US20080015407A1 - Device and Method for Modifying the Shape of a Body Organ - Google Patents

Abstract

An intravascular support device includes a support or reshaper wire, a proximal anchor and a distal anchor. The support wire engages a vessel wall to change the shape of tissue adjacent the vessel in which the intravascular support is placed. The anchors and support wire are designed such that the vessel in which the support is placed remains open and can be accessed by other devices if necessary. The device provides a minimal metal surface area to blood flowing within the vessel to limit the creation of thrombosis. The anchors can be locked in place to secure the support within the vessel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a divisional of pending U.S. application Ser. No. 10/429,172, filed May 2, 2003, entitled “Device and Method for Modifying the Shape of a Body Organ,” which application is incorporated by reference as if fully set forth herein.
FIELD OF THE INVENTION
• The present invention relates to medical devices in general, and in particular to devices for supporting internal body organs.
BACKGROUND OF THE INVENTION
• The mitral valve is a portion of the heart that is located between the chambers of the left atrium and the left ventricle. When the left ventricle contracts to pump blood throughout the body, the mitral valve closes to prevent the blood being pumped back into the left atrium. In some patients, whether due to genetic malformation, disease or injury, the mitral valve fails to close properly causing a condition known as regurgitation, whereby blood is pumped into the atrium upon each contraction of the heart muscle. Regurgitation is a serious, often rapidly deteriorating, condition that reduces circulatory efficiency and must be corrected.
• Two of the more common techniques for restoring the function of a damaged mitral valve are to surgically replace the valve with a mechanical valve or to suture a flexible ring around the valve to support it. Each of these procedures is highly invasive because access to the heart is obtained through an opening in the patient's chest. Patients with mitral valve regurgitation are often relatively frail thereby increasing the risks associated with such an operation.
• One less invasive approach for aiding the closure of the mitral valve involves the placement of a support structure in the cardiac sinus and vessel that passes adjacent the mitral valve. The support structure is designed to push the vessel and surrounding tissue against the valve to aid its closure. This technique has the advantage over other methods of mitral valve repair because it can be performed percutaneously without opening the chest wall. While this technique appears promising, some proposed supports appear to limit the amount of blood that can flow through the coronary sinus and may contribute to the formation of thrombosis in the vessel. Therefore, there is a need for a tissue support structure that does not inhibit the flow of blood in the vessel in which it is placed and reduces the likelihood of thrombosis formation. Furthermore, the device should be flexible and securely anchored such that it moves with the body and can adapt to changes in the shape of the vessel over time.
• The present invention is an intravascular support that is designed to change the shape of a body organ that is adjacent to a vessel in which the support is placed. In one embodiment of the invention, the support is designed to aid the closure of a mitral valve. The support is placed in a coronary sinus and vessel that are located adjacent the mitral valve and urges the vessel wall against the valve to aid its closure.
• The intravascular support of the present invention includes a proximal and distal anchor and a support wire or reshaper disposed therebetween. The proximal and distal anchors circumferentially engage a vessel in which the support is placed. A support wire is urged against the vessel by the proximal and distal anchors to support the tissue adjacent the vessel.
• In one embodiment of the invention, the proximal and distal supports are made from a wire hoop that presents a low metal coverage area to blood flowing within the vessel. The wire hoops may allow tissue to grow over the anchors to reduce the chance of thrombosis formation. The wire hoops have a figure eight configuration and can expand to maintain contact with the vessel walls if no vessel expands or changes shape.
• In another embodiment of the invention, the proximal and distal anchors of the intravascular support are rotationally offset from each other. Locks on the support wire allow a physician to ensure that the anchors have been successfully deployed and prevent the support wire from collapsing within a vessel.
SUMMARY OF THE INVENTION
• The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
• FIG. 1 illustrates an intravascular support for changing the shape of an internal body organ in accordance with one embodiment of the present invention;
• FIG. 2 illustrates one method of deploying an intravascular support in accordance with the present invention;
• FIG. 3 illustrates one embodiment of the intravascular support in accordance with the present invention;
