 may include one or more lumens 1421 sized and shaped to receive one or more guiderails 1431, such that first actuator component 1419 is moveable between the first and second positions along guiderails 1431. One or more guiderails 1413 are coupled at one end to second actuator component 1417, and coupled at an opposite end to pusher plate 1440 disposed at the proximal end of handle 1408, wherein pusher plate 1440 is fixedly coupled to a proximal portion of inner catheter 1411. Accordingly, movement of second actuator component 1417 from the first position to the second position causes pusher plate to move distally within the housing of handle 1408 via guiderails 1413, thereby causing inner catheter 1411 to move distally within the distal region of sheath 1410.

[0120] First actuator component 1419 includes a lumen sized and shaped to receive centering element 1429, wherein centering element 1429 is fixed relative to handle 1408. First actuator 1422 is further coupled to proximal portion 1427 sized and shaped to move within a lumen of centering element 1429. Proximal portion 1427 includes a lumen sized and shaped to receive inner catheter 1411, such that proximal portion 1427 is moveable between the first and second positions along inner catheter 1411. First actuator 1422 may be moveably coupled to inner catheter 1411 via proximal portion 1427, and may include port 1425 for coupling to a fluid source to introduce fluid into the guidewire lumen of inner catheter 1411 for flushing. In addition, first actuator component 1419 is coupled to sheath 1410 for extending and retracting the distal end of sheath 1410 as described in further detail below.

[0121] FIG. 16C illustrates distal end 1402 having device 400 coupled thereto in a collapsed state and catheter 1404 disposed within the distal portion of sheath 1410 (shown in cross-section for clarity), e.g., in a position suitable for percutaneous delivery to the left atrium of the patient. Distal end 1402 includes hub 1412 disposed distal to the distal end of catheter 1404. Hub 1412 may have engagement portion 1428 disposed distal to ring portion 1426, and a proximal portion that is moveably disposed within a cavity of catheter 1404 as described in further detail below. Ring portion 1426 has a diameter that is equal to or slightly less than the diameter of the inner wall of sheath 1410 such that hub 1412 may move backwards and forwards within sheath 1410. Engagement portion 1428 of hub 1412 has a diameter less than that of ring portion 1426, such that device 400 may fit between the outer surface of engagement portion 1428 and sheath 1410 when device 400 is in a collapsed, delivery state. Engagement portion 1428 may have a cylindrical shape and a curved distal end as shown. Hub 1412 is moveable relative to catheter 1404 within sheath 1410 along an inner catheter disposed within a lumen extending through hub 1412 and catheter 1404 as described in further detail below. Hub 1412 is releaseably coupled to the distal end of catheter 1404 via a locking mechanism operatively coupled to third actuator 1424, such that actuation of third actuator 1424 from the first position to the second position causes the locking mechanism to unlock, thereby decoupling hub 1412 from catheter 1404.

[0122] In addition, hub 1412 includes one or more engagers, e.g., protrusions 1414 and 1416, extending radially outward from a central axis of catheter 1404, such that the one or more engagers are disposed circumferentially about the outer surface of hub 1412, e.g., at engagement portion 1428, and are configured to fit securely between struts and rings of the interatrial devices for delivery. Thus, each of the one or more engagers may be sized to engage device 400 in openings between rings 402 and struts 404 when device 400 is in a contracted, delivery state. For example, the distance from the central axis of hub 1412 to the outermost surface of each of the one or more engagers is equal to or slightly less than the inner radius of sheath 1410 so that hub 1412 may be moveable within sheath 1410. The distance from the central axis of hub 1412 to the outermost surface of each of the one or more engagers may be equal to the distance from the central axis of hub 1412 to the outer surface of ring portion 1426. Accordingly, device 400 may be constrained between the one or more engagers and ring portion 1426, and between engagement portion 1428 and sheath 1410 in order to prevent dislodgement or early deployment of device 400 within sheath 1410. As shown in FIG. 16C, protrusions 1414 and 1416 engage device 400 in openings between rings 402 and struts 404 such that device 400 is constrained between hub 1412 and the inner wall of sheath 1410 in a contracted, delivery state. As will be readily understood by one of ordinary skill in the art, while two engagers are illustrated, more or fewer engagers may be used without departing from the scope of the present invention. For example, one, three, four, five, six, seven, eight, or more engagers may be used.

[0123] FIG. 16D is a partial cross-sectional schematic of the delivery apparatus within the sheath during step 1506, wherein the delivery apparatus is coupled to device 400, and FIG. 16E illustrates the delivery apparatus of FIG. 16D with device 400 omitted for clarity. As shown in FIG. 16D, the distal end of sheath 1410, with the delivery apparatus disposed therein, is advanced across the atrial septum AS. Protrusions 1414 and 1416 fit securely between struts and rings of device 400 such that device 400 is constrained between protrusions 1414 and 1416 and ring portion 1426, and between engagement portion 1428 and sheath 1410. As shown in FIG. 16E, hub 1412 is adjacent to catheter 1404 such that proximal portion 1432 of hub 1412 is disposed within cavity 1436 of catheter 1404. Cavity 1436 is sized and shaped to receive proximal portion 1432 of hub 1412 a predetermined distance. Cavity 1436 has a larger outer diameter than the outer diameter for the lumen in catheter 1404 that receives inner catheter 1411. Proximal portion 1432 is coupled to ring portion 1426 via connector 1434. Hub 1412 may be releaseably coupled to catheter 1404 via a locking mechanism for engaging catheter 1404 to at least one of ring portion 1426 or proximal portion 1432.

