WO2009151761A1

WO2009151761A1 - Angioplasty device with embolic filter and fixed filter housing

Info

Publication number: WO2009151761A1
Application number: PCT/US2009/040202
Authority: WO
Inventors: Ravish Sachar; Udayan Patel
Original assignee: Contego Medical Llc
Priority date: 2008-04-10
Filing date: 2009-04-10
Publication date: 2009-12-17

Abstract

An interventional catheter such as an angioplasty device has an embolic filter attached to the same catheter shaft as the angioplasty balloon. The filter includes a filter ring slidably attached to the catheter shaft adjacent the distal end of the catheter. An actuation wire is attached to the filter ring and extends to a location outside of the patient for manipulation by the physician. A filter frame supporting a filter mesh is mounted to the filter ring and has a shape memory that is normally expanded. A filter housing is attached to the catheter shaft. The filter housing has side walls spaced apart from the catheter shaft to define a space therebetween. When the filter ring is retracted into the opening between the filter housing and the catheter shaft, the filter frame is collapsed against the catheter shaft. Pushing on the actuation wire advances the filter ring out of the housing and permits the filter frame to expand, opening the filter.

Description

ANGIOPLASTY DEVICE WITH EMBOLIC FILTER AND FIXED

FILTER HOUSING

TECHNICAL FIELD

[0001] The present invention relates generally to surgical devices and relates more specifically to a percutaneous transluminal angioplasty device.

BACKGROUND OF THE INVENTION

[0002] The vascular bed supplies a constant flow of oxygen- rich blood to the organs. If plaque builds up in these vessels, blockages can develop, reducing blood flow to the organs and causing adverse clinical symptoms, up to and including fatality.

[0003] Angioplasty is a catheter-based procedure performed by a physician to open up a blocked vessel and restore blood flow. An entry site is opened, for example in the patient's groin, arm, or hand, and a guide wire and catheter are advanced under fluoroscopic guidance to the location of the blockage. A catheter having a small balloon adjacent its distal end is advanced under fluoroscopic guidance until the balloon lies within the stenosed region. The balloon is then inflated and deflated one or more times to expand the stenosed region of the artery.

[0004] Since diseased vessels are comprised of a range of material from early-stage thrombosis to late-stage calcified plaque, angioplasty can release embolic particles downstream from the stenosed location. These embolic particles can result in adverse clinical consequences. It has been shown that it is beneficial to trap these embolic particles to prevent them from traveling downstream with blood flow to the capillary bed (e.g., Bairn DS, Wahr D, George B, et al., Randomized Trial Of A Distal Embolic Protection Device During Percutaneous Intervention Of Saphenous Vein Aorto-Coronary Bypass Grafts, Circulation 2002; 105: 1285-90).

[0005] In addition to balloon angioplasty, stenoses may also be treated with stents and with mechanical thrombectomy devices. These devices are also prone to releasing embolic particles downstream from the stenosed location.

[0006] There are systems available today that are used to catch these embolic particles. They are primarily filter systems or occlusion balloon systems built on a guidewire. These systems have shortcomings related to simplicity of use and crossing tight lesions with a filter or balloon guidewire that is larger in diameter than the guidewire which is normally used. These embolic protection guidewires also have flexibility and stability problems that make the protected angioplasty procedure difficult in many cases. In the case of saphenous vein grafts, the problems relate specifically to aorto-ostial lesions, where the guidewire may not be long enough to provide support, or distal vein graft lesions, where there is not enough of a landing zone for the filter. The latter is a problem as currently available filter systems have a considerable distance between the treatment balloon and the distal filter. This distance is a problem not only in distal vein graft lesions, but also in arterial stenoses in which there is a side branch immediately after the stenosis. In such cases, the filter can often be deployed only distal to the side branch, thus leaving the side branch unprotected from embolic particles.

SUMMARY OF THE INVENTION

[0007] An interventional catheter such as an angioplasty device has an embolic filter attached to the same catheter shaft as the angioplasty balloon. The filter includes a filter ring slidably attached to the catheter shaft adjacent the distal end of the catheter. An actuation wire is attached to the filter ring and extends to a location outside of the patient for manipulation by the physician. A filter frame supporting a filter mesh is mounted to the filter ring and has a shape memory that is normally expanded. A filter housing is attached to the catheter shaft. The filter housing has side walls spaced apart from the catheter shaft to define a space therebetween. When the filter ring is retracted into the opening between the filter housing and the catheter shaft, the filter frame is collapsed against the catheter shaft. Pushing on the actuation wire advances the filter ring out of the housing and permits the filter frame to expand, opening the filter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a partial cut away side view of first embodiment of a percutaneous transluminal angioplasty device according to a first embodiment of the disclosed invention, with the angioplasty balloon and embolism filter in their collapsed positions.

[0009] FIG. 2 is a partial cut away side view of the percutaneous transluminal angioplasty device of FIG. 1 showing the angioplasty balloon and embolism filter in their erected positions.

[0010] FIG. 3 is a cross sectional view taken along line 3-3 of FIG. l.

[0011] FIG. 4 is a cross sectional view taken along line 4-4of FIG. 1.

[0012] FIG. 5 is a cross sectional view taken along line 5-5 of FIG. 1.