• FIG. 4 illustrates a distal anchor of the embodiment shown inFIG. 3;
• FIG. 5 illustrates a proximal anchor of the embodiment shown inFIG. 3;
• FIGS. 6A-6C are cross-sectional views of crimp tubes for use with one embodiment of the present invention;
• FIG. 7 illustrates a proximal lock at the proximal end of the intravascular support as shown inFIG. 3;
• FIG. 8 illustrates how the embodiment of the intravascular support shown inFIG. 3 is deployed from a catheter;
• FIG. 9 illustrates an intravascular support in accordance with another embodiment of the present invention;
• FIG. 10 illustrates a distal anchor of the intravascular support shown inFIG. 9;
• FIG. 11 illustrates a proximal anchor of the intravascular support shown inFIG. 9;
• FIG. 12 illustrates yet another embodiment of an intravascular support in accordance with the present invention;
• FIG. 13 illustrates a distal anchor of the intravascular support shown inFIG. 12;
• FIG. 14 illustrates a proximal anchor of the intravascular support shown inFIG. 12;
• FIG. 15 illustrates an anchor and strut according to another embodiment of the invention;
• FIG. 16 illustrates a double loop anchor according to another embodiment of the invention;
• FIG. 17 illustrates a double loop anchor with a cross strut according to another embodiment of the invention; and
• FIG. 18 illustrates an anchor with torsional springs according to another embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• As indicated above, the present invention is a medical device that supports or changes the shape of tissue that is adjacent a vessel in which the device is placed. The present invention can be used in any location in the body where the tissue needing support is located near a vessel in which the device can be deployed. The present invention is particularly useful in supporting a mitral valve in an area adjacent a coronary sinus and vessel. Therefore, although the embodiments of the invention described are designed to support a mitral valve, those skilled in the art will appreciate that the invention is not limited to use in supporting a mitral valve.
• FIG. 1 illustrates amitral valve20 having a number offlaps22,24 and26 that should overlap and close when the ventricle of the heart contracts. As indicated above, some hearts may have a mitral valve that fails to close properly thereby creating one ormore gaps28 that allow blood to be pumped back into the left atrium each time the heart contracts. To add support to the mitral valve such that the valve completely closes, anintravascular support50 is placed in a coronary sinus andvessel60 that passes adjacent one side of themitral valve20. Theintravascular support50 has aproximal anchor52, adistal anchor54, and asupport wire56 or reshaper extending between the proximal and distal anchors. With theanchors52 and54 in place, thesupport wire56 exerts a force through the coronary sinus wall on the postero-lateral mitral valve20 thereby closing the one ormore gaps28 formed between the valve flaps. With theintravascular support50 in place, the function of the mitral valve is improved.
• As will be explained in further detail below, each of the proximal anddistal anchors52,54 preferably circumferentially engages the wall of thevessel60 in which it is placed. Thesupport wire56 is secured to a peripheral edge of the proximal and distal anchors such that the support wire is urged by the anchors against the vessel wall. Therefore, thesupport wire56 andanchors52,54 present a minimal obstruction to blood flowing within the vessel.
• FIG. 2 shows one possible method of delivering the intravascular support of the present invention to a desired location in a patient's body. An incision80 is made in the patient's skin to access a blood vessel. Aguide catheter82 is advanced through the patient's vasculature until its distal end is positioned adjacent the desired location of the intravascular support. After positioning theguide catheter82, a delivery catheter and advancingmechanism84 are inserted through theguide catheter82 to deploy the intravascular support at the desired location in the patient's body. Further detail regarding one suitable advancingmechanism84 is described in commonly assigned U.S. patent application Ser. No. 10/313,914, filed Dec. 5, 2002, the disclosure of which is hereby incorporated by reference.
• FIG. 3 illustrates one embodiment of an intravascular support in accordance with the present invention. Theintravascular support100 includes asupport wire102 having aproximal end104 and adistal end106. Thesupport wire102 is made of a biocompatible material such as stainless steel or a shape memory material such as nitinol wire.
