MXPA99001842A - Folding device for endoprotesis and method of - Google Patents

Abstract

A slidably engageable device for enabling effective folding of an intravascular stent over a balloon catheter structure. The endoprosthesis folding device includes at least a releasable, compressible loop portion that allows the catheter and stent structure there to be held, and is radially compressed inwardly to effectively fold the stent over the balloon catheter structure.

Description

FOLDING DEVICE OF ENDQPROTESIS AND METHOD OF USE BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a stent-folding device of the type that will allow the user to fold a stent over the distal end of a balloon catheter structure, by example of the type used in a typical Percutaneous Transluminal Coronary Angioplasty Procedure (PTCA = Percutaneous Transluminal Coronary Angioplasty). Description of the Related Art In a typical PTCA procedure for compressing plaque of injury against the arterial wall to dilate the lumen of the artery, a guide catheter is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and it advances through the vasculature until its distant end is in the ostium. A guidewire and a dilatation catheter having a balloon at the distal end are introduced through the guide catheter with the guidewire sliding within the dilatation catheter. The guidewire is first advanced out of the catheter into the patient's coronary vasculature, and the dilatation catheter is moved over the advanced advanced advance guidewire until the dilatation balloon is properly positioned through the lesion. Once in position through the lesion, a pre-formed, expandable, flexible balloon is inflated to a pre-determined size at relatively high pressures to radially compress the arteriosclerotic plaque of the lesion-against the inside of the arterial wall and to thereby dilate the lumen of the artery. The balloon is then deflated to a small profile, such that the dilatation catheter can be removed from the patient's vasculature and the flow of blood through the dilated artery resumed. While this procedure is typical, it is not the only method used in angioplasty. Other methods for opening a vessel such as atherectomies and plaque dissolution drugs are known. In angioplasty procedures of the previously mentioned type, a restenosis of the artery may arise in several months, which may require another angioplasty procedure, a surgical bypass operation, or some method to repair or reinforce the area. To reduce the possibility of development of restenosis and strengthen the area, a physician can implant an intravascular prosthesis to maintain the vascular opening, typically called a stent. A stent is a device used to hold tissue in place in a vessel or to provide support for a vessel, to keep the vessel open so that blood flows freely. A variety of devices are known in the art for use as stents, including expandable tubular members, in a variety of patterns, which are capable of being folded over a balloon catheter and then expanded after intraluminal placement in the balloon catheter, and they retain their expanded form. Typically, the stent is loaded and folded over the portion of the catheter balloon and advanced to a site within the artery in the lesion. The stent is then expanded to a large diameter by the balloon portion of the catheter to implant the stent into the artery in the lesion. Examples of stent and delivery catheters as described are illustrated in more detail in U.S. Patent Nos. Nos. 5,102,417 (Palmaz), 5,569,295 (Lam), and 5,514,154 (Lau et al.). However, if the stent is not effectively folded over the balloon portion of the catheter, when the catheter is advanced into the vasculature of the patient, the stent may move or even slip out of the balloon portion of the catheter into the body lumen or artery. coronary before expansion, and may block blood flow, requiring procedures to remove the stent.

