US20040147955A1 - Embolic protection filter having an improved filter frame - Google Patents

Abstract

An embolic protection filter having an improved filter frame and method of making the same. In at least some embodiments, the present invention includes an embolic protection filter coupled to an elongate shaft. The filter may include a filter frame assembly having one or more frame members. The frame members may include a filter mouth defining portion.

Description

FIELD OF THE INVENTION
• The present invention pertains to embolic protection devices. More particularly, the present invention pertains to embolic protection devices having a refined filter frame.[0001]
BACKGROUND
• Heart and vascular disease are majors 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.[0002]
• 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.[0003]
• 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. 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 embolic protection devices, have been developed to filter out this debris.[0004]
BRIEF SUMMARY
• The present invention pertains to refinements to embolic protection filters, frames, and methods of making the same. In some embodiments, an embolic protection filter device includes an elongate shaft having an embolic protection filter coupled thereto. The filter may include a filter frame assembly and a filter material or fabric coupled to the filter assembly.[0005]
• In at least some embodiments, the filter frame assembly may include two or more filter member. Each filter member may include a filter mouth defining portion and a shaft engaging portion. Including a plurality of filter members may incorporate a number of desirable features into the filtering device as described in more detail below.[0006]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a partial cross-sectional view of an example embolic protection device disposed within a body lumen;[0007]
• FIG. 2 is a perspective view of an example embolic protection device;[0008]
• FIG. 3 is a flattened view of an example frame member;[0009]
• FIG. 4 is a plan view of an example frame member having a filter material coupled thereto;[0010]
• FIG. 5 is a cross-sectional view taken through line[0011]5-5 in FIG. 2;
• FIG. 6 is a plan view of a frame member;[0012]
• FIG. 7 is a plan view of a frame member that is partially flattened;[0013]
• FIG. 8 is a plan view of a frame member that is partially flattened and split;[0014]
• FIG. 9 is a flattened view of another example frame member;[0015]
• FIG. 10 is a plan view of another example frame member having a filter material coupled thereto;[0016]
• FIG. 11 is a perspective view of another example embolic protection device; and[0017]
• FIG. 12 is a cross-sectional view taken through line[0018]12-12 in FIG. 11.
DETAILED DESCRIPTION
• 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.[0019]
• FIG. 1 is a partial cross-sectional view of an example[0020]embolic protection device10 disposed within ablood vessel12 adjacent anintravascular lesion14. In at least some embodiments,device10 can be used to filter embolic debris generated, for example, by treatment oflesion14.Device10 may include an elongate shaft orguidewire16 having anembolic protection filter18 coupled thereto.Device10 may include a number of refinements that, for example, improve apposition of the walls ofblood vessel12 byfilter18, shorten the landing zone offilter18, shorten the vessel footprint, as well as other desirable features as described in more detail below.
• [0021]Filter18 may include afilter frame assembly20 and a filter material orfabric22 coupled toframe assembly20. In general,filter18 may be adapted to operate between a first generally collapsed configuration and a second generally expanded configuration for collecting debris in a body lumen.Filter material22 can be drilled (for example, formed by known laser techniques) or otherwise manufactured to include at least one opening. The holes or openings can be sized to allow blood flow therethrough but restrict flow of debris or emboli floating in the body lumen or cavity.Frame assembly20 may be coupled toshaft14 by acoupling24.Coupling24 may be one or more windings of frame assembly aboutshaft14 or may be a fitting disposed over an end offrame assembly20 to attach it toshaft14.
• [0022]Frame assembly20 may include one ormore frame members26. For example, a perspective view of anexample frame assembly20 having two frame members, indicated byreference numbers26aand26b,is shown in FIG. 2. It can be appreciated, however, that the precise number offrame members26 can be altered without departing from the spirit of the invention. For example, it may be desirable to include three ormore frame members26 in alternative example frame assemblies.
• Each of the one or[0023]more frame members26a/bcan each be configured to include a mouth defining portion, indicated byreference numbers28aand28b,and a shaft engaging portion, indicated byreference numbers30aand30band best seen in FIG. 3. Themouth defining portions28a/bmay be arranged to define an opening ormouth29 offilter18. In some embodiments,mouth defining portions28a/bform a portion of a generallycircular filter mouth29. For example, the twomouth defining portions28a/bshown in FIG. 2 each span about 180° or are each roughly a semi-circular portion of acircular filter mouth29. It can be appreciated that the shape offilter mouth29 can vary without departing from the spirit of the invention. For example,filter mouth29 may be oval, irregular, polygonal, or any other suitable shape. Moreover, the relative proportion offilter mouth29 that eachmouth defining portion28a/bspans can also vary. For example eachmouth defining portion28a/bmay span an equal proportion or each may span differing proportions.
• [0024]Mouth defining portions28a/bmay be skewed or angled in the proximal or distal direction relative to the longitudinal axis ofshaft14. For example,mouth defining portions28a/bmay each include aproximal end32a/band adistal end34a/b,andportions28a/bmay be skewed so thatdistal ends34a/bare positioned distally along the longitudinal axis ofshaft14 relative toproximal ends32a/b.This structural feature may result in a number of desirable features as described below. In some embodiments,distal ends34a/bmay include a slight curve or bend, which may decrease or otherwise blunt any sharpness that may be associated withdistal ends34a/b.Alternatively, distal ends34a/bmay include other modifications such as a solder or weld ball, a radiused or rounded end, and the like.
