Abstract:
Methods and devices for separating plaque from vessel walls using everting membranes. Everting tubes disposed on catheters are used in one embodiment of the invention to separate plaque from blood vessel walls. One embodiment of the invention utilizes a single everting membrane including a fixed portion, a leading edge, and an advancing portion. The everting tube can have an interior which can be pressurized to propel the everting tube distal edge distally onward, so as to separate the plaque from the vessel inner wall. One device has double everting membranes fixedly attached to a tubular member and having facing advancing membrane portions which may be proximally fixed relative to one another, but are preferably both free to travel distally. The outermost tube can be laid down over the vessel inner wall and the innermost tube laid down over the plaque, with the advancing surfaces of each everting membrane facing each other. Fluid can be supplied under pressure to fill the interior of the everting tubes and thereby distally advance the tube leading edges. The present invention may be used in conjunction with distal emboli capturing filter or distal occlusion devices.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is related generally to medical devices. More specifically, the present invention includes intravascular devices and catheters for performing endarterectomy.  
         BACKGROUND OF THE INVENTION  
         [0002]    Arteriosclerosis is a common vascular disease in which blood vessels become hardened and blocked or partially blocked by plaque that can substantially reduce blood flow. The accumulation of plaque is often a major factor in the occurrence of myocardial infarction, stroke, and high blood pressure.  
           [0003]    To treat arteriosclerosis, minimally invasive techniques have been developed. One minimally invasive technique utilizes percutaneous transluminal coronary angioplasty (PTCA) which can include expanding a balloon under pressure within a coronary artery, and dilating a narrowed area of that artery. While PTCA procedures can significantly dilate narrowed coronary arteries, the treated vessel region may become narrow again in a process known as restenosis. In a substantial percentage of PTCA procedures, the dilated vessel region becomes restenosed.  
           [0004]    Another example of a minimally invasive technique is atherectomy. In an atherectomy procedure, a guide catheter can be inserted into the patient&#39;s femoral artery and advanced until the distal end of the guide catheter is disposed near the patient&#39;s ostium or coronary artery. A guidewire can be inserted into the guide catheter and further advanced into the coronary artery, distally past the occluded region. A therapeutic atherectomy catheter having an atherectomy burr may be advanced over the guidewire, through the guide catheter, and to the narrowed region. The atherectomy burr can be rotated at high speed, causing the plaque to be removed in small particles as the plaque is abraded by the atherectomy burr.  
           [0005]    Endarterectomy techniques have been utilized in open chest surgeries. In the endarterectomy technique, an artery may be slit longitudinally along its length by a surgeon, commonly after clamping opposite ends of the exposed vessel. The surgeon may strip the internal plaque away from the vessel walls, and remove the plaque from the vessel through the slit. A significant cleaning procedure typically follows the removal procedure to increase the chance of success. In a high percentage of cases, the vessel thus treated may remain potent for a long time period, rather than rapidly becoming restenosed.  
           [0006]    What would be desirable are endarterectomy techniques and devices for performing endarterectomy intravascularly. In particular, what would be advantageous are techniques for performing intravascular endarterectomy using a distant entry site, such as a radial artery entry near the groin.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention includes methods and devices for removing plaque and separating plaque from blood vessels using everting membranes. In one method according to the present invention, an everting membrane is provided and distally advanced through a vessel having a plaque deposit along the vessel wall. The everting membrane may be considered to have a distally advancing portion, a distally leading edge, and a non-advancing portion, where the advancing portion is distally advanced into the vessel. As the advancing portion is distally advanced into the vessel, the leading edge is distally advancing into the vessel as well. As the advancing membrane portion and leading edge are advanced into the vessel along the vessel inner wall, the everting membrane advances between the plaque and the vessel inner wall, thereby separating the plaque from the inner wall. The non-advancing portion can be effectively laid down over either the vessel inner wall or plaque outer walls, depending on orientation. After separation, the separated plaque may be removed from the vessel.  