In procedures where the stent is placed over the portion of the catheter balloon, the endoprosthesis must be folded over the balloon portion to prevent the stent from sliding out of the catheter when the catheter is advanced into the vasculature of the patient. In the past, this fold was often done by hand, which does not provide optimal results due to the non-uniform force applied, and will result in non-uniform folds. In addition, it was difficult to judge when a uniform and reliable fold had been applied. The tools and methods of the prior art have not been completely adequate to achieve a uniform folding. Stent designs are generally based on a uniform metal-to-artery ratio for the highest success rate, so a stent that is not uniformly folded can result in a stent that is not evenly expanded in the vessel or artery, which It is inconvenient. SUMMARY OF THE INVENTION This invention is directed to a vascular prosthesis folding device that allows uniform and firm folding of a stent over a portion of a catheter balloon to better hold the stent over the catheter for delivery of the stent through the stent. vasculature of the patient. The present invention attempts to solve several problems associated with folding stent over balloon catheters. In an exemplary embodiment of the present invention, the endoprosthesis folding device includes a releasable, compressible loop portion of a flexible sleeve in a hand tool, held at its opposite ends with slidably engageable members of the hand tool. The loop portion is compressed radially inwardly with application of compressive force slidably engageable to the hand tool by the user, to uniformly and tightly fold the stent onto the balloon catheter structure. The loop portion is further released when the wearer releases the compressive force that is applied to the hand tool, to allow release of the folded stent onto the balloon catheter structure. The folding device allows the stent to fold uniformly and tightly over the distal end of a balloon catheter, reducing the risk that the stent may slip out of the catheter balloon portion. It is also easy to use when performing the procedure of stent folding. In an exemplary method of folding the stent over the balloon portion of a catheter, the folding device is designed to be held by hand and the folding method is performed by one person. The endoprosthesis is first preloaded onto the balloon by sliding the stent over the deflated balloon. The balloon catheter and stent structure is positioned or disposed within the radially compressible device and held therein such that the stent and globe are placed within the loop portion of the flexible sleeve. While the user holds the stent and balloon catheter assembly with one hand, a compressive force is applied using the other hand by applying force slidably engageable with the folding device. Since the loop portion restricts the diameter, it will compress the stent uniformly and firmly or tightly over the balloon portion of the catheter. Subsequently, the user releases the force of. compression, thereby releasing the tension in the loop such that the stent, now firmly compressed on the portion of the catheter balloon, can be withdrawn in a folding device. These and other advantages of the invention will become more apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of an exemplary embodiment of the present invention, wherein the slidably engageable member slidably moves in engagement with the receiving member; FIGURE 2 is a side elevational view of the exemplary embodiment of the present invention in the expanded loop portion condition. FIGURE 3 is a side elevation view of the exemplary embodiment of the present invention wherein the loop portion of the hand tool is in a compressed condition to fold the stent over the portion of the catheter balloon. FIGURE 4 is a side elevational view of the slidable coupling member and the first fastening member. FIGURE 5 is a top plan view of the slidable coupling member and the first clamping member, which is taken on line 5-5 of FIGURE 4. FIGURE 6 is an end view of the first clamping member that is take on line 6-6 of FIGURE 5. FIGURE 7 is a side elevation view of the receiving member and the second holding member.

FIGURE 8 is a top plan view of the receiving member and second holding member taken on line 8-8 of FIGURE 7. FIGURE 9 is an end view of the second holding member that is taken on the line 9-9 of FIGURE 8. FIGURE 10 is a perspective view illustrating one embodiment of the loop portion. FIGURE 11 is a perspective view illustrating an alternate embodiment of the loop portion. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES A device 10 comprises a tool 20 for enabling effective folding in an intravascular stent 5 over the portion of the squashed balloon 6 adjacent the distal end 7 of the balloon catheter structure 8. In an exemplary embodiment of device 10, as illustrated in FIGS. Figures 1 to 9, the tool 20 is adapted to be held in the user's hand, to allow the stent 5 and catheter 8 to be held in the tool 20, and to allow the user to apply compression force to the tool 20 for folding the stent on the catheter. The tool 20 includes a receiver member 22, and a slidably engageable member 24 that slidably moves in engagement with the receiver member 22.

