Abstract:
An endovascular stapler for securing an endograft to a vessel is disclosed. The stapler includes a staple housing adapted for storing at least one staple therein. The staple housing having an exit area for discharge of the at least one staple therethrough. The stapler also includes an actuating assembly adapted for discharging the at least one staple through the exit area and a displacement mechanism in operative association with the staple housing near the exit area. The displacement member is operative for pushing the exit area against the endograft when discharging the at least one staple therethrough. The displacement mechanism may comprise a balloon adapted to be inflated and deflated positioned near the exit area. The unbent staples may be shaped as elongate W shapes, or may alternatively be straight wire segments. The staples may be bent upon discharge.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present provisional application relates to U.S. Provisional Patent Application Ser. No. 60/433,692 filed Dec. 16, 2002, and U.S. Provisional Application No. 60/501,060 filed Sep. 8, 2003, the disclosures of which are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a stapling device for use in the fixation of endovascular grafts to the walls of vessels. Fixation of grafts utilizing the present invention may be conducted during initial implantation. However, the present invention may also be utilized to arrest the vexing complication of proximal or distal migrations following the prior implantation of such grafts. 
     It is well known that endovascular grafts may be inserted into the human body during numerous medical procedures. Grafts are typically inserted into vessels and held in place by friction, such as with self-expanding or balloon expandable stents. The grafts may also be affixed to vessels with hooks or barbs. 
     The grafts may be formed from synthetic materials, such as polyester, expanded polytetraflouroethylene (“ePTFE”), or others. The grafts may also be formed of natural vessels harvested from other areas of the body or from a donor mammal. Notwithstanding the various materials utilized, migration of the grafts over time remains a problem. 
     Caudad device migration is known to lead to a Type 1 endoleak with aneurysm sac reperfusion, enlargement and rupture. Cephalad device migration may lead to coverage of the renal artery orifices and renal insufficiency. 
     Such device migration is caused by many factors. One known factor is poor patient selection. Patients with cone shaped aortic necks, severe neck tortuosity, short necks or who have a laminated thrombus present at the landing site are generally susceptible to device migration problems. Other device migration issues are caused by changing aortic morphology following device implantation. Finally, migration may be caused by device structural fatigue and device design related issues. Even absent these conditions, device migration has been found. 
     Treatment of caudad migrations have traditionally been conducted by the addition of “sleeves” to the proximal end of the graft in an effort to regain purchase between the graft and the vessel it is attached to in order to maintain a seal between the two. More drastic options include resorting to conventional surgery. These late conversions are, unfortunately, associated with a high mortality rate. 
     Treatment options for the cephalad migrations are even less attractive. In the face of continued migration, resignation may be the only option as such migration may lead to renal insufficiency requiring hemodialysis. To permit device removal, a typical conversion in this case involves supra-celiac aortic cross-clamping, and its associated problems. 
     Prior attempts at fixation of migrating devices, including additions of hooks, barbs, tackers, and other fastening devices have proven to be insufficient or impractical. It would therefore be advantageous to provide an endovascular stapling device which may be used to adequately arrest existing migrations, as well as secure new grafts in a manner likely to eliminate future migration. Actual fixation of the graft to the aortic neck at multiple points will also prevent the aorta itself from enlarging. 
     SUMMARY OF THE INVENTION 
     The endovascular stapler of the present invention is designed to overcome the deficiencies of the prior art. In one embodiment, the endovascular stapler may comprise a staple housing adapted for storing at least one staple therein, the staple housing may have an exit area for discharge of the at least one staple therethrough, an actuating assembly adapted for discharging the at least one staple through the exit area, and a displacement mechanism in operative association with the staple housing near the exit area, the displacement member operative for pushing the exit area against the endograft when discharging the at least one staple therethrough. The displacement mechanism may comprise a balloon positioned near the exit area. The balloon may be adapted to be selectively inflated and deflated. The balloon may also be noncompliant. The staple may be deformed prior to exiting the exit area. The stapler may also be adapted for use with a staple having an elongated W shape. In addition, the actuating assembly may comprise a pusher and a trigger, the pusher adapted to be advanced by the trigger to discharge the at least one staple. 
     In another embodiment, the endovascular stapler for securing an endograft to a vessel may comprise a trigger housing comprising a trigger mechanism within the housing; a staple housing having a proximal end and a distal end, the staple housing coupled at the proximal end of the staple housing to the trigger housing, the staple housing adapted to store a staple, the staple housing having a staple exit area formed therein near the distal end thereof; and, a balloon exterior to the staple housing near the distal end thereof, the balloon adapted to be selectively inflated and deflated to push the staple exit area against the endograft. The trigger mechanism may be actuated to drive a staple from the staple housing through the staple exit area into the endograft and the vessel. The endovascular stapler may further comprise an output boss penetrating the trigger housing; a guide wire exit port near the distal end of the staple housing; a guide wire channel extending from the guide wire exit port to the output boss; and, a guide wire extending within the guide wire channel. The staple housing may be guided to a particular location within the vessel by sliding the staple housing along the guide wire. The trigger assembly may further comprise a pusher operatively engaged with a trigger, the pusher extending from within the trigger housing to the staple exit area, wherein the pusher is adapted to advance through the staple housing to push the staple from the staple exit area. The endovascular stapler may further comprise an actuator having an inclined surface, wherein the pusher further comprises an inclined surface adjacent to the inclined surface of the actuator, advancement of the pusher in an advancement direction through the staple housing bringing the inclined surface of the pusher into contact with the inclined surface of the actuator to shift the actuator in a direction substantially perpendicular to the advancement direction of the pusher. The shifting of the actuator may drive a staple through the staple exit area. The stapler may further comprise a staple détente associated with the staple exit area, the staple détente adapted to deform the staple prior to exiting the staple exit area. The pusher may further comprise a ramped surface on a side of the pusher, the ramped surface adapted to rotate the staple détente away from the staple exit area during advancement of the pusher. 
