The present invention relates generally to devices and methods for surgically performing an end-to-side anastomosis of hollow organs.  More particularly, it relates to vascular anastomosis devices for joining the end of a graft vessel, such as a coronary bypass graft, to the side wall of a target vessel, such as the aorta or a coronary artery. 
Anastomosis is the surgical joining of biological tissues, especially the joining of tubular organs to create an intercommunication between them.  Vascular surgery often involves creating an anastomosis between blood vessels or between a blood vessel and a vascular graft to create or restore a blood flow path to essential tissues.  Coronary artery bypass graft surgery (CABG) is a surgical procedure to restore blood flow to ischemic heart muscle whose blood supply has been compromised by occlusion or stenosis of one or more of the coronary arteries.  One method for performing CABG surgery involves harvesting a saphenous vein or other venous or arterial conduit from elsewhere in the body, or using an artificial conduit, such as one made of Dacron or Goretex tubing, and connecting this conduit as a bypass graft from a viable artery, such as the aorta, to the coronary artery downstream of the blockage or narrowing.  A graft with both the proximal and distal ends of the graft detached is known as a xe2x80x9cfree graftxe2x80x9d.  A second method involves rerouting a less essential artery, such as the internal mammary artery, from its native location so that it may be connected to the coronary artery downstream of the blockage.  The proximal end of the graft vessel remains attached in its native position.  This type of graft is known as a xe2x80x9cpedicled graftxe2x80x9d.  In the first case, the bypass graft must be attached to the native arteries by an end-to-side anastomosis at both the proximal and distal ends of the graft.  In the second technique at least one end-to-side anastomosis must be made at the distal end of the artery used for the bypass.  In the description below we will refer to the anastomoses on a free graft as the proximal anastomosis and the distal anastomosis.  A proximal anastomosis is an anastomosis on the end of the graft vessel connected to a source of blood (e.g. the aorta) and a distal anastomosis is an anastomosis on the end of the graft vessel connected to the destination of the blood flowing through it (e.g. a coronary artery).  The anastomoses will also sometimes be called the first anastomosis or second anastomosis, which refers to the order in which the anastomoses are performed regardless of whether the anastomosis is on the proximal or distal end of the graft. 
At present, essentially all vascular anastomoses are performed by conventional hand suturing.  Suturing the anastomoses is a time-consuming and difficult task, requiring much skill and practice on the part of the surgeon.  It is important that each anastomosis provide a smooth, open flow path for the blood and that the attachment be completely free of leaks.  A completely leak-free seal is not always achieved on the very first try.  Consequently, there is a frequent need for resuturing of the anastomosis to close any leaks that are detected. 
The time consuming nature of hand sutured anastomoses is of special concern in CABG surgery for several reasons.  Firstly, the patient is required to be supported on cardiopulmonary bypass (CPB) for most of the surgical procedure, the heart must be isolated from the systemic circulation (i.e. xe2x80x9ccross-clampedxe2x80x9d), and the heart must usually be stopped, typically by infusion of cold cardioplegia solution, so that the anastomosis site on the heart is still and blood-free during the suturing of the anastomosis.  CPB, circulatory isolation and cardiac arrest are inherently very traumatic, and it has been found that the frequency of certain post-surgical complications varies directly with the duration for which the heart is under cardioplegic arrest (frequently referred to as the xe2x80x9ccrossclamp timexe2x80x9d).  Secondly, because of the high cost of cardiac operating room time, any prolongation of the surgical procedure can significantly increase the cost of the bypass operation to the hospital and to the patient.  Thus, it is desirable to reduce the duration of the crossclamp time and of the entire surgery by expediting the anastomosis procedure without reducing the quality or effectiveness of the anastomoses. 