The slidable engagement member 24 includes a handle portion 26, and a projecting portion 28 that slidably engages with the receiving member. The receiving member 22 has a slot 30 there. The projecting portion 28 of the slidably engageable member 24 and the slot 30 of the receiver member 22 engage and are generally complementary in shape. The receiving member 22 and the slidable coupling member 24 are both preferably translucent. The tool 20 further includes a folding member 32 attached at its ends to the slidably engageable member 24 and the receiving member 22, to hold the stent 5 and the catheter 8 there. The folding member 32 includes a first end 34, adapted to be clamped with the slidably engageable member 24 and a second end 36, at the end of the folding member 32 opposite the first end, adapted to be attached to the receiving member 22. A first clamping member 38 is adapted to hold the first end 34 to the slidably engagable member 24 and a second clamping member 40 is adapted to hold the second end 36 to the receiving member 22. The folding member 32 further includes at least a portion of the loop compressible 42 wherein the portion of the balloon catheter structure 8 with the loaded stent 5 can be held. The folding member 32 is comprised of compressible material, such that by sliding the slidably engageable member 24 into engagement with the receiving member 22, the loop portion 42 is compressed radially inwardly, to fold the stent 5 over the portion of balloon 6. In other words, the diameter of the loop portion 42 decreases as the receiving member 22 and the slidably engagable member 24 are compressed together, thereby folding the stent 5 onto the balloon portion 6. When releasing the force applied by the slidably engageable member 24 by pulling the slidably engageable member 24 out of engagement with the receiving member 22, the folded stent 5 and the catheter can be removed from the loop portion 42. The compressible material of which the folding member 32 is formed, preferably is a film polyester, such as that sold under the MYLAR brand by EI duPont de Nemours Company of Wilmington, Delaware. If the receiving member 22 and the slidably engagable member 24 are repeatedly compressed together, the stent will fold even more tightly over the balloon. In the embodiment shown in Figures 1 to 9, the slidably engageable member 20 to 24 includes the recessed portion 44 that includes a plurality of projection pins 46 and the first fastening member 38 includes a slot 48 for coupling the folding member. 32 and the plurality of pins 46, for aligning and holding the folding member 32 to the slidably engageable member 24. The second holding member 40 includes a front surface 50 comprising a plurality of pegs 52 projecting therefrom, and the member receiver 22 includes a slot 54 for coupling the folding member 32 and the pins of the second holding member 52, to align and hold the folding member 32 to the receiving member 22. As seen in Figures 11 and 12, two alternate embodiments of the folding member 32 are illustrated. The loop portion 42 includes a plurality of loops and is dimensioned to accept the stent 5 and the balloon portion 6 of the catheter before bending. As the slidably engageable member 24 and the receiver member 22 are pushed together, the first end 34 of the folding member and the second end 36 of the folding member move in opposite directions, thereby restricting the loop portion 42 on the stent. and folding it over the balloon in increased force. As illustrated in Figures 10 and 11, in order to hold the folding member 32 and assist in positioning the first end 34 and the second end 36 of the bending member in tension, the holes 35 in the second end align with the pins 52 at the second end and holes 37 at the first end align with pins 46 at the first end. In this way, the first and second ends 34, 36 of the folding member are securely connected to the respective sets of pins, such that according to the receiving member 22 and the slidably engageable member 24 are compressed together, the first and second ends 35, 37 move with the pins 46, 52. In operation, to load the stent 5 onto the flattened globe portion 6 of the balloon catheter structure 8, the stent 5 is mounted on the balloon in such a way that the