     In yet another embodiment, the endovascular stapler for securing an endograft to a vessel may comprise a trigger housing comprising a trigger mechanism; a staple housing having a proximal end at the trigger housing and a distal end remote from the trigger housing, the staple housing comprising a staple channel adapted to store a plurality of staples in tandem, the staple channel extending from the proximal end of the staple housing to a staple exit area near the distal end of the staple housing; and, a pusher extending into the staple channel from within the trigger housing; wherein the pusher is adapted to advance through the staple channel upon actuation of the trigger mechanism to advance the plurality of staples stored in tandem in the staple channel such that a first staple may be discharged through the staple exit area. The staple channel may comprise a curved portion adjacent the staple exit area, the curved portion configured to shape the staples as they are discharged from the staple exit area. The stapler may further comprise a balloon inflation port penetrating the trigger housing; a balloon inflation channel extending within the staple housing and in fluid communication with the balloon inflation port; and, a balloon exterior to the staple housing and in fluid communication with the balloon inflation channel; wherein the balloon may be selectively inflated and deflated to push the staple exit area against the endograft. The balloon may be positioned opposite to the staple exit area. The stapler may further comprise an output boss penetrating the trigger housing; a guide wire exit port near the distal end of the staple housing; a guide wire channel extending within the staple housing from the output boss to the guide wire exit port; and, a guide wire extending within the guide wire channel; wherein the staple housing may be guided to a vessel by sliding the staple housing along the guide wire. 
     In yet another embodiment, the stapler for stapling a vessel may comprise a trigger housing having an internal cavity; a trigger mechanism extending from within the internal cavity of the trigger housing; an elongate staple housing extending from the trigger housing to a staple exit area formed in the elongate staple housing, the elongate staple housing adapted to store at least one staple; a pusher having a leading portion within the staple housing and a trailing portion within the internal cavity of the trigger housing, the pusher having an inclined surface at its leading end; an actuator having an inclined surface disposed adjacent to the inclined surface of the pusher; and, a staple détente mounted within the staple housing between the actuator and the staple exit area; wherein actuation of the trigger advances the leading portion of the pusher such that the inclined surface of the pusher interacts with the inclined surface of the actuator to force the actuator toward the staple exit area thereby deforming the at least one staple by engagement with the staple détente prior to discharging the at least one staple from the staple exit area. The at least one staple stored in the staple housing may be formed in the shape of an elongated W prior to being discharged from the staple exit area. 
     In yet another embodiment, the endovascular stapler for connecting a stent graft to a vessel may comprise a trigger housing having an elongate staple housing extending therefrom, the elongate staple housing having a staple exit area adapted to be inserted into a vessel, the elongate staple housing adapted to store a staple; a pusher extending within the staple housing from the trigger housing; a trigger mechanism within the housing, the trigger mechanism adapted to advance the pusher within the staple housing to push a staple stored in the elongate staple housing through the staple exit area to connect the stent graft to the vessel; and, a balloon adjacent the staple housing, the balloon inflatable to force the staple exit area against the stent graft. The stapler may further comprise a staple détente mounted within the staple housing, the staple détente adapted to shape the staple prior to exiting the staple exit area. The staple may be formed in the shape of an elongated W prior to being discharged from the staple exit area. 
     In one method of repairing an endograft in a vessel with an endovascular stapler having a distal end and a balloon associated therewith, the method may comprise inserting the distal end of the endovascular stapler into the endograft; inflating the balloon so as to push the distal end of the endovascular stapler against the endograft; discharging a staple from the endovascular stapler into the endograft. 
     In a further method of repairing an endograft in a vessel with an endovascular stapler having a distal end forming a staple exit area, a trigger for deploying staples, and a balloon near the staple exit area, the method may comprise inserting the distal end of the endovascular stapler into the endograft; inflating the balloon to push the staple exit area against the endograft; and, deploying a staple from the staple exit area into the endograft and the vessel. The method may further comprise partially deflating the balloon; rotating the endovascular stapler; reinflating the balloon so as to push the stapler exit area against the endograft in a location adjacent to the first staple; and, deploying a second staple from the staple exit area into the endograft and the vessel. 
     A still further method of performing surgery on a vessel having an endograft therein may comprise providing a plurality of staplers, each stapler having a stapler housing storing a staple and a balloon capable of being inflated and deflated; inserting the stapler housing of the first of said plurality of staplers into said endograft; inflating the balloon of said first of said plurality of staplers so as to push the stapler housing against the endograft; and, advancing the first staple from within the stapler housing such that the first staple pierces the endograft and the vessel wall. The method may further comprise deflating the balloon; removing the stapler housing of said first of said plurality of staplers from said endograft; inserting the second of said plurality of stapler housings into said endograft; inflating the balloon so as to push the second of said plurality of stapler housings against the endograft area other than at the location of the first staple; advancing the staple of the second of said plurality of staplers from within the stapler housing such that the second staple pierces the endograft in an area other than at the location of the first staple. 