• [0025]Shaft engaging portions30a/bgenerally are the regions offrame assembly20 whereframe members26a/bare coupled toshaft16, for example bycoupling24. In general,shaft engaging portions30a/bcan be disposedadjacent shaft16 so as to at least partiallysecure filter18 toshaft16. The exact attachment means can vary and is not necessarily limited tocoupling24. For example,shaft engaging portions30a/bmay be coupled to shaft by a mechanical bond such as a crimp, by adhesives, by thermal bond such as a weld, and the like.
• As suggested above, the above features of[0026]device10 may enhance the apposition of the walls ofvessel12 and/or the compliance to the vessel walls. It can be appreciated that the greater the wall apposition achieved byfilter18, the less likely it is that embolic debris will be able float pastfilter18 at locations wherefilter18 is spaced from the vessel wall. In at least some embodiments, the inclusion of aplurality frame members26a/ballowsframe assembly20 to be more compliant to the vessel wall. More particularly, becausemouth defining portions28a/bofframe members26a/beach define a portion of filter mouth29 (e.g., each defining about 180° of a circular filter mouth29), irregularities in the shape of the vessel wall can be “absorbed” by one frame member without having a major effect on the shape of the other. For example, a blood vessel having an inward projecting stenosisadjacent filter18 could cause one of the mouth defining portions (e.g.,portion28a) to be partially displaced by the irregular or non-circular cross-sectional shape at the stenosis. However, because the remainder of the vessel may have a different, generally circular cross-sectional shape, the other mouth defining portion (e.g.,portion28b) can remain essentially apposed, independently ofportion28a.Thus, the overall wall apposition realized bydevice10 may be enhanced relative to other filter types. Additionally, it may be desirable to add additional frame members, which may add to this feature.
• In some embodiments, frame assembly[0027]20 (including the individual components thereof) can be made of any suitable materials including metals, metal alloys, polymers, or the like, or combinations or mixtures thereof. Some examples of suitable metals and metal alloys include stainless steel, such as 304v stainless steel; nickel-titanium alloy, such as nitinol, nickel-chromium alloy, nickel-chromium-iron alloy, cobalt alloy, or the like; or other suitable material. The word nitinol was coined by a group of researchers at the United States Naval Ordinance Laboratory (NOL) who were the first to observe the shape memory behavior of this material. The word nitinol is an acronym including the chemical symbol for nickel (Ni), the chemical symbol for titanium (Ti), and an acronym identifying the Naval Ordinance Laboratory (NOL).
• Additionally,[0028]frame assembly20 can be configured from a number of structurally different members. For example,frame assembly20 can be manufactured from wires, ribbons, tubes, and the like. These structures may have a generally round cross-sectional area, be flattened, be irregular in shape, etc. The used of wires or other “pre-assembled” structures may also help to decrease manufacturing cost by obviating the need to laser cut or otherwise process components offrame assembly20.
• [0029]Shaft16 may also be comprised of materials similar to those listed above. In at least someembodiments shaft16 can be a guidewire. It can be appreciated, however, thatshaft16 could also be essentially any medical device. For example,shaft16 may comprise a catheter (e.g., therapeutic, diagnostic, or guide catheter), a tubular filter cartridge configured to be slidable over a guidewire or catheter, an endoscopic device, a laproscopic device, or any other suitable device.
• The construction of[0030]device10 may include steps generally illustrated in FIGS. 3 and 4. For example, FIG. 3 depicts a flat view of an example set offrame members26a/b.Frame members26a/bcan be adapted and configured for the manufacture offilter18 having the desired dimensions for the appropriate invention. For example, the lengths ofmembers26a/bcan be varied relative to the circumference of the target site in a blood vessel (πD_v, where D_vis the diameter of the blood vessel adjacent the target site) so that the size offilter mouth29 approximates the circumference or size along the inside of the vessel wall. This feature allowsfilter18 to have improved 360° apposition to the inside wall of the vessel.
• [0031]Frame members26a/bcan be disposed over a mandrel (not shown) to bend them into the appropriate shape. For example,shaft defining portions30a/bcan be bent into a configuration appropriate for attaching them toshaft16. Additionally, in at least someembodiments frame members26a/bcan be bent adjacent filtermouth defining portions28a/bso that these regions are generally semi-circular. It can be appreciated that the invention should not be limited to only this particular shape and, in general, filtermouth defining portions28a/bare configured to occupy as much of vessel circumference as desired. For example, the cross-sectional shape of the target site in the vessel may be slightly oval in shape or otherwise differ from being circular. Accordingly, the shape ofmouth defining portions28a/bcan be varied to approximate these shapes and, thus, better achieve 360° wall apposition. As stated above, the relative proportions that each of the filtermouth defining portions28a/bspan can also vary.
• At some point in the manufacturing process it may be desirable to couple or attach[0032]filter material22 to frameassembly20. For example,filter material22 can be coupled toframe assembly20 atmouth defining portions28a/bas shown in FIG. 4. A number of different attachment mechanisms may be used to couplemouth defining portions28a/bandfilter material22. Some suitable attachment mechanism may include adhesive bonding, thermal bonding, and the like.
