Abstract:
A surgical apparatus and a method to restore blood flow capacity to occluded and partially occluded arterial vessels is disclosed. More particularly, the invention is an endarterectomy instrument and a method associated with its use. The instrument combines a separation ring with a wire loop at the distal end of a resilient, flexible catheter. The separation ring separates the plaque and the inner wall from a segment of an occluded artery. The wire loop is then constricted around the undesired material. IN a preferred embodiment the wire loop of the endarterectomy instrument is used to sever, snare and remove the separated inner arterial wall with the occlusion. In an alternative embodiment, the wire loop of the endarterectomy instrument is heated by passing a current therethrough in order to sever the undesired material from the arterial wall. The undesired occlusion is removed along with the inner layers of the artery by snaring the material with the wire loop and removing the instrument from the vessel in a single step.

Description:
CLAIM OF PRIORITY 
     This application claims priority to U.S. Provisional Application entitled, “An Apparatus and Method for Performing an Endarterectomy,” issued Ser. No. 06/154,288, filed Sep. 16, 1999, which is entirely incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to the restoration of blood flow capacity to occluded and partially occluded blood vessels, and more particularly to an apparatus and procedure for removing the interior lining of an artery. 
     BACKGROUND OF THE INVENTION 
     A common technique for treating arterial stenosis has been surgical construction of a bypass conduit around the site of the occlusion. Bypass grafting with a vein or prosthetic graft, has been the dominant technique for arterial reconstruction. Endarterectomy is also performed as an alternative treatment method. An endarterectomy is defined as the physical separation and removal of the inner layer of the blood vessel wall, the tunica-intima, over the length of the blood vessel where the blockage is located. The blockage is thereby removed along with the tunica-intima from the wall of the blood vessel. After removal of the blockage and the tunica-intima from the vessel, a new tunica-intima grows to replace that portion of the tunica-intima that was removed. 
     A problem with current ring separators/cutters is that the tunica-intima is separated from the blood vessel for a distance past where it is to be severed. Hence, upon removal of the tunica-intima and the blockage, a significant portion of the tunica-intima remains displaced loosely around the circumference of the inner wall of the vessel. This loosely attached tunica-intima is believed to hasten restenosis of the blood vessel. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus and method for surgical removal of an occlusion from a blood vessel. Briefly described, in architecture, the apparatus can be constructed as follows. A separator ring configured to remove the interior lining of a blood vessel may be fixed to the distal end of a resilient, flexible catheter. The catheter operationally connected with the separator ring, may have a bore extending therethrough to permit the placement of an electrical conductor therethrough. The electrical conductor may be configured such that it is concentrically co-located with the separator ring at the distal end of the catheter. The electrical conductor may be configured with a mechanism for snaring, as well as, for severing the inner layers of an artery with the outer wall of the artery. A cautery control unit electrically connected to the electrical conductor may control the supply of electric current in the wire loop. 
     The present invention can also be viewed as providing a method for surgically removing an inner layer of a segment of a blood vessel to remove an occlusion. In this regard, the method can be broadly summarized by the following steps: Forming an incision in the blood vessel. Inserting the distal end of a resilient, flexible catheter with a separator ring and a wire loop affixed thereto, thereby introducing the separator ring between at least one of the inner layers of the arterial wall from the outermost layer of the blood vessel. Advancing the distal end of the catheter with the separator ring and the wire loop along the blood vessel past the occlusion. Using the wire loop to snare and sever the inner layers of the arterial wall. Removing the occlusion along with the inner layers of the arterial wall by withdrawing the catheter from the blood vessel. Last, closing the incision in the blood vessel. 
     Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
     FIG. 1 is a side view of a surgical apparatus consistent with the present invention. 
     FIG. 2 is a perspective view of the separator ring of the surgical apparatus of FIG.  1 . 
     FIG. 3 is another view of the separator ring looking down the major axis of the flexible catheter of the surgical apparatus of FIG.  1 . 