     In accordance with another aspect of the invention, an endovascular stapler for securing an endograft to a vessel may comprise a staple housing adapted for storing a plurality of staples therein, the staple housing having a plurality of exit areas for discharge of the plurality of staples therethrough; an actuating assembly adapted for discharging the plurality of staples through the plurality of exit areas, the actuating assembly comprising a plurality of staple pushers adapted to advance the plurality of staples through the plurality of exit areas and a trigger adapted to advance the plurality of staple pushers; and, a displacement mechanism in operative association with the staple housing near the exit areas, the displacement member operative for pushing the exit areas against the endograft when discharging the plurality of staples therethrough. The plurality of staples may be arranged radially about a longitudinal centerline of the staple housing. Alternatively, the plurality of staples may be arranged linerally within said staple housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with features, objects, and advantages thereof will be or become apparent to one with skill in the art upon reference to the following detailed description when read with the accompanying drawings. It is intended that any additional organizations, methods of operation, features, objects or advantages ascertained by one skilled in the art be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
       In regard to the drawings, 
         FIG. 1  is plan view of the handle portion of a stapler in accordance with one embodiment of the present invention; 
         FIG. 2  is a sectional view of the stapler of  FIG. 1  showing the internal components thereof; 
         FIG. 3  is a perspective view of a pusher forming a portion of the stapler of  FIG. 1 ; 
         FIG. 4  is a longitudinal sectional view of the distal end of the staple housing forming a portion of the stapler of  FIG. 1  showing the internal components thereof; 
         FIG. 5  is a cross-sectional view of the distal end of the staple housing shown in  FIG. 4  taken along section lines A-A; 
         FIG. 6  is a cross-sectional view of the distal end of the staple housing shown in  FIG. 4  taken along section lines B-B; 
         FIG. 7  is a cross-sectional view of the distal end of the staple housing shown in  FIG. 4  taken along section lines C-C; 
         FIG. 8  is a longitudinal section of the distal end of the staple housing shown in  FIG. 4  taken along section lines D-D; 
         FIG. 9  is a cut-away view of the abdominal cavity of a patient depicting the general orientation of the staple housing forming a portion of the stapler utilized in a method of arresting graft migration in accordance with one embodiment of the present invention; 
         FIG. 10  is a second cut-away view of the abdominal cavity of a patient depicting the general orientation of the staple housing forming a portion of the stapler utilized in the method of arresting graft migration in accordance with one embodiment of the present invention; 
         FIG. 11  is a cut-away view of the abdominal cavity of a patient depicting an initial step of the method of affixing a graft into an aortic aneurysm in accordance with one embodiment of the present invention; 
         FIG. 12  is a cut-away view of the abdominal cavity of a patient depicting a further step of the method of affixing a graft into an aortic aneurysm of  FIG. 11 ; 
         FIG. 13  is a sectional view of a portion of an endovascular stapler in accordance with a second embodiment of the present invention inserted into an aortic wall; 
         FIG. 14  depicts a cross-sectional view of the distal end of the staple housing of the stapler in accordance with the second embodiment of the present invention in an initial position; 
         FIG. 15  depicts a longitudinal section view of the distal end of the staple housing of the stapler in accordance with the second embodiment of the present invention in the initial position shown in  FIG. 14 ; 
         FIG. 16  depicts a longitudinal section view of the distal end of the staple housing of the stapler in accordance with the second embodiment of the present invention in an advanced position; 
         FIG. 17  depicts a cross-sectional view of the distal end of the staple housing of the stapler in accordance with the second embodiment of the present invention in the advanced position shown in  FIG. 16 ; 
         FIG. 18  depicts a longitudinal section view of the distal end of the staple housing of the stapler in accordance with the second embodiment of the present invention in an further advanced position; 
         FIG. 19  depicts a cross-sectional view of the distal end of the staple housing of the stapler in accordance with the second embodiment of the present invention in the further advanced position of  FIG. 18 ; 
         FIG. 20  depicts a perspective view of several internal components forming a portion of the stapler in accordance with the second embodiment of the present invention; 
         FIG. 21  depicts a cross-sectional view of the distal end of the stapler of the present invention in accordance with a third embodiment; and, 
         FIGS. 22   a  and  22   b  depict a triangular apparatus forming a portion of the staple housing which may be utilized in accordance with certain embodiments of the present invention,  FIG. 22   b  depicting the triangular apparatus in a parallel relation and  FIG. 22   a  depicting the triangular apparatus in an angled relation. 
     
    
    
     DETAILED DESCRIPTION 
     In the following is described the preferred embodiments of the endovascular stapler of the present invention. In describing the embodiments illustrated in the drawings, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. 
     In general, the endovascular stapler is a device which includes a stapling portion, or staple housing, intended to be inserted into the human body of a patient through an artery and apposed against a vessel wall, such as an aortic wall, or a graft. In order to maintain this position, a displacement device, such as a balloon, may be inflated near the stapling portion to push the stapling portion against the aortic wall or graft. Preferably, the displacement device is a noncompliant balloon. However, compliant balloons may also be utilized. Other displacement devices comprising webbed elements or multiple rods may also be utilized. A staple may then be advanced through the aortic wall and graft by actuating a trigger located on the body of the endovascular stapler, which remains outside of the patient&#39;s body. The staple may be either preformed with the some initial curvature or it may be flat. Either way, the stapling portion typically includes a conforming element to curve the staple as it advances. The staple will then penetrate the aortic wall and the graft and will curve in a predictable path such that its leading edge loops back, possibly repenetrating the exterior of the aortic wall and graft, thus holding the aortic wall and the graft against each other. 
     In embodiments where multiple staples may be inserted, the noncompliant balloon may be deflated and the stapler may be rotated to a second position, wherein another staple may be driven. The process may be repeated numerous times over the full 360° until a sufficient number of staples have been driven to adequately secure the graft to the aortic wall. Typically, this will entail driving up to eight staples. 
     In embodiments where the endovascular stapler houses only a single staple, the central portion of the stapler may be removed, reloaded and reinserted numerous times in order to drive multiple staples. Alternatively, several pre-loaded staplers may be provided. After discharging the staple from the first stapler, the stapler may be removed and discarded, wherein a second stapler may be inserted. This process may be repeated until a sufficient number of staples have been driven. Thus, the surgical staff will generally be ready with up to eight pre-loaded staplers per procedure, each stapler being utilized successively. 
     The endovascular stapler of the present invention may be an “over the wire” device designed to fit through a typical sheath for aortic and iliac arterial use, such as a 10 French sheath. It is also possible that the stapler may be miniaturized to fit through smaller sheaths for fixation of endografts in smaller caliber vessels. 