The already high degree of manual skill required for conventional manually sutured anastomoses is even more elevated for closed-chest or port-access thoracoscopic bypass surgery a newly developed surgical procedure designed to reduce the morbidity of CABG surgery as compared to the standard open-chest CABG procedure.  This procedure is more fully described in commonly-assigned.  U.S. Pat.  No.  5,452,733, issued Sep. 26, 1995 and U.S. Pat.  No.  5,735,290, issued Apr. 7, 1998, the complete disclosures of which are hereby incorporated by reference.  In the closed-chest procedure, surgical access to the heart is made through narrow access ports made in the intercostal spaces of the patient""s chest, and the procedure is performed under thoracoscopic observation.  Because the patient""s chest is not opened, the suturing of the anastomoses must be performed at some distance, using elongated instruments positioned through the access ports for approximating the tissues and for holding and manipulating the needles and sutures used to make the anastomoses.  This requires even greater manual skill than the already difficult procedure of suturing anastomoses during open-chest CABG surgery. 
In order to reduce the difficulty of creating the vascular anastomoses during either open or closed-chest CABG surgery, it would be desirable to provide a rapid means for making a reliable end-to-side anastomosis between a bypass graft or artery and the aorta or the native vessels of the heart.  A first approach to expediting and improving anastomosis procedures has been through stapling technology.  Stapling technology has been successfully employed in many different areas of surgery for making tissue attachments faster and more reliably.  The greatest progress in stapling technology has been in the area of gastrointestinal surgery.  Various surgical stapling instruments have been developed for end-to-end, side-to-side, and end-to-side anastomoses of hollow or tubular organs, such as the bowel.  These instruments, unfortunately, are not easily adaptable for use in creating vascular anastomoses.  This is partially due to the difficulty in miniaturizing the instruments to make them suitable for smaller organs such as blood vessels.  Possibly even more important is the necessity of providing a smooth, open flow path for the blood.  Known gastrointestinal stapling instruments for end-to-side or end-to-end anastomosis of tubular organs are designed to create an inverted anastomosis, that is, one where the tissue folds inward into the lumen of the organ that is being attached.  This is acceptable in gastrointestinal surgery, where it is most important to approximate the outer layers of the intestinal tract (the serosa).  This is the tissue which grows together to form a strong, permanent connection.  However, in vascular surgery this geometry is unacceptable for several reasons.  Firstly, the inverted vessel walls would cause a disruption in the blood flow.  This could cause decreased flow and ischemia downstream of the disruption, or, worse yet, the flow disruption or eddies created could become a locus for thrombosis which could shed emboli or occlude the vessel at the anastomosis site.  Secondly, unlike the intestinal tract, the outer surfaces of the blood vessels (the adventitia) will not grow together when approximated.  The sutures, staples, or other joining device may therefore be needed permanently to maintain the structural integrity of the vascular anastomosis.  Thirdly, to establish a permanent, nonthrombogenic vessel, the innermost layer (the endothelium) should grow together for a continuous, uninterrupted lining of the entire vessel.  Thus, it would be preferable to have a stapling instrument that would create vascular anastomoses that are everted, that is folded outward, or which create direct edge-to-edge coaptation without inversion. 
At least one stapling instrument has been applied to performing vascular anastomoses during CABG surgery.  This device, first adapted for use in CABG surgery by Dr. Vasilii I. Kolesov and later refined by Dr. Evgenii V. Kolesov (U.S. Pat.  No.  4,350,160), was used to create an end-to-end anastomosis between the internal mammary artery (IMA) or a vein graft and one of the coronary arteries, primarily the left anterior descending coronary artery (LAD).  Because the device could only perform end-to-end anastomoses, the coronary artery first had to be severed and dissected from the surrounding myocardium, and the exposed end everted for attachment.  This technique limited the indications of the device to cases where the coronary artery was totally occluded, and therefore there was no loss of blood flow by completely severing the coronary artery downstream of the blockage to make the anastomosis.  Consequently, this device is not applicable where the coronary artery is only partially occluded and is not at all applicable to making the proximal side-to-end anastomosis between a bypass graft and the aorta. 
