Device for percutaneous cutting and dilating a stenosis of the aortic valve

[0002] The present invention pertains generally to interventional medical devices. More particularly, the present invention pertains to catheters that can be used to incise tissue in the vasculature of a patient. The present invention is particularly, but not exclusively, useful as a catheter for incising the aortic valve between the left ventricle of the heart and the aorta for the purpose of relieving the heart condition known as aortic valve stenosis (AS).

[0003] In its normal operation, the left ventricle of the heart pumps oxygen-rich blood to arteries in the vasculature of the body through the aorta. As the heart pumps, the aortic valve, which is located between the ventricle and the aorta, opens and closes to control the direction of blood flow. Specifically, during a heartbeat, the valve is open to allow blood to flow from the ventricle into the aorta. Between heartbeats, however, the aortic valve closes to form a tight seal that prevents blood from leaking back into the ventricle. For any of several reasons (e.g. aging, or birth defects), it can happen that the aortic valve is somehow damaged and may become stenosed. When this happens, the aortic valve does not open to its normal extent and the flow of blood from the heart into the aorta is constricted. This leads to a heart condition that is commonly known as aortic valve stenosis (AS).

[0004] In a patient with AS, the aortic valve is stenosed and the heart is forced to pump blood through a narrowed opening through the aortic valve. Over time, this narrowing causes pressure to build up in the left ventricle of the heart. In order to compensate for this pressure overload, the muscles of the left ventricle enlarge (hypertrophy) so that the heart can pump with more force. It eventually happens, however, that the stenosis in the aortic valve increases to the point the heart can no longer maintain adequate blood flow through the stenosis. At this point, the patient experiences several characteristic symptoms of AS. In general, this occurs when the aortic valve, when open, has a valve opening area that is approximately one square centimeter (1 cm²).

[0005] Heretofore, the treatment for AS has been accomplished either surgically by doing a valve replacement, or by performing a percutaneous balloon valvuloplasty. In the case of a valve replacement, an extensive surgical procedure is required wherein the aortic valve is replaced either by a mechanical or a porcine valve. On the other hand, being a percutaneous procedure, balloon valvuloplasty is somewhat less involved than a valve replacement procedure. Nevertheless, for many reasons including a high recurrence rate, and despite its initial acceptance, balloon valvuloplasty is now used infrequently and only palliatively or as a bridge to surgery.

[0006] In light of the above it is an object of the present invention to provide a percutaneous device and method for treating aortic valve stenosis that effectively makes controlled shallow incisions in the leaflets, of the aortic valve to thereby establish a more normal flow of blood from the left ventricle of the heart into the aorta. Another object of the present invention is to provide a cutting device that can be safely advanced through the vasculature of a patient, and subsequently withdrawn therefrom, while permitting surgical incisions at selected locations in the vasculature. Still another object of the present invention is to provide a cutting device and method for treating aortic valve stenosis that is simple to manufacture, easy to use, and comparatively cost effective.

[0007] In accordance with the present invention, a cutting device for treating aortic valve stenosis includes a catheter that has an elongated balloon mounted near its distal end. As intended for the present invention, the balloon can be reconfigured on the catheter between an inflated configuration and a deflated configuration. Structurally, the balloon defines an axis and, in its inflated configuration, it has three identifiable sections that are located between its distal end and its proximal end. These sections are: a substantially conical-shaped distal section having a taper with an increasing radius in the proximal direction; a substantially conical-shaped proximal section having a taper with a decreasing radius in the proximal direction; and a substantially cylindrical-shaped intermediate section that is located between the distal section and the proximal section.

[0008] At least one, but as many as three or possibly four, substantially straight, elongated blades are attached to the balloon. Importantly, these blades are oriented on the balloon so as to be coplanar with the axis of the balloon. Further, each blade is formed with a sharp edge, and each blade is attached to the balloon to project the sharp edge of the blade in a radial direction from the axis of the balloon. In more detail, the proximal portion of each blade is attached to the proximal section of the balloon, with the distal end of the blade adjacent the distal end of the balloon. The blades, however, are longer than the proximal section of the balloon. Therefore, the distal portion and the distal end of each blade is not attached to the balloon.