     In some embodiments, the stapler fires multiple staples sequentially. In such cases, the staples may consist of special precuts of alloy, such as Phynox, with sufficient column strength to be stacked in tandem within the staple channel and to be sequentially pushed therethrough. The staples must also be sufficiently pliable to easily track the curved internal staple guide, for some embodiments of the invention. In other embodiments, the staples must be loaded individually. In still further embodiments, the staples may be loaded automatically from a cartridge, but are not stacked in tandem. Rather, they may reside side-by-side in the cartridge. 
     The stapler is generally introduced through a groin sheath or other suitable access into the lumen of an endograft. Its leading elements are advanced to the proximal end of the endograft which should be accurately identified. Such identification may be by utilizing an ultrasonic probe. For future endografts, the ends of the graft fabric may be boldly marked with radio opaque thread. For older devices, radiologic techniques such as road mapping may be used to locate the ends of the graft. As is known in the art, multiple guide wires may be used during surgery. 
     When the stapling portion of the stapler is aligned with the proximal end of the endograft, the stapler head may be forcibly abutted against the endograft and vessel wall by inflation of a preferably noncompliant balloon. In this position, a single stroke of the stapler trigger preferably causes forward displacement of the staple pusher sufficient to advance a single staple through the graft and vessel wall. 
     In some embodiments, the curve of the staple guide causes the staple to form a circle or spiral, with a single piercing point on the leading portion of the staple. In other embodiments, the staple may form an exaggerated W. In this case, each end of the staple will pierce the endograft and the vessel wall as the staple is deformed by a staple détente. 
     In the case of an automatically loading stapler with staples aligned in tandem, the trigger of the stapler handle is then ratcheted back and cocked for the next firing. The specialized ratcheted design of this pusher and trigger is such that when fully cocked, a single trigger pull causes exactly the pusher excursion required to deploy the lead staple fully and bring the trailing staple segment into position at the tip of the curved staple guide for the firing of the next staple. For single staple designs, the stapler may be retracted and reloaded prior to the firing of a second staple. Alternately, additional staplers may be utilized during a single procedure, each firing only a single staple. Where multiple staples are fired from a cartridge holding staples side-by-side, the ratcheting mechanism of the trigger may include a feature permitting the pusher to be withdrawn back toward the body of the stapler, such that it is positioned for the firing of subsequent staples after the firing of a previous staple. 
     Inflation and deflation of the preferably noncompliant balloon may be performed manually or with any of the many available devices used for inflation and deflation of angioplasty balloons. A liquid such as dilute contrast or saline may also be used to distend the balloon. 
     Following each staple deployment, the balloon may be partially deflated, the stapler rotated, and the process repeated to deploy the next staple. For embodiments where staples are aligned in tandem, one limiting factor to the number of staples per device, and thus the length of the device, is the column strength of the staple alloy as the staples aligned in a row are each driven by the trailing staples, and ultimately by the excursion of the staple pusher. It will be readily apparent that the staples should be of sufficient column strength so as not to become deformed within the stapler prior to being applied. It will also be apparent that a single staple may be required to push several proceeding staples. 
     In embodiments where the staples are stored in tandem, the staples may be cut such that the diamond shaped tip of each trailing staple fits into a diamond shaped cavity formed at the end of each leading staple. For devices employing a single staple or employing a cartridge of side-by-side staples, the column strength of the individual staple is less of a concern. Of course, it should be sufficient to adequately secure the stent graft, however. 
     Referring to the figures,  FIG. 1  depicts an endovascular stapler  100  in accordance with one embodiment of the present invention. As is shown, the stapler  100  may generally be shaped like a gun. The stapler  100  may comprise a housing  102  having a handle  104  and a trigger  106  extending therefrom. The housing may also include a barrel  101  having an output aperture  110 . An input boss  108  may be located at the rear  103  of the housing  102 . A guide wire  112  may extend into the input boss. Extending from the output aperture  110  may be a staple housing  114 . The stapler  100  may also include a balloon inflation port  116 . 
       FIG. 2  depicts a cut-away view of the stapler  100  of  FIG. 1 . As shown, the trigger  106  may comprise an inner section  105  and an outer section  107 . The inner section  15  may also include a grip  109 , exterior to the housing  102 . The inner section  105  may include a pin  128  attaching the trigger  106  to the housing  102 , and about which the trigger may rotate. The trigger  106  may also include a spring mechanism (not shown) to bias the trigger  106  away from the handle  104 . The outer section  107  of the trigger  106  may be attached to the inner section by a spring  132 . Advantageously, the outer section  107  is permitted to shift relative to the inner section  105 , to compress the spring  132 . A toothed element  126  of the outer section  107  includes teeth  109  having sloped sections  138  and edges, or lips  140 . Each of the sloped sections  138  of the teeth  109  assist with ratcheting action of the trigger  106 , as will be discussed hereinafter. 
     A ratcheted stapler pusher  120  may curve between the trigger  106  and a path created by the internal cavity  118  formed from the housing  102 . The pusher  120  may include a ratcheted portion  122  at its trailing portion and a cylindrical portion  124  at its leading portion. The ratcheted portion  122  includes sloped sections  138  which may engage the toothed elements  126  of the stapler trigger  106 . Upon actuation of the stapler trigger  106 , which initiates rotation of the toothed elements  126  about pin  128 , the pusher  120  may be displaced through the barrel  101  toward the distal end  130  ( FIG. 4 ) of the stapler  100 . As the trigger  106  is returned to its initial position, spring  132  permits ratcheting of the toothed elements  126  such that the pusher  120  remains in this advanced position. Portions of the ratcheted portion  122  of the pusher  120  may be stored in a spiral configuration within staging area  134 , located within the handle  104  of the stapler  100 . 
     Also shown in  FIG. 2  are the internal components of the input boss  108 . The input boss  108  comprises a flange  111  formed from the housing  102 . The flange includes a cavity  113  extending into the internal cavity  118  of the housing  102 . Within the cavity  113  near the flange  111  may be a pair of rubberized elements  115  having a boundary  117  therebetween. The guide wire  112  ( FIG. 1 ) may be permitted to pass along this boundary from the exterior of the housing  102  to the internal cavity  118 . Once inside the internal cavity  118 , the guide wire may be permitted to extend through the barrel  101  into the guide wire channel  144  ( FIG. 4 ) of the staple housing  114 , as will be discussed. 