• In one embodiment of the invention, thesupport wire102 comprises a double length of nitinol wire that has both ends positioned within adistal crimp tube108. To form thesupport wire102, the wire extends distally from thecrimp tube108 where it is bent to form a distal stop loop (see121 inFIG. 4) having a diameter that is larger than the lumens within thedistal crimp tube108. After forming the distal stop loop, the wire returns proximally through thecrimp tube108 towards the proximal end of thesupport100. Proximal to the proximal end of thecrimp tube108, is adistal lock110 that is formed by the support wire bending away from the longitudinal axis of thesupport102 and then being bent parallel to the longitudinal axis of the support before being bent again towards the longitudinal axis of the support. Therefore, the bends in the support wire form ahalf110aof the distal lock that is used to secure the distal anchor in the manner described below. From thedistal lock110, the wire continues proximally through aproximal crimp tube112. On exiting the proximal end of theproximal crimp tube112, the wire is bent to form an arrowhead-shapedproximal lock114. The wire of thesupport102 then returns distally through theproximal crimp tube112 to a position just proximal to the proximal end of thedistal crimp tube108 wherein the wire is bent to form asecond half110bof thedistal lock110.
• Support wire102 has a length that is selected based on its intended destination within a patient's vessel. For use in supporting a mitral valve, the support wire is preferably between one and six inches long and has a curved bend between itsproximal end104 anddistal end106 with a radius of curvature between 1 and 3 inches and most preferably with a radius of curvature of 1.8 inches. In addition, the wire used to form thesupport wire102 is flexible enough to move with each heartbeat (thereby changing the force applied to the mitral valve annulus during the heartbeat) and stiff enough to support the mitral valve. In one embodiment, the wire used to form thesupport wire102 is made of nitinol having a modulus of elasticity of 5-20×10⁶psi and a diameter of between 0.0110″ and 0.0150″ and most preferably 0.0140″. Other shape memory materials may be used for support wire as well.
• At the distal end of thesupport wire102 is adistal anchor120 that is formed of a flexible wire such as nitinol or some other shape memory material. As is best shown inFIGS. 3 and 4, the wire forming the distal anchor has one end positioned within thedistal crimp tube108. After exiting the distal end of thecrimp tube108, the wire forms a figure eight configuration whereby it bends upward and radially outward from the longitudinal axis of thecrimp tube108. The wire then bends back proximally and crosses the longitudinal axis of thecrimp tube108 to form one leg of the figure eight. The wire is then bent to form a double loop eyelet orloop122 around the longitudinal axis of thesupport wire102 before extending radially outwards and distally back over the longitudinal axis of thecrimp tube108 to form the other leg of the figure eight. Finally, the wire is bent proximally into the distal end of thecrimp tube108 to complete thedistal anchor120.
• The distal anchor is expanded by sliding thedouble eyelet122 of the distal anchor from a position that is proximal to thedistal lock110 on the support wire to a position that is distal to thedistal lock110. The bent-outportions110aand110bofsupport wire110 are spaced wider than the width ofdouble eyelet122 and provide camming surfaces for the locking action. Distal movement ofeyelet122 pushes these camming surfaces inward to permiteyelet122 to pass distally of thelock110, then return to their original spacing to keepeyelet122 in the locked position.
• The dimensions of the distal anchor are selected so that the diameter of the distal anchor in a plane perpendicular to the axis of the lumen in which the anchor is deployed is preferably between 100% and 300%, most preferably between 130% and 200%, of the diameter of the lumen prior to deployment. When treating mitral valve regurgitation by placement of the device in the coronary sinus, the diameter of the coronary sinus may expand over time after deployment. Oversizing the anchor combined with the inherent deformability and recoverability properties of the anchor material (particularly nitinol or some other shape memory material) enables the anchor to continue to expand from its initial deployment size as the lumen distends and expands over time.
• Upon expansion, the distal anchor circumferentially engages the vessel wall with a radially outwardly directed force that is distributed unequally around the circumference of the anchor by distending the vessel wall in variable amounts along the axial length of the anchor. The unequal distribution of force helps the anchor contact the lumen wall securely by creating bumps and ridges that are not parallel to the central axis of the lumen. In its expanded configuration the distal anchor's diameter is at least 50%-500% and most preferably 100%-300% of the anchor's diameter in the unexpanded configuration. The open cross-sectional area of the lumen through the anchor is at least 50% and most preferably 80%-100% of the lumen cross sectional area prior to redeployment of the anchor.
• In addition, the metal coverage of the anchor, as defined by the percentage of the lumen surface area through which the anchor extends that is exposed to a metal surface, is between 5% and 30% and most preferably 10%. The wire used to form thedistal anchor120 is preferably nitinol having a diameter of between 0.0110″ and 0.0150″ and most preferably 0.0140 inches. Other shape memory materials may be used as well.
