US20150134056A1 - Catheter deliverable artificial multi-leaflet heart valve prosthesis and intravascular delivery system for a catheter deliverable heart valve prosthesis - Google Patents

Abstract

A heart valve prosthesis includes a collapsible stent and a one-piece multi-leaflet valve. The stent includes at least one length of wire having a series of turns forming a spring-like stent. The one-piece multi-leaflet valve is attached to the stent and includes a cylinder of polyester material secured thereto at three points. The stent is collapsible in a radial direction between a contracted state and an expanded state. The contracted state has a radial dimension smaller than a radial dimension of the expanded state. The stent is spring biased toward the expanded state such that it occupies an active state when implanted into a heart. The active state has a radial dimension that is between the radial dimension of the contracted state and the radial dimension of the expanded state such that a radial load generated by the bias of the collapsible stent is sufficient to retain the heart valve prosthesis in the heart.

Description

RELATED APPLICATIONS
• The priority benefit of U.S. Provisional Patent Application No. 61/032,636, filed Feb. 29, 2008 is hereby claimed and the entire contents thereof are incorporated herein by reference.
FIELD OF THE DISCLOSURE
• The present disclosure is generally directed to an artificial heart valve and, more particularly, to a catheter deliverable artificial heart valve and delivery system therefor.
BACKGROUND
• The heart is the organ responsible for keeping blood circulating through the body. This task would not be possible if it was not for the action of valves. Four heart valves are key components that facilitate blood circulation in a single direction, and that the contraction force exerted by the heart is effectively transformed into blood flow.
• Each time the heart contracts or relaxes, two of the four valves close and the other two open. There are two states of the heart: relaxed or contracted. Depending on the state of the heart, a heart valve has two specific functions: either to open smoothly without interfering blood flow or to close sharply to impede the flow in the opposite direction.
• The anatomy of the heart allows it to simultaneously maintain the flow of the two major blood circuits in the body: pulmonary circulation and systemic circulation, which also includes the coronary circulation. This simultaneous action of keeping blood flowing through both circuits requires that the heart valves work in pairs, namely, the tricuspid and the pulmonary valve work together to direct the flow toward the lungs, and the mitral and aortic valves direct the flow toward the rest of the body including the heart.
• From the two circulations, the systemic circulation is the one that demands most of the energy of the heart because it operates under higher pressures and greater flow resistance. Consequently, the left heart is more susceptible to valve disorders. This condition makes the aortic and mitral valves primary subjects of research.
• According to the American Heart Association it is estimated that around 19,700 people in the United States die every year from heart valve disease, and another 42,000 die from different causes aggravated by valvular problems. During 1996, 79,000 heart valve replacements were carried out in the United States, a quantity that was reported to increase by 5,000 more replacements by 1997. Although improvement has been evident in this area of medical treatments, still a mortality rate between 30% and 55% exists in patients with valvular prostheses during the first 10 years after surgery.
• The aortic valve, representing almost 60% of the valve replacement cases, is located at the beginning of the systemic circulation and right next to the coronary ostia. Once the aortic valve closes the oxygenated blood flows into the heart through the right and left coronary arteries.
• The mitral valve, located between the left atrium and the left ventricle offers a different set of conditions. Although the mitral valve is not surrounded by any arterial entrances, it is located in a zone with greater access difficulties, and its anatomical structure contains a set of “leaflet tensors” called chordae tendinae.
• The human application of prosthetic heart valves goes back to 1960 when, for the first time, a human aortic valve was replaced. Since then, the use of valvular implants has been enhanced with new materials and new designs.
• The first mechanical valves used a caged-ball mechanism to control blood flow. Pressure gradients across the occluder-ball produced its movement to close or open the flow area. Even though this design performed the function of a valve, there were several problems associated with it: The ball geometry and the closing impact of the ball against the cage ring were both causes of large downstream turbulence and hemolysis. In addition to blood damage, obstruction to myocardial contraction and thrombogenic materials were also problems.