[0124] In addition, inner catheter 1411 is disposed within a central lumen extending through hub 1412 and catheter 1404. Inner catheter 1411 may include a stop, e.g., lock ring 1438, fixed at a distal end of inner catheter 1411, wherein lock ring 1438 is sized and shaped to be disposed within cavity 1430 of hub 1412. Cavity 1430 may extend through at least a portion of engagement portion 1428 of hub 1412, or completely through engagement portion 1428 of hub 1412 and at least a portion of ring portion 1426 of hub 1412. Lock ring 1438 ensures that hub 1412 does not extend beyond a predetermined distance distally along inner catheter 1411, and that inner catheter 1411 does not retract beyond the predetermined distance proximally relative to hub 1412. Inner catheter 1411 also may include guidewire lumen 1425 sized and shaped to receive a guidewire therethrough. For example, delivery apparatus 1400 may be advanced over a guidewire such that the distal end of sheath 1410 having distal end 1402 coupled to device 400 disposed therein, is positioned across the fossa ovalis.

[0125] Referring now to FIGS. 16F and 16G, first actuator 1422 is then moved from a first initial position to a second position within opening 1437 of the housing of handle 1408, which causes distal end 1402 including inner catheter 1411 and hub 1412 having device 400 coupled thereto, and catheter 1404 to move relative to sheath 1410. As illustrated in FIG. 16G, movement of first actuator 1422 causes first actuator component 1419 to move from the first initial position to the second position through the lumens of second actuator component 1417, actuator ring 1415, and third actuator component 1413 along guiderail 1431, and proximal portion 1427 to move from the first initial position to the second position along inner catheter 1411 within centering element 1429. Specifically, movement of first actuator 1424 from the first initial position to the second position causes first actuator component 1419 operatively coupled to sheath 1410 to move sheath 1410 relative to catheter 1404, hub 1412, and inner catheter 1411, thereby exposing first flared end region 401 of device 400 beyond the distal end of sheath 1410 such that first flared end region 401 expands to its deployed state in the left atrium as shown in FIG. 16H (step 1507). According to one aspect of the invention, actuation of first actuator 1422 may cause catheter 1404, hub 1412, and inner catheter 1411 to be advanced distally while sheath 1410 remains stationary with respect to atrial septum AS.

[0126] FIG. 16I is a cross-sectional schematic of the delivery apparatus within the sheath during step 1507, wherein device 400 is partially deployed, and FIG. 16J illustrates the delivery apparatus of FIG. 16I with device 400 omitted for clarity. As shown in FIG. 16I, first flared end region 401 of device 400 is deployed in the left atrium of the patient a predetermined distance from the atrial septum AS. Referring to FIG. 16J, the delivery apparatus, e.g., hub 1412 and catheter 1404 moves distally within sheath 1410 relative to sheath 1410, such that first flared end region 401 extends beyond the distal end of sheath 1410 and transitions from a collapsed, delivery state to an expanded, deployed state within the left atrium, while the second flared end of device 400 remains in a collapsed, delivery state within the distal end of sheath 1410.

[0127] Referring now to FIGS. 16K and 16L, second actuator 1423 may then be moved from the first initial position to the second position which causes second actuator component 1417 to move distally along first actuator component 1419 within the housing of handle 1408. As second actuator component 1417 moves distally along first actuator component 1419, the distal edge of second actuator component 1417 interacts with the groove of actuator ring 1415, thereby causing actuator ring 1415 to rotate until the indent of actuator ring 1415 engages with the edge of the tooth of third actuator component 1413. In addition, movement of second actuator component 1417 from the first initial position to the second position causes inner catheter 1411 to move distally relative to hub 1412, catheter 1404, and sheath 1410 via guiderails 1431 and pusher plate 1440 as illustrated in FIG. 16M. Accordingly, the delivery apparatus, e.g., sheath 1410, inner catheter 1411, catheter 1404, and hub 1412 coupled to device 400, may be pulled proximally until first flared end region 401 engages the atrial septum from within the left atrium (step 1508).

[0128] FIG. 16N is a cross-sectional schematic of the delivery apparatus within the sheath during step 1508, wherein inner catheter 1411 has been moved distally relative to sheath 1410, hub 1412, and catheter 1404 such that lock ring 1438 is no longer disposed within cavity 1430 of engagement portion 1428 of hub 1412, and the delivery apparatus is pulled proximally until first flared end region 401 engages the left side of atrial septum AS. FIG. 16O illustrates the delivery apparatus of FIG. 16N with device 400 omitted for clarity. Specifically, FIG. 16O illustrates sheath 1410, hub 1412, inner catheter 1411, and catheter 1404 pulled proximally with respect to atrial septum AS. Using fluoroscopic or echocardiographic visualization, the clinician next verifies that the device is positioned across the fossa ovalis. The clinician then reduces the pulling force of sheath 1410, catheter 1404, and hub 1412, and allows the fossa ovalis to straighten. In accordance with one aspect of the present invention, the physician may reduce and/or stop the pulling force of the delivery apparatus upon force feedback provided by the atrial septum against the delivery apparatus, which indicates that device 400 is properly positioned within the opening of the atrial septum. This may prevent accidentally deploying the entire device in the left atrium and may assist in positioning the device when advanced at non-perpendicular angles.

[0129] Referring back to FIG. 16L, third actuator 1424 may then be moved from the first initial position to the second position, which causes third actuator component 1413 to rotate about first actuator component 1419. The engagement between the tooth of third actuator component 1413 and the indent of actuator ring 1415 allows rotation of third actuator component 1413 to rotate actuator ring 1415 in the same direction, e.g., counter-clockwise, until the groove of actuator ring 1415 engages with the indent of second actuator component 1417. This causes the locking mechanism to decouple hub 1412 and catheter 1404 to permit full deployment of device 400.

[0130] If for any reason device 400 is not in the proper position for deployment within the atrial septum, sheath 1410 may be advanced over device 400 while catheter 1404 is stationary, thereby collapsing first flared end region 401 within sheath 1410. Specifically, knob 1401 of handle 1408 may be rotated to cause sheath 1410 to move translationally relative to catheter 1404 and device 400, to thereby collapse device 400 within sheath 1410. For example, sheath 1410 may be moved over collapsed device 400 until device 400 is completely collapsed within sheath 1410. Distal end 1402, with device 400 disposed therein, may then be retrieved. Alternatively, distal end 1402 may be repositioned relative to the fossa ovalis of the atrial septum prior to partially advancing first flared end region 401 out of sheath 1410 within the left atrium.