       FIG. 3  depicts a perspective view of the pusher  120 . This figure clearly depicts the cylindrical portion  124  at the front of the pusher  120  and the ratcheted portion  122  at the rear of the pusher. The ratcheted portion  122  may comprise a series of ramps  136  having sloped sections  138  ending in lips  140 . As discussed, the toothed element  126  of the stapler trigger  106  incorporates teeth  109  which may be sized and configured similarly to the sloped sections  138 . The engagement of each of these elements facilitates displacement of the pusher  120  when the trigger  106  is activated, but permits ratcheting of the trigger upon the return stroke. 
     Also shown in  FIG. 3  is the front face  119  of pusher  120 . As will be discussed, the front face  119  of the pusher may be adapted to contact and advance a series of staples  148  ( FIG. 4 ). 
       FIG. 4  depicts a longitudinal sectional view of the distal end  130  of the staple housing  114 . As shown, the staple housing  114  may incorporate a staple channel  142 , a guide wire channel  144 , and a balloon inflation channel  146 . Each of the channels may be generally cylindrical and typically run the entire length of the staple housing  114  from the outlet aperture  110  of the housing  102  to the distal end  130  of the staple channel  146 . 
     The staple channel  142  typically houses a series of staples  148  placed consecutively in tandem including a first staple  148   a  and a second staple  148   b . Preferably, each staple has a pointed proximal end  150  and a distal end  152  with a cavity  154  or recess matching the pointed proximal end. The cavity of the leading staple, such as the first staple  148   a , therefore may be filled by the pointed proximal end  150  of the subsequent staple, such as the second staple  148   b.    
     As will be discussed, the stapler  100  is generally employed to fire a multiplicity of staples  148  sequentially to secure a graft to a vessel. The staples  148  preferably consist of special precuts of alloy, such as Phynox, with sufficient column strength to be placed in tandem within the staple channel  142  so as to be pushed ahead by the trailing staples. Each of the staples  148  is also preferably sufficiently pliable to easily track the curved internal staple guide  151 . 
     For example, the first staple  148   a  may be pushed by the second staple  148   b , as well as the subsequent staples, by the pusher  120  upon actuation of the trigger  106 . As the first staple travels along the staple channel  142 , it will begin to be bent by a bending portion  153  of the staple channel  142 , toward the distal end  130  of the staple housing  114 . It will be appreciated that the bending portion  153  of the staple housing curves such that the staple  148  exiting the bending portion will be pre-curved as it enters the internal staple guide  151 . As will be discussed hereinafter, as the staple  148  passes the staple guide  151 , it will continue to be shaped such that the staple will form a loop capable of penetrating each of a graft and a vessel in at least two locations. 
     The guide wire channel  144  extends along the entire length of the staple housing  114  parallel and adjacent to the staple channel  142 . The guide wire channel provides a housing for the guide wire  112 , which is used to advance the distal end  130  of the stapler  100  to the location where the stapling is to be conducted. 
     Generally, advancement of the endovascular stapler  100  is considered to be via an “over the wire” type system. As an “over the wire” device, the staple housing  114  portion of the stapler  100  is designed to be guided through vessels following the path of a previously installed guide wire  112 . For example, a guide wire  112  may be placed in an artery in a surgical procedure. The distal end  130  of the staple housing  114  may then be pushed along the length of the guide wire  112 , which travels from a guide wire exit point  155  at the distal end  130 , through the guide wire channel  144  and out the input boss  108  of the housing  102 . Once the distal end  130  reaches its destination, advancement may cease and the stapler  100  is ready deploy a staple  148 . It will be appreciated that the staple housing  114  may be constructed of flexible materials such that it may bend as necessary along the path toward the area in which a staple  148  is to be deployed. 
     Preferably, the endovascular stapler of the present invention is designed to fit through a 10 French sheath for aortic and iliac arterial use. However, it is also foreseeable that the stapler may be miniaturized to fit through smaller sheaths for fixation of endografts in smaller caliber vessels. 
     Also shown in  FIG. 4  is the balloon inflation channel  146  of the staple housing  114 . Extending from the balloon inflation channel  146  is a noncompliant balloon  156 . In the view shown in  FIG. 4 , it will be appreciated that the noncompliant balloon  156  is shown inflated. In a deflated condition, the noncompliant balloon is generally quite thin, and typically fits neatly against the balloon inflation channel  146 . 
     The noncompliant balloon  156  may be inflated prior to the firing of a staple  148 . One purpose of inflating the noncompliant balloon  156  is to force the staple exit area  158  of the staple housing  114  against the area where the staple  148  is to be fired. This not only places the staple  148  immediately adjacent to the receiving area, but it assists with preventing the staple housing  114  from being moved, linearly or rotationally, during the firing of the staple  148 . 
     Selective inflation and deflation of the noncompliant balloon  156  is completed through the balloon inflation port  116  of the housing  102 . It will be appreciated that the balloon inflation port  116  may include a valve (not shown) upon which a liquid source (not shown) may be attached. The liquid source may be permitted to flow into the balloon inflation port  116  to inflate the noncompliant balloon  156 . Deflation of the noncompliant balloon  156  may be accomplished at the balloon inflation port  116  by releasing liquid therefrom, such as by opening the valve or by sucking liquid out of the noncompliant balloon  156  through use of the liquid source, which may have the capability of reversing direction of flow to form a vacuum. It will be appreciated that the balloon inflation port  116  is in fluid communication with the noncompliant balloon  156  via the balloon inflation channel  146 . Inflation and deflation may also be conducted with any of the available devices used for inflation and deflation of angioplasty balloons. Typically, the liquid used for inflating and deflating the balloon will be dilute contrast or saline. 