One attempt to provide a vascular stapling device for end-to-side vascular anastomoses is described in U.S. Pat.  No.  5,234,447, granted to Kaster et al, for a Side-to-end Vascular Anastomotic Staple Apparatus.  Kaster et al.  provide a ring-shaped staple with staple legs extending from the proximal and distal ends of the ring to join two blood vessels together in an end-to-side anastomosis.  However, this device falls short of fulfilling the desired objectives of the present invention.  Specifically, Kaster does not provide a complete system for quickly and automatically performing an anastomosis.  The method of applying the anastomosis staple disclosed by Kaster involves a great deal of manual manipulation of the staple, using hand operated tools to individually deform the distal tines of the staple after the graft has been attached and before it is inserted into the opening made in the aortic wall.  One of the more difficult maneuvers in applying the Kaster staple involves carefully everting the graft vessel over the sharpened ends of the staple legs, then piercing the everted edge of the vessel with the staple legs.  Experimental attempts to apply this technique have proven to be very problematic because of difficulty in manipulating the graft vessel and the potential for damage to the graft vessel wall.  For speed, reliability and convenience, it is preferable to avoid the need for complex maneuvers while performing the anastomosis.  Further bending operations must then be performed on the staple legs.  Once the distal tines of the staple have been deformed, it may be difficult to insert the staple through the aortotomy opening.  Another disadvantage of the Kaster device is that the distal tines of the staple pierce the wall of the graft vessel at the point where it is everted over the staple.  Piercing the wall of the graft vessel potentially invites leaking of the anastomosis and may compromise the structural integrity of the graft vessel wall, serving as a locus for a dissection or even a tear which could lead to catastrophic failure.  Because the Kaster staple legs only apply pressure to the anastomosis at selected points, there is a potential for leaks between the staple legs.  The distal tines of the staple are also exposed to the blood flow path at the anastomotic site where it is most critical to avoid the potential for thrombosis.  There is also the potential that exposure of the medial layers of the graft vessel where the staple pierces the wall could be a site for the onset of intimal hyperplasia, which would compromise the long-term patency of the graft.  Because of these potential drawbacks, it is desirable to make the attachment to the graft vessel as atraumatic to the vessel wall as possible and to eliminate as much as possible the exposure of any foreign materials or any vessel layers other than a smooth uninterrupted intimal layer within the anastomosis site or within the graft vessel lumen. 
A second approach to expediting and improving anastomosis procedures is through the use of anastomotic fittings for joining blood vessels together.  One attempt to provide a vascular anastomotic fitting device for end-to-side vascular anastomoses is described in U.S. Pat.  No.  4,366,819, granted to Kaster for an Anastomotic Fitting.  This device is a four-part anastomotic fitting having a tubular member over which the graft vessel is everted, a ring flange which engages the aortic wall from within the aortic lumen, and a fixation ring and a locking ring which engage the exterior of the aortic wall.  Another similar Anastomotic Fitting is described in U.S. Pat.  No.  4,368,736, also granted to Kaster.  This device is a tubular fitting with a flanged distal end that fastens to the aortic wall with an attachment ring, and a proximal end with a graft fixation collar for attaching to the graft vessel.  These devices have a number of drawbacks that the present invention seeks to overcome.  Firstly, the anastomotic fittings described expose the foreign material of the anastomotic device to the blood flow path within the arteries.  This is undesirable because foreign materials within the blood flow path can have a tendency to cause hemolysis, platelet deposition and thrombosis.  Immune responses to foreign material, such as rejection of the foreign material or auto-immune responses triggered by the presence of foreign material, tend to be stronger when the material is exposed to the bloodstream.  As such, it is preferable that as much as possible of the interior surfaces of an anastomotic fitting that will be exposed to the blood flow path be covered with vascular tissue, either from the target vessel or from the graft vessel, so that a smooth, continuous, hemocompatible endothelial layer will be presented to the bloodstream.  The anastomotic fitting described by Kaster in the ""819 patent also has the potential drawback that the spikes that hold the draft vessel onto the anastomotic fitting are very close to the blood flow path, potentially causing trauma to the blood vessel that could lead to leaks in the anastomosis or compromise of the mechanical integrity of the vessels.  Consequently, it is desirable to provide an anastomosis fitting that is as atraumatic to the graft vessel as possible.  Any sharp features such as attachment spikes should be placed as far away from the blood flow path and the anastomosis site as possible so that there is no compromise of the anastomosis seal or the structural integrity of the vessels. 
