Method and device for closing holes in tissue

[0001] The present invention relates to surgery and in particular to closing holes in tissue during minimally invasive surgery. The invention is particularly useful for closing holes left by catheters during percutaneous surgical procedures such as minimally invasive cardiac surgery and other surgeries requiring access to body lumens.

[0002] More and more surgical procedures are performed percutaneously by the use of catheter-delivered devices. The main advantages are fast patient recovery and lower costs to the medical system. Some tissues, such as muscular tissue or arterial walls, do not seal well and are sometimes subject to blood pressure; therefore they require an immediate hemostatic seal after the surgery. Prior art solutions mainly rely on some form of a plug, such as an expanding foam plug, expanding metal plug or a barbed plug to seal the hole. The main disadvantage of plugs is that in order to form a good seal they are forcing the hole to become larger, rather than the more natural way which is to shrink the hole in order to promote healing. A prior art device operating by shrinking the hole is the Star Closure device sold by Abbott Vascular (www.abbottvasculardevices.com) however this device is only suitable to thin walled body lumens as it relies on folding the tissue. When sealing larger holes in thicker tissue the gripping points for pulling the tissue inwards have to be spread over an area significantly larger than the hole size, similar to what is done in traditional suturing. Attaching the closure device too close to the hole does not allow sufficient forces to be applied, therefore creating a marginal closure.

[0003] Another major shortcoming of the Star Closure and other devices is that the operation is not reversible. It is sometimes required to remove the closure, as in the case of bleeding or an additional procedure.

[0004] It is therefore desired to provide a hole closure method that provides an immediate liquid and gas tight closure and it can be delivered by a catheter to the inside wall of a body lumen.

[0005] It is also desired to provide a closure method suitable for a large range of tissue thicknesses and hole sizes.

[0006] It is also desired to be able to test, and if required to remove, the closure.

[0007] It further would be desired for the closing device to have permanent elastic properties to accommodate any movement or future changes in the tissue. Furthermore, the gripping area of the closure device has to be significantly larger than the original hole.

[0008] In view of the foregoing, the invention provides a method and device for closing holes in body lumens, and in particular in the heart and blood vessels, achieving an immediate hemostatic seal. The device can be applied via a wide range of catheters sizes to close a wide range of round and elongated holes with performance and reliability of traditional sutures but without requiring access to the tissue, except via the catheter. Furthermore, the device can be removed via the same catheter, and by using the same tools used to install it and can be re-used immediately if so desired. The device has a high degree of elastic compliance allowing a wide accommodation range to changes in the tissue. These and other objects of the present invention are achieved by providing a flexible clip that is temporarily attaches to an insertion tool. The clip has three different positions: a storage position, in which it is folded inside a delivery tube; an expanded position, in which it opens up to reach an area significantly larger than the hole, and a closed position in which elastic forces try to close the clip, pulling the tissue with it to close the hole. The clip has multiple sharp barbs for gripping the tissue and a stem for attaching to the insertion tool, as well as for re-attaching in case removal is required.

[0009] Methods for implanting and removal of the device are also provided.

[0010] The invention will become apparent by studying the drawings and the detailed description.

[0011] FIG. 1 is a perspective view of the invention and the installation tool.

[0012] FIG. 2-a to FIG. 2-f are sectional views showing the steps in installing the device using the installation tool.

[0013] FIG. 3 is a perspective “exploded” view of the device.

[0014] FIG. 4 is a perspective “exploded” view of an alternate embodiment.

[0015] FIG. 5 is an “exploded” view of another alternate embodiment.

[0016] FIG. 6-a is a perspective view of an alternate embodiment in the relaxed state.

[0017] FIG. 6-b is a perspective view of the same alternate embodiment in the expanded state.

[0018] FIG. 7-a is a sectional view of the tool used to install the device embodiment of FIG. 6-a in the relaxed state.

[0019] FIG. 7-b is a sectional view of the tool used to install the device embodiment of FIG. 6-a in the expanded state.

[0020] FIG. 8-a to FIG. 8-f are sectional views showing the steps in removing the device,

[0021] FIG. 9-a and FIG. 9-b are perspective views of a device installed on the outside of a catheter.

[0022] FIG. 10 is an “exploded” view of the preferred embodiment.

[0023] FIG. 11 is a “phantom” view of the actuation mechanism.

[0024] FIG. 12-a is a perspective view of the preferred embodiment in the fully open position.

[0025] FIG. 12-b is a perspective view of the preferred embodiment in the retracted position.