     FIG. 4 is a side view of an artery with a partial occlusion, highlighting operation of the surgical apparatus of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     To this end, the apparatus of the present invention uses a separation ring with an electrically conductive wire loop disposed at the distal end of a catheter. The separation ring is used to loosen the tunica-intima or the tunica-media together with the tunica-intima and the blockage from the outer wall of the blood vessel. In a preferred embodiment, the wire loop is used to introduce physical pressure along the circumference of the separated vessel layer(s) thereby severing the vessel layer(s). The inner diameter of the electrical conductor may be provided with a cutting edge. The cutting edge, may be extended throughout the entire length of the inner circumference of the electrical conductor when the electrical conductor is diametrically extended and resting on the following edge of the separator ring. Alternatively, the cutting edge may be provided along a portion of the inner diameter of the electrical conductor. 
     In an alternative embodiment electro-cautery may be used to assist in severing the vessel layer(s). Upon introduction of electrical current to the wire loop, the wire heats up with the heat acting to cleanly sever the undesired portion of the vessel tissue containing the blockage from the blood vessel. Once the wire loop has sufficiently cooled such that it will no longer damage human tissue (i.e., sever), the wire loop can be used to snare and remove the undesired layer(s) of the portion of the vessel containing the blockage. 
     It is a primary object of the present invention to restore blood flow capacity to a wholly or partially occluded blood vessel. The apparatus and method of the present invention serve to minimize the recurrence of stenosis and permit removal of vascular occlusions along any arterial length from a location outside of the patient. 
     The illustrated embodiments are illustrative of an apparatus and method by which a partially or totally occluded blood vessel is recanalized and the risk of restenosis is substantially reduced by cleanly severing the undesired vessel layer(s) from the vessel wall. 
     The arterial wall layers are from the outside progressing toward the interior, the tunica-adventitia, the tunica-media, and the tunica-intima. In occluded arteries the interface between the tunica-media and the tunica-adventitia becomes weakened, thereby, providing vascular surgeons the opportunity to easily remove the occlusion by taking advantage of the naturally weakened interface between the inner and outer arterial layers. 
     Under appropriate anesthesia, the occluded artery is exposed, clamped, and at least a single arteriotomy is performed distal to the clamp and proximal to the occlusion. While two arteriotomies, one upstream and one downstream of the occlusion could be performed to permit insertion of surgical catheters into the occluded artery to enable removal of the occlusion, one arteriotomy is preferred. 
     A guide wire can then be manually advanced through the upstream arteriotomy until the guide wire contacts or passes the arterial occlusion. The guide wire may then be used as a guide to introduce the apparatus of the present invention into the occluded artery. 
     As illustrated in FIG. 1, an endarterectoscope  100  may be constructed of a separator ring  112 , a resilient, flexible catheter  115 , and a base  113 . The endarterectoscope  100  may comprise a properly sized separator ring  112  fixably attached at the distal end of the flexible catheter  115 . The proximal end of the resilient, flexible catheter  115  may be attached to the base  113 . The resilient, flexible catheter  115  may be further configured with a bore traversing its entire length for receiving a rod  129 . The rod  129  may be introduced in the resilient, flexible catheter  115  of the endarterectoscope  100  such that a first end, proximal to the base  113 , is fixedly attached to a portion thereof to permit the rod  129  to move in relation to the major axis of the resilient, flexible catheter  115 . The rod  129  may be further configured such that portion of the rod  129 , which extends beyond the bore of the resilient, flexible catheter  115  is connected to an electrical conductor  114  substantially concentrically located with the separator ring  112  at the distal end of the resilient, flexible catheter  115 . The electrical conductor  114  may be temporarily affixed to the surface of the separator ring  112  that faces the base  113  so that it remains on the following edge of the separator ring  112  when the endarterectoscope  100  is being advanced through a blood vessel. 