Another device, the 3M-Unilink device for end-to-end anastomosis (U.S. Pat.  Nos.  4,624,257; 4,917,090; 4,917,091) is designed for use in microsurgery, such as for reattaching vessels severed in accidents.  This device provides an anastomosis clamp that has two eversion rings which are locked together by a series of impaling spikes on their opposing faces.  However, this device is awkward for use in end-to-side anastomosis and tends to deform the target vessel; therefore it is not currently used in CABG surgery.  Due to the delicate process needed to insert the vessels into the device, it would also be unsuitable for port-access surgery. 
In order to solve these and other problems, it is desirable to provide an anastomosis device which performs an end-to-side anastomosis between blood vessels or other hollow organs and vessels.  It is also desirable to provide an anastomosis device which minimizes the trauma to the blood vessels while performing the anastomosis, which minimizes the amount of foreign materials exposed to the blood flow path within the blood vessels and which avoids leakage problems, and which promotes rapid endothelialization and healing.  Further, it would be desirable to provide such a device which could be used in port-access CABG surgery.  Whether it is used with open-chest or closed-chest surgical techniques, it is also desirable that the invention provide a complete system for quickly and automatically performing an anastomosis with a minimal amount of manual manipulation. 
In keeping with the foregoing discussion, the present invention provides an anastomosis system for quickly and reliably performing an end-to-side vascular anastomosis.  The anastomosis system includes an anastomosis device, an application instrument and methods for their use in performing an end-to-side vascular anastomosis.  The system is especially useful for performing an anastomosis between a vascular graft and the wall of the ascending aorta in CABG surgery, particularly in port-access CABG surgery.  One desirable attribute of the anastomosis system is that the system should be as atraumatic as possible to the graft vessel in creating the anastomosis.  Another desirable attribute of the anastomosis system is that the anastomosis device should minimize the amount of foreign material exposed to the blood flow path in the completed anastomosis.  The anastomosis device of the system has a generally tubular or ring-shaped body having a proximal end and a distal end.  An orifice or internal lumen in the body allows the graft vessel to pass through the device from the proximal end to the distal end.  The body of the device has an attachment means at the distal end for attachment to the graft vessel, generally by everting the graft vessel over the attachment means.  Means are provided for attaching the device and the graft vessel to the wall of the target vessel.  Different embodiments of the anastomosis device are presented which vary in the form of the means used for attaching to the graft vessel and the target vessel. 
A first aspect of the present invention takes the form of a vascular anastomosis staple device which may be used as part of an overall anastomosis stapling system and method designed to efficiently and reliably perform an end-to-side anastomosis between a graft vessel and the wall of a target vessel.  The anastomosis staple device forms an atraumatic attachment to the end of the graft vessel so that only a smooth uninterrupted layer of intimal cells is exposed at the anastomosis site or within the graft vessel lumen.  The anastomosis staple device creates a firm, reliable attachment between the graft vessel and the target vessel wall, with a tailored amount of tissue compression applied at the anastomosis site to form a leak-proof joint between the graft vessel and the target vessel wall.  The anastomosis stapling system is designed to combine the various functions of graft vessel preparation, target vessel preparation, vessel approximation and anastomosis stapling into an integrated system of instruments so that the anastomosis can be performed efficiently with a minimum of manual manipulation of the vessels or the instruments involved.  Different embodiments of the anastomosis stapling system are provided to meet the needs of performing either a first anastomosis or a second anastomosis of a bypass procedure.  The anastomosis stapling system is configured to be adaptable for closed-chest or port-access CABG surgery or for more conventional open-chest CABG surgery. 