• Several designs having new materials including disks or leaflets instead of balls, improved the hemodynamic performance and durability of the implants, but two critical aspects remain pending for better solutions: 1) the highly invasive surgery required to implant the prosthesis, and 2) the thrombogenic effect of the implant's materials.
• Typically, mechanical heart valve prostheses are made from pyrolytic carbon or other prosthetic materials that require rigorous anticoagulant therapy because the risk of coagulation is higher over the surface of the prosthesis. The thrombogenic aspect has drawn the attention of many biomedical institutions towards the creation and study of more biocompatible materials.
• Currently, prosthetic heart valve technology includes several designs with disks or leaflets integrated into a rigid stent. This rigid stent is generally surrounded by a sewing cuff which allows the surgeon to suture the interface between the cuff and the tissue. This procedure, however, is highly invasive and its materials generally have a negative thrombogenic effect.
• Prosthetic heart valves with rigid stents require open heart surgery for implantation. During the implantation procedure the patient is maintained alive by a heart-lung machine while the surgeon sutures the device into the heart. Due to the highly invasive nature of this procedure, not all individuals suffering from heart valve disease are considered proper candidates.
• In those cases where a heart valve replacement has been performed, the risk of coagulation of blood becomes higher over the surface of the prosthesis. Mechanical heart valve prostheses made from pyrolytic carbon or other prosthetic metals require rigorous anticoagulant therapy. Other prosthetic valves use animal tissues, with which the thrombogenic effect is not as severe as for other materials, but durability is noticeably lower. Specifically, prosthetic valves constructed using animal tissue are prone to hardening as a result of being rejected by the body. Such hardening and rejection can ultimately lead to less than optimal performance.
SUMMARY
• A heart valve prosthesis includes a collapsible stent and a one-piece multi-leaflet valve. The stent includes at least one length of wire having a series of turns forming a spring-like stent. The one-piece multi-leaflet valve is attached to the stent and includes a cylinder of polyester material secured thereto at three points. The stent is collapsible in a radial direction between an expanded state and a contracted state. The contracted state has a radial dimension smaller than a radial dimension of the expanded state. The stent is spring biased toward the expanded state such that it occupies an active state when implanted into a heart. The active state has a radial dimension that is between the radial dimension of the contracted state and the radial dimension of the expanded state such that a radial load generated by the bias of the collapsible stent is sufficient to retain the heart valve prosthesis in the heart.
• In one embodiment, the one-piece multi-leaflet valve further comprises a cylindrical cuff wrapped around an end of the collapsible stent. The cylindrical cuff is for preventing regurgitation during use of the valve.
• In one embodiment, the multi-leaflet valve further comprises a polymer coating the polyester material.
• Another embodiment further includes surgical sutures connecting the one-piece multi-leaflet valve to the collapsible stent.
• In one embodiment, the collapsible stent includes first and second lengths of wire, each of the first and second lengths of wire occupying a sinusoidal pattern.
• In one embodiment, the first and second lengths of sinusoidal wires are disposed adjacent to each other and in opposite phase to provide structural integrity to the collapsible stent.
• In one embodiment, the collapsible stent further includes a third length of wire occupying a pattern of alternating bows and attached to the first and second lengths of wires at a location axially offset therefrom. The third length of wire serves to bias the collapsible stent into the expanded state.
• In one embodiment, the collapsible stent is constructed of a shape memory nickel titanium alloy.
• In one embodiment, the collapsible stent occupies a generally tapered cylindrical shape at least when in the expanded state.
• In one embodiment, the multi-leaflet valve includes a trileaflet valve.
• Another aspect of the present disclosure includes a system for intravascular delivery of a heart valve prosthesis. The system includes a handle, a flexible elongated sheath, a cavity defined by the sheath, and a tapered tip. The flexible elongated sheath extends from the handle. The cavity is defined by an end of the elongated sheath that is disposed opposite the handle. The cavity is adapted to contain a heart valve prosthesis during intravascular delivery of the heart valve prosthesis. The tapered tip is coupled to the end of the elongated sheath adjacent to the cavity. The tapered tip is adapted to guide the elongated sheath during intravascular delivery of the heart valve prosthesis. The tapered tip and the elongated sheath are separable such that the heart valve prosthesis can be released from the cavity in the elongated sheath upon proper positioning of the heart valve prosthesis.