• During insertion, a physician can tactilely feel when theeyelet122 has been slid over thedistal lock110 in order to determine when the distal anchor has been set within a vessel lumen. In addition, if the anchor is misplaced, it can be collapsed by pulling theeyelet122 proximally over thedistal lock110 and repositioning the anchor in the unexpanded configuration. The force required to capture the distal anchor is preferably less than 20 lbs. and more preferably less than 10 lbs.
• FIG. 4 also illustrates how thecrimp tube108 is held in place between thedistal lock110 on the proximal side and thestop loop121 at the distal end of thesupport wire102. The wires of thedistal anchor120 exit the distal end of thecrimp tube108 at an angle of approximately 45 degrees before looping back over the length of thedistal crimp tube108. Therefore, the distal end of the anchor is relatively atraumatic to avoid damage to a vessel during placement.
• At the proximal end of the intravascular support is aproximal anchor140 that is preferably formed of a biocompatible, elastic wire such as stainless steel or a shape memory material such as nitinol. As is best shown inFIGS. 3 and 5, theproximal anchor140 in one embodiment is made of a single length of wire having a first end positioned within aproximal crimp tube112. The wire extends distally from thecrimp tube112 and bends radially outward and away from the longitudinal axis of thecrimp tube112 before being bent proximally and crossing the longitudinal axis of thecrimp tube112 in order to form a first leg of a figure eight configuration. The wire then is bent to form a double eyelet orloop142 around the longitudinal axis of thesupport wire102 wherein theeyelet142 has a diameter that allows it to be forced over theproximal lock114. After forming theeyelet142, the wire extends outwardly and away from the longitudinal axis of thecrimp tube112 before being bent distally over and across the longitudinal axis of thecrimp tube112 to form the second leg of a figure eight. Finally, the wire is bent proximally and extends into the distal end of thecrimp tube112.
• Like the distal anchor, the proximal anchor is expanded and locked by sliding thedouble eyelet142 of the proximal anchor from a position that is proximal to theproximal lock114 on the support wire to a position that is distal to theproximal lock114. As can be seen inFIG. 7, theproximal lock114 has an “arrowhead” shape whereby the proximal end of the lock is bent away from the longitudinal axis of the support wire at an angle that is less steep than the distal end of the proximal lock. The less steep section makes it easier to advance theeyelet142 over the lock in the distal direction than to retrieve theeyelet142 over theproximal lock114 in the proximal direction. Distal movement ofeyelet142 cams the less steep proximal surfaces inward to permiteyelet142 to pass distally of thelock114, then return to their original spacing to keepeyelet142 in the locked position.
• As can be seen by comparing theproximal anchor140 with thedistal anchor120 inFIG. 3, the proximal anchor has a larger radius of curvature because it is designed to fit within a larger diameter portion of the coronary sinus. The dimensions of the proximal anchor are selected so that the diameter of the proximal anchor in a plane perpendicular to the axis of the lumen in which the anchor is deployed is preferably between 100% and 300%, most preferably between 130% and 200%, of the diameter of the lumen prior to deployment. As with the distal anchor, oversizing the proximal anchor combined with the inherent deformability and recoverability properties of the anchor material (particularly nitinol or some other shape memory material) enables the anchor to continue to expand from its initial deployment size as the lumen distends and expands over time.
• Upon expansion, the proximal anchor circumferentially engages the vessel wall with a radially outwardly directed force that is distributed unequally around the circumference of the anchor by distending the vessel wall in variable amounts along the axial length of the anchor. As with the distal anchor, the unequal distribution of force helps the proximal anchor contact the lumen wall securely by creating bumps and ridges that are not parallel to the central axis of the lumen. In its expanded configuration the proximal anchor's diameter is at least 50%-500% and most preferably 100%-300% of the anchor's diameter in the unexpanded configuration. The open cross-sectional area of the lumen through the anchor is at least 50% and most preferably 80%-100% of the lumen cross sectional area prior to redeployment of the anchor.
• In one embodiment of the invention, the proximal and distal anchors are oriented such that the planes of the anchors are offset with respect to each other by an angle of approximately 30 degrees. The offset helps theintravascular support100 seat itself in the coronary sinus and vessel surrounding the mitral valve in certain mammals. However, it will be appreciated that if the support is designed for other uses, the proximal and distal anchors may be offset by more or less depending upon the anatomy of the intended destination.
