Abstract:
Apparatus for filtering and entrapping debris in the vascular system of a patient, the apparatus including a filter to allow blood to flow therethrough and to restrict passage of debris, wherein the filter captures debris carried in a first direction of blood flow. The apparatus further includes an entrapment mechanism which allows passage of debris and blood therethrough, in the first direction of blood flow and prevents debris passage in a second direction. The entrapment mechanism and filter allow blood and debris therethrough in the first direction of blood flow. The entrapment mechanism prevents debris flow in the second direction of blood flow A method for filtering and entrapping debris in the vascular system includes inserting the apparatus into the vascular system, allowing blood and debris carried therein to flow through the entrapment mechanism, and removing the apparatus and accumulated debris from the vascular system.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
     This patent application claims benefit of prior U.S. Provisional Patent Application Ser. No. 60/215,542, filed Jun. 30, 2000 by Richard B. Streeter et al. for INTRAVASCULAR FILTER WITH DEBRIS ENTRAPMENT MECHANISM, which patent application is hereby incorporated herein by reference, and of prior U.S. Provisional Patent Application Ser. No. 60/231,101, filed Sep. 8, 2000 by Richard B. Streeter et al. for INTRAVASCULAR FILTER WITH DEBRIS ENTRAPMENT MECHANISM, which patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to intravascular filtering apparatus and methods in general, and more particularly to apparatus and methods for filtering and irreversibly entrapping embolic debris from the vascular system during an intravascular or intracardiac procedure. 
     BACKGROUND OF THE INVENTION 
     Intracardiac and intravascular procedures, whether performed percutaneously or in an open, surgical, fashion, may liberate particulate debris. Such debris, once free in the vascular system, may cause complications including vascular occlusion, end-organ ischemia, stroke, and heart attack. Ideally, this debris is filtered from the vascular system before it can travel to distal organ beds. 
     Using known filter mechanisms deployed in the arterial system, debris is captured during systole. There is a danger, however, that such debris may escape the filter mechanism during diastole or during filter removal. Apparatus and methods to reduce debris escape during diastole or during filter removal may be desirable to reduce embolic complications. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a filtering mechanism that irreversibly entraps debris therein. 
     Another object of the invention is to provide a filtering mechanism that permanently captures debris from the intravascular system of a patient. 
     A further object of the invention is to provide a filtering mechanism with greater ability to collect debris in the intravascular system of a patient to decrease the number of complications attributable to such debris. 
     Another further object of this invention is to provide a filter holding mechanism suitable to be secured to a retractor used to create access to the heart and surrounding structures during heart surgery procedures. 
     A still further object is to provide a method for using a filtering mechanism in the intravascular system of a patient to permanently capture debris therefrom. 
     Another still further object of the present invention is to provide a method for introducing a filtering device in the aorta downstream of the aortic valve to restrict the passage of emboli while allowing blood to flow through the aorta during cardiovascular procedures, and to entrap debris collected in the filter so as to prevent its escape during cardiac diastole or during manipulation, repositioning or removal of the device from the aorta. 
     With the above and other objects in view, as will hereinafter appear, there is provided apparatus for debris removal from the vascular system of a patient, the apparatus comprising: a filtering device having a proximal side and a distal side, the filter being sized to allow blood flow therethrough and to restrict debris therethrough and the filter having a first given perimeter, wherein blood flow in a first direction passes from the proximal side to the distal side of the filtering device; an entrapment mechanism having a proximal side and a distal side, the entrapment mechanism forming a selective opening to allow debris and blood flow passage in the first direction from the proximal side to the distal side therethrough, the selective opening having a restriction mechanism to prevent debris passage in a second direction opposite to the first direction, the selective opening having a second given perimeter, the first given perimeter and the second given perimeter being deployed within the vascular system so as to form a chamber between the distal side of the entrapment mechanism and the proximal side of the filtering device, wherein the entrapment mechanism allows blood flow and debris to pass therethrough in the first direction, the filtering device allows blood flow to pass therethrough in the first direction, the restriction mechanism prevents debris from passing back through the selective opening in a second direction opposite to the first direction and the chamber contains the debris received through the entrapment mechanism so as to prevent the escape of the debris therein by the filtering device in the first direction and the restriction mechanism in the second direction. 