• In one embodiment, the elongated sheath has an inner diameter of less than or equal to 7 mm and an outer diameter of less than or equal to 8 mm.
• One embodiment further includes a string connected to the elongated sheath at a location adjacent the cavity and extending through the sheath to the handle. So configured, a user can pull the string to bend the elongated sheath to facilitate navigation of the elongated sheath during intravascular delivery of the heart valve prosthesis.
• One embodiment further includes a stop plug disposed in the elongated sheath adjacent the cavity. The stop plug prevents the heart valve prosthesis from traveling into the elongated sheath beyond the cavity.
• In one embodiment, the elongated sheath is movably mounted to the handle such that movement of the sheath toward the handle separates the elongated sheath and the tapered tip.
• Another aspect of the present disclosure includes a device for loading a collapsible heart valve prosthesis into a flexible elongated sheath of an intravascular heart valve delivery system. The device includes a handle, a pin, and a loop of material. The pin is rotatably mounted to the handle. The loop of material has a first end fixed to the handle and a second end fixed to the pin. The loop of material is adapted to receive a collapsible heart valve prosthesis in an expanded state. The pin is rotatable relative to the handle to roll the loop of material onto the pin, thereby applying a radial force to collapse the heart valve prosthesis from the expanded state to a contracted state. A radial dimension of the collapsible heart valve prosthesis in the contracted state is less than a radial dimension of the collapsible heart valve prosthesis in the expanded state such that the collapsible heart valve prosthesis in the contracted state can be loaded into the flexible elongated sheath of the intravascular heart valve delivery system.
• In one embodiment, the pin includes a slot formed therein that receives the first end of the loop of material.
BRIEF DESCRIPTION OF THE DRAWINGS
• Objects, features, and advantages of the present invention will become apparent upon reading the following description in conjunction with the drawing figures, in which:
• FIG. 1 is a cross-sectional representation of a heart;
• FIG. 2 is a cross-sectional representation of a heart including a collapsible heart valve prosthesis constructed in accordance with the teachings of the present disclosure;
• FIGS. 3A-3C are side, top, and bottom views, respectively, of a collapsible heart valve prosthesis constructed in accordance with the teachings of the present disclosure;
• FIG. 4 is a cross-sectional side view of a system for intravascular delivery of a collapsible heart valve prosthesis constructed in accordance with the teachings of the present disclosure;
• FIGS. 5 and 6 are detailed views of the system for intravascular delivery of a collapsible heart valve prosthesis of the present disclosure, illustrating its use and taken from circle V, VI ofFIG. 4; and
• FIGS. 7 and 8 are side views of a device for loading the system ofFIGS. 4-6 with a collapsible heart valve prosthesis constructed in accordance with the teachings of the present disclosure.
DETAILED DESCRIPTION OF THE DISCLOSURE
• FIG. 1 is a schematic cross-sectional illustration of the anatomical structure and major blood vessels of ahuman heart10. Deoxygenated blood is delivered to theright atrium12 of theheart10 by the superior andinferior vena cava14,16. Blood in theright atrium12 is allowed to pass into theright ventricle18 through thetricuspid valve20. Once in theright ventricle18, theheart10 delivers this blood through the pulmonary valve to the pulmonary arteries and to the lungs for a gaseous exchange of oxygen. The circulatory pressures carry this blood back to the heart via thepulmonary veins26 and into theleft atrium28. Filling of theleft atrium28 occurs as themitral valve30 opens to allow blood to be drawn into theleft ventricle32 for expulsion through theaortic valve34 and on to the body extremities through theaorta36. Theaorta36 comprises (i) an ascendingaorta38, which arises from theleft ventricle32 of theheart10, (ii) anaortic arch10, which arches from the ascendingaorta38 and (iii) a descendingaorta42, which descends from theaortic arch35 towards the abdominal aorta (not shown). When theheart10 fails to continuously produce normal flow and pressures, a disease commonly referred to as heart failure occurs.
• One cause of heart failure is failure or malfunction of one or more of the valves of theheart10. For example, theaortic valve34 can malfunction for several reasons. Theaortic valve34 may be abnormal from birth (e.g., bicuspid, calcification, congenital aortic valve disease), or it could become diseased with age (e.g., acquired aortic valve disease). In such situations, it can be desirable to replace the abnormal ordiseased valve34.