• FIGS. 6A-6C illustrate cross-sectional views of the crimp tubes in which the wires that form thesupport wire102 and proximal anddistal anchors120,140 are threaded. In one embodiment, the crimp tubes comprise a biocompatible material such as titanium having a number of holes extending longitudinally through the tube through which the wires are threaded. InFIG. 6A, atube150 has fourholes152,154,156,158 positioned in approximately a square configuration within the circumference of thetube150. As shown inFIG. 6B, atube160 includes fourholes162,164,166,168 therein that are positioned in a diamond configuration.FIG. 6C shows anothertube170 having fourholes172,174,176,178. Here theholes172,174 lie in a first plane and the second pair ofholes176,178 lie in a second plane that is offset from the plane of theholes172,174. By changing the orientation of theholes176,178 with respect to theholes172,174, the relative plane of wires passing through the holes can be adjusted. Thus in the example shown inFIG. 3, the proximal anchor may be formed with a crimp tube such as that shown inFIG. 6A orFIG. 6B while the proximal anchor may be formed in a crimp tube such as that shown inFIG. 6C in order to adjust the angular orientation between the proximal anchor and the distal anchor. In an alternative embodiment, the crimp tubes at the proximal and distal ends of thesupport wire102 are the same and the angular offset between the proximal and distal anchor is achieved by bending the wires at the desired angle. Although the crimp tubes shown use one hole for each wire passing through the crimp tube, it will be appreciated that other configurations may be provided such as slots or other passages for the wires to pass through.
• In another embodiment, the distal and proximal anchors are attached to the support wire by a wire, such as nitinol wire or other shape memory material. The attaching wire may be spiral wrapped around the base of each anchor and around the support wire. In another embodiment, each anchor may be attached to the support wire by wrapping the anchor wire around the support wire. In yet another embodiment, the two anchors and the support wire may be made from a single wire, such as nitinol wire or other shape memory material.
• FIG. 8 illustrates one method for delivering anintravascular support100 in accordance with the present invention to a desired location in the body. As indicated above,intravascular support100 is preferably loaded into and routed to a desired location within acatheter200 with the proximal and distal anchors in a collapsed or deformed condition. That is, theeyelet122 of thedistal anchor120 is positioned proximally of thedistal lock110 and theeyelet142 of theproximal anchor140 is positioned proximal to theproximal lock114. The physician ejects the distal end of the intravascular support from thecatheter200 into the lumen by advancing the intravascular support or retracting the catheter or a combination thereof. A pusher (not shown) provides distal movement of the intravascular support with respect tocatheter200, and a tether201 provides proximal movement of the intravascular support with respect tocatheter200. Because of the inherent recoverability of the material from which it is formed, the distal anchor begins to expand as soon as it is outside the catheter. Once the intravascular support is properly positioned, theeyelet122 of the distal anchor is pushed distally over thedistal lock110 so that thedistal anchor120 further expands and locks in place to securely engage the lumen wall and remains in the expanded condition. Next, the proximal end of thesupport wire102 is tensioned by applying a proximally-directed force on the support wire and distal anchor to apply sufficient pressure on the tissue adjacent the support wire to modify the shape of that tissue. In the case of the mitral valve, fluoroscopy, ultrasound or other imaging technology may be used to see when the support wire supplies sufficient pressure on the mitral valve to aid in its complete closure with each ventricular contraction without otherwise adversely affecting the patient. A preferred method of assessing efficacy and safety during a mitral valve procedure is disclosed in copending U.S. patent application Ser. No. 10/366,585, filed Feb. 12, 2003, and titled “Method of Implanting a Mitral Valve Therapy Device,” the disclosure of which is incorporated herein by reference. Once the proper pressure of the support wire has been determined, the proximal anchor is deployed from the catheter and allowed to begin its expansion. Theeyelet142 of theproximal anchor140 is advanced distally over theproximal lock114 to expand and lock the proximal anchor, thereby securely engaging the lumen wall and maintaining the pressure of the support wire against the lumen wall. Finally, the mechanism for securing the proximal end of the intravascular support can be released. In one embodiment, the securement is made with abraided loop202 at the end of tether201 and ahitch pin204. Thehitch pin204 is withdrawn thereby releasing theloop202 so it can be pulled through theproximal lock114 at the proximal end of theintravascular support100.