[0009] In the operation of the present invention, the balloon (in its deflated configuration) is advanced into the vasculature of the patient. Specifically, for the treatment of AS, the balloon is positioned inside the left ventricle of the heart. This then places the balloon distal to the aortic valve. In any event, once the balloon is in the left ventricle it is then inflated.

[0010] In its inflated configuration, the balloon inclines each blade relative to the axis of the balloon. Specifically, this inclination is characterized by an increasing distance between the blade and the axis of the balloon, in a distal direction along the axis. In cooperation with the balloon, each blade is inclined relative to the balloon's axis at an angle (α) that is established by the taper of the balloon's proximal section, when the balloon is inflated. Preferably, this angle (α) is in a range between approximately zero degrees, when the balloon is in its deflated configuration, and approximately forty-five degrees, when the balloon is in its inflated configuration. (0°-45°). An important consequence of this is that, when the balloon is in its inflated configuration, the sharp edges of the blades are presented for cutting (incising) the aortic valve. More specifically, the distal portions and distal ends of respective blades are projected radially outward from the axis through a distance that extends beyond the radius of the cylindrical-shaped intermediate section.

[0011] An incising action on the aortic valve is accomplished as the inflated balloon is retracted through the aortic valve in a proximal direction. After the inflated balloon has been retracted through the aortic valve, and the valve has been incised, the balloon is deflated. The deflated balloon is then withdrawn from the vasculature and the procedure is completed.

[0012] The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

[0013] FIG. 1 is a perspective view of the incising device of the present invention;

[0014] FIG. 2A is a side view of the balloon of the device of the present invention when the balloon is in its deflated configuration;

[0015] FIG. 2B is a side view of the balloon of the device of the present invention when the balloon is in its inflated configuration;

[0016] FIG. 3A is an end view of the balloon of the device of the present invention as seen along the line 3A—3A in FIG. 2A;

[0017] FIG. 3B is an end view of the balloon of the device of the present invention as seen along the line 3B—3B in FIG. 2B;

[0018] FIG. 4 is a cross sectional view of the catheter as seen along the line 4—4 in FIG. 1; and

[0019] FIG. 5 is a schematic view of an inflated balloon of the present invention, positioned inside the left ventricle of a patent, ready for retraction in a proximal direction through an aortic valve for the purpose of incising the aortic valve.

[0020] Referring initially to FIG. 1, a system for incising tissue in accordance with the present invention is shown and generally designated 10. As shown, the system 10 includes a catheter 12 which has a distal end 14 and a proximal end 16. System 10 also has an inflatable, elongated balloon 18 that is mounted on the catheter 12 near its distal end 16. Further, it is seen that a y-site 20 is attached to the proximal end 14 of the catheter 12. Specifically, the y-site 20 allows the catheter 12 to be operationally engaged with a guidewire 22 for the purpose of advancing the catheter 12 over the guidewire 22 after the guidewire 22 has been pre-positioned in the vasculature of a patient (not shown). FIG. 1 also shows that an inflation/deflation device 24 can be connected to the y-site 20 for fluid communication with the balloon 18. Preferably, the balloon 18 is made of a resilient material such as Polyethylene Napthalate (PEN), or Polyethylene Teraphthlate.

[0021] Still referring to FIG. 1, it will be seen that the system 10 of the present invention includes a plurality of substantially straight cutting blades 26, of which the cutting blades 26aand 26bare only exemplary. As envisioned for the present invention, the system 10 may include only one such blade 26, or it may include as many as three or four such blades 26. With this in mind, and using the blade 26aas a specific example for purposes of disclosure, it will be seen that the proximal end 28 of the blade 26ais positioned adjacent, or near, the proximal end 30 of the balloon 18. Further, it is to be appreciated that the blade 26ais oriented on the balloon 18 so that it is coplanar with the longitudinal axis 32 of the balloon 18 (see FIG. 2A). Also, it is to be appreciated by cross-referencing FIG. 1 with FIG. 2B, that the blade 26ais attached to a proximal section of the balloon 18. For purposes of the present invention, the blades 26 can be attached to the balloon 18 by any means well known in the pertinent art, such as by bonding.