• As stated above,[0033]mouth defining portions28a/bmay be skewed or angled relative to the longitudinal axis ofshaft16. This skew angle θ can be seen in the flat view of FIG. 4 as amouth defining portions28a/bbeing slanted or angled. Skew angle θ ofmouth defining portions28a/bcan be equal to each other as shown or may be different. The inclusion of skew angle θ can give filter18 a number of desirable features. For example, if proximal ends32a/bofmouth defining portions28a/bare aligned, a vessel footprint length L_fis defined that is proportional to angle θ. The footprint length L_fis understood to be the length offilter18 that can be in direct contact with the inside wall of the vessel. It can be appreciated that in at least some embodiments, regions offilter18 that are distal of L_fmay be conical in shape and, thus, taper away from the vessel wall.
• Because of skew angle θ,[0034]frame members26a/bmay be generally parallel to one another. According to these embodiments, one or more relatively short, bridgingregions36a/boffilter material22 may be disposed betweenframe members26a/b.It can be appreciated that the length of bridgingregions36a/bare about equal to each other and to footprint length L_f. In some other embodiments, the skew angle θ of eachframe member26a/bmay be different and, thus, the lengths of bridgingregions36a/bmay have different lengths. Bridgingregions36a/bcan also prevent gaps from being present betweenframe members26a/b,which can maintain the integrity of the vessel wall apposition.
• As stated above, footprint length L[0035]_fand skew angle θ are generally proportional to one another. More particularly, as angle θ becomes larger, footprint length L_fbecomes longer. Thus, a number of variations of angle θ and footprint length L_fcan be utilized in different embodiments of the invention. For example, it may be desirable due to the physiology or anatomy of the treatment site, for footprint length L_foffilter18 to be relatively short. According to this embodiment, manufacturing offilter18 can includefilter members26a/bbeing skewed a relatively small skew angle θ.
• Footprint length L[0036]_fcan also be related to the size the landing zone of the filter. The footprint length L_fis understood to be the longitudinal length offilter18 that is designed to be in contact with the vessel wall whenfilter18 is deployed in the vessel. Landing zone is generally understood to be the overall longitudinal length of the filter. Thus, in embodiments where the footprint length L_fis decreased, the landing zone can also be decreased. Having a short landing zone can advantageously permitfilter18 to be used at intravascular locations that are relatively short and would otherwise be inaccessible to traditional filters. For example, the length of a portion of the renal artery between the abdominal aorta and the kidney is relatively short. Diagnosis or other interventions at the junction of the renal artery and the kidney would not easily be accomplished by using conically shaped filter because the filter may extend into the kidney, possibly causing damage to the kidney. Thus, example embodiments offilter18 having a generally short landing zone make this location more accessible for filtering. A number of additional intravascular locations may similarly benefit from example filters18 having a shortened landing zone.
• At the desired time in the manufacturing process,[0037]frame assembly20 can be formed into the appropriate shape to define filter18 (please see FIG. 2). A cross-sectional view taken through line5-5 of FIG. 2 is shown in FIG. 5. From FIG. 5 it can be seen that eachmouth defining portion28a/bcan be configured to span about 180°.
• As stated above, however, the relative proportion that each[0038]portion28a/bcan be varied as well as the number of mouth defining portions. For example,frame assembly20 may include three mouth defining portions and each may span about 120°.
• [0039]Frame members26a/bcan be shafts having a relatively constant outside diameter D_was shown in FIG. 6. According to this embodiment, ageneric frame member26 can be configured to have the desired shape, for example the shape depicted in FIG. 3. Alternatively,frame member26 may be include anon-flattened portion38 and a flattenedportion40 as shown in FIG. 7. Flattenedportion40 offrame member26 may have a flattened thickness F_Tand a flattened cross-sectional length F_L, both of which may vary in alternative embodiments of the invention. A taperedportion42 may be disposed betweennon-flatted portion38 and flattenedportion40. It should be noted that in alternative embodiments,frame member26 may comprise a generally flat or rectangular ribbon, which would include any desirable features of flattenedportion40.
• In at least some embodiments, flattened[0040]portion40 may be disposed adjacent the filtermouth defining regions28a/b.Because of the attenuated F_T, disposing flattenedportion40 adjacent filtermouth defining regions28a/bcan reduce the crossing profile diameter offilter18. This feature may be desirable, for example during interventions within small or sensitive blood vessels.
• FIG. 8 illustrates an alternative[0041]example frame member126.Frame member126 is essentially the same asframe member26 except that it flattenedportion140 is cut to define two flattenedportions140/140′.Frame member126 may also include a taperedregion142. It can be appreciated that variations to the length of the taper LT (i.e., the length offrame member126 adjacent taper142), the length of flattened portion LF, thickness of the cut CT, and length of the cut region LC offrame member126 are within the scope of the invention.
• One or more of[0042]frame members126 may be used to manufacture an alternative example filter. For example, FIG. 9 illustrates a flattened view offrame members126a/bconfigured in a fashion that is essentially analogous to the flattened view shown in FIG. 3. According to this embodiment, eachframe member126a/bincludes a multi-leg filtermouth defining portion128a/a′ and128/b/b′. It can be seen in FIG. 9 that the legs are at least partially curved. The amount of or sharpness of the curve can be altered to vary the footprint length L_F, similar to how skew angle θ can be varied in the above discussion. Similar to what is described above,filter material22 can be coupled to framemembers126a/bas shown in FIG. 10.
• At the desired time in the manufacturing process, filter[0043]members126a/bcan be formed into the appropriate shape to define afilter118 as illustrated in FIG. 11. Theresultant filter118 is essentially the same in form and function asfilter18 except thatframe members126a/binclude multi-legmouth defining portions128a/a′ and128b/b′ as described above. A cross-sectional view offilter118 that is taken through line12-12 is shown in FIG. 12.
• 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.[0044]