[0131] When third actuator 1424 is in the second position and hub 1412 and catheter 1404 are decoupled, the delivery apparatus may be pulled proximally by the physician such that the atrial septum maintains device 400 in position against the left side of the atrial septum until second flared end region 403 of device 400 is no longer constrained between hub 1412 and sheath 1410 as shown in FIG. 16P. As sheath 1410, catheter 1402, and inner catheter 1411 are retracted proximally, hub 1412 remains stationary with respect to the atrial septum as the one or more engagers of hub 1412 are engaged with the struts of second flared end region 403 of device 400 within sheath 1410. Hub 1412 is permitted to move distally along inner catheter 1411 until cavity 1430 of hub 1412 prevents lock ring 1438 of inner catheter 1411 from further proximal movement. When second flared end region 403 of device 400 is exposed beyond the distal end of sheath 1410, second flared end region 403 then transitions from a collapsed, delivery state to an expanded, deployed state within the right atrium, and neck region 405 is lodged in the puncture of the atrial septum (step 1509).

[0132] FIG. 16Q is a cross-sectional schematic of the delivery apparatus within the sheath during step 1509, wherein the delivery apparatus is pulled proximally such that second flared end region 403 of device 400 is no longer constrained between hub 1412 and sheath 1410. FIG. 16R illustrates the delivery apparatus of FIG. 16Q with device 400 omitted for clarity. As shown in FIG. 16Q, sheath 1410 is no longer disposed over protrusions 1414 and 1416 such that second flared end region 403 is no longer constrained in the collapsed, delivery state, thereby causing first flared end region 401 to engage the left side of the atrial septum and neck region 405 of the device to lodge in the puncture through the fossa ovalis, and allowing expansion of second flared end region 403 of the device into the right atrium as shown in FIG. 16S.

[0133] Referring back to FIG. 16R, inner catheter 1411, catheter 1404, and sheath 1410 are pulled proximally while hub 1412 of the delivery apparatus, e.g., engagement portion 1428, ring portion 1426, and proximal portion 1432, remains stationary with respect to atrial septum AS until at least a portion of proximal portion 1432 of hub 1412 is no longer disposed within cavity 1436 of catheter 1404. In addition, at least a partial portion of ring lock 1438 of inner catheter 1411 may be disposed within cavity 1430 of engagement portion 1428 of the hub. As described above, ring lock 1438 and cavity 1430 prevent inner catheter 1411 from being pulled proximally relative to the hub beyond a predetermined distance.

[0134] Any remaining components of the delivery system then may be removed, e.g., sheath, distal end of delivery apparatus, the catheter, and the guidewire (step 1510). Once positioned in the fossa ovalis as shown in FIG. 16T, device 400 shunts blood from the left atrium to the right atrium when the left atrial pressure exceeds the right atrial pressure (step 1511), thus facilitating treatment and/or the amelioration of symptoms associated with CHF.

[0135] It should be noted that the inventive devices also may be used with patients having disorders other than heart failure. For example, in one embodiment the device may be implanted in a subject suffering from myocardial infarction, for example in the period immediately following myocardial infarction (e.g., within a few days of the event, or within two weeks of the event, or even within six months of the event). During such a period, the heart remodels to compensate for reduced myocardial function. For some subjects suffering from severe myocardial infarction, such remodeling may cause the function of the left ventricle to significantly deteriorate, which may lead to development of heart failure Implanting an inventive device during the period immediately following myocardial infarction may inhibit such deterioration in the left ventricle by reducing LAP and LVEDP during the remodeling period. The device optionally then may be removed as described in further detail below.

[0136] Exemplary method 1700 of retrieving device 400 from a subject, for example, from a puncture through the fossa ovalis, will now be described with reference to FIG. 17. The steps of method 1700 may be further elaborated by referring to FIGS. 18A-18F.

[0137] FIG. 17 is a flow chart of steps in an exemplary method of retrieving an hourglass-shaped device implanted in a puncture through the fossa ovalis in accordance with the present invention. At step 1701, a retrieval system for retrieving an implanted shunt device, e.g., hourglass-shaped device 400 of FIG. 4, is provided. For example, the retrieval system includes a retrieval catheter, e.g., grappling hook, having one or more hook portions at the distal end thereof which preferably are formed of a shape memory metal and are biased toward a position radially outward from a central axis of the retrieval catheter, a restraint member coupled to a control tube and positioned over at least a portion of the retrieval catheter, and a sheath having a lumen sized and shaped to receive the retrieval catheter and the restraint member. The hook portions are sized and shaped to align with the openings between the struts and rings of the shunt device. Accordingly, the number of hook portions may correspond with the number of openings between the struts and rings of the shunt device.

[0138] At step 1702, a guidewire is inserted through the neck of the implanted shunt device through the fossa ovalis of the atrial septum into the left atrium. The guidewire may be inserted using techniques readily known in the art. At step 1703, the sheath is inserted over the guidewire and positioned in proximity to the flared end region of the shunt device disposed in right atrium. The guidewire may then be removed. At step 1704, the retrieval catheter and the restraint member are delivered through the sheath in proximity to the flared end region of the shunt device disposed in right atrium. FIG. 18A is a partial cross-sectional schematic of retrieval system 1800 during step 1704. As illustrated in FIG. 18A, sheath 1802 having retrieval catheter 1804 and restraint member 1808 disposed therein is positioned in proximity to second flared end region 403 of device 400 within the right atrium. Restraint member 1808 is positioned over a portion of retrieval catheter 1804 such that hook portions 1806 are maintained in a compressed configuration within sheath 1802. Although only two hook portions 1806 are illustrated in FIG. 18A, as will be understood by a person ordinarily skilled in the art, retrieval catheter 1804 may include less or more than two hook portions, e.g., one, three, four, five, or six hook portions. Restraint member 1808 may be moved proximally and distally over retrieval catheter 1804 within sheath 1802 via control tube 1810. Alternatively, a control wire having sufficient stiffness may be used to move restraint member 1808 within sheath 1802.