     In accordance with another further feature of the invention there is provided a method for filtering and entrapping debris from the vascular system of a patient, the method comprising: providing apparatus for filtering and entrapping debris from the vascular system of a patient, the apparatus comprising: a filter device being sized to allow blood flow therethrough and to restrict passage of debris therethrough, and the filter device having a first given perimeter, a proximal side and a distal side; and wherein the filtering device captures debris carried in a first direction of blood flow from the proximal side to the distal side thereof on the proximal side of the filter device; an entrapment mechanism having a proximal side and a distal side, the entrapment mechanism including a selective opening to allow passage of blood and debris therethrough, the selective opening being configured to allow passage of blood and debris carried therein therethrough in the first direction of blood flow from the proximal side to the distal side of the entrapment mechanism, the selective opening having a restriction mechanism to prevent debris passage from the distal side to the proximal side of the entrapment mechanism in a second direction opposite to the first direction, the selective opening forming a second given perimeter, and the first given perimeter and the second given perimeter being deployed witin the vascular system so as to form a chamber between the distal side of the entrapment mechanism and the proximal side of the filtering device; wherein the entrapment mechanism allows blood and debris carried therein therethrough in the first direction of blood flow, the filtering device allows blood therethrough in the first direction of blood flow, and the restriction mechanism prevents debris back through the selective opening in the second direction of blood flow opposite to the first direction of blood flow such that the chamber entraps the filtered debris received therein for debris removal from the vascular system of the patient; inserting the apparatus into the vascular system of the patient; allowing blood and debris carried therein to flow through the entrapment mechanism, and into the chamber; and removing the apparatus from the vascular system of the patient. 
     The above and other features of the invention, including various novel details of construction and combinations of parts and method steps will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular devices and method steps embodying the invention are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which are to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
     FIG. 1A is a perspective view of a deployable entrapment filtering device for debris removal showing the filtering device in its fully deployed shape as released from its cannula into the blood stream of a patient; 
     FIG. 1B is an exploded perspective view of the deployable entrapment filtering device of FIG. 1A showing the components thereof; 
     FIG. 1C is a schematic cross-sectional illustration depicting the deployable entrapment filtering device of FIGS. 1A and 1B during cardiac systole; 
     FIG. 1D is a schematic cross-sectional illustration depicting the deployable entrapment filtering device of FIGS. 1A and 1B during cardiac diastole; 
     FIG. 2A is an exploded perspective view of a deployable entrapment filtering device for debris removal showing the components thereof including a set of filter mesh entrapment leaflets; 
     FIG. 2B is a schematic cross-sectional illustration depicting the deployable entrapment filtering device of FIG. 2A during cardiac systole; 
     FIGS. 3A-3D are a series of schematic illustrations depicting a method of using the deployable entrapment filtering device of FIGS. 2A and 2B; 
     FIG. 4A is an exploded perspective view of a deployable entrapment filtering device for debris removal showing the components thereof including a set of non-porous valve leaflets; 
     FIG. 4B is a schematic cross-sectional illustration depicting the deployable entrapment filtering device of FIG. 4A during cardiac systole; 
     FIGS. 5A-5D are a series of schematic illustrations depicting a method of using the deployable entrapment filtering device of FIGS. 4A and 4B; and 
     FIGS. 6A-6D are schematic illustrations depicting an orthogonally deployable valve/filter apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A filtration and entrapment apparatus  5  is shown in FIGS. 1A-5D for debris removal from the vascular system of a patient. Filtration and entrapment apparatus  5  generally includes a filter device  10  and an entrapment mechanism  15 . Filtration and entrapment apparatus  5  can be used to filter emboli during a variety of intravascular or intracardiac procedures, including, but not limited to, the following procedures: vascular diagnostic procedures, angioplasty, stenting, angioplasty and stenting, endovascular stent-graft and surgical procedures for aneurysm repairs, coronary artery bypass procedures, cardiac valve replacement and repair procedures, and carotid endardarectomy procedures. 
     Now looking at FIGS. 1A-1D, a preferred embodiment of the present invention is shown with filtration and entrapment apparatus  5  as described herein below. 
     FIG. 1A depicts the profile of filtration and entrapment apparatus  5  in its fully deployed shape, with filter device  10  and entrapment mechanism  15  released from cannula  20  into the blood stream (not shown). Prior to deployment, filter device  10  and entrapment mechanism  15  are collapsed within cannula  20 , e.g., by moving the proximal end  25 A proximally along center post  50 . 