Claims (36)

What is claimed is:

1. An embolic protection filter assembly, comprising:

a first frame member having a first shaft-engaging portion and a first mouth portion;

a second frame member having a second shaft-engaging portion and a second mouth portion;

wherein the first mouth portion and the second mouth portion define a filter mouth;

a filter material coupled to the first and second frame members adjacent the first and second mouth portions; and

an elongate shaft coupled to the first and second shaft-engaging portions and extending through the filter.

2. The assembly ofclaim 1, wherein the shaft comprises a guidewire.

3. The assembly ofclaim 1, wherein the shaft comprises a tube adapted and configured for being slidably disposed over an elongate wire.

4. The assembly ofclaim 1, wherein the filter mouth has a generally circular shape spanning 360 degrees.

5. The assembly ofclaim 4, wherein each of the first and second filter mouth portions includes one or more legs configured to span about 180 degrees of the filter mouth.

6. The assembly ofclaim 4, wherein the first and second filter mouth portions each span different proportions of the filter mouth.

7. The assembly ofclaim 4, further comprising a third frame member having a third shaft-engaging portion and a third mouth portion.

8. The assembly ofclaim 7, wherein each of first, second, and third mouth portions include one or more legs configured to span about 120 degrees of the filter mouth.

9. The assembly ofclaim 7, wherein the first, second, and third filter mouth portions span different proportions of the filter mouth.

10. The assembly ofclaim 1, wherein the shaft has a longitudinal axis and wherein the first mouth portion is oriented perpendicularly to the longitudinal axis.

11. The assembly ofclaim 1, wherein the shaft has a longitudinal axis and wherein the first mouth portion is skewed at an angle relative to an axis pointed perpendicularly to the longitudinal axis.