           [0008]    One device according to the present invention has a tubular member having a single everting membrane, the membrane having an interior in fluid communication with a fluid source. The fluid may be supplied through a fluid lumen, thereby supplying the everting membrane interior with fluid under pressure. The pressurized fluid may then cause the everting membrane to travel distally. The distally traveling membrane leading edge may be used to separate the plaque from the vessel inner wall. In one embodiment of the invention, the everting membrane has a more proximal section slidably and sealingly disposed along the tubular member inner wall.  
           [0009]    One double everting membrane device according to the present invention includes an inner tube and an outer tube, with the inner tube having an inner fold and the outer tube having an outer fold. The inner and outer folds may be joined and/or simply travel together at a more proximal location. The inner and/or outer folds preferably have interior portions which may be provided with fluid under pressure, thereby causing the inner and outer folds to travel distally. The inner and outer folds may be considered to have facing advancing portions, leading edge distally advancing portions, and relatively non-advancing portions which will unfold and be laid down against the vessel inner wall and the outer wall of the newly separated plaque. The pair of everting membranes may thus be deployed to separate the plaque from the inner wall. After separation, the everted membranes having the plaque disposed within the inner fold may be removed from the formerly constricted vessel site.  
           [0010]    Everting membranes in some methods according to the present invention may be used in conjunction with more distally positioned emboli filters. The deployed emboli filters may provide additional assurance of optimal results during the treatment. In one method, the emboli filter and percutaneous endarterectomy catheter are advanced over a guidewire positioned within the coronary artery from a femoral groin entry site. The present invention allows the stripping or removal of plaque from within coronary and other arteries using an intravascular device, not requiring open chest surgery. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a highly diagrammatic, longitudinal, cross-sectional view of a pair of everting membranes in a first, proximal position;  
         [0012]    [0012]FIG. 2 is a highly diagrammatic, longitudinal, cross-sectional view of the everting membranes of FIG. 1, shown in a more distally advanced position;  
         [0013]    [0013]FIG. 3 is a highly diagrammatic, longitudinal, cross-sectional view of a catheter proximal region having a single fold everting membrane;  
         [0014]    [0014]FIG. 4 is a transverse, cross-sectional view taken through line  4 - 4  of FIG. 3;  
         [0015]    [0015]FIG. 5 is a transverse, cross-sectional view taken through line  5 - 5  of FIG. 3;  
         [0016]    [0016]FIG. 6 is a highly diagrammatic, longitudinal, cross-sectional view of a catheter distal region having a two-fold everting membrane;  
         [0017]    [0017]FIG. 7 is a transverse, cross-sectional view taken through line  7 - 7  of FIG. 6;  
         [0018]    [0018]FIG. 8 is a transverse, cross-sectional view taken through line  8 - 8  of FIG. 6;  
         [0019]    [0019]FIG. 9 is a highly diagrammatic, transverse, cross-sectional view of one double everting membrane device having inflation lumens within the inner and outer tubes;  
         [0020]    [0020]FIG. 10 is a highly diagrammatic, transverse, cross-sectional view of a double everting membrane device having separate inflation tubes for providing fluid pressure;  
         [0021]    [0021]FIG. 11 is a highly diagrammatic, longitudinal, cross-sectional view of a vessel inner wall and plaque, prior to separation by a two-fold everting membrane catheter; and  
         [0022]    [0022]FIG. 12 is a highly diagrammatic, longitudinal, cross-sectional view of the vessel of FIG. 11, after distal advancement of the everting membranes of FIG. 11. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    [0023]FIG. 1 is a simplified diagram of one membrane pair of an everting membrane device  20  including an outer membrane fold  22  and an inner membrane fold  24 . Inner fold  22  and outer fold  24  are disposed relative to a reference line  33 , illustrated as a dashed line. Outer fold  22  includes generally a distally advancing portion  26 , a distally leading edge portion  48 , and a relatively non-advancing portion  28 . Outer fold  22  also includes generally an interior region  23 . Inner fold  24  includes generally a distally advancing portion  30 , a distally leading edge portion  58 , and a relatively non-advancing portion  32 . Inner fold  24  also includes generally an interior region  25 .  