[0013] FIG- 6 is a second embodiment of a percutaneous transluminal angioplasty device according to the present invention, which differs from the percutaneous transluminal angioplasty of FIGS. 1 and 2 in that the actuation balloon is on the proximal side of the embolic filter, and the filter erects from a different direction.

[0014] FIG. 7 is a view of the percutaneous transluminal angioplasty device of FIG. 6 showing the angioplasty balloon inflated and the embolic filter erected.

[0015] FIG. 8 is still another embodiment of a percutaneous transluminal angioplasty device according to the present invention. This embodiment employs a pull wire operable from outside the patient which is attached to a front ring of the embolic filter. When the physician exerts tension on the wire, the distal ring is displaced proximally, bringing it closer to the proximal ring, thereby causing the ribs to bow outward and thereby erecting the embolic mesh filter. FIG. 8 shows the device with the angioplasty balloon deflated and the embolic filter collapsed against the catheter shaft.

[0016] FIG. 9 is a different view of the embodiment of FIG. 8 and shows the angioplasty balloon inflated and the embolic filter erected.

[0017] FIG. 10 is another embodiment of a percutaneous transluminal angioplasty device according to the present invention, showing the angioplasty balloon and the embolic filter in their collapsed conditions.

[0018] FIG. 11 is another view of the embodiment of FIG. 10, showing the angioplasty balloon inflated and the embolic filter raised.

[0019] FIG. 12 is yet another embodiment of a percutaneous transluminal angioplasty device according to the present invention, showing the angioplasty balloon and the embolic filter in their collapsed conditions.

[0020] FIG. 13 is another view of the embodiment of FIG. 12, showing the angioplasty balloon inflated and the embolic filter raised.

[0021] FIG. 14 shows a side cut away view of a coronary artery with a stenosis.

[0022] FIG. 15 shows the coronary artery of FIG. 12 with a guide wire fed through the coronary artery and through the stenosis. [0023] FIG. 16 shows the device of FIG. 1 threaded over the guide wire of FIG. 15 and positioned such that the angioplasty balloon is located within the stenosis.

[0024] FIG. 17 illustrates the angioplasty balloon in its inflated condition to reduce the stenosis, and the embolic filter has been erected to capture any embolic particles that may break loose into the blood stream as a result of the angioplasty procedure.

[0025] FIG. 18 is a partial cut away side view of an embodiment of a device in which the angioplasty balloon and embolism filter, shown in their collapsed positions, are reversed on the catheter shaft for peripheral vascular applications in which blood flows in the opposite direction.

[0026] FIG. 19 is a partial cut away side view of the device of FIG. 18 showing the angioplasty balloon and embolism filter in their erected positions.

[0027] FIG. 20 is a side view of an embolism filter according to another embodiment of the present invention.

[0028] FIG. 21 is a side view of the embolism filter of FIG. 20 with the inflation balloon expanded to erect the embolism filter; filter mesh is shown removed to reveal interior detail.

[0029] FIG. 22 is a side view of the embolism filter of FIG. 20 with the inflation balloon deflated; filter mesh is shown removed to reveal interior detail. [0030] FIG. 23 is a side view of the embolism filter of FIG. 20 being retracted into the forward end of a catheter to collapse the filter; filter mesh is shown removed to reveal interior detail.

[0031] FIG. 24 is a side view of the embolism filter of FIG. 20 with the filter expanded and filter mesh in place.

[0032] FIG. 25 is a side cutaway view of another embodiment of an angioplasty device showing an angioplasty balloon in its deflated condition and an embolic filter in a retracted state.

[0033] FIG. 26 is a side cutaway view of the angioplasty device of FIG. 25 showing the angioplasty balloon inflated and the embolic filter erected.

[0034] FIG. 27 is a side view of a further embodiment of an angioplasty device in which the filter mesh extends beyond the end of the ribs so as to form a sac when the filter is collapsed.

[0035] FIG. 28 is a side view of the angioplasty device of FIG. 27 showing the filter in its collapsed condition.

[0036] FIG. 29 is a side view of another embodiment of an angioplasty device in an erected condition.

[0037] FIG. 30 is a side view of the embodiment of FIG. 29 showing the angioplasty device in a collapsed condition.

[0038] FIG. 31 is an exploded view of a filter basket according to a further embodiment of the present invention.

[0039] FIG. 32 is a side view of the filter basket of FIG. 31 mounted to a balloon catheter, with the filter basket erected. [0040] FIG. 33 is a side view of the filter basket and balloon catheter assembly of FIG. 32, with the filter basket collapsed.

[0041] FIG. 34 is an exploded view of a filter basket according to still another embodiment of the present invention.

[0042] FIG. 35 is a side view of the filter basket of FIG. 34 mounted to a balloon catheter, with the filter basket erected.

[0043] FIG. 36 is a side view of the filter basket and balloon catheter assembly of FIG. 35, with the filter basket collapsed.

[0044] FIG. 37 is an exploded view of a filter basket according to still another embodiment of the present invention.

[0045] FIG. 38 is a side view of the filter basket of FIG. 37 mounted to a balloon catheter, with the filter basket erected.