The stent superimposes the portion of the balloon but does not fold over. To allow the endoprosthesis 5 to be folded over the catheter balloon portion 6, the stent and the catheter balloon portion can be inserted and held in the loop position 42 of the bending member for tool holder 32. At this point, the stent 5 does not fold over the balloon because it has not been compressed. To fold the stent 5 over the portion of the catheter balloon 6, the user of the tool 20 holds the ends 34, 36 of the folding member 32 to the slidable engageable member 24 and the receiving member 22. The folding member 32 is attached to the slidably engagable member 24, by placing the first end 34 of the folding member 32 between the pins 46 in the recessed portion 44 of the slidably engageable member 24 and pressing the slot 48 in the first clamping member 38, in engagement with the folding member 32 and the pins 46 on the slidable engagable member 34. The folding member 32 is fastened to the receiving member22 when placing the second end 36 of the folding member 32 between the pins 52 on the front surface .50 of the second clamping member 40 and pressing the pins 50 in the second clamping member 40 in engagement with the folding member 32 and the tool 54 in the receiving member 22. The use of the tool 20 can then apply force to slide the slidably engageable member 24 in engagement with the receiving member 22, such that as the projecting portion 28_ of the slidably engagable member 24 pushes the folding member 32, attached at both ends 35, 37 within the slot 30 of the receiver member 22. This movement will then move the first end 34 and the second end 36 in opposite directions, which causes the diameter of the loop portion 42 to be smaller and compress radially inwardly , thereby compressing the endoprosthesis 5 radially inwardly over the portion of the catheter balloon 6. After the stent 5 has collapsed. On the portion of the catheter balloon 6, the user can release the force applied to the folding member 32 by pulling the slidably engageable member 24 out of engagement with the receiving member 22. This movement allows the loop portion 42 to increase in length. diameter. The user again can release the folding member 32 from being held by the first clamping member 38 and the second clamping member 40, by detaching the first member 38 from the folding member 32 and the slidably engagable member 24 and detaching the second member. clamp 40 of the bending member 32 and the receiving member 22, allowing removal of the folded stent and the catheter balloon portion of the loop portion 42. The catheter structure of the balloon 8, with the stent 5 folded over , is ready to be inserted over the patient's body for deployment there of the stent. A novel feature of the present invention is the ability of the folding tool to vary the restriction of the various parts of the stent. In this way, the stent will fold more tightly over the balloon at some sites, locating the traction (interface) between the stent and the balloon. Even when there are variations in the folding force experienced by the endoprosthesis, the force remains within the limits of uniformity. In the case of a stent for coronary artery, the folded stent may have a diameter over its length in the range of 0.0762 mm to 0.127 mm (0.003 to 0.005 in) and still be considered a uniform fold with good traction or good holding force on the globe. While the preferred embodiment of the disclosed endoprosthesis is intended to be an intraluminal vascular prosthesis for use within a blood vessel and the balloon delivery catheter is the same or similar to that used in therapeutic coronary angioplasty, it will be appreciated by those with skill in the art that modifications to the present invention can be made to allow the present invention to be used to fold any type of prosthesis. The present invention is not limited to endoprostheses that deploy in the vasculature of a patient, but has wide applications for folding any type of graft, prosthesis, lining or similar structure. In addition, the endoprosthesis can be delivered not only in coronary arteries but in any body lumen. Other modifications to the present invention may be practiced by those skilled in the art without departing from its scope.