• FIG. 2 is a schematic illustration of theheart10 implanted with aheart valve prosthesis100, which is constructed in accordance with one embodiment of the present disclosure. InFIG. 2, theheart valve prosthesis100 replaces the nativeaortic valve34 and includes aninlet100aand anoutlet100b. Theoutlet100bis naturally located downstream from theinlet100aalong the flow of blood through theaorta36. Theheart valve prosthesis100 will be described in detail below. Additionally, a means for and method of delivering theheart valve prosthesis100 using an intravascular delivery system300 (shown inFIG. 2) is described below.
• While the following disclosure primarily focuses on replacing or repairing an abnormal or diseasedaortic valve34, the various features, aspects, structures, and methods disclosed herein are applicable to replacing or repairing the mitral30, pulmonary22, and/or tricuspid20 valves of theheart10 as those of ordinary skill in the art will appreciate. In addition, those of ordinary skill in the art will also recognize that the various features and aspects of the methods and structures disclosed herein can be used in other parts of the body that include valves or can benefit from the addition of a valve, such as, for example, the esophagus, stomach, ureter and/or vesice, biliary ducts, the lymphatic system and in the intestines.
• Referring now toFIGS. 3A-3C, one embodiment of theheart valve prosthesis100 of the present disclosure will be described. In general, theheart valve prosthesis100 includes astent102 and amulti-leaflet valve104. Thestent102 is collapsible to facilitate intravascular delivery to theheart10, with a catheter for example, as will be described below.
• Themulti-leaflet valve104 includes a one-piece valve component, i.e., it is constructed from a single piece of material, positioned at theinlet100aof theprosthesis100. More specifically, themulti-leaflet valve104 includes a single piece of material having a generallycylindrical valve portion104aand a generallycylindrical cuff portion104b. Because themulti-leaflet valve104 is constructed from a single piece of material, thecuff portion104brolls outward and back upon or concentric with thevalve portion104a. As such, thevalve portion104ais disposed inside of thestent102 and thecuff portion104bis disposed outside of thestent102. So configured, thecuff portion104bserves to reduce or prevent regurgitation when the prosthesis is implanted in theheart10, as depicted inFIG. 2. In the disclosed embodiment, themulti-leaflet valve104 is secured to thestent102 at a plurality of locations using conventional surgical sutures, but it should be appreciated that other devices for fixing the two components together are intended to be within the scope of the disclosure.
• As shown inFIG. 3B, thevalve portion104aof themulti-leaflet valve104 is secured to thestent102 at three distinct points, each of which are identified with reference numeral103. So secured, thevalve portion104aincludes threewalls105 defined as being located between the points103. Each of thewalls105 serves as one leaflet of themulti-leaflet valve104, thereby defining themulti-leaflet valve104 as a trileaflet valve. In other embodiments, themulti-leaflet valve104 can include more or less than three leaflets, as desired.
• In one embodiment, themulti-leaflet valve104 is constructed of a polymer-coated polyester material. The polyester material can include Dacron™, which is commercially available from Bard Peripheral Vascular of Tempe, Ariz., USA, and the coating can include Quatromer™, which is commercially available from Innovia, LLC of Miami, Fla., USA.
• In the disclosed form of the prosthesis, thestent102 includes at least one length of wire bent and shaped such that thestent102 has a multitude of turns forming a spring-like member that is resiliently deformable between an expanded state (shown inFIGS. 3A-3C) and a contracted state (not shown), wherein thestent102 is collapsed upon itself in the radial direction. That is, in the contracted state, theprosthesis100 has a radial dimension that is smaller than a radial dimension of theprosthesis100 in the expanded state.
• So configured, thestent102 is biased toward the expanded state. When theprosthesis100 is positioned in theheart10, as depicted inFIG. 2, it occupies an active state that can be between the contracted state and the expanded state, for example, wherein theprosthesis100 frictionally and forcefully engages the wall of theheart10. This design therefore advantageously secures the position of theprosthesis100 in theheart10 without requiring any fasteners, mechanical or otherwise.
• With continued reference toFIGS. 3A-3C, thestent102 of the disclosed embodiment of theprosthesis100 is formed such that the prosthesis occupies a generally tapered cylindrical shape. Thestent102 includes first through third lengths of wire, which are numbered106,108, and110, respectively. Other embodiments can have less than or more than three lengths of wire. The first and second lengths of wire106,108 of the disclosed embodiment each occupy a wave pattern and are shaped into cylinders. In the present embodiment, the cylinders are generally tapered cylinders and the wave patterns constitute sinusoidal waves.