[0046] FIG. 39 is a side view of the filter basket and balloon catheter assembly of FIG. 38, with the filter basket collapsed.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENTS

[0047] Referring now to the drawings, in which identical numbers indicate identical elements throughout the various views, FIGS. 1 and 2 illustrate a first embodiment of a percutaneous transluminal angioplasty device 10 according to the present invention. The device 10 comprises an elongated catheter 12 having a shaft 14 with a proximal end (not shown) and a distal end 16. Spaced a short distance proximally from the distal end 16 of the catheter 12 is an angioplasty balloon 18 of conventional design. In FIG. 1 the angioplasty balloon 18 is shown in a deflated or collapsed condition. In FIG. 2 the angioplasty balloon 18 is shown in an inflated condition.

[0048] Located between the angioplasty balloon 18 and the distal tip 14 of the catheter 12 is a collapsible filter 20. The filter 20 includes a proximal ring portion 22 and a distal ring portion 24. A plurality of elongated ribs 26 extend generally longitudinally between the proximal and distal rings 22, 24. These ribs can be made of a shape memory material, such as nitinol, and in their baseline position, these ribs are collapsed. A filter mesh 28 overlies the distal portion of the ribs 26. In the embodiment of FIGS. 1 and 2, the distal ring 24 is movable toward and away from the proximal ring 22. As the distal ring 24 moves toward the proximal ring 22, the ribs 26 bow outward. As the ribs 26 bow outward, the filter mesh 28 overlaying the ribs is erected. FIG. 1 shows the filter 20 in its collapsed condition, while FIG. 2 shows the filter in its erected condition. Means 34 are included for erecting and collapsing the filter 20 of the device 10 shown in FIGS. 1 and 2. Specifically a balloon 36 has its distal end 38 bonded to the shaft 14 of the catheter 12. When the distal ring 24 is in its withdrawn position, as shown in FIG. 1, the bulk of the balloon 36 is folded forward over the shaft 14 of the catheter 12. When the balloon 36 is inflated, as shown in FIG. 2, the balloon 36 expands proximally, pushing the distal ring 24 in a proximal direction, causing the ribs 26 to bow outward and thereby erecting the filter 20. When the balloon 32 is deflated, the shape memory ribs straighten, urging the distal ring 24 in a distal direction and collapsing the filter 20 close to the shaft 14 of the catheter 12.

[0049] FIGS. 3, 4, and 5 show cross sections of the device 10 at various locations along its length. Referring first to FIG. 3, the catheter shaft 12 has three lumens: two smaller lumens and a large main lumen. The two smaller lumens are inflation lumens, one lumen 40 for the angioplasty balloon 18, and one lumen 42 for the balloon 36 which controls the filter 20. The larger main lumen 44 is used to receive a guide wire (not shown) over which the device 10 advanced to position the device for performing an angioplasty procedure.

[0050] Referring now to FIG. 4, this cross section is taken at a location distal to the angioplasty balloon 18. Consequently, the angioplasty balloon inflation lumen 40 has terminated and is no longer visible. Thus, FIG. 4 shows only two lumens, the main lumen 44 for receiving the guide wire, and the smaller inflation lumen 42 for the filter balloon 36.

[0051] Referring now to FIG. 5, this cross section is taken at a location distal to the filter balloon 36, and hence only the main lumen 44 is visible.

[0052] FIGS. 6 and 7 show an alternate embodiment of a percutaneous transluminal angioplasty device 110 according to the present invention. This device is similar to the device 10 previously described, with the exception that the filter 120, in this case, has its distal ring 124 fixed, and the proximal ring 122 of the filter 120 is movable toward and away from the distal ring to cause the ribs 126 to bow outwardly or to straighten. The balloon 136 is located on the proximal side of the filter 120 and pushes the proximal ring 122 in a distal direction when the balloon 136 is inflated.

[0053] The embodiment 610 shown in FIGS. 8 and 9 employs a different means for erecting the filter 620. In the embodiment 610 a pull wire 650 is used. The pull wire 650 extends through what would formerly have been used as the filter balloon inflation lumen 644, and the distal end 652 of the pull wire 650 is attached to the distal ring 624. When the physician wishes to raise the filter 620, he exerts a tension on the wire 650, as indicated by the arrow 653, thus drawing the distal ring 624 in a proximal direction as indicated by the arrow 655 toward the proximal ring 622. The ribs 626 bow outward, erecting the filter mesh 628 as shown in FIG. 9.

[0054] In the device 710 shown in FIGS. 10 and 11, the distal end 752 of a push wire 750 is attached to the proximal ring 722. Thus when the wire 750 is pushed in the direction indicated by the arrow 753, the proximal ring 722 is advanced distally toward the distal ring 724 in the direction indicated by the arrow 755, causing the ribs 726 to bow outward and thereby erecting the filter 720, as shown in FIG. 11.

[0055] The device 810 shown in FIGS. 12 and 13 uses a pull wire 850 to erect the filter 820. The pull wire 850 wraps around an opening 851 in the stationary distal ring 824 and extends rearward toward the proximal ring 822 to which the distal end 852 of the pull wire is attached. Thus when tension is exerted on the pull wire 850 in the direction indicated by the arrow 853, the proximal ring 822 is drawn distally toward the distal ring 824 in the direction indicated by the arrow 855, causing the ribs 826 to bow outward and thereby erecting the filter 820, as shown in FIG. 13.

[0056] The operation of the device 10 will now be explained with respect to FIGS. 14-17, and it will be understood that the other devices operate on a substantially the same principles. FIG. 14 shows a vascular structure (e.g., coronary artery, saphenous vein graft, renal artery, carotid artery, superficial femoral artery, etc.) 900 with upper and lower walls 902, 904, a branch vessel 905, and a stenosis or blockage 906 caused by the build up of plaque or other substances on the arterial walls in such a way as to narrow the diameter of the arterial lumen, and in the process, constrict the flow of blood therethrough.