         [0024]    Several marker points have been artificially displayed on outer fold  22  and inner fold  24  to illustrate the everting membrane movement. Inner fold  24  has a first marker  50 , a second marker  52 , a third marker  53 , and a fourth marker  54 . Similarly, outer fold  22  has a first marker  40 , a second marker  42 , a third marker  43 , and a fourth marker  44 . The relative movements of the marker points may be seen in FIG. 2.  
         [0025]    [0025]FIG. 2 illustrates inner fold  24  and outer fold  22  after the membranes have been everted. In this example, inner fold stationary portion  32  has not moved relative to stationary marker line  33 . Similarly, outer fold stationary portion  28  has also not moved with respect to stationary marker line  33 . In inner fold  24 , advancing portion  30  has been distally advanced relative to stationary marker line  33 , thus advancing marker point  50  distally. Distally leading edge  58  now contains marker point  52  which was previously disposed near marker line  33 . Outer fold distally leading edge  48  now contains marker point  42  which was also previously disposed near marker line  33 . It may be seen from inspection of FIG. 2 that distally advancing membrane portions  26  and  30  cause the respective distally leading edges to advance distally, even though the outermost, stationary portions  28  and  32  remain unmoved. In this way, distally leading edges  58  and  48  are distally advanced by advancing the inner pair of opposed membranes  26  and  30 . In one embodiment, opposing membranes  26  and  30  may be coupled at a more proximal location, thus forming inner fold  24  and outer fold  22  out of a single membrane, having a shared interior region.  
         [0026]    [0026]FIG. 3 illustrates a distal region of a medial device or catheter  60  having a single everting membrane. Catheter  60  includes a tube  64  having a wall  66  and extending between a distal region  61  and a more proximal region  62 . Tube  64  includes a central lumen  68  disposed therethrough and having an everting membrane tube  70  disposed within lumen  68 . Everting tube  70  includes a non-advancing portion  74  which, in one embodiment, can be fixed relative to tube  64 . Everting tube  70  also includes a leading edge  72  and an inner, advancing membrane portion  76 . Advancing membrane portion  76  is coupled to an annular sealing ring  80 , thereby forming an interior region  78  within everting tube  70 . In one embodiment, everting tube  70  has only a relatively short non-advancing portion relative to the advancing portion. In one example of the invention, outer, non-advancing membrane portion  74  begins at about the location denoted by line  4 - 4  in FIG. 3.  
         [0027]    Everting tube interior region  78  may be filled with fluid or gas under pressure which can cause annular sliding seal  80  to move distally, as leading edge  72  is propelled distally forward by the pressure within everting tube  70 . The source of the fluid pressure may vary from embodiment to embodiment, with no particular embodiment illustrated in FIG. 3.  
         [0028]    Referring now to FIG. 4, tube wall  66  may be seen to be disposed about non-advancing membrane portion  74  and advancing membrane portion  76 , having leading edge  72  disposed therebetween. Tube lumen  68  may be seen to be centrally disposed within tube wall  66 . FIG. 5 illustrates a more proximal cross-sectional view of device  60 , having tube wall  66  disposed about annular sealing ring  80 , which is in turn disposed about tube lumen  68 . Sealing ring or seal  80 , in a preferred embodiment, is free to slide distally and proximally within tube  64 .  