• The second length of wire108 is positioned radially inside of the first length of wire106 and circumferentially offset therefrom. The first and second lengths of wire106,108 are secured together at a plurality of locations with conventional surgical sutures, but other devices for securing the two components together are intended to be within the scope of the disclosure. So configured, the sinusoidal patterns of the first and second lengths of wire106,108 can be described as being opposite in phase. That is, each peak106aof the first length of wire106 is aligned with each trough108bof the second length of wire108, and each peak108aof the second length of wire108 is aligned with each trough106bof the first length of wire106. For the sake of clarity,FIG. 3A only identifies onepeak106a,108aand one trough106b,108bon each of the first and second lengths of wire106,108 with reference numerals. So configured, the first and second lengths of wire106,108 provide structural rigidity and integrity to thestent102 and therefore, to theprosthesis100.
• The third length ofwire110 of thestent102 of theprosthesis100 depicted inFIGS. 3A-3C is also generally shaped as a tapered cylinder at least in the expanded state, and is attached to either or both of the first and second lengths of wire106,108 at a plurality of locations with conventional surgical sutures. In other embodiments, the third length ofwire110 could be attached to the first and second lengths of wire106,108 with any other foreseeable device. In contrast to the sinusoidal patterns of the first and second lengths of wire106,108, however, the third length ofwire110 includes a wave pattern that also includes alternating bows. That is, the third length ofwire110 includes a plurality ofpeaks110aandtroughs110b, but instead of thepeaks110aandtroughs110bhaving smooth sinusoidal transitions, each includes abow112. Thebows112 basically constitute small loops of wire extending away from thepeaks110aandtroughs110bof the third length ofwire110. This design of the third length ofwire110 advantageously increases the radial stiffness of thestent102, which increases the radial load generated by the prosthesis when it occupies the contracted and/or active states. Thus, it may be said that the third length ofwire110 is primarily responsible for generating the radial load required for securing the prosthesis in theheart10, while the first and second lengths of wire106,108 are primarily responsible for maintaining the structural integrity of theoverall prosthesis100.
• In one embodiment, the first, second, and third lengths ofwire106,108,110 each comprises a continuous piece of a shape memory nickel titanium alloy such as Nitinol. Thewires106,108,110 may be bound at the free ends with a length of stainless steel hypo-tubing and an adhesive, for example. In one form, the Nitinol wires are heat treated to retain the shapes and patterns illustrated inFIGS. 3A-3C. In other embodiments of theprosthesis100, thewires106,108,100 can be constructed of generally any other biocompatible material capable of serving the purpose of thestent102.
• As mentioned above, theheart valve prosthesis100 of the present disclose is designed to be implanted via intravascular delivery. One device for accomplishing such a delivery is depicted inFIGS. 4-6. Specifically,FIGS. 4-6 depict one embodiment of asystem300 for intravascular delivery of theheart valve prosthesis100, which includes, for example, a catheter. Thesystem300 generally comprises a handle302, an elongatedflexible sheath304, and atip306. In practice, thesheath304 can be rather long, but for the sake of clarity,FIG. 4 illustrates thesheath304 only at its end sections adjacent the handle302 and thetip306.
• During use, thesheath304 is adapted to store aheart valve prosthesis100 in acavity308 formed adjacent to thetip306. As such, thesheath304 would preferably have an inner diameter of less than or equal to 7 millimeters and an outer diameter of less than or equal to 8 millimeters to sufficiently accommodate the large payload of theheart valve prosthesis100, even when it is in its fully contracted state. So configured, thetip306 andsheath304 can be threaded through a blood vessel from a patient's groin, for example, to theheart10 to deliver theprosthesis100 in a manner that will be described below.
• Referring to the bottom portion ofFIG. 4, the handle302 includes ahollow grip310, ahollow slide rod312, and ahollow spool314. Thegrip310 can be connected to theslide rod312 at a threadedconnection316. Thespool314 is slidably mounted on theslide rod312 and fixed to afirst end304aof thesheath304 at a threadedconnection316. Thespool314 has a pair ofradial flanges314afor accommodating a user's grip, as will be described.
• Referring now to the top portion ofFIG. 4, thecavity308 for receiving theheart valve prosthesis100 is defined in asecond end304bof thesheath304, which as mentioned is disposed adjacent thetip306. Thetip306 includes a taperedbody portion306aand aplug portion306b. Theplug portion306bis friction fit within thesecond end304bof thesheath304. Thetip306 further defines a throughbore318 and ablind bore320 for receiving wires of thesystem300, as will be described. Also, as depicted inFIG. 4, thesecond end304bof thesheath304 includes astop plug322 disposed therein. Thestop plug322 includes a generally solid cylindrical disk-shaped member having a plurality of bores therein for receiving various wires of the system, as will be described. Thestop plug322 defines the internal boundary of thecavity308 for receiving theheart valve prosthesis100.