[0057] In FIG. 15, a guide wire 908 has been inserted by the physician, such as through the femoral artery, and guided through the vascular system until the guide wire passes through the stenosis 906 in the vascular structure 900.

[0058] Referring now to FIG. 16, the apparatus 10 has been inserted over the guide wire 908 and advanced to a location wherein the angioplasty balloon resides within the stenosis 906. The embolic filter 20 resides a few centimeters distal or downstream from the angioplasty location. In FIG. 16 both the angioplasty balloon and the embolic filter are shown in their collapsed conditions. [0059] In FIG. 17 the embolic filter 20 has been erected by inflating the filter balloon 36, causing the distal ring 22 to slide in a proximal direction along the catheter shaft 12. As the ribs 26 bow outward, the mesh filter material 28 supported by the ribs spreads so as to cover substantially the entire arterial lumen. The angioplasty balloon 18 is now inflated. As the balloon 1 S inflates, it pushes tissue and plaque forming the stenosis 906 outward, opening the stenosis and possibly loosening embolic particles in the process. Any such embolic particles which get captured in the blood stream will be caught by the embolic filter 20 and will thereby be prevented from traveling to a location where they can cause clinical damage.

[0060] Of interest in FIG. 17 is the close proximity in which the filter 20 is erected relative to the stenosis 906. Despite the short "landing area" between the stenosis 906 and the branch vessel 905, the filter 20 is erected to capture embolic particles upstream of the branch vessel.

[0061] When removing the device 10 from the coronary artery, the preferred procedure is to deflate the angioplasty balloon 18 first, prior to collapsing the embolic filter 20. In this way, any embolic particles that are broken loose as the angioplasty balloon 18 deflates will be captured by the filter 20. The embolic filter balloon 20 is then deflated, permitting the ribs 26 and filter mesh 28 to collapse against the shaft 14 of the catheter 12. Any embolic particles captured by the mesh 28 are trapped against the shaft 14. The device 10 is then withdrawn over the guide wire 908 and removed from the patient's body.

[0062] In various peripheral vascular applications, it may be necessary to insert the catheter against the direction of blood flow (e.g., the aorta). FIGS. 18 and 19 illustrate a device 1000 in which the angioplasty balloon 1018 and the embolic filter 1020 are reversed on the shaft 1014 of the catheter 1012. Thus with the blood flowing within the vessel in the direction indicated by the arrow 1080, the embolic filter 1020 will be proximal to the angioplasty balloon 1018 and thus positioned to capture any embolic particles that may be dislodged by the angioplasty balloon. While the embodiment 1000 of FIGS. 18 and 19 employs the same method and device for erecting the embolic filter as the embodiment 10 of FIGS. 1-3, it will be understood that the methods and devices for erecting the embolic filter of other embodiments disclosed above are equally applicable to a configuration like the device of embodiment 1000 where the angioplasty balloon is positioned between the embolic filter and the tip of the device.

[0063] FIGS. 20-24 show still another embodiment of an embolic filter 1120 for use in conjunction with an angioplasty balloon. FIGS. 20-24 show only the embolic filter 1120 and not the angioplasty balloon, but it will be understood that the embolic filter is located on the same catheter 1114 as the angioplasty balloon in the same manner as the embodiments previously disclosed. Further, FIGS. 21-23 show the embolic filter 1120 without its filter mesh 1128 for clarity of illustration. [0064] In FIG. 20 the embolic filter 1120 is folded closely against the shaft 1114 of the catheter 1112. The ribs 1126 of the filter 1120 extend between a proximal ring portion 1122 and a distal ring portion 1124. The distal ring portion 1124 is slidably mounted on the shaft 1114 of the catheter 1112, and the proximal ring portion 1122 is fixed with relation to the shaft of the catheter. In FIG. 21 the embolic filter balloon 1136 has been inflated, expanding the ribs 1126 of the embolic filter. As the ribs expand, the distal ring portion 1124 slides in the proximal direction, as shown by the arrow 1188. Once expanded, the ribs 1126 maintain their shape, such that when the embolic filter balloon 1136 is deflated, as shown in FIG. 22, the embolic filter 1120 remains expanded.

[0065] To retract the embolic filter 1120, a second, outer catheter 1190 is advanced over the catheter 1112, as shown in FIG. 23, causing the ribs 1126 to collapse as the embolic filter is withdrawn into the forward end of the outer catheter 1190. As the ribs 1126 collapse, the distal ring portion 1124 slides in the distal direction. Once the embolic filter 1120 has been completely retracted into the forward end of the outer catheter 1190, the outer and inner catheters are withdrawn simultaneously.

[0066] FIG. 24 shows the embolic filter 1120 with filter mesh 1128 positioned over the ribs 1126.

