US20060130332A1 - Filter frame - Google Patents

Abstract

Distal protection filter frame and method for using and manufacturing the same. A distal protection filter frame may include one or more struts, a mouth, and a filter coupled to the mouth.

Description

• This application is a continuation application of U.S. patent application Ser. No. 10/099,219 filed on Mar. 13, 2002.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention pertains to distal protection catheters for filtering embolic debris. More precisely, the present invention pertains to distal protection filters including a refinement to the filter frame.
• 2. Description of the Related Art
• Heart disease is a major problem in the United States and throughout the world. Conditions such as atherosclerosis result in blood vessels becoming blocked or narrowed. This blockage can result in lack of oxygenation of the heart, which has significant consequences since the heart muscle must be well oxygenated in order to maintain its blood pumping action.
• Occluded, stenotic, or narrowed blood vessels may be treated with a number of relatively non-invasive medical procedures including percutaneous transluminal angioplasty (PTA), percutaneous transluminal coronary angioplasty (PTCA), and atherectomy. Angioplasty techniques typically involve the use of a balloon catheter. The balloon catheter is advanced over a guidewire such that the balloon is positioned adjacent a stenotic lesion. The balloon is then inflated and the restriction of the vessel is opened. During an atherectomy procedure, the stenotic lesion may be mechanically cut away from the blood vessel wall using an atherectomy catheter.
• During angioplasty and atherectomy procedures, embolic debris can be separated from the wall of the blood vessel. If this debris enters the circulatory system, it could block other vascular regions including the neural and pulmonary vasculature, both of which are highly undesirable. During angioplasty procedures, stenotic debris may also break loose due to manipulation of the blood vessel. Because of this debris, a number of devices, termed distal protection devices, have been developed to filter out this debris.
BRIEF SUMMARY OF THE INVENTION
• The present invention pertains to distal protection filter assemblies. More particularly, the present invention pertains to distal protection filter frames. A filter frame may include a plurality of struts or ribs and a crown or mouth portion. The crown portion may be adapted and configured to have a distal protection filter coupled thereto.
• A number of different mandrels may be used to manufacture the filter frame. For example, a mandrel may include a proximal region, a distal region, and a middle region. In addition, the mandrel may include grooves for holding the filter frame in place. Further, the mandrel may include openings leading to a guidewire channel or a screw dip rod.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
• FIG. 1 is a cross sectional view of a distal protection filter disposed within the vasculature of a patient;
• FIG. 2 is a perspective view of a filter frame for use with a distal protection filter;
• FIG. 3 is a flattened plan view of the filter frame;
• FIG. 4 is a perspective view of an alternate filter frame for use with a distal protection filter;
• FIG. 5 is a flattened plan view of the alternate distal protection filter frame;
• FIG. 6 is a perspective view of a mandrel for use in forming a distal protection filter frame;
• FIG. 7 is a perspective view of an alternate mandrel for use in forming a distal protection filter frame;
• FIG. 8 is a cross sectional view taken through line7-7 of the mandrel shown inFIG. 7; and
• FIG. 9 is a perspective view of a second alternate mandrel for use in forming a distal protection filter frame.
DETAILED DESCRIPTION OF THE INVENTION
• The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings illustrate example embodiments of the claimed invention.
• FIG. 1 is a cross sectional view of a distal protection filter disposed within the vasculature of a patient. When performing any one of a number of differing intravascular procedures, embolic debris may drift away from the treatment site and, potentially, obstruct downstream vascular regions. These obstructions could lead to adverse medical conditions and/or tissue damage. A strategy that may help prevent embolic debris from causing problems downstream of an intravascular procedure may include the use of adistal protection filter10.Distal protection filter10 includes afilter frame12 having afilter material14 coupled thereto.
• Filter frame12 may be comprised of metal such as nickel-titanium alloy or stainless steel and configured to have one ormore struts18 coupled to an elongate shaft orguidewire20, and a crown definingmouth portion22 coupled tofilter material14.Frame12 may be self-expanding so thatframe12 will expand to engage and generally conform to the internal lumen ablood vessel16 when being delivered (e.g., from a delivery catheter or sheath).
• Distalprotection filter material14 may be coupled to guidewire20 proximate a distal end ofguidewire20.Filter material14 andguidewire20 may generally comprise a number of configurations known to those skilled in the appropriate art.Filter material14 may be comprised of a polyurethane sheet and include at least one opening that may be, for example, formed by known laser techniques. The holes or openings are sized to allow blood flow therethrough but restrict flow of debris or emboli floating in the body lumen or cavity.