• As mentioned and illustrated inFIG. 4, thesystem300 includes a plurality of wires extending through thesheath304. Specifically, thesystem300 includes aguide wire324, afirst stop wire326, asecond stop wire328, and amaneuvering string330.
• Theguide wire324 passes through the through-bore318 in thetip306, through thesheath304, through the handle302, and out of anopening332 formed in thegrip310 of the handle302. Theguide wire324 is a conventional wire that a surgeon may first thread through the blood vessel to theheart10 of the patient prior to threading thesheath304 to theheart10. When positioned in the blood vessel, theguide wire324 guides thesheath304 along the proper path to theheart10.
• Thefirst stop wire326 can be fixed to aback wall302aof the handle302, for example, and extends through the length of the handle302 andsheath304 and into theblind bore320 of thetip306. Accordingly, thefirst stop wire326 also passes through an opening in thestop plug322. Thefirst stop wire326 can be fixed to thestop plug322 and thetip306 with an adhesive, for example, to fix the position of thetip306 and stopplug322 relative to each other.
• Similar to thefirst stop wire326, thesecond stop wire328 can be fixed to theback wall302aof the handle302, for example, and extends through the length of the handle302 andsheath304. Unlike thefirst stop wire326, however, thesecond stop wire328 stops at thestop plug322. In one embodiment, thesecond stop wire328 can be fixed into an opening or recess in the stop plug322 with an adhesive, for example. In another embodiment, thesecond stop wire328 may simply terminate immediately adjacent thestop plug322. In either case, thesecond stop wire328 serves to prevent the stop plug322 from traveling up into thesheath304 during operation, as will be described.
• Finally, themaneuvering string330 of the disclosed embodiment includes a first end that is fixed to aring333 adjacent theback wall302aof the handle302, and a second end that is fixed to thesecond end304bof thesheath304 at a location neat thestop plug322, for example. Thestring330 can include a conventional nylon string, a metallic wire, or generally any other type of material. While threading thesheath304 into the patient'sheart10, a surgeon, for example, may pull thering333 to bend thesecond end304bof thesheath304 to help maneuver thesheath304 through sharp turns. For example, with reference toFIGS. 1 and 2, this manipulation of thestring330 andsheath304 may be beneficial to turn thesecond end304bof thesheath304 to traverse theaortic arch35 when replacing theaortic valve34.
• Referring now toFIG. 5, as mentioned, thecavity308 in thesecond end304bof thesheath304 is adapted to accommodate aheart valve prosthesis100 in a contracted state, as depicted schematically in phantom. With theprosthesis100 so loaded into thecavity308, thetip306 andsheath304 can be threaded from the patient's groin, for example, and to theheart10 such that thetip306 is positioned just beyond the nativeaortic valve34. Once thetip306 is properly positioned, the surgeon, for example, grasps the spool314 (shown inFIG. 4) of the handle302 of thesystem300 and pulls thespool314 backwards along theslide rod312 toward thegrip310. This movement of thespool314 pulls thesheath304 backwards such that thesecond end304bof thesheath304 disengages theplug portion306bof thetip306. The surgeon pulls thespool314 until thesecond end304bof thesheath304 reaches the position depicted inFIG. 6.
• With thesheath304 out of the way, theheart valve prosthesis100 is free to expand to an active state and engage the walls of theheart10, as depicted inFIG. 2. During this process of setting theheart valve prosthesis100, thefirst stop wire326 maintains the position of thetip306 relative to thestop plug322 and thesecond stop wire328 prevents the stop plug322 from moving in thesheath304 toward the handle302. With theheart valve prosthesis100 expanded and set in theheart10, the surgeon can reengage thesheath304 with theplug portion306bof thetip306 by pushing thespool314 andsheath304 away from thegrip310 of the handle302. Then, the surgeon can draw the entire system back through the center opening of theprosthesis100, out of theheart10, and finally out of the patient's groin.
• In view of the foregoing description, it should be understood that loading theheart valve prosthesis100 into thecavity308 of thesheath304 can be accomplished by performing the above-described deployment steps in reverse. That is, with theheart valve prosthesis100 in its expanded state, thetip306 andsecond end304bof thesheath304 can be passed through the center thereof and thesheath304 can be disengaged from theplug portion306bof thetip306 through manipulation of thespool314 on the handle302. With theprosthesis100 andsystem300 arranged as depicted inFIG. 6, a radial load can be applied to the circumference of theprosthesis100. This radial load contracts theprosthesis100 into a small cylinder that is able to fit into thecavity308 of thesheath304. The second end of thesheath304 can then be slide over theprosthesis100 either by manually grasping thesecond end304bof thesheath304 or through manipulation of thespool314. Finally, thesecond end304bof thesheath304 can be friction fit onto theplug portion306bof thetip306. This completes the loading process.