[0067] FIGS. 25 and 26 illustrate a further embodiment of a percutaneous angioplasty device 1210, in which the embolic filter 1220 is located on a different carrier than the angioplasty balloon 1218. Specifically, the angioplasty balloon 1218 is located on an outer catheter 1294, and the embolic filter 1220 is located at the forward end of an inner catheter 1295. (The embolic filter 1220 is shown without filter mesh in FIGS. 25 and 26 for clarity of illustration.) The outer catheter preferably has three lumens, one for inflating the angioplasty balloon 1218, one for accommodating a guide wire (not shown), and one for receiving the inner catheter 1295 and embolic filter 1220. The inner catheter 1295 is slidably telescopically disposed within the outer catheter 1294. The ribs 1226 of the embolic filter 1220 are formed from a shape-memory metal such as nitinol and are constructed to normally assume an "open" configuration. When retracted within the forward end of the outer catheter 1294, the ribs 1226 of the embolic filter collapse.

[0068] To use the percutaneous angioplasty device 1210, the inner catheter is inserted into the outer catheter so that the embolic filter 1220 is collapsed within the distal end of the device, as shown in FIG. 25. The outer and inner catheters 1294, 1295 are inserted together, such as through the femoral artery, over a guidewire and advanced through the vascular system to a location wherein the uninflated angioplasty balloon 1218 resides within the stenosis. Once location of the angioplasty balloon 1218 within the stenosis has been verified by suitable medical imaging technology, the inner catheter is advanced to progress the embolic filter 1220 beyond the forward end of the outer catheter 1294. As the embolic filter 1220 is freed from the confines of the outer catheter 1294, the ribs assume their expanded configuration and erect the embolic filter. Thereafter the angioplasty balloon 1218 may be inflated to treat the stenosis, and any emboli loosened during the procedure will be captured by the embolic filter 1220 downstream of the stenosis.

[0069] When the angioplasty procedure has been completed, the angioplasty balloon 1218 is deflated, and the embolic filter 1220 is withdrawn back into the forward end of the outer catheter 1294. The outer and inner catheters 1294, 1295 are then withdrawn together from the patient.

[0070] In the foregoing embodiment a wire can be substituted for the inner catheter 1295 as a means for carrying the embolic filter 1220.

[0071 ] FIGS. 27 and 28 show an angioplasty device 1310 that is identical to the device 10, with the exception that the filter mesh 1328 extends distally beyond the end of the ribs 1326 and is attached to the distal end of the distal ring 1324. When the filter 1320 is collapsed, as shown in FIG. 28, a sac 1398 is formed which helps contain the embolic particles, thereby minimizing the possibility that the ribs 1326 will squeeze the particles out of the filter.

[0072] FIGS. 29 and 30 disclose an angioplasty device 1500 according to another embodiment of the invention. The device 1500 includes a balloon catheter 1502 comprising a catheter shaft 1503 and a balloon 1504. The balloon 1504 is inflatable by means of an inflation lumen 1507. A filter basket 1505 is disposed at the distal end 1506 of the shaft 1503. To facilitate guidance of the device 1500 to the treatment location within the patient's body, a guidewire 1509 is received through a lumen (not shown) extending through the catheter shaft 1503. The guide wire may extend from the distal end of the catheter to the proximal end of the catheter or it may extend from the distal end of the catheter and exit out the catheter body proximal to the inflation balloon.

[0073] The filter basket 1505 consists of a filter membrane

1508 attached to a support frame 1510. The support frame 1510 is generally tubular in shape with a proximal ring 1512 and a distal ring 1514 at opposite ends. A first set of elongated struts 1516 is attached to and extends between the end rings 1512, 1514. The frame 1510 of the filter basket 1504 is formed from Nitinol or other suitable shape-memory material.

[0074] For ease of illustration, the frame 1510 of the device 1500 is shown as only one set of elongated struts 1516. However, it will be appreciated that a second set of struts may be located in between the first set of longitudinal struts 1516 to form a serpentine pattern. This second set of struts is formed of strut sections connected by hinges. The width of the hinges is different than the width of the adjacent strut sections so as to provide a zone of weakness along which the hinges bend. The bending of the hinges allows the second set of serpentine struts to expand in the radial direction. In some cases there could be more than one set of such serpentine struts placed in a row along the length of the support frame, as shown in FIG. 27. In another form a pair of struts are connected between the serpentine struts to provide extra support to the filter membrane.

[0075] It will be understood that providing a portion of the strut with a narrowed width to facilitate bending is but one way of achieving a zone of weakness. For example, the hinges can also be formed by scored lines transverse to the strut to facilitate bending.

[0076] The distal ring 1514 of the filter frame 1510 is either slidably or fixedly mounted to the distal end 1506 of the catheter shaft. The proximal ring 1512 of the filter frame 1510 is slidably mounted along a portion of the shaft 1503 between the distal end 1506 and the balloon 1504.

[0077] The filter frame 1510 is formed from a shape memory material such as nitinol. The filter frame 1510 is heat set in the expanded shape. This normally expanded shape will cause the filter frame 1510 to bow outward if not constrained. When the filter frame 1510 expands, it draws the proximal ring 1512 distally toward the distal ring 1514. When the proximal ring 1512 is moved in a proximal direction, the filter frame 1510 will collapse.

[0078] The filter membrane 1508 of the disclosed embodiment consists of a funnel shape, but is not limited to this shape. The filter membrane 1508 is made up of semi-compliant material such as nylon or Pebax®, or could be made up of elastic materials such as thermoplastic elastomers or thermoset elastomers. Some examples of thermoset elastomers include polyurethane and copolymers (e.g., Pellathane™, Tecothane™, or Chronoflex™,). These materials allow the openings in the filter material to be placed close to each other. The size of the filter openings could be 40 microns and be placed 40 microns apart. The filter membrane can also consist of a wire mesh woven such that when it opens it forms the filter screen.