Claims (3)

1. CLAIMS 1. - A device for supporting with the mana, for folding an endoprosthesis on a balloon catheter structure, characterized in that it comprises: means for supporting a portion of the balloon catheter structure in which the endoprosthesis can be loaded, the support means have a compressible portion that is compressed radially inward before the application of force to fold the stent over the catheter portion and is releasable when the applied force is released to release the catheter portion and folded stent; and means for allowing force to be applied to the support means and to be slidably and dockable mobiles, to enable the user to apply slidably engageable compression force to generate -compression, radially inwardly of the compressible portion of the support means, for folding the stent over the catheter portion. 2. - A device according to claim 1, characterized in that the compression portion of the support means comprises a sleeve that includes at least one loop to support the endoprosthesis and the catheter portion and to allow folding of the endoprosthesis on the catheter portion. 3. - A device according to claim 1, characterized in that the means for applying force include means for receiving the compressible portion of the support means. 4. - A device according to claim 2, characterized in that the sleeve is constituted by flexible material. 5. A device according to claim 3, characterized in that the means for allowing application of force also comprise means capable of slidably engaging the receiving means for compressing the compression portion of the support means. 6. - A device according to claim 3, characterized in that the receiving means include a slot. 7. - A device according to claim 3, characterized in that the reception means are constituted by a translucent material. 8. A device according to claim 4, characterized in that the flexible sleeve material comprises a polyester film. 9. A device according to claim 5, characterized in that the means for allowing application of force also comprise means for holding the compression portion of the support means to the slidably engageable means and the receiving means. 10. - A device according to claim 5, characterized in that the slidably coupling means include a handle portion, and a projecting portion slidably engaging with the receiving means. 11. A device according to claim 9, characterized in that the compression portion of the support means comprises a second portion and the securing means comprise means for holding the first portion of the compressible portion of the support means to the means of reception. 12. A device according to claim 10, characterized in that the receiving means includes a slot, and the projecting portion of the slidably engaging means and the slot of the receiving means are generally complementary in shape. 13. - A device according to claim 11, characterized in that the compression portion of the support means further comprises a second portion and the securing means further comprise means for holding the first portion of the compressible portion of the support means to slidable coupling means. 1 . - A method for folding an intravascular stent over a balloon catheter structure, characterized in that it comprises: placing a portion of the balloon catheter structure in which the stent is placed in a radially compressible device; applying slidably engageable compression force, to compress the compression device radially inward, to fold the stent over the balloon catheter structure, and release the compression force to allow removal of the balloon catheter structure and the folded stent. 15. - A method according to claim 14, characterized in that the step of placing the balloon catheter and stent structure in the radially compressible device, comprises placing the balloon catheter structure in a compressible portion of means for supporting the endoprosthesis and the balloon catheter structure in a device adapted to be held in the user's hand, in order to allow the user to apply the compressive force. 16. - A method according to claim 14, characterized by the step of supporting the structure of balloon catheter and stent-in the radially compressible device, comprises supporting the structure of balloon catheter and stent at least in a loop in a sleeve and the step of applying force to the compression device comprises applying force to at least one loop in the sleeve. 17. A method according to claim 14, characterized by the step of applying compressive force to the compressible device, comprising applying force to a slidably engageable member and a receiving member to which the compression portion of the stent is clamped and the support means of the balloon catheter structure, and compressing the slidably engageable member and the receiving member, to compress the support means for folding the stent over the catheter. 18. An intravascular stent folded over a portion of a balloon catheter structure, characterized in that it comprises: a portion of a balloon catheter structure; and a stent grafted onto the balloon catheter structure by compression force applied through a device adapted to be held in the user's hand, comprising a slidably engageable member and a receiving member. 19. A folding tool for uniformly and tightly folding an endoprosthesis over the balloon portion of a catheter, characterized in that it comprises: a folding member having a flexible sleeve, the flexible sleeve has a loop portion capable of change from a larger first diameter to a smaller second diameter; a receiving member configured for sliding engagement with a projecting member, the receiving member and the projecting member having generally complementary shapes ergonomically designed to fit the hand of a user; the flexible sleeve has a first end and a second end, the ends are connected to the projecting member, such that when the balloon and stent portion are placed within the loop portion, the user will slidably engage the receiving member and the limb. projecting to pull the ends of the flexible sleeve, which in turn will restrict the loop portion from the first largest diameter to the second smallest diameter, thereby applying compression forces to tightly fold the stent over the portion of the catheter balloon. 20. A folding tool according to claim 19, characterized in that the receiving member has a groove configured to receive the projecting member in a complementary manner. 21. - A folding tool according to claim 19, characterized in that the folding tool is formed from a substantially rigid material. 22. - A folding tool according to claim 19, characterized in that the flexible sleeve of the folding member is formed of plastic material. 23. - A folding tool according to claim 19, characterized in that the first end of the flexible sleeve of the folding tool is connected to the receiving member by a second clamping member and the second end of the flexible sleeve is connected to the projecting member by a first clamping member. 24. - A folding tool according to claim 23, characterized in that the first end and the second end of the flexible sleeve are aligned by a plurality of pins projecting through the ends and into the second and first clamping members . 25. A folding tool according to claim 19, characterized in that the flexible sleeve of the folding member has a plurality of loop portions capable of changing from the first larger diameter to the second smaller diameter, in order to apply a folding force, to fold the stent over the portion of the catheter balloon. 26. A folding tool according to claim 25, characterized in that the folding force applied to the stent by the plurality of loop portions, varies over the length of the stent.