[0026] FIG. 13-a to FIG. 13-f are sectional view of the preferred embodiment showing the steps in installing the device.

[0027] Referring to FIG. 1, a hole closure clip 3 is inserted into a body lumen such a cavity in the heart via catheter 1. Catheter 1 has a seal allowing insertion and removal of tools without much blood loss. This is well known in the art of minimally invasive surgery. When the surgical procedure is completed and hole needs to be closed, tube 5 carrying clip 3 mounted on rod 4 is inserted via catheter 1 through the tissue 2. Both rod 4 and tube 5 have flanges 7 and 8 allowing a pulling tool 6 to exert a significant pulling force on rod 4 relative to tube 5. Pulling tool 6 may be made of plastic or metal, plastic being preferred if tool is to be disposable. Rod 4 and tube 5 are preferable made of stainless steel and closure device 3 is made of Nitinol, a highly flexible Nickel.Ti˜anium alloy well known in the art of medical devices. Tool 6 is similar in construction t the well known clothe-pin. Since the elastic range of Nitinol is about ten times larger than steel, the clip 3 can be made to fold into a small diameter tube and expand to grip the tissue over an area significantly larger than the area of the hole, in order to establish reliable closure. When clip 3 is released it tries to return to its natural (relaxed) shape, which covers a significantly smaller area, pulling the tissue with it and forming an instant hemostatic seal. These steps are shown in FIG. 2-a to FIG. 2-f.

[0028] In FIG. 2-a the tube 5 containing the folded clip 3 mounted on rod 4 is inserted via catheter 1 through the wall of the tissue 2. Rod 4 is pushed forward by finger pressure till it is felt that clip 3 is released from tube 5 (or moved till it reaches a pre-determined distance), as shown in FIG. 2-b. At this pint it is pulled back and pulling tool 6 is installed by sliding it on rod 4. Pulling tool 6 can be permanently mounted on rod 4 or slide in and out via two slots as shown in Figi. The slots rest against flanges 7 and 8. Flange 7 is rigidly connected to rod 4 while flange 8 is rigidly connected to tube 5. Using pulling tool 6, rod 4 is pulled out a pre-determined amount which forces clip 3 to open as shown in FIG. 2-c, as it rests against end of tube 5. At this point the whole assembly, including catheter 1, is pulled back to engage the sharp barbs of tool 3 in tissue 2. This is shown in FIG. 2-d. An enlarged view of clip 3 is shown in FIG. 3. In FIG. 3, clip 3 comprises of multiple sharp barbs 11 held by a threaded stem 8. Clip 3, including barbs 11 are made of Nitinol wire typically 0.3-0.8 mm in diameter, Stem 8 can be made of type 316 stainless steel and held to wires by crimping. It contains a threaded portion 10 for attaching to rod 4. The end of rod 4 has a mating thread 12. When clip 3 rests on edge of tube 5 it can be opened widely by pulling rod 4 and barbs 11 can reach over an area having a diameter from 1.5 to over 3 times the diameter of the hole. This is important to achieve proper hemostatic closure. When rod 4 is detached from clip 3, the natural elasticity pulls barb 11 in the direction shown by arrows 13 and the tissue is pulled with them. Centering ferrule 19 on rod 4 keeps the location of clip 3 centered to tube 5, therefore centered to hole in tissue. Returning now to FIG. 2-e, pulling tool 6 is released and removed allowing clip 3 to compress the tissue. Rod 4 is removed by turning flange 7 to unthread rod. After rod is removed the closure can be tested for leaks by leaving tube 5 in place. When used in the heart, any imperfection in closure will cause blood to come out of tube 5. In such a case the clip 3 can be removed and re-installed as shown later on in this disclosure. One verified, both tube 5 and catheter 1 are removed.

[0029] FIG. 4 shows an alternate design for clip 3. The main differences are that the Nitinol wire is bent into a loop 15 to add elasticity and a string 14 is used as a method of holding clip 3 to tube 5. The string can be removed by releasing one end.

[0030] FIG. 5 shows another alternate design, preferred when hole is an elongated cut rather than a round hole. Clip 3 is bent to have barbs 11 move in parallel rather than radially, as shown by arrows 13. Clip 3 is placed with the direction of motion 11 perpendicular to long dimension of hole in tissue. Loops 15 are used to add elasticity, as in FIG. 4.

[0031] FIG. 6 shows yet another alternate design. The clip 3 can be fabricated from Nitinol sheet, tubing or wire. The preferred way would be laser-cut tubing. FIG. 6-a shows the clip in the relaxed state, FIG. 6-b shows it in the expanded state. This design is suitable when a large number of barbs 111 are desired or for thin˜walled lumens.