[0139] At step 1705, retrieval catheter 1804 along with restraint member 1808 are advanced distally and exposed beyond the distal end of sheath 1802 within the right atrium such that hook portions 1806 are within at least a portion of second flared end region 403 of device 400, as illustrated in FIG. 18B. At step 1706, restraint member 1808 is retracted proximally along retrieval catheter 1804 within sheath 1802 via control tube 1810. Accordingly, hook portions 1806 expand radially outward from the central axis of retrieval catheter 1804 as they are no longer restrained by restraint member 1808, as illustrated in FIG. 18C. At step 1707, retrieval catheter 1804 may be adjusted to align hook portions 1806 with the openings between the struts and rings of second flared end region 403 of device 400.

[0140] At step 1708, while hook portions 1806 are maintained in placed and engaged with second flared end region 403 of device 400, restraint member 1808 is advanced distally toward hook portions 1806 via control tube 1810, thereby causing hook portions 1806, and accordingly second flared end region 403, to transition to a compressed configuration, as illustrated in FIG. 18D. Next, at step 1709, sheath 1802 is advanced distally over retrieval catheter 1804 and device 400, through the atrial septum AS and into the left atrium, thereby causing first flared end region 401 of device 400 to transition to a compressed configuration within sheath 1802, as illustrated in FIG. 18E. Finally, at step 1710, system 1800 is pulled proximally to remove retrieval system 1800 and device 400 from the patient, as illustrated in FIG. 18F.

[0141] In accordance with another aspect of the present invention, exemplary method 1900 of retrieving device 400 from a subject, for example, from a puncture through the fossa ovalis, will now be described with reference to FIG. 19. The steps of method 1900 may be further elaborated by referring to FIGS. 20A-20G.

[0142] FIG. 19 is a flow chart of steps in an exemplary method of retrieving an hourglass-shaped device implanted in a puncture through the fossa ovalis in accordance with the present invention. At step 1901, a retrieval system for retrieving an implanted shunt device, e.g., hourglass-shaped device 400 of FIG. 4, is provided. For example, the retrieval system includes grappling hook having one or more hook portions at the distal region thereof which preferably are formed of a shape memory metal and are biased radially inward toward a central axis of the retrieval system, an inflatable balloon catheter, and a sheath having a lumen sized and shaped to receive the grappling hook and the inflatable balloon catheter. The one or more curved hooked portions of the grappling hook are sized and shaped to align with the openings between the struts and rings of the shunt device in an expanded state. Accordingly, the number of hook portions may correspond with the number of openings between the struts and rings of the shunt device. As will be understood by a person ordinarily skilled in the art, the inflatable balloon catheter may be delivered within a separate balloon channel moveable within the sheath.

[0143] At step 1902, a guidewire is inserted through the neck of the implanted shunt device through the fossa ovalis of the atrial septum into the left atrium. The guidewire may be inserted using techniques readily known in the art. At step 1903, the sheath is inserted over the guidewire and positioned in proximity to the flared end region of the shunt device disposed in right atrium. At step 1904, the grappling hook and the inflatable balloon catheter are delivered through the sheath over the guidewire in proximity to the flared end region of the shunt device disposed in right atrium. FIG. 20A is a partial cross-sectional schematic of retrieval system 2000 during step 1904. As illustrated in FIG. 20A, sheath 2002 having grappling hook 2004 and inflatable balloon catheter 2008 in a deflated state disposed therein is positioned in proximity to second flared end region 403 of device 400 within the right atrium. Although only two hook portions 2006 are illustrated in FIG. 20A, as will be understood by a person ordinarily skilled in the art, grappling hook 2004 may include less or more than two hook portions 2006, e.g., one, three, four, five, or six hook portions. Hook portions 2006 of grappling hook 2004 may be joined together at a proximal region of grappling hook 2004, e.g., via a ring having a lumen sized and shaped to receive inflatable balloon catheter 2008 such that grappling hook 2004 may move proximally or distally over inflatable balloon catheter 2008 within sheath 2002.

[0144] At step 1905, inflatable balloon catheter 2008 is advanced distally, e.g., over the guidewire (not shown), and exposed beyond the distal end of sheath 2002 within the right atrium in a deflated condition such that inflatable balloon catheter 2008 is positioned within at least a portion of second flared end region 403 of device 400, as illustrated in FIG. 20B. At step 1906, inflatable balloon catheter 2008 is inflated to an inflated state within at least a portion of second flared end region 403 and neck region 405 of device 400, as illustrated in FIG. 20C. For example, inflatable balloon catheter 2008 may be coupled to a source of fluid at its proximal end outside the patient's body for inflation of inflatable balloon catheter 2008, and may expand to have a diameter equal to the diameter of neck region 405 of device 400. Inflation of inflatable balloon catheter 2008 aligns retrieval system 2000 with device 400.

[0145] At step 1907, grappling hook 2004 is advanced distally and exposed beyond the distal end of sheath 2002 within the right atrium. As illustrated in FIG. 20D, hook portions 2006 of grappling hook 2004 bend radially outwardly in an expanded state as they move across the surface of inflatable balloon catheter 2008 in the inflated state. At step 1908, grappling hook 2004 may be adjusted to align hook portions 2006 with the openings between the struts and rings of second flared end region 403 of device 400.