     Upon firing of the staple  148 , the noncompliant balloon  156  may then be deflated so the staple housing  114  may be rotated to a second position in preparation for the firing of a second staple  148 . Prior to firing the second staple  148 , the noncompliant balloon  156  may be re-inflated to place the staple exit area  158  of the stapler  100  in position in preparation for firing. 
       FIG. 5  depicts a cross sectional view of the staple housing  114  taken along section line A-A of  FIG. 4 . As with  FIG. 4 , the noncompliant balloon  156  is shown inflated. As shown in  FIG. 5 , the guide wire channel  144  may be offset within the staple housing  114  around the staple exit area  158  (also shown in  FIG. 4 ). This offset allows for the formation of the curved area  153  of the staple channel  142 , as well as the staple guide  151  along the longitudinal centerline of the staple housing  114 . 
       FIG. 6  depicts a cross sectional view of the staple housing  114  taken along section line B-B of  FIG. 4 . As shown in  FIG. 4 , section line B-B is taken closer to the housing  102  than section line A-A. In this cross-section, the staple exit area  158  is not yet visible. Yet, a staple  148  within the staple channel  142  and the guide wire  112  within the guide wire channel  144  clearly are. In addition, the noncompliant balloon  156  is shown in the inflated condition. 
       FIG. 7  depicts a cross sectional view of the staple housing  114  taken along section line C-C of  FIG. 4 . In this upstream section, it is clearly shown that the stapled channel  142 , guide wire channel  144  and balloon inflation channel  146  may all be stacked on a single vertical axis within the staple housing  114 . This orientation constitutes the orientation of the various channels  142 ,  144 ,  146  for most of the length of the staple housing  114 . 
       FIG. 8  depicts a longitudinal section view of the distal end  130  of staple housing  114  shown in  FIG. 4  taken along section lines D-D. In this view, the staple exit area  158  is clearly depicted with the proximal end  150  of the staple  148  nearest the distal end  130  of the staple housing  114 . Also shown in the guide wire channel  144  with the guide wire  112  offset to permit formation of the staple exit area  158 . 
       FIG. 9  depicts a staple housing  114  inserted into a sheath within the human body. The staple housing  114  is typically introduced into the groin or other suitable access area where it follows the previously inserted guide wire  112  into the lumen of the endograft to be sutured. Also shown in  FIG. 9  is the noncompliant balloon  156  in a fully inflated condition. As previously discussed, the distal end  130  of the staple housing  114  will be pushed against the aortic sidewall by the noncompliant balloon  156 . When so pushed, a first staple  148   a  may be fired. Subsequent staples  148  may be fired after deflation of the noncompliant balloon  156 , rotation of the staple housing  114  and inflation of the noncompliant balloon such that the staple exit area  158  is aligned at the intended deployment location. 
       FIG. 10  depicts a close-up cut-away view of the distal end  130  of the endovascular stapler  100  in use. As discussed, the distal end  130  of the stapler  100  may be inserted into the aorta  160  through a sheath (not shown) along a guide wire  112 . The proximal end  130  may then be positioned so as to cover the aortic aneurysm  162  intended to be cured. As previously discussed, the noncompliant balloon  156  may then be enlarged such that the staple exit area  158  of the stapler  100  will be pushed up against the endograft  164  and the aortic sidewall  160 , as shown in  FIG. 10 . 
       FIG. 11  depicts a longitudinal section view of this arrangement showing the internal components of the staple housing  114 . In this view, it is clearly shown that the first staple  148   a  is being pushed by the second staple  148   b  through the curved area  153  of the staple channel  142 . Such curvature of the staple channel deforms the first staple  148   a  permitting the staple to curve around the curved internal staple guide  151  toward the staple exit area  158 . Again, the staple exit area  158  is shown adjacent to the area in which the staple  148  is to be deployed. Secure placement of the staple exit area  158  is achieved via inflation of the noncompliant balloon  156 . 
       FIG. 12  depicts the longitudinal section view of  FIG. 11  after the firing of a staple  148 . As shown, internal staple guide  151  has formed the staple  148  into a ring or loop engaging the endograft  164  and the aortic sidewall  160  from the interior of the aorta  160  and then returning back around to again engage the aortic sidewall  160  and the endograft  164  from the exterior of the aorta. As previously discussed, the noncompliant balloon  156  may then be temporarily deflated such that the staple housing  114  may be rotated and placed in a position for the firing of a second staple  148   b.    
     The stapler is typically introduced into the patient through a groin sheath or other suitable access into the lumen of the endograft. It is advanced to the proximal end of the endograft which should be accurately identified. For future endografts, the ends of the graft fabric is boldly marked with radio opaque thread. For older devices, radiologic techniques such as road mapping may be used to locate the ends of the graft. As is known in the art, multiple guide wires may be used during surgery. 
     When the stapling end of the stapler is aligned with the end of the endograft, the stapler head is forcibly abutted against the endograft and vessel wall by inflation of a balloon. In this position, pulling of the stapler trigger causes forward displacement of the staple pusher sufficient to advance a single staple through the graft and vessel wall. The curve of the staple guide causes the staple to form a circle. The trigger of the stapler handle is then cocked for the next firing. The specialized ratcheted design of this pusher and trigger is such that when fully cocked, the trigger pull causes exactly the pusher excursion needed to deploy the lead staple fully and bring the trailing staple segment into position at the tip of the curved staple guide. 
     Inflation of the preferably noncompliant balloon may be performed manually or with any of the many available devices used for inflation of angioplasty balloons. A liquid such as dilute contrast or saline may be used to distend the balloon. 
     Following each staple deployment, the balloon is deflated, the stapler is rotated and the process is repeated to deploy the next staple. The only limiting factor to the number of staples per device, and thus the length of the device, is the column strength of the staple alloy as the staples aligned in a row are driven each by the trailing staple and ultimately by the excursion of the staple pusher. 