In one preferred configuration of the invention, the anastomosis staple device consists of two parts: an anchor member and a coupling member.  The anchor member forms the attachment with the target vessel wall.  The coupling member separately forms the attachment with the bypass graft vessel.  The complete anastomosis is created when the coupling member, with the graft vessel attached, is inserted into the anchor member.  In a second preferred configuration of the invention, the anastomosis staple device combines the functions of the anchor member and the coupling member into a single member.  A one-piece anastomosis staple device attaches to both the target vessel wall and the graft vessel to form a complete end-to-side anastomosis.  In all embodiments of the anastomosis staple device, certain desirable aspects are maintained, specifically the atraumatic attachment of the device to the graft vessel and the rapid, reliable formation of the anastomosis as well as the adaptability of the staple device to port-access CABG surgery. 
A second aspect of the present invention takes the form of an anastomotic fitting for attaching the end of a graft vessel to an opening formed in the side wall of a target vessel.  The anastomotic fitting has an inner flange which provides an atraumatic attachment for the everted end of a graft vessel.  The inner flange is configured so that, wherever possible, a smooth, continuous, uninterrupted layer of intimal tissue lines the graft vessel, the target vessel and the anastomotic site, with as little foreign material as possible exposed to the blood flow path.  The outer flange contacts the exterior surface of the target vessel.  A locking means, which may be part of the outer flange, locks the outer flange in a fixed position relative to the inner flange.  The inner flange, in combination with the outer flange, provides a firm attachment to the target vessel wall.  A tailored amount of compression applied by the inner and outer flanges rips the target vessel wall and creates a leak-proof seal between the graft vessel and the target vessel.  Optionally, attachment spikes on the surfaces of either the inner or the outer flange provide additional grip on the graft vessel and/or the target vessel.  The attachment spikes are isolated from the blood flow lumens of the graft vessel and the target vessel so that they do not compromise the anastomotic seal or the structural integrity of the anastomotic attachment. 
In a first representative embodiment, the anastomotic fitting is made up of two coacting parts: a) a tubular inner sleeve, which has an internal lumen of sufficient size to accommodate the external diameter of the graft vessel and an inner flange which is attached at the distal end of the inner sleeve, and b) an outer flange which has a central orifice that is sized to fit over the exterior of the inner sleeve.  An adjustable locking mechanism holds the outer flange on the inner sleeve at a selected position to create a tailored degree of tissue compression at the anastomotic site. 
The anastomosis procedure is performed by passing the end of the graft vessel through the inner lumen of the inner sleeve until the end of the vessel extends a short distance from the distal end of the sleeve.  The end of the graft vessel is then everted over the inner flange of the fitting to form an atraumatic attachment.  A loop of suture or spikes on the outside of the inner sleeve or flange may be added to help retain the graft vessel in its everted position.  The inner flange and the everted end of the graft vessel are then passed through an opening that has previously been made in the wall of the target vessel with an instrument such as an aortic punch.  The opening must stretch slightly to allow the inner flange to pass through.  The elastic recovery of the target vessel wall around the opening helps to create an anastomotic seal by contracting around the inner sleeve and the everted graft vessel wall.  The outer flange is then slid onto the proximal end of the inner sleeve.  If the anastomosis being performed is the first anastomosis on a free graft, such as a saphenous vein graft, then the outer flange can be slid over the graft vessel from the free end.  If the other end of the graft vessel is not free, such as when performing the second anastomosis of a free graft or a distal anastomosis on a pedicled graft like the IMA, then the outer flange should be back loaded onto the graft vessel or preloaded onto the proximal end of the inner sleeve before the end of the graft vessel is attached to the inner flange of the fitting.  The outer flange is slid down the inner sleeve until it contacts the exterior wall of the target vessel.  A tailored amount of compression is applied to the anastomosis and the locking mechanism is engaged to complete the anastomosis. 
A second representative embodiment of the anastomotic fitting has an expanding inner flange which facilitates the atraumatic attachment of the graft vessel to the fitting and makes it easier to pass the inner flange and the everted graft vessel through the opening in the target vessel wall.  The graft vessel is passed through an internal lumen of an inner sleeve which has the expandable inner flange attached at its distal end.  The end of the graft vessel is everted over the unexpanded inner flange.  The inner flange and the everted end of the graft vessel are passed through the opening in the target vessel wall.  Once the inner flange of the fitting is in the lumen of the target vessel, it is expanded to a diameter which is significantly larger than the opening in the target vessel wall.  Then an outer flange is applied and locked into a selected position on the inner sleeve as described above to complete the anastomosis. 