     FIG. 1B depicts the primary components of filtration and entrapment apparatus  5  comprising filter device  10  and entrapment mechanism  15  in attachment to deployable frame  25 . In the present embodiment of the invention, filter device  10  comprises a filter mesh bag  30 , and entrapment mechanism  15  comprises a piece of coarse mesh  35  and a set of entrapment flaps  40 . 
     FIG. 1C depicts filtration and entrapment apparatus  5  deployed within an aorta  45  during cardiac systole. Blood and debris flow through opened deployable frame  25 , across course mesh  35 , between and through entrapment flaps  40  and into the end of the filter mesh bag  30 . Entrapment flaps  40  ensure unidirectional flow of blood and debris into filter mesh bag  30 . 
     FIG. 1D depicts filtration and entrapment apparatus  5  within the aorta  45  responding to any retrograde flow of blood and/or back pressure within the aorta  45  during cardiac diastole. The back flow of blood and/or back pressure causes filter mesh bag  30  to partially deform and entrapment flaps  40  to close against coarse mesh  35 . Coarse mesh  35  is of a structure adequate to permit the free flow of blood and debris through it and into filter mesh bag  30 , and serves as a supporting structure against which entrapment flaps  40  can close and remain in a closed position to prevent the escape of embolic debris. 
     Still looking at FIGS. 1A-1D, it should also be appreciated that the entrapment flaps  40  may be attached to structures other than deployable frame  25 , e.g., the entrapment flaps  40  may be attached to center post  50 , or to coarse mesh  35 , etc. Furthermore, if desired, entrapment flaps  40  may be biased closed or biased open. In addition, entrapment mechanism  15  may consist of one or more flaps  55 , and have a configuration including, but not limited to, a single disk diaphragm (not shown), a semi-lunar configuration (not shown), a gill slit configuration (not shown), a multi-leaflet flap configuration (not shown), etc. 
     It should also be appreciated that, while in the foregoing description the apparatus shown in FIGS. 1A-1D has been described in the context of functioning as a filter, it may also function as a one-way check valve. To the extent that the apparatus shown in FIGS. 1A-1D is intended to function primarily as a one-way check valve, filter mesh bag  30  (see FIG. 1B) may be retained or it may be omitted. 
     Looking next at FIGS. 2A and 2B, there is shown an alternative form of the present invention as a bidirectional flow filtration and entrapment apparatus  105 . Bidirectional flow filtration and entrapment apparatus  105  of FIGS. 2A and 2B generally comprises a filter device  110  and an entrapment mechanism  115  delivered by a cannula  120  to the interior of a vascular structure  122  (see FIGS.  3 A- 3 D); a deployable filter frame  125 ; a filter bag  130  attached to the perimeter of deployable filter frame  125 ; a compliant, soft outer cuff  135  (preferably formed out of a biologically inert material such as Teflon, Dacron, Silastic, etc.) for sealing filtration and entrapment apparatus  105  against the inner wall of vascular structure  122  when deployable filter frame  125  is expanded; entrapment leaflets  140 , preferably in the form of a fine filter mesh; a center post  150  (preferably formed out of steel or the equivalent) passing across the interior of the deployable filter frame  125 ; a hinge line  155  on entrapment leaflets  140 , connected to center post  150 , for permitting the entrapment leaflets  140  to open and close; co-aptation strands  160  extending across the interior of deployable filter frame  125  and providing a seat against which entrapment leaflets  140  may close during diastole; and a perimeter seal  165  (preferably formed out of expanded Teflon or the like). Perimeter seal  165  acts like a step to help support entrapment leaflets  140  during diastole. 
     In addition, it should also be appreciated that soft outer cuff  135  may comprise a radially expandable mechanism (e.g., a balloon, a decompressed sponge, a spring loaded leaflet, etc.) for sealing filtration and entrapment apparatus  105  against the inner wall of vascular structure  122 . 
     As noted above, entrapment leaflets  140  are preferably formed out of a fine filter mesh. This filter mesh is sized so that it will pass blood therethrough but not debris. Furthermore, this filter mesh is sized so that it will provide a modest resistance to blood flow, such that the entrapment leaflets will open during systole and close during diastole. By way of example but not limitation, the filter mesh may have a pore size of between about 40 microns and about 300 microns. 