[0146] At step 1909, while hook portions 2006 are maintained in placed and engaged with second flared end region 403 of device 400, inflatable balloon catheter 2008 is deflated and advanced distally into the left atrium. Alternatively, inflatable balloon catheter 2008 may be deflated and removed from the patient's body or deflated and retracted into a balloon channel within sheath 2002. Deflation of inflatable balloon catheter 2008 causes hook portions 2006 of grappling hook 2004, and accordingly second flared end region 403, to transition to a compressed configuration, as illustrated in FIG. 20E.

[0147] Next, at step 1910, sheath 2002 is advanced distally over grappling hook 2004, device 400, and inflatable balloon catheter 2008, through the atrial septum AS and into the left atrium, thereby causing first flared end region 401 of device 400 to transition to a compressed configuration within sheath 2002, as illustrated in FIG. 20F. Finally, at step 1911, system 2000 is pulled proximally to remove retrieval system 2000 and device 400 from the patient, as illustrated in FIG. 18G.

[0148] Referring to FIG. 21A, an alternative exemplary apparatus is provided for delivering interatrial shunt devices, e.g., device 400 of FIG. 4A, 4B or 6Q, and/or devices described in U.S. Pat. No. 9,629,715 to Nitzan, U.S. Pat. No. 9,713,696 to Yacoby, and U.S. Pat. No. 10,076,403 to Eigler. Apparatus 2100 includes distal end 2102, catheter 2104, and proximal end 2106 having handle 2108 for actuating distal end 2102. Distal end 2102 is removeably coupled to distal tip 2110 having flexible pigtail-shaped portion 2112 extending therefrom as illustrated in FIG. 21B. Apparatus 2100 may include an engagement apparatus disposed within catheter 2104 extending from proximal end 2106 to distal end 2102 for delivery and/or retrieval of the interatrial shunt device. The components of apparatus 2100 may include a guidewire lumen sized to receive a guidewire therethrough as described in further detail below.

[0149] Referring now to FIG. 22, an exemplary loading tool is provided for loading an exemplary hourglass-shaped interatrial shunt constructed in accordance with the principles of the present invention into distal end 2102 of apparatus 2100. Loading tool 2200 includes proximal loader 2202 and distal loader 2204. Proximal loader 2202 and distal loader 2204 may be constructed from, e.g., injection molding, and made of a transparent plastic material such that loading of device 400 therein may be visible by the user. Proximal loader 2202 has lumen 2208 extending from proximal end 2201 to distal end 2203 of proximal loader 2202, wherein lumen 2208 is sized and shaped to receive device 400 in a collapsed delivery state as well as distal tip 2110 and catheter 2104 of apparatus 2100. As illustrated in FIG. 22, lumen 2208 has conical shaped cavity 2206 at its distal open end which corresponds to the shape of one of the flared end regions of device 400, e.g., the flared end region configured to be disposed within the left atrium when device 400 is implanted. Further, cavity 2206 is sized such that device 400 must be inserted into proximal loader 2202 in a specific orientation as will be described in further detail below, thereby ensuring proper loading of device 400 into apparatus 2100. In addition, distal loader 2204 has cavity 2210 sized and shaped to receive distal end 2203 of proximal loader 2202.

[0150] Exemplary method 2300 of using loading tool 2200 to load device 400 into apparatus 2100 will now be described with reference to FIG. 23. Some of the steps of method 2300 may be further elaborated be referring to FIGS. 24A-24F. FIG. 24A illustrates proximal loader 2202, distal loader 2204, the distal components of apparatus 2100, and device 400. As illustrated in FIG. 24A, apparatus 2100 is positioned within proximal loader 2202 such that the distal portion of catheter 2104 and engagement apparatus 2120 are disposed within lumen 2208, and distal tip 2110 extends beyond distal end 2203 of proximal loader 2202 (step 2301). As shown in FIG. 24A, distal tip 2110 is moveably coupled to catheter 2104 via pull-cord 2114. Engagement apparatus 2120 may be constructed similar to delivery apparatus 100 of FIG. 1A and delivery apparatus 700 of FIG. 7A. For example, engagement apparatus 2120 includes latching legs having hook portions which may be controllably transitioned between a disengaged and engaged position for engaging with device 400 in a collapsed delivery state. Engagement apparatus 2120 is moveably disposed within the lumen of catheter 2104 and may be coupled to the distal end of an inner catheter disposed within catheter 2104.

[0151] FIG. 24B illustrates device 400 coupled to distal tip 2110 of apparatus 2100 while apparatus 2100 is disposed within lumen 2208 of proximal loader 2202 (step 2302). Specifically, device 400 is inserted over pigtail-shaped portion 2112 to be disposed over distal tip 2110, such that the outlet end of second flared end region 403 of device 400 is adjacent to cavity 2206 of proximal loader 2202. Cavity 2206 has a size and shape that corresponds to first flared end region 401 in an expanded state, and which may receive the outlet end of second flared end region 403 of device 400 in the expanded state. This ensures that device 400 is properly loaded into apparatus 2100 as the inlet end of first flared end region 401 could not be inserted into cavity 2206 of proximal loader 2202.

[0152] FIG. 24C illustrates proximal loader 2202 having apparatus 2100 coupled to device 400 therein, advanced within cavity 2210 of distal loader 2204 (step 2303). Specifically, proximal loader 2202 is advanced within cavity 2210 of distal loader 2204 until first flared end region 401 of device 400 contacts the inner wall of cavity 2210. As proximal loader 2202, and accordingly apparatus 2201, are further advanced into cavity 2210 of distal loader 2204 (step 2304), second flared end region 403 transitions from an expanded stated to a collapsed delivery state within lumen 2208 of proximal loader 2202 as illustrated in FIG. 24D. Specifically, the conical shape of cavity 2206 of proximal loader 2202 causes second flared end region 403 to crimp into the collapsed state as force is applied to second flared end region 403 by proximal loader 2202. In addition, pigtail-shaped portion 2212 and at least a portion of distal tip 2110 extend beyond an opening of distal loader 2204. Steps 2303 and 2304 may be completed in a single motion.