Different mechanisms are disclosed to accomplish the expansion of the inner flange.  In a first variant of the expanding inner flange, the flange and a portion of the inner sleeve are slotted to create multiple fingers which are initially collapsed inward toward the center of the sleeve.  A second inner sleeve is slidably received within the slotted inner sleeve.  The graft vessel is inserted through the internal lumen of both sleeves and everted over the collapsed fingers of the flange.  The collapsed flange is inserted through the opening in the target vessel.  Then, the second inner sleeve is slid distally within the slotted inner sleeve.  The second inner sleeve forces the fingers outward, expanding the flange within the target vessel.  The anastomosis is completed by applying the outer flange to the fitting as described above. 
A second variant of the expanding inner flange has a slotted inner sleeve with multiple fingers that are oriented essentially longitudinally to the inner sleeve.  Each of the fingers has a bend in it to predispose it to bend outward at the middle when under longitudinal compression.  A tubular forming tool slidably received within the slotted sleeve is crenellated with multiple radially extending tabs.  The radially extending tabs engage the distal ends of the fingers of the slotted inner sleeve.  The anastomosis is performed by passing the graft vessel through the internal lumen of the fitting and everting it over the finders.  If desired, a loop of suture can be used to hold the everted vessel in place.  The fingers of the fitting and the everted end of the graft vessel are inserted through an opening in the target vessel wall.  When the tubular forming tool is slid proximally with respect to the slotted inner sleeve, the radially extending tabs bear against the distal ends of the fingers, compressing them longitudinally.  The fingers bow outward, folding at the bend to expand and create an inner flange which engages the inner surface of the target vessel wall.  In a preferred embodiment of this variation, the slotted inner sleeve has a proximal collar which captures the outer flange of the fitting so that the outer flange is applied simultaneously with the expansion of the inner flange.  After the inner flange has been expanded, the tubular forming tool can be removed by rotating it with respect to the slotted inner sleeve so that the tabs align with the slots allowing it to be withdrawn from the fitting.  This reduces the mass of foreign material that is left as an implant at the anastomotic site. 
A third representative embodiment is a one-piece anastomotic fitting with an inner sleeve that is integrally attached to a fixed inner flange and to a deformable outer flange.  The anastomosis is performed by passing the graft vessel through the internal lumen of the inner sleeve and everting it over the inner flange.  The inner flange and the everted end of the graft vessel are inserted through an opening in the wall of the target vessel.  Then, the outer flange is deformed against the exterior surface of the target vessel wall with a tailored degree of tissue compression to complete the anastomosis.  Two variants of the deformable outer flange are disclosed.  The first variant has an outer flange that is divided into flange segments.  The flange segments are attached to the inner sleeve by deformable hinges.  The second variant has an outer flange in the form of a deformable hollow body.  The hollow body is deformed against the exterior surface of the target vessel to complete the anastomosis. 
The vascular anastomotic fitting is also part of a complete anastomosis system which includes instruments for applying the anastomosis fitting in a rapid, efficient and reliable manner to expedite the anastomosis process and to reduce the amount of manual manipulation necessary to perform the anastomosis.  The application instrument has an elongated body with means at the distal end for grasping the anastomosis fitting and inserting the fitting into the chest cavity of a patient through an access port.  The instrument includes an actuating means for deploying the inner and/or outer flange of the fitting to create the anastomosis.  Variants of the instrument are specially adapted for each different embodiment and subvariation of the anastomosis fitting. 
A third approach to expediting and improving anastomosis procedures used by the present invention combines the advantages of surgical stapling technology with other advantages of anastomotic fittings.  Surgical stapling technology has the potential to improve anastomosis procedures over hand suturing techniques by decreasing the difficulty and complexity of the manipulations necessary and by increasing the speed and reliability of creating the anastomosis.  The Kaster vascular staple in U.S. Pat.  No.  5,234,447 overcomes one of the major limitations of the previous Kolesoy stapling device by allowing a stapled end-to-side anastomosis.  This device, however, requires many delicate manual manipulations of the graft vessel and the staple while performing the anastomosis.  This device therefore does not take full advantage of the time saving potential usually associated with stapling techniques. 