• In one embodiment, the loading process can include the use of adevice400 for loading theheart valve prosthesis100, such as that depicted inFIGS. 7 and 8. In the depicted embodiment, thedevice400 includes ahandle402, apin404, and a loop ofmaterial406. Thehandle402 is a generally U-shaped member defining a pair of legs408 having through-bores410. Moreover, a plurality of threaded fasteners428 are positioned in a corresponding plurality of threaded bores430 formed in thehandle402.
• Thepin404 is rotatably disposed in the through-bores410 of thehandle402 and includes aknurled knob412 on one end and abutton414 on the other end. Theknurled knob412 includes a pair ofpins416 adapted to be received in a pair ofcorresponding bores418 formed in thehandle402 for locking rotation of thepin404. The end of thepin404 adjacent thebutton414 accommodates aspring420 between thebutton414 and the adjacent leg408 of thehandle402. Additionally, thepin404 includes anelongated slot422 formed in a central portion thereof and a pair of threaded fasteners424 positioned in threaded bores426 of thepin404 that traverse radially to theelongated slot422.
• The loop ofmaterial406 can include generally any type of material such as nylon, for example, and includes a first end406aand a second end406b. The first end406ais fixed to thehandle402. More specifically, the first end406aof the loop ofmaterial406 includes a plurality of holes (not shown) that receive the plurality of fasteners428 such that the fasteners428 can be tightened against thehandle402 to fix the position of the first end406aof the loop ofmaterial406.
• The second end406bof the loop ofmaterial406 is fixed to thepin404. More specifically, the second end406bof the loop ofmaterial406 is received in theslot422 formed in thepin404 and the fasteners424 are tightened to clamp the second end406bof the loop ofmaterial406 in place.
• As depicted inFIG. 7, when the loop ofmaterial406 is fixed to thedevice400, it is adapted to receive the heart valve prosthesis100 (shown schematically in phantom) in its expanded state. To contract theprosthesis100, a user pullsknurled knob412 of thepin404 to the left relative to the orientation ofFIG. 7. This pulls thepins416 on theknurled knob412 out of the correspondingbores418 such that the user can rotate thepin404. Rotation of thepin404 rolls the loop ofmaterial406 onto thepin404 which thereby apples a radial force to collapse theheart valve prosthesis100 from the expanded state to the contracted state, which is depicted schematically in phantom inFIG. 8. A radial dimension of theheart valve prosthesis100 in the contracted state is less than a radial dimension of theheart valve prosthesis100 in the expanded state such that theprosthesis100 can be loaded into thecavity308 of thesheath304. Thus, with theprosthesis100 sufficiently contracted, as depicted inFIG. 8, the surgeon or other user can manipulate thesecond end304bof thesheath304 into the loop ofmaterial406 and around theprosthesis100, and finally in engagement with theplug portion306bof thetip306. With theprosthesis100 thus loaded, it can be implanted according to the process described above.
• In light of the foregoing, it should be appreciated that the present disclosure provides aheart valve prosthesis100 adapted for intravascular delivery and which is constructed completely of synthetic materials that are more resistant to degradation and rejection than animal based materials. Moreover, theprosthesis100 advantageously retains its position in theheart10 with friction and self-loading and does not require the use of any sutures, hooks, or other type of invasive mechanical fasteners.
• Furthermore, the present disclosure advantageously provides a unique system for implanting a heart valve prosthesis. Thesystem300 disclosed with reference toFIGS. 4-6 advantageously enables the surgeon to remotely deflect thetip406 of thesystem300 in vivo through the use of themaneuvering string300, thereby facilitating the traversal of difficult passageways such as the aortic arch. Additionally, thesystem300 is advantageously designed to accommodate the large pay load of a heart valve prosthesis, which may have a diameter of approximately 25 millimeters in the fully expanded state and approximately 7 millimeters when occupying the contracted state within thesheath304. Furthermore, the manual manipulation of thespool314 relative to thegrip312 of thehandle310 provides for precise retraction of thesheath304 and calculated deployment of theprosthesis100.
• The scope of the invention is not limited to the specific embodiments described hereinabove, but rather, is intended to be defined by the spirit and scope of the claims and all equivalents thereof.