         [0029]    [0029]FIG. 6 illustrates a distal region of an everting catheter device  100  having a tube  102  disposed about an outer everting membrane  120 , disposed about an inner everting membrane  140 , disposed in turn about an inner tubular member  160 . Tube  102  and device  100  may be seen to have a distal region  106  and a more proximal region  108 . Tube  102 , in the embodiment illustrated, has a lumen  110  disposed within a tube wall  104 . Tube lumen  110  may also be seen to have an orifice  112  that is inwardly directed. Outer everting membrane  120  may be seen to have a fixed or non-advancing portion  122  which can be fixedly secured to the tube wall. Outer everting membrane  120  may also be seen to have a distally leading edge  124  and an advancing membrane portion  126 , which is secured to an outer seal  128 , which is slidably disposed within tube  102 . A second sealing member  144  may be seen to be also disposed within tube  102 , having an advancing membrane portion  145 , a distally leading edge  152 , and a non-advancing or fixed portion  142 . Non-advancing portion  142  can be fixedly secured to inner tube  160  as illustrated. Tube  160  may be seen to have a lumen  166  therethrough in fluid communication with an outwardly directed orifice  170 . Inner everting membrane  140  may also be seen to have an interior  146 . In one embodiment, seals  128  and  144  are one and the same and operate together as a single seal. In another embodiment, the seals slide independent of each other. As may be seen from inspection of FIG. 6, fluid supplied under pressure within tube lumen  110  may flow through orifice  112 , into outer everting membrane interior  130 , thus propelling outer everting membrane leading edge  124  and seal  128  distally. Similarly, fluids applied under pressure into lumen  166  may be seen to enter inner everting tube interior  146  through orifice  170 . The supplied fluid pressure may propel inner membrane leading edge  152  and seal  144  distally. The two everting membranes of FIG. 6 may operate in a manner similar to the everting membranes illustrated in FIGS. 1 and 2.  
         [0030]    [0030]FIG. 7 illustrates a cross-section taken through line  7 - 7  of FIG. 6. Outer tube  102  may be seen to enclose non-advancing membrane portion  122 , leading edge  124 , and advancing membrane portion  126 . Inner everting membrane advancing portion  145  may be seen to be disposed about leading edge  152 , which is in turn disposed about fixed membrane portion  142 . Fixed membrane portion  142  may be seen to fixedly attached to inner tubular member  160 . Orifices  112  may be seen to supply the interior of outer everting membrane  120 , while orifices  170  may be seen to supply the interior of inner everting membrane  140 . The cross-sectional view illustrated in FIG. 7 illustrates some elements, for example, tube  160 , shown in projection, that would not be seen in a strict cross-sectional view, but has been added to more clearly illustrate the present invention.  
         [0031]    [0031]FIG. 8 illustrates a more proximal, transverse cross-sectional view taken through device  100 . Outer tube  102  may be seen to be disposed about outer sealing ring  128 , which is in turn disposed about inner sealing ring  144 , which is slidably disposed on inner tube  160 . Inner tube  160  may have a lumen within, not illustrated in FIG. 8. As previously described, outer sealing ring  128  and inner sealing ring  144  are secured to travel together in some embodiments, and allowed to slide separately in other embodiments.  
         [0032]    Referring again to FIG. 6, it may be seen that orifices  112  of FIG. 6, illustrated as being disposed on either side of central lumen  110 , are not required in some embodiments of the invention. In particular, in one embodiment of the invention, only a portion of tube wall  104  has a lumen  110  therein, and orifice  112  may exist only as a single orifice. In one embodiment where outer everting membrane  120  is a tubular member, it is only necessary to supply the interior of the tubular member at a single orifice in order to distally move outer tube leading edge  124 . Similarly, only a single orifice  170  is required to pressurize inner everting membrane  152 . In one embodiment of the invention, sealing rings  128  and  144  are tethered or secured to a more proximal, proximally extending member in order to proximally capture the sliding annular rings. In one example, fluid pressure is used to distally advance leading edge  124  and  152  together with sealing rings  128  and  144 . In this embodiment, a tethering element, strong in tension but not in compression, may be used to retrieve sealing rings  128  and  144  after the everting membranes have been distally deployed.  