The present invention attempts to marry the advantages of stapling approaches and anastomotic fitting approaches while carefully avoiding their potential drawbacks.  As such, the present invention takes full advantage of the speed and reliability of stapling techniques, avoiding inasmuch as possible the need for complex manual manipulations.  The invention also profits from the advantages of anastomotic fittings by providing a ring or flange that exerts even pressure around the anastomotic interface to eliminate potential leaks between the stapled attachments.  The ring or flange also serves as a stent or support for the anastomosis site to prevent acute or long-term closure of the anastomosis.  Inasmuch as possible the bulk of the fitting is kept on the exterior of the anastomosis so as to eliminate exposed foreign material in the bloodstream of the graft vessel or the target vessel.  In most cases, only the narrow staple legs penetrate the anastomosis site, so that an absolute minimum of foreign material is exposed to the blood flow path, on the same order as the mass of suture exposed in a standard sutured anastomosis.  The attachment technique for the anastomosis device eliminates the need to evert the graft vessel over a complex, irregular or sharp object such as the sharpened ends of the staple legs.  Instead, a smooth ring or flange surface is provided for everting the graft vessel without damage or undue complication.  The staple legs are separate or recessed within the flange to avoid potential damage to the graft vessel while attaching it to the device. 
In a third aspect, the present invention takes the form of an anastomosis device which has a ring or flange to which the graft vessel attaches, typically by everting the graft vessel over the distal end of the ring.  The ring or flange resides on the exterior of the graft vessel so that it does not contact the blood flow path.  A plurality of staple-like members attach the ring and the everted end of the graft vessel to the wall of the target vessel, which may be the aorta, a coronary artery or other vessel.  An opening is created in the target vessel wall with an aortic punch or similar instrument to allow the target vessel lumen to communicate with the graft vessel lumen.  The opening in the target vessel wall can be made before or after the device has been attached, depending on the application technique employed.  In most of the examples disclosed, the staple members pierce the everted wall of the graft vessel and the wall of the target vessel to hold the two vessels together.  Alternatively, the staple members may enter the lumen of the target vessel through the opening in the wall and then pierce the wall of the target vessel in the reverse direction.  This variation pins together the vascular layers in the target vessel at the cut edge, potentially reducing the incidence of hemodynamically generated dissections in the wall of the target vessel. 
Various configurations of the invention are disclosed which all exhibit the unifying characteristics of a cooperating ring or flange and a plurality of staple members.  A first exemplary embodiment includes a ring-like fastening flange with deformable staple members for attaching the flange.  A specially adapted staple applying device which operates through the lumen of the graft vessel is used to deform the staples to complete the anastomosis.  A second embodiment includes a ring-like fastening flange with preformed, spring-like staple members.  The elastic memory of the spring-like staple members holds the anastomosis tightly together.  A family of embodiments includes a tubular fastening flange with U-shaped staple members and a locking means for fastening the staple members to complete the anastomosis.  Another family of embodiments includes one or more ring-shaped fastening flanges with integrally formed staple members.  Another family of embodiments includes a ring-like fastening flange with self-deploying staple members made of a superelastic metal alloy or a thermally activated shape-memory alloy.  A specially adapted staple applying device deploys the superelastic staple members.  The specially adapted staple applying device together with the anastomosis device itself forms a total anastomosis system that is adaptable for either conventional open-chest CABG surgery or port-access CABG surgery. 
Catheter devices are described which can be used as part of the total anastomosis system for isolating a portion of the target artery to facilitate performing the anastomosis procedure.  One catheter device is configured to isolate a portion of the ascending aorta wall without occluding blood flow through the lumen of the aorta.  A second catheter device is configured to be delivered by a transluminal approach for isolating a portion of a coronary artery during the anastomosis procedure.  A third catheter device is configured to be delivered through the lumen of the graft vessel for isolating a portion of a coronary artery during the anastomosis procedure.