• In many contexts, it is important for the device to occupy as little of the lumen as possible. For example, when using the device and method of this invention to treat mitral valve regurgitation, the device should be as open as possible to blood flow in the coronary sinus (and to the introduction of other medical devices, such as pacing leads) while still providing the support necessary to reshape the mitral valve annulus through the coronary sinus wall. The combination of the device's open design and the use of nitinol or some other shape memory material enables the invention to meet these goals. When deployed in the coronary sinus or other lumen, the device preferably occupies between about 1.5% and about 5.5% of the overall volume of the section of lumen in which it is deployed.
• In many embodiments of the invention, the use of a shape memory material such as nitinol is particularly important. The percentage of shape memory material by volume in the device is preferably between about 30% and 100%, most preferably between about 40% and 60%.
• In some instances it may be necessary to move or remove an intravascular support after deployment by recapturing the device into a catheter. Prior to deployment of the proximal anchor, the distal anchor may be recaptured into the delivery catheter by simultaneously holding the device in place with tether201 while advancing catheter distally overdistal anchor120 so that the entire device is once again insidecatheter200. The distally directed force of the catheter collapsesdistal anchor120 into a size small enough to fit intocatheter200 again. Likewise, after deployment of both anchors but prior to releasing the securement mechanism as described above, the intravascular support may be recaptured into the delivery catheter by simultaneously holding the device in place with tether201 while advancing catheter distally first overproximal anchor140, oversupport wire102, and finally overdistal anchor120. The distally directed forced ofcatheter200 collapsesanchors120 and140 into a size small enough to fit intocatheter200 again. If the securement mechanism has been detached from the device prior to recapture, the device still may be recaptured into the delivery catheter or another catheter by grasping the proximal end of the device with a grasper or tether and by advancing the catheter distally over the device.
• In one embodiment of the invention,proximal anchor140 includes a recapture guidance and compression element. In the embodiment shown inFIG. 5, the slope of the twoproximal arms143 and144 ofproximal anchor140 is small inproximal portions145 and146 of the arms, then increases in moredistal portions147 and148 of the arms. This shape guides the catheter to move distally over the anchor more easily and to help compress the anchor to a collapsed shape as the catheter advances during recapture.
• Likewise, the two proximal arms123 and124 ofdistal anchor120 have a shallower slope in theirproximal portions145 and146 and an increased slope in moredistal portions147 and148. While recapture of the distal anchor is somewhat easier due to its smaller size compared to the proximal anchor, this recapture guidance and compression feature enhances the ease with which recapture is performed.
• FIG. 9 illustrates an alternative embodiment of the intravascular support of the present invention. In this embodiment, anintravascular support250 has asupport wire252 and adistal anchor254 and aproximal anchor256. In the embodiment shown inFIG. 9, thedistal anchor254 is made from the same wire used to form thesupport wire252. As best shown inFIG. 10, the wire used to form thesupport wire252 extends distally through adistal crimp tube260 before looping radially outward and returning proximally and across the longitudinal axis of thecrimp tube260 to form one leg of a figure eight. The wire then winds around the axis of thesuspension wire252 to form aneyelet262. The wire then continues radially outward and distally across the longitudinal axis of thecrimp tube260 to form the second leg of a figure eight. After forming the figure eight, the wire enters the distal end of thecrimp tube260 in the proximal direction to form the other half of thesupport wire252. Adistal lock264 is formed proximal to thedistal crimp tube260 by outwardly extending bends in the wires that form thesupport wire252. Thedistal lock264 prevents thedouble eyelet262 from sliding proximally and collapsing thedistal anchor254 when positioned in a vessel.
• As shown inFIG. 11, adistal anchor256 is constructed in a fashion similar to theproximal anchor140 shown inFIG. 3. That is, theproximal anchor256 is formed of a separate wire than the wire used to form thesupport wire252 anddistal anchor254. The wire of the proximal anchor has one end within aproximal crimp tube270. The wire extends distally out of the end of the crimp tube and bends radially outward before returning back and across the longitudinal axis of thecrimp tube270. At the proximal end of thecrimp tube270, the wire of the proximal anchor forms adouble eyelet272 around the longitudinal axis of thesupport wire252. The wire then continues radially outward and distally over the longitudinal axis of thecrimp tube270 to form the second leg of the figure eight whereupon it is bent proximally into the distal end of thecrimp tube270.