[0079] The filter membrane 1508 is attached to the filter frame 1510 such that it covers the distal half of the frame. The proximal portion of the frame remains open. The filter membrane 1508 may be attached on the outside of the frame 1510 or on the inside of the frame. The filter membrane 1508 may also be attached to the mid-portion of the frame 1510 that expands the most to conform to the vessel wall, while the distal portion of the filter membrane is attached to the distal end 1506 of the catheter shaft 1503.

[0080] Because the filter frame 1510 will bow outward if not constrained, a mechanism is provided for constraining the filter frame as the device 1500 is being introduced into and withdrawn from the patient. Adjacent to the distal end of the balloon 1504, a fixed filter housing 1520 is concentrically mounted to the catheter shaft 1503. The inner wall 1522 of the fixed filter housing 1520 is spaced apart from the exterior wall of the catheter shaft 1503 to create an annular space. When at least a major portion of the filter basket 1504 has been retracted into the fixed filter housing 1520, the filter frame 1510 is constrained from expanding, thus reducing the overall diameter of the device 1500 and enabling the device to be introduced into or withdrawn from the patient. [0081] The fixed filter housing 1520 is made of a soft, elastic material such as polyurethane or silicon rubber that will keep the filter basket 1504 collapsed as well as retrieve the filter after use when it may be filled with embolic debris. Because of this feature the catheter shaft 1503 can be built with a distal tip that has a low profile and is very flexible and hence allows true navigation through tortuous anatomy and cross through narrow passageways. The filter housing 1520 may also have a semi-rigid proximal portion and a more flexible distal portion. The flexible distal portion guides the filter into the housing while the semirigid portion forces the filter into a lower constrained profile.

[0082] To enable manipulation of the proximal ring 1512 from a location outside of the patient to move the filter basket 1505 into and out of the fixed filter housing 1520 to expand and retract the filter 1505, an actuation wire 1526 is provided. The actuation wire is flexible and kink resistant as well as of high resistance to compression. The flexibility allows ease of navigation through the arterial system while the high compression resistance conveys the necessary force to the filter. In the disclosed embodiment the actuation wire is metal such as stainless steel. A stainless steel wire ideally could be produced by drawing stainless steel and then partially annealing. In the disclosed embodiment the actuation wire has a constant diameter of 0.012 inches. Alternatively, the actuation wire can be tapered from proximal to distal end. In one embodiment the actuation wire has a diameter of about 0.014 inches at its proximal end, tapering to a diameter of about 0.005 inches at its distal end.

[0083] The actuation wire is supported along most of its length to prevent buckling of the wire during pushing of the actuation wire. The distal end of the actuation wire 1526 is coupled to the proximal ring 1512. From there, the actuation wire 1526 extends through a lumen 1528 along the catheter shaft 1503 to a location outside of the patient. The lumen 1528 can be formed within the catheter shaft 1503 or can comprise a separate tube bonded to the exterior of the catheter shaft. The proximal end 1530 of the actuation wire 1526 extends to a location that will be outside the patient during normal operation such that the actuation wire can be manually operated by the physician. Alternatively the proximal end of the actuation wire can be coupled to a mechanical actuator that, in turn, is manipulated by the physician.

[0084] The balloon catheter 1500 is packaged and supplied with the filter basket 1505 extended beyond the distal end of the filter housing 1520 in its normally open position so as to retain its shape memory. At the time of use the filter basket 1505 is retracted into the fixed filter housing 1520 by pulling on the actuation wire 1526. The catheter 1500 with filter basket 1505 retracted is tracked up to the point of treatment. The actuation wire 1526 is then pushed so that the filter basket 1505 is advanced out of the filter housing 1520. As the filter basket 1505 is released from the confines of the filter housing 1520, the filter basket expands to its predetermined shape and diameter. [0085] After the procedure the filter basket 1505 is retracted back into the filter housing 1520 by simply pulling the actuation wire 1526. As the struts 1516 of the filter frame confront the distal end of the filter housing 1520, they are deflected inward, causing the filter frame to collapse against the catheter shaft 1503.

[0086] The exact mechanism by which the filter basket 1505 collapses depends upon whether the distal ring 1514 of the filter basket is slidably or fixedly attached to the catheter shaft 1503. If the distal ring 1514 is fixed, then pulling the proximal ring 1512 in a proximal direction will draw the proximal ring away from the distal ring, place the filter ribs under tension , and collapse the filter frame 1510. This could also bring the proximal ring 1512 and part of the filter membrane 1508 into the fixed filter housing, where it remains confined in its collapsed state. If the distal ring 1514 is slidably mounted, then initially withdrawing the proximal ring 1512 will simply pull the distal ring along with it. However, once the proximal ring 1512 enters the fixed filter housing 1520, the filter frame 1510 will impinge upon the distal edge of the filter housing and be biased inward. Further retraction of the proximal ring 1512 collapses the filter frame 1510 within the filter housing 1520, as shown in FIG. 30.