         [0033]    [0033]FIG. 9 illustrates one embodiment of the invention having an outer wall  260 , a lumen  262 , and an inner wall  266 , with a plurality of orifices  268  disposed through inner wall  266 . Orifices  268  are in fluid communication with the interior of an outer everted membrane, shown having a leading edge  270  and advancing inner membrane portion  272 . An inner tube or shaft  286  may be seen to be surrounded by an inner tube lumen  284  in communication with a plurality of orifices  290  which are in fluid communication with the interior of an inner, everted tube having a leading edge  282  and a distally advancing membrane portion  280 .  
         [0034]    [0034]FIG. 10 illustrates yet another embodiment of the invention, shown in a transverse, cross-sectional view. A tubular everting membrane device  300  may be seen to have an outer tube  302  having a tube wall  304  and an inner wall  306  disposed about an outer everted tube  308  and an inner everted tube  330 . Outer everted tube  308  may be seen to have a leading edge  310  and an inner slidably disposed distally advancing edge  312 . In the embodiment illustrated, fluid to supply the interior of outer everting tube  310  is supplied by an external tube  314  having a lumen  316  disposed within, and having an orifice  318  supplying outer everting tube  310 . Similarly, an inner shaft or tube  320  may be seen to have a separate inflation tube  322  having a lumen  324  in fluid communication with an inflation orifice  326 . Inflation orifice  326  may be seen to be in fluid communication with the interior of inner everting tube  330 .  
         [0035]    [0035]FIG. 11 illustrates a vessel  200 , such as a blood vessel, which can be a coronary blood vessel or artery. Vessel  200  includes a vessel wall  202  and a vessel inner wall  208 . Vessel  200  has a distal region  204  and a proximal region  206 . A plaque deposit  210  is illustrated as at least partially occluding vessel lumen  201 . Plaque deposit  210  has an outer portion or surface  212  which is disposed against vessel inner wall  208 . In the embodiment illustrated, plaque  210  has at least partial patency, having a lumen  214  therethrough. Double everting membrane device  100  of FIG. 6 may be seen to be disposed proximal of plaque deposit  210 . In FIG. 11, outer everting tube leading edge  124  and inner everting tube leading edge  152  are disposed proximally of plaque deposit  210 .  
         [0036]    [0036]FIG. 12 illustrates double everting membrane device  100 , after outer everting membrane  120  and inner everting membrane  140  have been distally advanced past plaque deposit  210 . As may be seen from inspection of FIG. 12, outer tube distally leading edge  124  and inner tube distally leading edge  152  have been distally advanced past plaque deposit  210 . The two everting membranes have been used to separate plaque deposit  210  from vessel wall or walls  202 . With the everting membranes thus advanced distally beyond plaque deposit  210 , the plaque deposit may be removed from within the vessel. In one embodiment, everting membranes  120  and  140  may be distally advanced even further, to more completely engulf plaque deposit  210 . In one use of the present invention, inner tube  140  and outer tube  120  may be distally retracted, while containing plaque deposit  210  within.  
         [0037]    In one method according to the present invention, a guidewire is initially advanced through vessel lumen  201  and through plaque lumen  214 . After a guidewire has been disposed distally of plaque  210 , an emboli-capturing mechanism such as a distal occlusion filter may be distally advanced over the positioned guidewire. The distal occlusion device may be used to capture any small portion of plaque deposit  210  which became free in the blood stream as a result of the process. After plaque deposit  210  has been separated from wall  202 , both the emboli filter and plaque deposit may be proximally retracted from within the vessel. In one method according to the present invention, device  100  may be advanced distally through the vasculature from an entry point near the groin in the femoral artery. In a preferred use of the present invention, vessel  200  is a coronary artery.  
         [0038]    Numerous characteristics and advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size and ordering of steps without exceeding the scope of the invention. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.