     As further illustrated in FIG. 1, the base  113  may comprise a cauterization interface  117 , a pivot  119 , an attachment point  121 , and a trigger mechanism  127 . The cauterization interface  117  permits an electrically conductive coupling to an external cautery control unit (not shown). The pivot  119 , along with attachment point  121 , enable the trigger mechanism  127  to move radially about pivot  119  to manipulate rod  129  in order to manually adjust that portion of the electrical conductor  114  that is concentrically co-located with the separator ring  112 . It is important to note that the base  113  illustrated in FIG. 1, and the particular implementation whereby the position of the rod  129  is adjusted with respect to the resilient, flexible catheter  115 , is by way of example only. Other physical arrangements that permit relative movement of the rod  129  within the bore extending through the resilient, flexible catheter  115  are within the scope of the present invention. It will be apparent to those skilled in the art that many alternative configurations are available to provide an electrically conductive interface between the cauterization interface  117  and the electrical conductor  114 . Configurations that support electrical conductivity between the cauterization interface  117  and the electrical conductor  114  need not be presented herein for one skilled in the art to appreciate the endarterectoscope  100  of the present invention. 
     Having briefly described the endarterectoscope  100  as illustrated in FIG. 1, reference is now directed to FIG. 2 which further illustrates the distal end of the resilient, flexible catheter  115  and the separator ring  112  of the endarterectoscope  100  of FIG.  1 . In this regard, the distal end of the resilient, flexible catheter  115  is fixably attached to the separator ring  112 . The separator ring may be configured with a beveled first edge as illustrated in FIG.  2 . As further illustrated in FIG. 2, the separator ring  112  may be attached at an angle from the major axis of the resilient, flexible catheter  115  so as to minimize the amount of arterial lining that being separated at any instant as the endarterectoscope  100  is manipulated radially around the major axis of the occluded arterial lining. 
     Reference is now directed to FIG. 3, which illustrates the relationship between the separator ring  112  and the electrical conductor  114  at the distal end of the endarterectoscope  100  of FIG.  1 . In this regard, FIG. 3 illustrates a following surface of the separator ring  112  as viewed from the base  113  down the major axis of the resilient, flexible catheter  115  of the endarterectoscope  100 . As illustrated in FIG. 3, the electrical conductor  114  may be positioned so that it substantially rests on the following surface of the separator ring  112 . The electrical conductor  114  may be configured such that loop  123  permits adjustment of the electrical conductor  114  around the separated layers of arterial tissue. Adjustment of the electrical conductor  114  around the arterial tissue may be accomplished by placing the end of the electrical conductor  114  through loop  123  before connecting the electrical conductor to the rod  129  and moving rod  129  in relation to the resilient, flexible catheter  115 . The rod  129  may be moved in relation to the resilient, flexible catheter  115  by manipulating the trigger mechanism  127  around the pivot  119  (as previously described in relation to FIG.  1 ). 
     Those skilled in the art will appreciate that other methods of forming loop  123  in the electrical conductor  114  are available. As by way of a non-limiting example, a sleeve (not shown) configured from an electrically insulating material may be introduced in such a manner as to be fixably connected to the end of the electrical conductor  114 . The sleeve may be further configured to closely receive that portion of the electrical conductor  114  that is external to the flexible catheter  115 . 
     In an alternative embodiment (not shown) the separator ring  112  may be configured with a non-beveled following edge. The following edge may have a concentric first recess for closely receiving a substantial portion of the length of the loop formed by the electrical conductor  114 . In this way, the electrical conductor  114  may be kept from obstructing the passage of the separated vessel layer(s) until the vascular surgeon has advanced the separator ring  112  past the affected portion of the blood vessel. 
     It will be appreciated by those skilled in the art that a second recess may be provided along the longitudinal axis of the resilient, flexible catheter  115  to further prohibit the electrical conductor  114  and the loop  123  from obstructing passage of the severed tissue through the separator ring  112 . 