[0032] The tool used to expand the clip is shown in FIG. 7-a (relaxed state) and FIG. 7-b (expanded state). Rod 4 is equipped with a tapered end 17 used to expand four pivoting arms 16. The sequence of operations is identical to the sequence shown in FIG. 2-a to FIG. 2-f.

[0033] It is desirable to be able to reverse the clip installation and, if needed, remove the clip completely via the same catheter used to install it. The current inventions, in all its forms, allows this to be done. Referring now to FIG. 8-a to FIG. 8-f: the sequence of partial and full removal is shown.

[0034] In FIG. 8-a a dilator 18 is used to expand the opening in the tissue 2 as well as the surrounding tissue, in order to feed tube 5 back into its original position. In FIG. 8-b Rod 4 is inserted in tube 5 and is attached to clip 3 by threading it onto stem 8 of clip 3. Centering ferrule 19 keeps rod 4 aligned with stem 8. Tool 6 in mounted on rod 4 and used to expand slip 3 as shown in FIG. 8-c. Once expanded, the whole assembly of catheter 1 and tube 5 is pushed forward to remove clip 3 from tissue 2, as shown in FIG. 8-d. At this point clip 3 can be re-installed following the steps in FIG. 2-c to FIG. 2—for removed completely by pulling clip into tube 5 as shown in FIG. 8-e and FIG. 8-f. Once clip 3 is fully inside tube 5, it can be easily pulled out by hand using rod 4. If desired, clip 3 can be re-used immediately by pushing it back into tube 5 to assume the position shown in FIG. 2-a. When the clip style shown in FIG. 4 is used, the retrieval tool is equipped with a small hook to engage with loop 15.

[0035] The large elastic range of Nitinol allows full removal without permanently deforming clip 3. Because of this large elasticity, clip 3 can not be manufactured by cold forming. It has to be held in the relaxed position (shown in FIG. 2-b) and heated to about 510 degrees C. for a few minutes. The exact heat treatment details given by the manufacturer of the Nitinol wire have to be carefully followed.

[0036] While the invention will work for any dimension of catheter, the preferred range is for catheters with internal diameters of 4 mm to 15 mm. The Nitinol wire diameter is about 0.4 mm for the 4 mm catheter and about 1 mm for the 15 mm catheter. The thread 10 on stem 8 is from M1 for the 4 mm catheter to M4 on the 15 mm catheter, M2 being a typical value. Tube 5 is made from standard stainless hypodermic tubing. All materials to construct the invention are available from Small Parts Inc (www.smallparts.com). While the detailed description showed a specific embodiment of a clip with four barbs, it is obvious that the inventions covers many other configurations of barbs, made from many materials including materials used to make absorbable sutures and other non-metallic clips. It is also obvious that the invention can be configured to be used on the outside rather than the inside wall of the body lumen by sliding a clip shown in FIG. 6-b on the outside of tube 5 and expanding it with the method shown in FIG. 7-b.

[0037] This is shown in FIG. 9-a (closed position) and 9-b (open position). Tubes 4 and 5 slide over catheter 1 (but can be inside a larger catheter, not shown). Catheter 1 penetrates the wall of tissue 2 but tube 5 only reaches to the outside of tissue 2. Clip 3 is expanded by arms 16 actuated by taper 17 connected to tube 4. Many alternate expansion mechanisms are well known. After clip 3 is embedded in tissue 2, arms 16 are retracted and tubes 4 and 5 are withdrawn.

[0038] The preferred embodiment is shown in FIG. 10 as an “exploded” view. This embodiment used similar clips as the previous embodiments and a slightly more complex installation tool. The main additional advantages of this embodiment are:

• • [0039] ability to locate the tool within a lumen without use of monitoring such as x-ray or ultrasound.
  • [0040] ability to move the tool within the lumen without damage to the surrounding tissue.