[0087] In each of the foregoing examples, it will be appreciated that an angioplasty balloon is but one means for relieving a stenosis in a vessel. Stents, mechanical thrombectomy devices, or other suitable apparatus may be substituted for the angioplasty balloon and positioned on the catheter at a location proximal to the embolic filter. Thus any emboli loosened by the stent or mechanical thrombectomy device will be captured by the embolic filter in the same manner as described above with respect to the angioplasty balloon.

[0088] While the foregoing disclosed embodiments comprise filter ribs of a shape memory metal such as nitinol, it will be appreciated that similar results can be obtained by using any suitable resilient material. The ribs would be formed straight, forced open by the balloon, and return to their normal shape as a result of the resiliency of the structure. Or, in the case of the embodiment of FIGS. 25 and 26, the ribs would be initially formed in an open position, deformed inwardly to fit within the outer catheter, and return to their normal open position when released from the confines of the outer catheter.

[0089] Variations in the design of the filter are also contemplated. For example, while both ends of the ribs 26 of the filter 20 are mounted to rings 22, 24, it will be appreciated that the ends of the ribs at the fixed end of the filter can be secured directly to the catheter shaft.

[0090] A further embodiment of a filter basket 1550 is shown in FIGS. 31-33. The filter basket 1550 includes a shape memory frame 1552 without the distal half. In other words, the filter frame 1552 comprises a plurality of struts 1554 attached to a ring 1556 and extending distally and outward therefrom. The distal ends of the struts 1554 are circumferentially connected by another set of struts 1558 that forms a serpentine pattern. The filter frame 1552 could also be made up of semi- flexible polymeric materials and composites.

[0091] The ring 1556 is slidably mounted to a catheter shaft

1560. A filter membrane 1562 is attached to the distal end of the filter frame 1552, and the other end of the filter membrane is attached to the distal portion of the catheter shaft 1560. Thus the filter frame 1552 extends only a part of the length of the filter basket 1550.

[0092] The frame 1552 is partially retracted into a fixed filter housing 1564 by means of an actuation wire 1566 to collapse the filter frame 1552, as shown in FIG. 33, to contain the captured emboli.

[0093] FIGS. 34-36 illustrate a variation of the filter design shown in FIGS. 31-33. The filter basket 1570 is similar in most respects to the filter basket 1550 previously described. However, while the proximal end of the filter membrane 1572 is still attached to the distal end of the filter frame 1574, a distal ring 1575 is attached to the distal end of the filter membrane. The distal ring 1575 in turn is slidably attached to the distal portion of a catheter shaft 1576. The distal ring 1575 may be made up of a rigid or semi-rigid material such as a plastic or a very thin metal. An actuation wire 1578 is attached not only to the proximal ring 1580 but also extends beyond the proximal ring to attach to the distal ring 1575. Thus advancing or withdrawing the actuation wire 1578 advances or retracts not only the proximal ring 1580 but also the distal ring 1575. The filter basket 1570 is deployed by pushing the actuation wire 1578 distally, which in turn will push both the distal and proximal rings 1575, 1580 of the filter distally out of the fixed filter housing 1582 and permit the filter basket to expand to its normal shape.

[0094] Because the actuation wire 1578 is attached not only to a proximal ring 1580 but also extends beyond the proximal ring to attach to the distal ring 1575, the distance between the rings 1575, 1580 is fixed, as indicated by the arrows 1584. It will be understood, however, that the two rings 1575, 1580 can be maintained in fixed, spaced-apart relation by a member separate from the actuation wire 1578 without departing from the scope and spirit of the appended claims.

[0095] FIGS. 37-39 illustrate still another embodiment of a filter basket 1590. The filter basket 1590 includes a filter membrane 1591 and a filter frame 1592. The filter frame 1592 comprises a proximal ring 1593 slidably mounted to a catheter shaft 1594. A strut 1595 extends distally from the proximal ring 1593. A loop 1596 is mounted to the strut generally coaxial with the proximal ring 1593. The filter membrane 1591 has a generally circular proximal end that attaches to the loop 1596 of the filter frame 1592. The distal end of the filter membrane 1591 is attached to a distal ring 1597.

[0096] FIG. 38 shows the filter basket 1590 in its erected condition. The loop 1596 of the filter frame 1592 holds the filter membrane 1591 open and ready to receive embolic particles. To collapse the filter basket 1590, an actuation wire 1598 is pulled, drawing the proximal ring 1593 rearward into a fixed filter housing 1599. As the loop 1596 of the filter frame 1592 confronts the distal end of the fixed filter housing 1599, it vertically elongates, and the lower end of the loop collapses distally, as shown in FIG. 39. As the loop 1596 collapses and is drawn into the fixed filter housing 1599, the filter membrane 1591 is drawn into the fixed filter housing.