Claims (8)

1.-10. (canceled)

11. A system for intravascular delivery of a heart valve prosthesis, the system comprising:

a handle;

a flexible elongated sheath extending from the handle;

a cavity defined by an end of the elongated sheath that is disposed opposite the handle, the cavity adapted to contain a heart valve prosthesis during intravascular delivery of the heart valve prosthesis;

a tapered tip coupled to the end of the elongated sheath adjacent to the cavity, the tapered tip adapted to guide the elongated sheath during intravascular delivery of the heart valve prosthesis, the tapered tip and the elongated sheath being separable such that the heart valve prosthesis can be released from the cavity in the elongated sheath upon proper positioning of the heart valve prosthesis.

12. The system ofclaim 11, wherein the elongated sheath has an inner diameter of less than or equal to 7 mm and an outer diameter of less than or equal to 8 mm.

13. The system ofclaim 11, further comprising a string connected to the elongated sheath at a location adjacent the cavity and extending through the sheath to the handle such that a user can pull the string to bend the elongated sheath to facilitate navigation of the elongated sheath during intravascular delivery of the heart valve prosthesis.

14. The system ofclaim 11, further comprising a stop plug disposed in the elongated sheath adjacent the cavity, the stop plug preventing the heart valve prosthesis from traveling into the elongated sheath beyond the cavity.

15. The system ofclaim 11, wherein the elongated sheath is movable mounted to the handle such that movement of the sheath toward the handle separates the elongated sheath and the tapered tip.

16. (canceled)

17. (canceled)

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