     FIGS. 3A-3D illustrate operation or bidirectional flow filtration and entrapment apparatus  105  shown in FIGS. 2A and 2B. More particularly, cannula  120  of deployable filtration and entrapment apparatus  105  is first inserted through a small incision  170  in the wall of the vascular structure  122  (see FIG.  3 A). Then deployable filter frame  125  is deployed (see FIG. 3B) Thereafter, during systole (see FIG.  3 C), blood flows through deployable filter frame  125 , forcing entrapment leaflets  140  open, and proceeds through filter bag  130 . Any debris contained in the blood is captured by filter bag  130  and thereby prevented from moving downstream past bidirectional flow filtration and entrapment apparatus  105 . During diastole (see FIG.  3 D), when the blood flow momentarily reverses direction, entrapment leaflets  140  (shown in FIGS. 2A and 2B) close, seating against co-aptation strands  160  (shown in FIGS. 2A and 2B) extending across the interior of deployable filter frame  125  (shown in FIGS.  2 A and  2 B). The blood passes through the fine mesh of entrapment leaflets  140  (shown in FIGS.  2 A and  2 B), being filtered as it passes, thus permitting coronary profusion to take place during the diastolic phase. The fine mesh of entrapment leaflets  140  (shown in FIGS. 2A and 2B) prevents debris from passing back through bidirectional flow filtration and entrapment apparatus  105 . 
     It should also be appreciated that with bidirectional flow filtration and entrapment apparatus  105  of FIGS. 2A,  2 B and  3 A- 3 D, entrapment leaflets  140  may be attached to structures other than center post  150 , e.g., they may be attached to co-aptation strands  160 , or to deployable filter frame  125 , etc. Furthermore, if desired, entrapment leaflets  140  may be biased closed, or biased open. In addition, entrapment mechanism  115  may consist of one or more flaps (not shown), and have a configuration including, but not limited to, a single disk diaphragm (not shown), a semi-lunar configuration (not shown), a gill slit configuration (not shown), a multi-leaflet flap configuration (not shown), etc. 
     Looking next at FIGS. 4A and 4B, there is shown a deployable valve/filter apparatus  205 . Deployable valve/filter apparatus  205  of FIGS. 4A and 4B generally comprises a filter device  210  and a valve entrapment mechanism  215  delivered by a cannula  220  to the interior of the vascular structure  222 ; a deployable valve/filter frame  225 ; a filter bag  230  attached to the perimeter of deployable valve/filter frame  225 ; a compliant, soft outer cuff  235  (preferably formed out of a biologically inert material such as Teflon, Dacron, Silastic, etc.) for sealing the filter device  210  against the inner wall of vascular structure  222  when deployable valve/filter frame  225  is expanded; valve leaflets  240 , preferably in the form of a blood-impervious material; a center post  250  (preferably formed out of steel or the equivalent) passing across the interior of deployable valve/filter frame  225 ; a hinge line  255  on valve leaflets  240 , connected to center post  250 , for permitting valve leaflets  240  to open and close; co-aptation strands  260  extending across the interior of deployable valve/filter frame  225  and providing a seat against which valve leaflets  240  may close during diastole; and a perimeter seal  265  (preferably formed out of expanded Teflon or the like). Perimeter seal  265  acts like a step to help support valve leaflets  240  during diastole. 
     In addition, it should also be appreciated that soft outer cuff  235  may comprise a radially expandable mechanism (e.g., a balloon, a decompressed sponge, a spring loaded leaflet, etc.) for sealing deployable valve/filter apparatus  205  against the inner wall of vascular structure  222 . 
     FIGS. 5A-5D illustrate operation of deployable valve/filter apparatus  205  of FIGS. 4A and 4B. More particularly, valve/filter apparatus  205  is first inserted through a small incision  270  in the wall of the vascular structure  222  (see FIG.  5 A). Then deployable valve/filter frame  225  is deployed (see FIG.  5 B). Thereafter, during systole (see FIG.  5 C), blood flows through deployable valve/filter frame  225 , forcing valve leaflets  240  open, and proceeds through filter bag  230 . Any debris contained in the blood is captured by filter bag  230  and thereby prevented from moving downstream past valve/filter apparatus  205 . During diastole (see FIG.  5 D), when the blood flow momentarily reverses direction, valve leaflets  240  (shown in FIGS. 4A and 4B) close, seating against co-aptation strands  260  (shown in FIGS. 4A and 4B) across the interior of deployable valve/filter frame  225  (shown in FIGS.  4 A and  4 B). The closed leaflets  240  (shown in FIGS. 4A and 4B) prevent blood from passing back through the valve/filter frame  225  (shown in FIGS.  4 A and  4 B). 