[0153] In accordance with the principles of the present invention, the latching legs and hook portions of engagement apparatus 2120 may be actuated to be in a disengaged position, e.g., contracted inward, before proximal loader 2202 is completely advanced within distal loader 2204 so that the engagement hooks of engagement apparatus 2120 may be appropriately aligned with the struts of second flared end region 403 of device 400, and so that second flared end region 403 can smoothly enter lumen 2208 of proximal loader 2202. Once aligned, the latching legs and hook portions of engagement apparatus 2120 may be actuated to be in a engaged position to engage with second flared end region 403 of device 400 within lumen 2208 of proximal loader 2202 (step 2305).

[0154] FIG. 24E illustrates catheter 2104 advanced further through lumen 2208 of proximal loader 2202 over engagement apparatus 2120, device 400, and pull-cord 2114 until the distal end of catheter 2104 engages with distal tip 2110 (step 2306). Specifically, as the distal tip of catheter 2104 comes into contact with first flared end region 401, further advancement of catheter 2104 against the outer surface of first flared end region 401 cause first flared end region 401 to crimp into a collapsed state within the lumen of catheter 2104. The distal end of catheter 2104 may then be coupled to distal tip 2110 (step 2307). Finally, apparatus 2100 having device 400 in a collapsed delivery state therein and engaged with engagement apparatus 2120 within catheter 2104 of apparatus 2100, is removed from proximal loader 2202 and distal loader 2204 (step 2308).

[0155] FIG. 25A illustrates catheter 2104 coupled to distal tip 2110 of apparatus 2100. As shown in FIG. 25A, apparatus 2100 may include radiopaque marker 2122 disposed at the distal end of catheter 2104 for assisting in accurate deployment of device 400 within the interatrial septum. Specifically, as described in further detail below, radiopaque marker 2122 may be visualized by the physician during the delivery procedure to ensure that it is aligned with the atrial septum for proper delivery. FIG. 25B illustrates the components within catheter 2104 with device 400 loaded therein. As illustrated in FIG. 25B, collapsed device 400 is positioned within catheter 2104 such that one end is engaged with engagement apparatus 2120, and the other end is aligned with radiopaque marker 2122 so that the neck region of device 400 is a predetermined distance from radiopaque marker 2122. As described in further detail below, knowing where the neck region of device 400 is within catheter 2104, by knowing its distance from radiopaque marker 2122 will assist in proper and accurate deployment of device 400 within the fossa ovalis.

[0156] FIG. 25C is a cross-sectional view of the distal end of apparatus 2100. As shown in FIG. 25C, apparatus 2100 may include guidewire lumen 2116 extending therethrough, e.g., from an opening at the end of pigtail-shaped portion 2116 through distal tip 2110 and pull-cord 2114 to the proximal end of apparatus 2100. Guidewire lumen 2116 is sized and shaped to receive a guidewire so that apparatus 2100 may be advanced over the guidewire across the atrial septum for implantation of device 400. In addition, as illustrated in FIG. 25C, engagement apparatus 2120 includes hook portions 2118 which may be constructed similar to the hook portions of delivery apparatus 100 of FIG. 1A and delivery apparatus 700 of FIG. 7A, for engaging and disengaging device 400 with engagement apparatus 2120.

[0157] FIGS. 26A and 26B illustrates handle 2108 coupled to distal end 2106 of apparatus 2100. As shown in FIG. 26A, handle 2108 includes safety trigger 2126 and knob 2124. As illustrated in FIG. 26B, knob 2124 includes a threaded portion that corresponds with threaded portion of catheter component 2127 coupled to catheter 2104. Accordingly, as knob 2124 is rotated about the longitudinal axis of handle 2108, rotational movement of knob 2124 is converted to translational movement of catheter component 2127 along the longitudinal axis of handle 2108, thereby causing movement of catheter 2104 relative to engagement apparatus 2120. This permits gradual adjustment of the length of catheter 2104 relative to engagement apparatus 2120, and accordingly halfway-retrieval of device 400 when device is halfway deployed as will be described in further detail below. Knob 2124 may not be rotated until safety trigger 2126 is moved from a locked position to an unlocked position.

[0158] Exemplary method 2700 of delivering device 400 to reduce left atrial pressure in a subject, for example, a human having a heart pathology, using apparatus 2100 illustrated in FIG. 21A will now be described with reference to FIG. 27. Some of the steps of method 2700 may be further elaborated by referring to FIGS. 28A-28I.

[0159] At step 2701, an interatrial shunt, e.g., device 400, and apparatus 2100 of FIG. 21A for delivering device 400 are provided. Then, device 400 is collapsed radially to a contracted delivery state and coupled to apparatus 2100, e.g., using method 2300 of FIG. 23. Steps 2703 and 2704 are similar to steps 503 and 504 described in FIG. 5, and thus for brevity these steps are not discussed again here. FIG. 28A illustrates guidewire 2801 disposed across the atrial septum in left atrium LA (step 2704).

[0160] Pigtail-shaped portion 2112 of distal tip 2110 of delivery apparatus 2100 with device 400 collapsed therein and coupled to engagement apparatus 2120 of apparatus 2100 is then advanced over guidewire 2801 through the puncture in the fossa ovalis and into left atrium LA (step 2705) as illustrated in FIG. 28B. Next, catheter 2104 is retracted proximally relative to distal tip 2110 and engagement apparatus 2120 coupled to collapsed device 400 such that device 400 is partially advanced out of catheter 2104 (step 2706). Such advancement causes device 400 to partially protrude out of catheter 2401 and into left atrium LA, which causes the first flared end region to expand to its deployed expanded state in the left atrium LA, as shown in FIG. 28C.