     As further illustrated in FIG. 3, the distal end of the resilient, flexible catheter  115  may be configured with a port  131  to permit the rod  129  and the electrical conductor  114  to enter and exit the bore through the resilient, flexible catheter  115 . The port  131  may be configured with a plug with a bore therethrough (not shown) to closely receive the rod  129  or the electrical conductor  114  and to prevent contamination of the resilient, flexible catheter  115  and the rod  129 . Those skilled in the art will appreciate that loop  123  in the electrical conductor  114  however it is formed may be fixably connected to the flexible catheter to permit diametric adjustment of that portion of the electrical conductor  114  that extends beyond the flexible catheter  115 . 
     In another alternative embodiment, the inner diameter of the electrical conductor  114  may be provided with a cutting edge (not shown). The cutting edge, may be extended throughout the entire length of the inner circumference of the electrical conductor  114  when the electrical conductor  114  is resting on the following edge of the separator ring  112 . Alternatively, the cutting edge (not shown) may be provided along a portion of the inner diameter of the electrical conductor  114 . 
     Having briefly described the endarterectoscope  100  with regard to FIGS. 1 through 3, reference is now directed to FIG. 4, which illustrates the use of the endarterectoscope  100  in removing an arterial occlusion along with the proximal inner arterial lining. As illustrated in the cross-sectional view of FIG. 4, artery  400  may be adversely affected by an occlusion  40 . As shown, the artery  400  comprises three layers or linings. Progressing from the exterior of the artery  400  to the interior lining, one passes a first lining comprising the outer wall of the artery  400 , known as the tunica-adventitia  36 . Further traversing the arterial layers, a central layer of the arterial wall is encountered, known as the tunica-media  34 . Last, the interior lining of the artery  400 , known as the tunica-intima  32  is traversed. 
     As illustrated in FIG. 4, the resilient, flexible catheter  115  along with a suitably sized separator ring  112  may be introduced via a small arterial incision. The separator ring  112  of FIG. 4 has been sized such that both the tunica-media  34  and the tunica-intima  32  will be separated from the tunica-adventitia  36  as the separator ring  112  is directed toward and past the location of the occlusion  40  within the artery  400  by manual manipulation of the proximal portion of the endarterectoscope  100  (not shown) that remains external to the body. Alternatively, a separator ring  112  of a smaller size may be selected if the vascular surgeon determines that only the tunica-intima  32  and the occlusion  40  should be removed from the interior of the artery  400 . Once the vascular surgeon has advanced the separator ring  112  past the location of the occlusion  40 , the wire loop formed by the electrical conductor  114  on the following edge of the separator ring  112  may be drawn around the arterial layers herein illustrated as the tunica-intima  32  and the tunica-media  34  which contain the undesired occlusion  40 . 
     Once the vascular surgeon causes the wire loop of the electrical conductor  114  to contact the outer surface of the recently separated tunica-media  34 , the surgeon may elect to introduce an electrical current from an external cauterization control source (not shown), the cauterization control source conductively coupled to the cauterization interface  117  of the base  113  (see FIG.  1 ). As electrical current is supplied, that portion of the electrical conductor  114  heats to a controllable temperature thereby cleanly severing the undesired arterial layers from the tunica-adventitia. Once the exposed wire loop of the electrical conductor  114  cools, the electrical conductor  114  may be further manipulated by the vascular surgeon to snare the severed arterial layers  32 ,  34 . The occlusion  40  and severed arterial layers  32 ,  34  may then be removed from the artery by removing the endarterectoscope  100  from the artery  400  via the arteriotomy (not shown). 
     Alternatively, the vascular surgeon may use the wire loop of the electrical conductor  114  to sever the recently separated tunica-media  34  without the use of electrocautery. In this regard, after contacting the outer surface of the tunica-media  34 , the vascular surgeon may manipulate the exposed wire loop as required to sever the internal arterial layers  32 ,  34  from the tunica-adventitia  36 . 
     The endarterectoscope  100  configured as illustrated in FIGS. 1 through 4 enables a vascular surgeon to separate, sever, snare, and remove the arterial layers  32 ,  34  along with the occlusion from the remaining tunica-adventitia  36  of the artery  400 . In this regard, the vascular surgeon minimizes surgical time and limits surgical irritation of the interior of the artery  400 . 
     It should be emphasized that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.