[0041] To achieve these and further objectives, the sharp barbs of the clip are covered till ready to be embedded, and the tool provides a positive stop to locate the inside wall of the tissue. In FIG. 10 clip 3 is threaded onto the end of rod 4 via thread 12. A tube 5, made from extruded plastic or metal, has five holes running through it. Four of the holes are used for actuators 20 ending in arms 20′. The fifth hole is for rod 4. Actuators 20 can rotate inside tube 5 approximately 180 degrees, opening and closing clip 3. Actuators 20 engage in corresponding slots 22 in sleeve 21, which is free to rotate over shaft 23 which is clamped to extension 5′ of tube 5. Rod 4 terminates in a section 4′ resting on disc 27. By rotating disc 27 relative to shaft 23, disc 27 is moved axially away from shaft 23. This is achieved via inclined planes 25 and 26 but can be achieved by any one of the well known mechanisms converting rotary to linear motion such as threads, cams etc. When disc 27 is moved axially, it pulls rod 4 with it, causing clip 3 to slide over arms 20′ and expand further. In operation, the tool is held by sleeve 21 and ring 24 is rotated to cause tune 5 to rotate. Since ends of actuators 20 are in slots 22, rotating tube 5 will cause actuators 20 to rotate and expand clip 3. After tool is in position, disc 27 is rotated to pull clip over arms 20′ and embed barbs in tissue, followed by releasing the tool by turning end 4′ of rod 4 to release tool from clip.

[0042] FIG. 11 is an enlarged view of both ends of actuators 20. At the end of each arm 20′ there is a recess 28 into which barbed tip 11 of clip 3 fits. This provides a smooth outside surface till the barbs are exposed, and allows the tool to be moved inside a body lumen without damage. For example, when the device is used inside the heart, it is imperative to avoid snagging or damaging any one of the many cords attached to the valves. Clip 3 is attached to rod 4 via a thread 8 at center of clip.

[0043] FIG. 12-a is a close-up of the mounted clip in the expanded position while FIG. 12-b shows the retracted position. Each one of arms 20′ is semi-circular, with an outside diameter approximately equal that of tube 5. The holes in tube 5 act as the pivot points for arms. At. the outside edge of each arm 20′ there is a recess 28 to hold tip 11 of clip 3. In the retracted position the arms 20′ fold into a circle, overlapping each other. Clip 3 is still resting in recesses 28 of arms 20′. Clearly the semi-circles 20′ are also bent towards thread 8, in order to allow them to fold partially over each other, in a manner resembling a four-start thread. The amount of axial forward bending is approximately equal to twice the diameter of the wire used to make actuator 20.

[0044] By the way of example, tube 4 is extruded plastic with a diameter of 4 to 8 mm. Actuators 20 are made of stainless steel wire having a diameter of 1.2-1.6 mm. Clip 3 is made of 0.3-0.5 mm thick Nitinol sheet or 0.6-0.9 Nitinol wire, as shown in FIG. 3.

[0045] FIG. 13 shows the steps in using the device. It is inserted via catheter 1 as shown in FIG. 13-a. Clip 3 is expanded by rotating ring 24. The expanded arms 20′ provide a reference surface to locate the inner wall of tissue 2 without radiological means. Catheter 1 is pulled backwards till arms 20′ stop at tissue 2, as shown in FIG. 13-c. Barbs of clip 3 are exposed by rotating disc 27 as shown in FIG. 13-d, and are embedded into tissue 2. In FIG. 13-e, ring 24 is further turned to fold the arms 20′ into the retracted position while embedding clip 3 deeper in tissue 2, since rotating disc 24 both folds the arms and pulls on rod 4. After clip 3 is fully embedded in tissue rod 4 is turned to release clip 3 from tool 5. As with the other versions of the invention, the operation is reversible by re-attaching tool to clip. Note that ring 24 is turned to activate tool rather than bushing 21, since clip 3 needs to remain stationary relative to tissue 2 once it is embedded.

[0046] While the examples used an elastic clip, it is obvious that the invention can be practiced with a non-elastic deformable clip. By the way of example, the clip shown in FIG. 6 can be made of annealed stainless steel. The installation tools have to be slightly modified to be able to apply both tension and compression to the clip. Such a modification is shown in FIG. 7, wherein arm 16 has a bent tip 16′ holding clip 3 from both sides. The clip can be deformed plastically from the shape shown in FIG. 6-a to the shape in FIG. 6-b, embedded in tissue 2 and deformed plastically back to the shape of FIG. 6-a. After that tool 5 is pushed forward to disengage from clip, arms 16 retracted and tool pulled out of catheter 1. The words “clip” and “barb” should be interpreted in a broad sense. Any part left behind in the tissue is considered a clip, regardless of actual shape or material. Any part of the clip used for attachment to the tissue is considered a “barb”, regardless of shape, sharpness, material etc. By the way of example, in the context of this invention, an adhesive patch that can be placed over the hole from the inside and pull the hole to close is considered a clip and the adhesive is considered a barb.