[0097] The fixed filter housings 1520, 1564, 1582, and 1599 of the embodiments of FIGS. 29-39 provide certain advantages. First, the filter housing constrains the associated filter membrane 1508, 1562, 1572, or 1591 in the closed position during insertion and removal and prevents the membrane from being caught or snagged during retrieval. Next the filter housing prevents captured particles from escaping. With respect to the embodiments in which the distance between the proximal filter ring and the distal end of the filter is fixed, the filter frame confronts the distal end of the filter housing as it is withdrawn, forcing the frame to collapse inward. The distal edge of the filter housing is thus the mechanism by which the filter is collapsed. And even with respect to the embodiments in which the distance between the proximal filter ring and the distal end of the filter is variable, the filter housing facilitates collapse of the filter as the actuation wire is withdrawn. While initial proximal movement of the proximal filter ring tends to straighten the filter frame to cause it to collapse inward, the force required on the actuation wire to continue to collapse the frame becomes greater as the frame approaches its collapsed position. The radially inward force applied to the frame as it confronts the distal end of the fixed housing makes it easier to collapse the frame, thereby reducing the tension required to be exerted on the actuation wire. [0098] The filter baskets 1505, 1550, 1570, and 1590 can be completely or partially withdrawn into their respective fixed filter housings 1520, 1564, 1582, and 1599. From the perspective of maintaining the filter baskets in a closed position, the only requirement of the filter housing is that it be long enough such that when the proximal ring 1512, 1556, 1580, or 1593 is fully retracted within the proximal portion of the respective housing 1520, 1564, 1582, or 1599, the widest portion of the filter frame (as determined when the frame is in its normally open condition) is withdrawn within the housing.

[0099] The fixed filter housings 1520, 1564, 1582, and 1599 of the disclosed embodiments are cylindrical, but there is no requirement that the housings have a circular cross-section. The housings may have any suitable cross-sectional configuration that will accept the filter basket. While a cylindrical filter housing arguably has only one continuous interior wall, a filter housing having an octagonal cross- section would have eight wall sections. For ease of description, the interior surface of a filter housing will be said to have "an interior wall," whether the surface is one continuous wall or comprised of a plurality of conjoined wall segments.

[00100] The struts of the filter frames of the embodiments of FIGS. 29-39 are not limited to the configurations shown. For example, filter frame struts can be arranged in a crisscross manner to form a netlike structure. In yet another embodiment the struts could be configured in a sinusoidal wave pattern extending circumferentially, forming rings that are longitudinally connected by longitudinal struts.

[00101] It will be appreciated that the present invention permits the placement of the embolic filter very close to the means for treating the stenosis. This has the effect of minimizing the "landing area" of the filter and also permits the protection of side branches, as shown in FIGS. 14-17.

[00102] Finally, it will be understood that the foregoing embodiments have been disclosed by way of example, and that other modifications may occur to those skilled in the art.

Claims

CLAIMSWhat is claimed is:

1. A medical device, comprising: an elongated catheter having proximal and distal ends and an outer circumference; a selectively expandable interventional member attached to the catheter at a location spaced apart from the distal end of the catheter; a filter housing attached to the catheter in longitudinally fixed position with respect to the catheter at a location on the catheter between the interventional member and the distal end of the catheter, the filter housing having proximal and distal ends, an opening at its distal end, and a side wall spaced apart from the outer circumference of the catheter so as to define a space therebetween; a filter attached to the catheter and comprising: a filter ring slidably attached to the outer circumference of the catheter distal to the proximal end of the fixed filter housing and being configured to be received within the space between the filter housing side wall and the outer circumference of the catheter; a filter frame coupled to the filter ring and having a normally expanded configuration; and a filter mesh supported by the filter frame; and an actuation member having a distal end coupled to the filter ring, the actuation member being operable when advanced to displace the filter ring distal of the filter housing to permit the filter frame to attain its normally expanded condition and when retracted to withdraw the filter ring into the filter housing to cause the filter frame to collapse.

2. The medical device of Claim 1, wherein the filter frame comprises: a strut having proximal and distal ends, the proximal end being attached to the filter ring, and the strut normally extending distally and outward away from the catheter; and a circumferential member supported by the distal end of the strut for supporting a proximal portion of the filter mesh.

3. The medical device of Claim 2, wherein the strut comprises a first strut, and wherein the filter frame comprises one or more additional struts each having proximal and distal ends, the proximal end of each one or more additional struts being attached to the filter ring, each of the one or more additional struts normally extending distally and outward away from the catheter, and the distal end of each of the one or more additional struts supporting the circumferential member.

4. The medical device of Claim 2, wherein the circumferential member is a ring.

5. The medical device of Claim 1, wherein the filter ring is a proximal filter ring, wherein the device further comprises a distal filter ring attached to the outer circumference of the catheter at a location distal to the proximal filter ring, and wherein the filter frame has proximal and distal ends, the proximal end of the filter frame being coupled to the proximal filter ring, and the distal end of the filter frame being coupled to the distal filter ring.

6. The medical device of Claim 5, wherein the distal filter ring is immovably attached to the outer circumference of the catheter, whereby distal movement of the proximal filter ring displaces the proximal filter ring toward the distal filter ring, thereby permitting the filter frame to expand.

7. The medical device of Claim 5, wherein the distal filter ring is slidably attached to the outer circumference of the catheter and is free to move independently of the proximal filter ring.

8. The medical device of Claim 5, wherein the distal filter ring is slidably attached to the outer circumference of the catheter, and wherein the distance between the proximal and distal filter rings is fixed.

9. The medical device of Claim 1, wherein the filter mesh has proximal and distal portions; wherein the proximal portion of the filter mesh is attached to the filter frame; and wherein the distal portion of the filter mesh is attached to the catheter shaft.

10. The medical device of Claim 1, wherein the filter frame has a section of maximum cross-sectional width as determined when the filter is in its expanded condition; and wherein the filter housing has a length sufficient that when the filter ring is fully withdrawn toward the proximal end of the housing, the section of the filter frame of maximum cross- sectional width is received within the housing.