[0022] The structure for balloon 18 will be best understood by referencing both FIG. 1 and FIG. 2B. As shown, the balloon 18, when inflated, generally defines three sections. These are: a proximal section 34; an intermediate section 36; and a distal section 38. More specifically, when the balloon 18 is inflated, the proximal section 34 is generally conical-shaped and has a taper with an increasing radius in the distal direction. On the other hand, the intermediate section 36 is substantially cylindrical-shaped and has a generally constant radius. Again, there is a conical-shape for the distal section 38. This time, however, the taper for the distal section 38 has a decreasing radius in the distal direction. Preferably, the blade 26ais longer than the proximal section 34 and is attached to only the proximal section 34 of the balloon 18. Consequently, the distal end 40 of the blade 26ais not engaged with the balloon 18. As perhaps best seen in FIG. 2B, this cooperation of structure allows the sharp cutting edge 42 of the blade 26a, at the distal end 40 of the blade 26a, to extend radially outward from the axis 32 to a greater distance than the radius of the cylindrical-shaped intermediate section 36. Stated differently, with the balloon 18 in its inflated configuration, the blades 26 are inclined at an angle (α) relative to the axis 32. Preferably, the angle (α) is in a range between 0° and 45°.

[0023] FIG. 1 also shows that the system 10 of the present invention can include radiopaque markers 44aand 44bwhich will assist in positioning the balloon 18 in the vasculature of the patient. Identification of the balloon 18 at a location in the vasculature can be further facilitated by using a contrast medium to inflate the balloon 18. Other mechanisms, well known in the pertinent art, can be incorporated and used for these purposes.

[0024] As envisioned for the present invention, the balloon 18 of the present invention can be reconfigured between a deflated configuration (FIG. 2A and FIG. 3A) and an inflated configuration (FIG. 2B and FIG. 3B). As implied above, the actual inflation and deflation of the balloon 18 is accomplished by manipulating the inflation device 24 (See FIG. 1). Specifically, for this purpose, the inflation/deflation device 24 is connected at the y-site 20 in fluid communication with an inflation lumen 46 (see FIG. 4). A manipulation of the plunger 48 (see FIG. 1) can then cause the balloon 18 to selectively inflate or deflate. FIG. 4 also shows that the catheter 12 is formed with a guidewire lumen 50 for receiving the guidewire 22 therethrough.

[0025] Referring now to FIG. 5, in the operation of the system 10 of the present invention, the guidewire 22 is pre-positioned in the vasculature of the patient. The catheter 12, with the balloon 18 in its deflated configuration (FIG. 2A and FIG. 3A) is then advanced over the guidewire 22. Note that when the balloon 18 is in its deflated configuration, material of the balloon 18 will cover the blades 26 and thereby reduce the possibility of an unintended incision of tissue.

[0026] As intended for the operation of the present invention, the balloon 18 is advanced over the guidewire 22 until the balloon 18 has been positioned in the left ventricle 52 of the patient's heart. At this point, the inflation/deflation device 24 is manipulated to inflate the balloon 18 into its inflated configuration (FIG. 1, FIG. 2B and FIG. 3B). With the cutting blades 26 radially deployed, the system 10 is then retracted in a proximal direction through the aortic valve 54 and into the aorta 56. With this retraction, the cutting edges 42 of respective blades 26 incise the aortic valve 54 to relieve any stenosis that has developed in the aortic valve 54. After retraction, the balloon 18 is deflated, and the system 10 is withdrawn from the vasculature of the patient.

[0027] While the particular A Device for Percutaneous Cutting and Dilating a Stenosis of the Aortic Valve as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.