• Filter10 may be generally cone-shaped, and have a proximal and a distal end. The distal end may be a narrow, “V”-shaped end and is secured to guidewire20 and/orframe12. Alternatively,filter10 may be cylindrical with a relatively rounded distal end.Filter10 operates between a closed collapsed profile and an open radially-expanded deployed profile for collecting debris in a body lumen. In an expanded profile, the mouth is opened andstruts18 extend radially outwardly to support the mouth.Struts18 may be coupled to guidewire20 by astrut coupling member23. A number of differing configurations offilter material14 may be substituted without departing from the spirit of the invention.
• In addition, a portion offrame12 may be comprised of or plated with radiopaque materials. Radiopaque materials are understood to be capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during an intravascular procedure. This relatively bright image aids the user ofdistal protection assembly10 in determining the location offrame12 with respect to the patient's vascular anatomy. Radiopaque materials may include, but are not limited to, gold, platinum, tungsten alloy, and plastic material loaded with a radiopaque filler.
• FIG. 2 is a perspective view offilter frame12 for use with distalprotection filter material14. A number of features may be incorporated intofilter frame12. For example,filter frame12 may be constructed with a geometry that is optimized for essentially complete apposition to the internal wall of blood vessel16 (i.e.,frame12 conforms to the shape of blood vessel16) and minimal peak strains withinframe12. Peak strain is understood to be strain at points alongframe12 where force is concentrated. Therefore, peak strain may be minimized by distributing the force evenly throughoutframe12. In addition,frame12 includes a greater expansion ratio. Expansion ratio is understood to be the ratio of the diameter (or area) offrame12 between an expanded configuration and a collapsed configuration. Increasing the expansion ratio may allowframe12 to be collapsed to a generally small profile and still be capable of expanding to conform to the size of a blood vessel. These and other features may allowframe12 to be delivered with a small profile.
• Struts orribs18 may be pre-curved during manufacturing to include a firstcurved portion24. Whenframe12 is collapsed within a delivery sheath, stress onframe12 may longitudinally deform orstrain frame12.Curved portion24 has a constant radius so that whenframe12 is collapsed, stress and/or strain forces are evenly distributed longitudinally throughoutframe12. According to this embodiment, the peak strain within struts18 and/orframe12 whenframe12 may be minimized by includingcurved portion24.
• Struts18 andcrown portion22 may be continuous and be joined by a secondcurved portion26. Similarly tocurved portion24,portion26 is also curved to minimize peak strain nearcrown portion26. However, the radius of curvature ofcurved portion26 may be variable or include portions where the radius varies. In addition,crown portion22 extends between adistal end28 and a plurality of strut intersection points30.Struts18 may extend frompoints30 and be coupled toguidewire20.
• It should be noted that the number ofstruts18 and points30 can be altered without departing from the scope of the present invention. For example,frame12 may include two, three, four, five, six, or more points. It is believed that increasing the number ofstruts18 and/or points30 would decrease the expansion ratio offrame12. For example, increasing the number ofpoints30 from four to six would increase the inside diameter offrame12. Different diameter sizes may be favored when performing an intravascular procedure within different blood vessels.
• FIG. 3 is a flattened plan view of distalprotection filter frame12. When manufacturingframe12 it may be beneficial to first manufacture a planer version of the appropriate material (e.g., nickel-titanium alloy). The planer version may be formed into the desired shape by disposingframe12 about a mandrel (examples are shown below inFIGS. 6-9) and coupling opposite ends together, for example by soldering or welding.
• FIG. 4 is a perspective view of analternate filter frame112 for use with distalprotection filter material14.Frame112 is essentially the same in form and function asframe12 in thatframe112, except thatframe112 further comprises distally-orientedstruts132 in addition to struts118. Distally-orientedstruts132 extend distally betweendistal end128 ofcrown portion122 andguidewire20.
• Struts132 provide additional support forfilter material14. According to this embodiment, whenframe12 is coupled to filtermaterial14, struts132 may be adapted and configured to follow the contour offilter material14 and provide structural support along the length thereof. At a distal end, struts132 may be coupled to the distal end offilter material14 and/or be coupled toguidewire20. Similarly toFIG. 3,FIG. 5 is a flattened planview filter frame112.
• FIG. 6 is a perspective view of amandrel34 for use in manufacturing a distal protection filter frame (e.g.,frame12 and frame112).Mandrel34 includes a generally tapered or cone-likedistal region36, amiddle region38, and a taperedproximal region40. In addition,mandrel34 may include adistal tip42 and aproximal tip44 disposed proximate their respective regions. It should be appreciated that although the subsequent discussion is focused uponframe12 it is similarly applicable to frame112