[0161] Then, under fluoroscopic and/or echocardiographic visualization, apparatus 2100 may be repositioned such that radiopaque marker 2801 is aligned with the fossa ovalis (step 2707) as illustrated in FIGS. 28D and 28E. As shown in FIG. 28E, when apparatus 2100 is in the proper position, the neck region of device 400 will be aligned with the fossa ovalis for accurate deployment of device 400 within the atrial septum. Thus, device 400 will be loaded to a specific position within catheter 2104 of apparatus 2100 relative to radiopaque marker 2122 during method 2300 described above.

[0162] If for any reason device 400 is not in the proper position for deployment within the atrial septum, catheter 2104 may be advanced over device 400 while distal tip 2110 is stationary, thereby collapsing the first flared end region within catheter 2104 (step 2708) as illustrated in FIG. 28F. Specifically, knob 2124 of handle 2108 may be rotated to cause catheter 2104 to move translationally relative to engagement apparatus 2120 and distal tip 2110 of apparatus 2100, to thereby collapse device 400 within catheter 2104. For example, catheter 2104 may be moved over collapsed device 400 until catheter 2104 engages with distal tip 2110 as shown in FIG. 28F. Apparatus 2100, with device 400 disposed therein, may then be retrieved, e.g., over guidewire 2801 (step 2709). Alternatively, apparatus 2100 may be repositioned relative to the fossa ovalis of the atrial septum prior to returning to step 2706 and partially advancing the first flared end region out of catheter 2104 within left atrium LA.

[0163] After step 2707 described above, when device 400 is properly positioned relative to the atrial septum, engagement apparatus 2120 may be disengaged from device 400, e.g., hook portions 2118 may be moved from an engaged positioned radially inward to a disengaged position. Then, catheter 2104 may be retracted proximally relative to distal tip 2110, causing the second flared end region of device 400 to be exposed within right atrium RA beyond the distal end of catheter 2104 such that the second flared end region transitions from the collapsed delivery state to an expanded state within right atrium RA (step 2710) as illustrated in FIG. 28G. Specifically, knob 2124 of handle 2108 may be rotated in the opposite direction to cause catheter 2104 to move translationally relative to engagement apparatus 2120 and distal tip 2110 of apparatus 2100, to thereby expose the second flared end region of device 400 within right atrium RA. Accordingly, the flared end region of device 400 will be disposed within left atrium LA, the neck region of device 400 will be lodged within the puncture through the fossa ovalis, and the second flared end region of device 400 will be disposed within right atrium RA. In addition, pull-cord 2114 will be positioned within a central lumen of device 400.

[0164] As illustrated in FIG. 28H, which shows device 400 from within right atrium RA, distal tip 2110 is sized and shaped to fit through the central lumen of device 400 in the full expanded state. When device 400 is fully expanded within the atrial septum, apparatus 2100 may be retrieved (step 2711) by pulling distal 2100 proximally, e.g., until catheter 2104 engages with distal tip 2110 as shown in FIG. 28I. Guidewire 2801 may then be removed. Blood may then be shunted from left atrium LA to right atrium RA through device 400, e.g., when left atrial pressure exceeds right atrial pressure.

[0165] Referring now to FIGS. 29A-29D, an exemplary guidewire loading tool constructed in accordance with the principles of the present invention is described. Guidewire loading tool 2900 is designed for use with loading cartridge 614 of FIGS. 6D-6I. Specifically, as illustrated in FIGS. 29A-29D, guidewire loading tool 2900 has proximal portion 2903 and distal portion 2901, and two flexible wings, e.g., first flexible wing 2902 and second flexible wing 2904, coupled to and extending radially away from distal portion 2901. First flexible wing 2902 and second flexible wing 2904 each have lateral end portions having an edge that runs parallel to the longitudinal axis of proximal portion 2903 and distal portion 2901, which permit guidewire loading tool 2900 to be placed on a flat horizontal surface while a guidewire is loaded therein as described in further detail below.

[0166] In addition, guidewire loading tool 2900 has central lumen 2905 extending through proximal portion 2903 and distal portion 2901, sized and shaped to receive loading cartridge 614 therein, e.g., when device 400 is collapsed in a delivery state within loading cartridge 614 as described above with reference to FIG. 6F. Referring again to FIG. 29A, first and second flexible wings 2902 and 2904 are designed such that when a force is applied against first and second flexible wings 2902 and 2904 toward each other, the diameter of central lumen 2905 is increased to permit insertion and removal of loading cartridge 614 therein. Accordingly, first and second flexible wings 2902 and 2904 are biased toward an open position whereby central lumen 2905 has a smaller diameter than when first and second flexible wings 2902 and 2904 are pressed toward each other.

[0167] Referring now to FIGS. 30A-30E, an exemplary method of using guidewire loading tool 2900 to load a guidewire is provided. As shown in FIG. 30A, guidewire loading tool 2900 is inserted over loading cartridge 614 having device 400 collapsed therein. Specifically, first and second flexible wings 2902 and 2904 are pressed toward each other to increase the diameter of central lumen 2905, and loading cartridge 614 is positioned within central lumen 2905. First and second flexible wings may then be released such that loading cartridge 614 is securely disposed within central lumen 2905 of guidewire loading tool 2900 as illustrated in FIG. 30B.

[0168] Next, as illustrated in FIG. 30C, a guidewire is inserted through a lumen of device 400 collapsed within loading cartridge 614 disposed within central lumen 2905 of guidewire loading tool 2900. The guidewire may be fed therethrough and extend beyond a proximal end of loading cartridge 614. As shown in FIG. 30D, when the guidewire is sufficiently inserted within loading cartridge 614 and guidewire loading tool 2900, first and second flexible wings 2902 and 2904 may be pressed toward each other to enlarge central lumen 2905. Accordingly, guidewire loading tool 2900 may be removed from loading cartridge 614 as shown in FIG. 30E.