• FIG. 12 shows yet another embodiment of an intravascular support in accordance with the present invention. Here, anintravascular support300 comprises asupport wire302, adistal anchor304 and aproximal anchor306. As in the embodiment shown inFIG. 9, thedistal anchor304 and thesupport wire302 are formed of the same wire. To form the distal anchor, the wire extends distally through adistal crimp tube310 and exits out the distal end before extending radially outward and bending back and across the longitudinal axis of thecrimp tube310 to form one leg of a figure eight. The loop then forms aneyelet312 around the longitudinal axis of thesupport wire302 before bending radially outward and distally across the longitudinal axis of thecrimp tube310 to form a second leg of the figure eight. The wire then enters the distal end of thecrimp tube310 in the proximal direction. Thesupport wire302 may have one or two outwardly extending sections that form adistal stop314 to maintain the position of theeyelet312 once the distal anchor is set in the expanded configuration.
• Theproximal anchor306 is formed from a separate wire as shown inFIG. 14. The wire has one end positioned within theproximal crimp tube320 that extends distally outward and radially away from the longitudinal axis of thecrimp tube320 before being bent proximally and across the longitudinal axis of thecrimp tube320 to form one leg of the figure eight. The wire then winds around the longitudinal axis of the support wire to form aneyelet322 before being bent distally and across the longitudinal axis of thecrimp tube320 to enter the distal end of thecrimp tube320 in the proximal direction. As will be appreciated, theproximal crimp tube320 of the embodiment shown inFIG. 12 holds four wires wherein thedistal crimp tube310 need only hold two wires.
• FIGS. 15-18 show other embodiments of the invention. In the embodiment shown inFIG. 15, the intravascular support has ananchor400 formed as aloop404 emerging from awindow406 in acrimp tube408. Extending from oneend411 ofcrimp tube408 is asupport strut410 which connects withloop404. Also extending from thecrimp tube408 is asupport wire412.Loop404 andsupport410 may be formed from nitinol, stainless steel, or any other appropriate material. The intravascular support includes another anchor. The intravascular support of this embodiment may be delivered and deployed in the manner discussed above with respect to the embodiment described above.
• FIG. 16 shows another embodiment of ananchor450 for an intravascular support.Anchor450 is formed from twoloops452 and454 emerging from awindow456 and anend457 of acrimp tube458. Asupport wire462 also extends from the crimp tube.Loops452 and454 may be formed from nitinol, stainless steel, or any other appropriate material. The intravascular support includes another anchor. The intravascular support of this embodiment may be delivered and deployed in the manner discussed above with respect to the embodiment described above.
• FIG. 17 shows yet another embodiment of ananchor500 for an intravascular support according to this invention.Anchor500 is formed from twoloops502 and504 emerging from awindow506 and anend507 of acrimp tube508. Across strut505 connects the loops. Asupport wire512 also extends from the crimp tube.Loops502 and504 and strut505 may be formed from nitinol, stainless steel, or any other appropriate material. The intravascular support includes another anchor. The intravascular support of this embodiment may be delivered and deployed in the manner discussed above with respect to the embodiment described above.
• FIG. 18 is a modification of the embodiment shown inFIGS. 3-7. In this embodiment, torsional springs558 ofproximal anchor550 have been formed as single loops or eyelets in the anchor'swire552. These springs make theanchor550 more compliant by absorbing some of the force applied to the anchor during locking. WhileFIG. 18 shows a proximal anchor with two springs558, any number of springs could be used on either the proximal or the distal anchor.
• While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the scope of the invention. Therefore, the scope of the invention is to be determined from the following claims and equivalents thereto.

Claims (7)

1. An intravascular support comprising:

a proximal anchor that circumferentially engages a vessel wall in which the support is placed, the proximal anchor being disposed in a proximal anchor plane;

a distal anchor that circumferentially engages a vessel wall in which the support is placed, the distal anchor being in a distal anchor plane offset from the proximal anchor plane; and

a support member connected to and extending between the proximal and distal anchors.

2. The intravascular support ofclaim 1 wherein the proximal anchor and the distal anchor each comprise a wire and a crimp connected to the wire.

3. The intravascular support ofclaim 2 wherein the proximal anchor and the distal anchor each comprise a plurality of wires.

4. The intravascular support ofclaim 3 wherein the crimp comprises a bore, the bore of the crimp having a non-circular shape adapted to accommodate and orient the wires.

5. The intravascular support ofclaim 4 wherein the bore is substantially square.

6. The intravascular support ofclaim 1 wherein the support member comprises a wire.

7. The intravascular support ofclaim 1 wherein the distal anchor plane is offset from the proximal anchor plane by approximately 30 degrees.

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