     The staples are cut such that the diamond shaped tip of the trailing staple fits into the diamond shaped cavity formed at the end of the lead staple. 
       FIG. 14  depicts a cross-sectional view of a portion of the staple housing  214  of an endovascular stapler (not shown) in accordance with a second embodiment of the present invention. In this embodiment, a single staple  248 , formed in the shape of an elongated W may be applied to secure a graft  264  against a vessel, shown in  FIG. 14  as an aortic wall  260 . Typically, the chief function of a stapler in accordance with this embodiment is for use to arrest device migration of a previously placed endograft. Other embodiments employing multiple elongated W-shaped staples may also be used to arrest device migration of a previously implanted endograft or to affix a new endograft. Still further embodiments permit the withdrawal of portions of the stapler which may then be replaced with other portions pre-loaded with a staple for a subsequent firing. 
       FIG. 13  depicts a partially cut-away perspective view of a stapler housing  214  and a noncompliant balloon  256  inserted within an aortic wall  260  in preparation for attachment of a stent graft  264 . As shown in  FIG. 13 , the stapler housing  214  may be placed into position by being strung along a guide wire  212  in an “over the wire” type system, as previously discussed. Once positioned properly, such that the staple exit area  258  is adjacent to the intended deployment area, the noncompliant balloon  256  may be inflated, as shown in  FIG. 13 , to push the staple exit area against the stent graft  264 , which in turn is pushed against the aortic wall  260 . The staple  248  may then be fired and the stapler housing  214  removed. Firing of the staple  248  may be achieved utilizing a housing with a ratcheted trigger, as with other embodiments of the invention. 
     As shown in  FIG. 14 , the staple housing  214  may include an exterior casing  300  having a staple exit area  258  at its distal end  230  ( FIG. 15 ). A pusher  220  may extend the full length of the exterior casing  300 , from stapler to the staple exit area  258 . As shown in  FIG. 15 , the pusher  220  includes a tapered section  302  adjacent the staple exit area  258 . The tapered section  302  includes an inclined surface  304 . Adjacent the inclined surface  304  is an actuator  306 . The actuator  306  includes an inclined surface  308  adjacent the inclined surface  304  of the tapered section  302 . 
     Referring back to  FIG. 14 , there is shown a staple détente  310  shown within the exterior casing  300 . Although not shown in the figures, the stapler détente  310  is connected at one end to the exterior housing  300  by a rotatable connection, such as a hinge  312  mounted to the housing or to protruding portions of the housing. Two such protruding portions may also support a rod about which the détente  310  may be rotated and to which the détente  310  may be connected. The rod may span the protruding portions or may be connected to them at internal intervals of the rod. 
     The second end  314  of the staple détente  310  may extend toward the staple exit area  258 , to divide the staple exit area into a first staple exit area  258 A and a second staple exit area  258 B, as shown in  FIG. 15 . A spring  313  may be mounted between the exterior casing  300  and the staple détente  310  such that the détente is biased into the position shown in  FIG. 14 , where the spring is shown in its fully extended position. As will be discussed, the détente  310  may be rotated from this position upon application of a compressive force upon the spring  313 . 
     As with the first embodiment, a guide wire channel  244  is also located within the staple housing  214 . The guide wire channel  244  permits the use of a guide wire  212  in an “over the wire” system, to properly place the staple exit area  258 . 
       FIG. 14  also depicts a portion of a noncompliant balloon  256 . The noncompliant balloon  256  of the second embodiment may be completely exterior of the staple housing  214 . The noncompliant balloon  256  is intended to be inflated such that the staple housing  214  will be pushed against the stent graft  264  such that the stent graft may be firmly apposed against the aortic wall  260 . 
     Also included within the staple housing  214  is an elongated W-shaped staple  248 . As shown in  FIG. 15 , the staple  248  includes two U-shaped sections  316  connected by a bridge  318 . Each of the U-shaped sections  316  of the staple  248  sits against the front surface  320  of the actuator  306 . At the extreme ends of the staple  248 , the front surface  320  extends out to form flanges  324  which act to capture the staple and secure it in place. In addition, the front surface  320  of the actuator is curved, as shown in  FIG. 14 , to assist with securing the staple  248  in place. 
     As the trigger of the stapler is actuated, the ratcheted stapler pusher  220  is advanced toward the distal end  230  of the staple housing  214 . As shown in  FIG. 16 , advancement of the pusher  220  toward the distal end  230  of the staple housing  214  causes the inclined surface  304  of the pusher to contact the inclined surface  308  of the actuator  306 . As the pusher  220  is advanced, the front surface  320  of the actuator  306  will be pushed perpendicularly toward the staple exit area  258  due to the interaction between the inclined surfaces  304 ,  308 . Advancement of the actuator  306  will push the bridge  318  of the staple  248  against the second end  314  of the staple détente  310 , as shown in  FIGS. 16 and 17 . This advancement causes portions of the U-shaped sections  316  of the staple  248  to flatten along the axis of the bridge  318  and front surface  320  of the actuator  306 . Other portions of the U-shaped sections  316  extend from within the staple housing  214  such that the pointed ends  251  of the staple may penetrate the endograft  264  and the aortic wall  260 . 
     Referring briefly to  FIG. 20 , the pusher  220 , in accordance with the second embodiment of the present invention, is shown with an elevated portion  324  on its side  326 . The elevated portion  324  includes a transition area  328  ramping down toward the flat surface of the side  326  of the pusher  220 . As the pusher  220  is displaced, the elevated portion  324  moves toward the middle portion  313  of the staple détente  310 . Once the transition area  328  comes in contact with the middle portion  313  of the staple détente  310 , the staple détente will be rotated about its first end  311  at hinge  312  to compress the spring  313  such that its second end  314  is no longer in contact with the staple  248 . 
       FIG. 19  depicts a cross-sectional view of a portion of the staple housing  214  of an endovascular stapler where the pusher  220  has been advanced such that the elevated portion  324  is in contact with the staple détente  310 . It will be appreciated that advance of the pusher  220  and deflection of the staple détente  310  is conducted against the biasing force of the spring  313 . 