[0169] Exemplary method 3100 of delivering device 400 to reduce left atrial pressure in a subject, for example, a human having a heart pathology will now be described with reference to FIG. 27. Some of the steps of method 3100 may be further elaborated by referring to FIGS. 32A-32K. Steps 3101-3104 may be identical to steps 2701-2704 of FIG. 27, and therefore will not be discussed for brevity. Thus, at step 3104, guidewire 3201 will be positioned across atrial septum AS such that the distal end of guidewire 3201 is positioned in left atrium LA as shown in FIG. 32A.

[0170] At step 3105, the distal end of sheath 3202 having cap 3204 disposed thereon is advanced over guidewire 3201 to a position within right atrium RA adjacent atrial septum AS, as shown in FIG. 32B. Sheath 3202 includes balloon 3206 disposed thereon, proximal to the distal end of sheath 3202 by a predetermined distance as described in further detail below. Accordingly, balloon 3206 may be coupled to a source of fluid external to the patient via an inflation lumen disposed either within or along the exterior of sheath 3202. Cap 3204 may form a seal with the distal end of sheath 3202 such that fluid cannot leak into or out of the lumen of sheath 3202 during delivery of sheath 3202 to the target location.

[0171] At step 3106, balloon 3206 may be inflated via the external fluid source and the inflation lumen until balloon 3206 reaches a desired inflated size, as shown in FIG. 32C. For example, balloon 3206 may be inflate with any biocompatible fluid, e.g., saline, water, or air. At step 3107, when balloon 3206 is in its inflated state, the distal end of sheath 3202, along with cap 3204, are advanced through the puncture in the fossa ovalis of atrial septum AS until inflated balloon 3206 engages the right side of atrial septum AS from within right atrium RA, as shown in FIG. 32D. The force feedback provided by atrial septum AS against balloon 3206 informs the physician that the distal end of sheath 3202 is in the desired position within left atrium LA for the next phase of implantation of the shunt device. Accordingly, balloon 3206 will be disposed at a predetermined position along sheath 3202 from the distal end of sheath 3202. Thus, unlike the retention devices described in U.S. Pat. No. 5,312,341 to Turi, inflatable balloon 3206 of the present invention is inflated in the right atrium of the patient, proximal to the atrial septum to prevent sheath 3202 from advancing more than a predetermined distance into the left atrium, allowing for safe deployment of device 400.

[0172] At step 3108, cap 3204 may be decoupled from the distal end of sheath 3202, and retracted through the lumen of sheath 3202 and removed over guidewire 3201, as shown in FIG. 32E. Referring now to FIG. 31B, at step 3109, the distal end of the delivery apparatus having device 400 coupled thereto in a collapsed configured within sheath 3202 may be advanced through the lumen of sheath 3202 over guidewire 3201 such that device 400 is position within left atrium LA within sheath 3202.

[0173] Solely for exemplary purposes, FIGS. 32F-32I illustrate delivery apparatus 1301 of FIGS. 13B-13D as used to delivery device 400; however, as will be understood by a person having ordinary skill in the art, any of the delivery apparatuses discussed herein may be used to delivery device 400 in accordance with the exemplary steps of method 3100. Accordingly, at step 3110, delivery device 1301 is advanced through the lumen of sheath 3202 until device 400 is partially advanced out of the distal end of sheath 3202 such that the first flared end region of device 400 is exposed beyond the distal end of sheath 3202 and transitions from a collapsed delivery state to an expanded deployed state within left atrium LA, as shown in FIG. 32F. While delivery apparatus 1301 is being advanced through sheath 3202, the physician may continuously or periodically apply a slight forward force on sheath 3202 to ensure that force feedback is being observed by the physician due to atrial septum AS and balloon 3206 to ensure that the distal end of sheath 3202 is appropriately positioned during deployment of device 400.

[0174] At step 3111, delivery apparatus 1301 may be disengaged from the second flared end region of device 400 while the second flared end region is in a collapsed delivery state within sheath 3202 as discussed above. For example, the release ring of delivery apparatus 1301 may be retracted, thereby causing the hook portions to move radially inward to disengage with device 400 within sheath 3202. Once disengaged, delivery apparatus 1301 may be retracted and/or completely removed from sheath 3202, as shown in FIG. 32G. At step 3112, sheath 3202 is retracted along with device 400 partially disposed therein until the first flared end region of device 400 engages with the left side of atrial septum AS within left atrium LA, the neck of device 400 is lodged within the puncture of the fossa ovalis. As sheath 3202 is further retracted, the force of atrial septum AS against the first flared end region of device 400 causes device 400 to be fully exposed from the distal end of sheath 3202 such that the second flared end region transitions from the collapsed delivery state within sheath 3202 to the expanded deployed state within right atrium RA, as shown in FIG. 32H.

[0175] At step 3113, balloon 3206 is deflated via the inflation lumen, as shown in FIG. 32I. At step 3114, sheath 3202 and delivery apparatus 1301 may be retrieved as shown in FIG. 32J, followed by removal of guidewire 3201 as shown in FIG. 32K. At step 3115, as described above, blood may be shunted from left atrium LA to right atrium RA through device 400 implanted at atrial septum AS, e.g., when left atrial pressure exceeds right atrial pressure.

[0176] While various illustrative embodiments of the invention are described above, it will be apparent to one skilled in the art that various changes and modifications may be made herein without departing from the invention. It will further be appreciated that the devices described herein may be implanted in other positions in the heart. For example, device 400 may be implanted in an orientation so as to shunt blood from the right atrium to the left atrium, thus decreasing right atrial pressure; such a feature may be useful for treating a high right atrial pressure that occurs in pulmonary hypertension. Similarly, device 400 may be implanted across the ventricular septum, in an orientation suitable to shunt blood from the left ventricle to the right ventricle, or in an orientation suitable to shunt blood from the right ventricle to the left ventricle. The appended claims are intended to cover all such changes and modifications that fall within the true spirit and scope of the invention.