     It should also be appreciated that with valve/filter apparatus  205  shown in FIGS. 4A,  4 B and  5 A- 5 D, valve leaflets  240  may be attached to structures other than center post  250 , e.g., they may be attached to co-aptation strands  260 , or to deployable valve filter frame  225 , etc. Furthermore, if desired, valve leaflets  240  may be biased closed, or biased open. In addition, valve entrapment mechanism  215  may consist of one or more flaps (not shown), and have a configuration including, but not limited to, a single disk diaphragm (not shown), a semi-lunar configuration (not shown), a gill slit configuration (not shown), a multi-leaflet flap configuration (not shown), etc. 
     Looking next at FIGS. 6A-6B, there is shown an orthogonally deployable valve/filter apparatus  305 . Orthogonally deployable valve/filter apparatus  305  of FIGS. 6A-6D generally comprises a filter device  310  and a valve entrapment mechanism  315  deployed at an angle substantially orthogonal to an axis  318  of a cannula  320 , such as a catheter introduced to the vascular system at a location which may be remote from the point of operation, in the interior of a vascular structure  322 ; a deployable valve/filter frame  325 ; a filter bag  330  attached to the perimeter of deployable valve/filter frame  325 ; a compliant, soft outer cuff  335  (preferably formed out of a biologically inert material such as Teflon, Dacron, Silastic, etc.) for sealing the filter device  310  against the inner wall of vascular structure  322  when deployable valve/filter frame  325  is expanded; valve leaflets  340 , preferably in the form of a blood-impervious material, having a first portion  350  in attachment to deployable valve/filter frame  325 , and a second portion  355  separable from deployable valve/filter frame  325 , so as to allow valve leaflets  340  to open and close; and a mesh material  360  extending across the interior of deployable valve/filter frame  325  and providing a seat against which valve leaflets  340  may close during diastole. In addition, it should be appreciated that mesh material  360  may comprise coaptation strands such as coaptation strands  160  as first shown in FIG.  2 A. 
     In addition, it should also be appreciated that soft outer cuff  335  may comprise a radially expandable mechanism (e.g., a balloon, a decompressed sponge, a spring loaded leaflet, etc.) for sealing orthogonally deployable valve/filter apparatus  305  against the inner wall of vascular structure  322 . 
     In addition, it should also be appreciated that valve entrapment mechanism  315  may be mounted for blood flow in either direction within vascular structure  322 . FIGS. 6A-6D illustrate operation of deployable valve/filter apparatus  305 . More particularly, deployable valve/filter apparatus  305  is first inserted through the interior of vascular structure  322  to a desired location (see FIG.  6 C). Then deployable valve/filter frame  325  is deployed (see FIG. 6D) Thereafter, during systole (see FIG.  6 A), blood flows through deployable valve/filter frame  325 , forcing valve leaflets  340  open, and proceeds through filter bag  330 . Any debris contained in the blood is captured by filter bag  330  and thereby prevented from moving downstream past deployable valve/filter apparatus  305 . During diastole (see FIG.  6 B), when the blood flow momentarily reverses direction, valve leaflets  340  close, seating against mesh material  360  across the interior of deployable filter frame  325 . The closed leaflets  340  prevent blood from passing back through the valve/filter frame  325 . 
     It should also be appreciated that with valve/filter apparatus  305  shown in FIGS. 6A-6D, valve leaflets  340  may be attached to structures other than deployable valve/filter frame  325 , e.g., they may be attached to mesh material  360 , or to cannula  320 , etc. Furthermore, if desired, valve leaflets  340  may be biased closed, or biased open. In addition, valve entrapment mechanism  315  may consist of one or more flaps (not shown), and have a configuration including, but not limited to, a single disk diaphragm (not shown), a semi-lunar configuration (not shown), a gill slit configuration (not shown), a multi-leaflet flap configuration (not shown), etc. 
     The filter design as described herein to prevent the escape of captured debris during diastole or filter removal may also be applied to all intravascular filters. Such a filter design may comprise a one-way valve and a filtering mesh in series. Liberated debris may pass through the one-way valve and come to rest in the filtering mesh. The one-way valve ensures permanent entrapment of debris. Potential applications of such an apparatus extend to all percutaneous and surgical procedures on the heart and vascular system, including open heart surgery, balloon dilatation of cardiac valves and arteries, deployment of stents in arteries, diagnostic catheterizations, and other cardiac and vascular procedures. Advantages of such a system include more complete collection of liberated debris, with a resulting decrease in the complications attributable to such debris.