       FIG. 18  depicts a pusher  220  in its fully advanced position such that the staple détente  310  is no longer in contact with the staple  248 . As shown in  FIG. 18 , it will be appreciated that prior to the staple détente  310  being rotated away from the staple  248 , the U-shaped sections  316  of the staple  248  will have curved around such that the pointed ends  251  of the staple extend back into the aortic wall  260 , and the bridge  318  is extended to include portions of the U-shaped sections, thus forming a closed staple. 
     The endovascular stapler disclosed with respect to the second embodiment of the present invention is intended to fire a single staple  248 . As disclosed, if a subsequent staple  248  was required, the entire staple housing  214 , possibly including the noncompliant balloon  256 , would be removed from within the body so a second staple may be loaded. Once loaded, the staple housing  214  and, if necessary, the noncompliant balloon  256  may then be reinserted into the body such that a second staple  248  may be fired. This procedure may be repeated as necessary to arrest the migration of the endovascular graft or fully affix a new graft. Rather than reloading the endovascular stapler, a surgeon may choose to be provided with a plurality of endovascular staplers such that each may be utilized in succession without having to be reloaded. It will be appreciated that provision of numerous endovascular staplers saves time in the operating arena, where the duration of an operation is preferably minimized. 
     In a further embodiment, depicted in  FIG. 21 , a housing  330  may be disposed between the staple housing  214  and the noncompliant balloon  256 . Such a housing  330  permits withdrawal of the staple housing  214 , while leaving a cavity within the housing  330  wherein the staple housing may be returned after being reloaded with a subsequent staple (or where the housing of the second or subsequent stapler, may be inserted). The noncompliant balloon  256  may then be partially deflated to permit the staple exit area  258  to be rotated to a subsequent position for the firing of a subsequent staple  248 . In this regard, additional staples  248  beyond the initial staple may be inserted in a relatively quick manner, as compared to other embodiments where the noncompliant balloon  258  may be removed and reinserted. 
     In further embodiments, additional staples may be mounted on a cartridge within the staple housing  214  to permit the automatic reloading of the device with additional staples. If so provided, a mechanism is included within the housing of the stapler to override the ratcheting function of the stapler trigger, such that the pusher may be retracted to the position shown in  FIG. 15  from the position shown in  FIG. 18 . Once retracted into the position shown in  FIG. 15 , it is anticipated that a spring loaded stapler feed mechanism may re-load the actuator with an additional staple automatically. Preferably, the automatic loading device would be capable of feeding up to seven staples, such that a total of eight staples may be fired without removal of the staple housing. It will be appreciated that eight staples are generally sufficient to connect the graft to a vessel. Of course, a loading device capable of supplying a greater number of staples may also be provided. 
     In further embodiments, multiple staples may be fired simultaneously from a single staple housing  214 . In such embodiments, the staple housing  214  may include multiple staples  316  arranged radially about a centerline of the staple housing. The staples  316  may also be side-by-side in a linear relationship. Each of the staples  316  may be deployed simultaneously through interaction of the pusher  220  and the actuator  306 . In such embodiments, the staple housing  214  preferably includes a staple détente  310  for each staple to be deployed. For example, in one embodiment employing two staples  316 , a staple détente  310  may be mounted on each side of the pusher  220  by separate hinges  312 . Each of the détentes  310  may be on opposite sides of the pusher  220 , such that they can freely rotate without interfering with each other. 
     In addition to utilizing a balloon, such as the noncompliant balloon, to abut the staple exit area of the staple housing against the vessel wall or graft, other means may be employed. For example, as shown in  FIGS. 22   a  and  22   b , a simple triangular shaped apparatus  400  may be utilized. The apparatus  400  may comprise two elongate rods  402 ,  404 . The first end  406  of the first rod  402  may be pivotally attached to the distal end  130  of the staple housing  114  by a pin  408 . The second end  410  of the first rod  402  may be pivotally attached to the first end  412  of the second rod  404  by a pin  414 . Finally, the second end  416  of the second rod  404  may be slideingly engaged to the staple housing  114  This sliding engagement may be achieved by utilizing a pin  420  slideable within a groove  422  created in the staple housing. A handle  418  may extend the length of the staple housing  114  to the housing  102  of the stapler  100 . 
     Typically, if the rods  402 ,  404  are parallel to the longitudinal axis of the staple housing, such as shown in  FIG. 22   b , they will be adjacent to the staple housing  114 , tight against its exterior wall. If the handle  418  is pushed forward toward the distal end  130  of the stapler  100 , it will be appreciated that the pivot point between the first rod  402  and the second rod  404 , located at pin  414 , will be forced to extend from the exterior wall of the staple housing  114 , as shown in  FIG. 22   a . If that pivot point  414  contacts the inner wall of a vessel, it will force the opposite side of the staple housing to move away from the portion of the inner wall contacting the pivot portion. Thus, the apparatus may be mounted opposite the staple exit  158  area to appose the staple exit area against the vessel wall in a predetermined area. Of course, multiple such triangular apparatuses, or parallelograms of greater than three sides comprising additional components, may also be utilized. In certain applications this type of displacement device may be preferred as it will not completely block or occlude the vessel, such that blood flow may continue. 
     In addition, although not shown, it will be appreciated that in other embodiments, the handle  418  may be positioned within a channel extending through the interior of the staple housing, similar to the balloon inflation channel previously discussed. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. 
     In this regard, elements such as the trigger have been described in a particular manner. It is to be understood that the trigger mechanism and others like it, may be manufactured differently. For example, in lieu of a trigger, a simple dial advancement mechanism may be utilized to displace the pusher within the stapler cavity. If so provided, the gear ratio of the dial may be designed such that a given number of turns of the dial will advance the staple pusher a distance coordinated with the length of a single staple.