• Middle region38 includesgrooves46 adapted and configured for holding at least a portion offilter frame12.Grooves46 are curved such that disposingcrown portion22 withingrooves46 may lead to the formation of secondcurved portion26. In addition, the transition from the relatively straightmiddle region38 to the taperedproximal region40 may lead to the formation of firstcurved portion24, although pre-curving may be desirable if the transition betweenproximal region40 andmiddle region38 bends more sharply than desired.
• In use, the planer configurations shown inFIGS. 3 and 5 of frame12 (and/or frame112) may be disposed aboutmandrel34 such thatcrown portion22 or122 is disposed withingroove46.Struts18 may extend betweenmiddle region38 andproximal region40 wherein the transition between regions tapers struts18 toward the center and can be used to formfirst curve24. The proximal ends ofstruts18 may be disposed nearproximal tip44 where they may be coupled toguidewire20. Acollar47 may be slidably disposed alongmiddle region38 that is adapted and configured to be slid overstruts18 and/or crown portion22 (or crown portion122) to holdframe12 in position. Once held in position, the shape offrame12 may be set to conform to the shape of the mandrel using methods described below or those known in the art. Following shape setting,frame12 can be removed frommandrel34 or it may be coupled withfilter material14, for example by dippingdistal region36 into molten or partiallymolten filter material14.
• Heat setting may be used to set the shape of frame12 (and frame112). For example,frame12 may be comprised of a shape memory alloy that can be heat set. Thus,frame12 may be disposed aboutmandrel34 and heated to set the shape offrame12 to conform to the shape ofmandrel34. According to this embodiment, mandrel34 (and subsequently described mandrels) may be comprised of materials that would resist heat deformation such as stainless steel. Once heat set,frame12 deformed to an alternate shape will return to the heat set shape after force used to deformframe12 is removed. It may be desirable to heat setframe12 in the expanded configuration such that delivery offilter10 from within a relatively small delivery sheath permitsframe12 to self-expand when the delivery sheath is withdrawn.
• It should be noted thatmandrel34 may be hollow such thatguidewire20 may pass therethrough with opposing end extending fromdistal tip42 andproximal tip44. This embodiment may simplify the process of coupling struts18 (or struts132) to guidewire20 if desired by establishing proper alignment. This step may similarly achieved independently ofmandrel34.
• When used forframe112, the above steps occur analogously to what is described above. In addition, struts132 extend betweenmiddle region38 anddistal region36 whereinstruts132 taper toward the center. The distal ends ofstruts132 may be disposed neardistal tip42 where they may be coupled toguidewire20.
• Onceframe12 or112 is properly configured,filter material14 may be coupled thereto. For example, suitable filter materials may be molten or partially molten andframe12 or112 may be coupled to filtermaterial14 by dipping distal region36 (or136) into thesuitable filter materials14 as described above. It should be appreciated that a person of ordinary skill in the art would be familiar with suitable filter materials and method forcoupling filter material14 to frame12.
• FIG. 7 is a perspective view of analternate mandrel134 for use in forming a distal protection filter frame.Mandrel134 is similar tomandrel34 in that it includesdistal region136,middle region138,proximal region140,distal tip142, andgrooves146. In addition,middle region138 ofmandrel134 include one ormore openings148 to aguidewire channel150.Openings148 may be used for shaping struts or be a place for struts to extending during formation of the filter frame. According to this embodiment, a filter frame may be configured such that struts orribs18 pass throughopenings148, into astrut channel152 and come together at an apex154.Openings148 may be useful for taperingstruts18 towardguidewire20. Other than the differences noted above, use ofmandrel134 may be similar to that ofmandrel34.FIG. 8 is a cross sectional view taken through line7-7 of the mandrel shown inFIG. 7showing channels152.
• FIG. 9 is a perspective view of a secondalternate mandrel234 for use in forming a distal protection filter frame.Mandrel234 is similar tomandrel34 in form and function in that it includesdistal region236,middle region238,proximal region240,distal tip242, andgrooves246. In addition,middle region238 ofmandrel234 includes ascrew dip rod256.
• Filter frame112 may be coupled tomandrel234 such thatcrown portion122 is disposed aboutmiddle region238 and struts132 are disposed withingrooves246 and extend towarddistal tip242.Screw dip rod256 may be actuated so as to pass over and hold or set the shape ofcrown portion122 into a generally circular configuration. Then, heat may be used to set the shape similarly to what is described above.Struts132 may be coupled toguidewire20 that may pass throughmandrel234 and exit therefrom atdistal tip242.Filter material14 may be formed in a manner similar to what is described above.
• It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. The invention's scope is, of course, defined in the language in which the appended claims are expressed.

Claims (1)

1. A method of manufacturing a distal protection filter assembly, comprising the steps of:

providing a filter frame having a plurality of struts and a mouth;

providing a mandrel having a proximal region, a middle region, and a distal region, the middle region include a groove;

coupling the filter frame to the mandrel wherein the mouth is at least partially disposed within the groove;

coupling a filter to at least a portion of the filter frame.

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