12. The assembly ofclaim 11, wherein the angle is acute relative to the axis pointed perpendicularly to the longitudinal axis.

13. The assembly ofclaim 1, wherein the first and second mouth portions are connected by a bridging portion of the filter material disposed between the mouth portions.

14. The assembly ofclaim 1, wherein the first frame member includes a circular region having a generally circular cross-sectional shape and a flattened region having a generally oval cross-sectional shape.

15. The assembly ofclaim 14, wherein the flattened region is disposed adjacent the first filter mouth portion.

16. The assembly ofclaim 14, wherein the flattened portion is split to include a first leg and a second leg.

17. An embolic protection filter assembly, comprising:

a first frame member having a first shaft-engaging portion and a first mouth portion, the first mouth portion include a proximal end and a distal end;

a second frame member having a second shaft-engaging portion and a second mouth portion, the first mouth portion include a proximal end and a distal end;

wherein the first mouth portion and the second mouth portion define a filter mouth;

a filter material coupled to the first and second frame members; wherein a filtering portion of the filter material is coupled to and extends distally from the first and second mouth portions;

a first bridging portion of the filter material extending between the proximal end of the first mouth portion and the distal end of the second mouth portion;

a second bridging portion of the filter material extending between the proximal end of the second mouth portion and the distal end of the first mouth portion; and

an elongate shaft coupled to the first and second shaft-engaging portions.

18. The assembly ofclaim 17, wherein the shaft comprises a guidewire.

19. The assembly ofclaim 17, wherein the shaft comprises a tube adapted and configured for being slidably disposed over an elongate wire.

20. The assembly ofclaim 17, wherein the filter mouth has a generally circular shape.

21. The assembly ofclaim 20, wherein the first and second filter mouth portions each span different proportions of the filter mouth.

22. The assembly ofclaim 20, wherein each of the first and second filter mouth portions includes one or more legs and are each have a semicircular shape.

23. The assembly ofclaim 22, wherein the semicircular shapes of the first and second filter mouth portions are skewed relative to one another.

24. The assembly ofclaim 17, wherein the shaft has a longitudinal axis and wherein the first mouth and second mouth portions are oriented perpendicularly to the longitudinal axis.

25. The assembly ofclaim 17, wherein the shaft has a longitudinal axis and wherein the first and second mouths portions are skewed at an angle relative to an axis pointed perpendicularly to the longitudinal axis.

26. The assembly ofclaim 25, wherein the angle is acute relative to the axis pointed perpendicularly to the longitudinal axis.

27. The assembly ofclaim 17, wherein the first frame member includes a circular region having a generally circular cross-sectional shape and a flattened region having a generally oval cross-sectional shape.

28. The assembly ofclaim 27, wherein the flattened region is disposed adjacent the first filter mouth portion.

29. The assembly ofclaim 27, wherein the flattened portion is split to include a first leg and a second leg.

30. An embolic protection filter assembly, comprising:

an elongate shaft having a longitudinal axis and a perpendicular axis;

a first frame member having a first shaft-engaging portion coupled to the shaft and a first semi-circular portion, the first semi-circular portion being semi-circular in shape and including a proximal end and a distal end;

a second frame member having a second shaft-engaging portion coupled to the shaft and a second semi-circular portion, the second semi-circular portion being semi-circular in shape and including a proximal end and a distal end;

wherein the first and second semi-circular portions are skewed at an angle relative to the perpendicular axis;

a filter material coupled to the first and second frame members;

a filtering portion of the filter material coupled to and extends distally from the first and second semi-circular portions;

a first bridging portion of the filter material extending between the proximal end of the first semi-circular portion and the distal end of the semi-circular mouth portion; and

a second bridging portion of the filter material extending between the proximal end of the second semi-circular portion and the distal end of the first semi-circular portion.

31. The assembly ofclaim 30, wherein the shaft comprises a guidewire.

32. The assembly ofclaim 30, wherein the shaft comprises a tube adapted and configured for being slidably disposed over an elongate wire.

33. The assembly ofclaim 30, wherein each of the first and second semi-circular portions includes one or more legs.

34. The assembly ofclaim 30, wherein the first and second frame members each includes a circular region having a generally circular cross-sectional shape and a flattened region having a generally oval cross-sectional shape.

35. The assembly ofclaim 34, wherein the flattened regions are disposed adjacent the first and second semi-circular portions.

36. The assembly ofclaim 34, wherein at least one of the flattened portions is split to include a first leg and a second leg.

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