Method and system for attaching a graft to a blood vessel

Anastomotic stents for connecting a graft vessel to a target vessel, and methods of use thereof. The anastomotic stents of the invention are suitable for use in a variety of anastomosis procedures, including coronary artery bypass grafting. One embodiment of the invention comprises a large vessel anastomotic stent for use with large diameter target vessels such as the aorta or its major side branches. Another embodiment of the invention comprises a small vessel anastomotic stent for use on a target vessel which has a small diameter such as a coronary artery. Another aspect of the invention involves applicators for use with the stents of the invention.

BACKGROUND OF THE INVENTION
 This invention generally relates to devices and methods for performing a
 vascular anastomosis, and more particularly to stents for securing a graft
 vessel to a target vessel.
 Vascular anastomoses, in which two vessels within a patient are surgically
 joined together to form a continuous channel, are required for a variety
 of conditions including coronary artery disease, diseases of the great and
 peripheral vessels, organ transplantation, and trauma. For example, in
 coronary artery disease (CAD), an occlusion or stenosis in a coronary
 artery interferes with blood flow to the heart muscle. In order to restore
 adequate blood flow to the heart, a graft vessel in the form of a
 prosthesis or harvested artery or vein is used to reroute blood flow
 around the occlusion. The treatment, known as coronary artery bypass
 grafting (CABG), can be highly traumatic to the patient's system.
 In conventional CABG a large incision is made in the chest and the sternum
 is sawed in half to allow access to the heart. In addition,
 cardiopulmonary bypass, in which the patient's blood is circulated outside
 of the body through a heart-lung machine, is used so that the heart can be
 stopped and the anastomosis performed. In order to minimize the trauma to
 the patient's system induced by conventional CABG, less invasive
 techniques have been developed in which the surgery is performed through
 small incisions in the patient's chest with the aid of visualizing scopes.
 Less invasive CABG can be performed on a beating or a non-beating heart
 and thus may avoid the need for cardiopulmonary bypass.
 In both conventional and less invasive CABG, the surgeon has to suture the
 graft vessel in place between the coronary artery and a blood supplying
 vein or artery. The suturing procedure is a time consuming, difficult
 process requiring a high level of surgical skill. In order to perform the
 suturing procedure, the surgeon must have relatively unobstructed access
 to the anastomotic site within the patient. As a result, in less invasive
 approaches which provide only limited access to the patient's vessels,
 some of the major coronary vessels cannot be reached adequately, which can
 result in incomplete revascularization and a resulting negative effect on
 patient survival. Moreover, certain target vessels, such as heavily
 calcified coronary vessels, vessels having a very small diameter of less
 than about 1 mm, and previously bypassed vessels, may make the suturing
 process difficult or impossible, so that a sutured anastomosis is not
 possible.
 Additionally, a common problem with CABG has been the formation of thrombi
 and atherosclerotic lesions at and around the grafted artery, which can
 result in the reoccurrence of ischemia. Moreover, second operations
 necessitated by the reoccurrence of arterial occlusions are technically
 more difficult and risky due to the presence of the initial bypass. For
 example, surgeons have found it difficult to saw the sternum in half
 during the next operation without damaging the graft vessels from the
 first bypass which are positioned behind the sternum.
 Therefore, it would be a significant advance to provide a sutureless
 vascular anastomosis in which the graft vessels can be positioned on a
 variety of locations on target vessels having a variety of different
 diameters, which is easily performed, and which minimizes thrombosis
 associated with the anastomosis. The present invention satisfies these and
 other needs.
 SUMMARY OF THE INVENTION
 The invention is directed to anastomotic stents for connecting a graft
 vessel to a target vessel, and methods of use thereof. The anastomotic
 stents of the invention are suitable for use in a variety of anastomosis
 procedures, including coronary artery bypass grafting. The term "target
 vessel" refers to vessels within the patient which are connected to either
 or both of the upstream and the downstream end of the graft vessel. One
 embodiment of the invention comprises a large vessel anastomotic stent for
 use with large diameter target vessels such as the aorta or its major side
 branches. Another embodiment of the invention comprises a small vessel
 anastomotic stent for use on a target vessel which has a small diameter
 such as a coronary artery. Another aspect of the invention involves
 applicators for use with the stents of the invention. The terms "distal"
 and "proximal" as used herein refer to positions on the stents or
 applicators relative to the physician. Thus, the distal end of the stent
 is further from the physician than is the stent proximal end. The proximal
 end of an implanted stent is further from the center of the target vessel
 lumen than is the stent distal end.
 The large vessel anastomotic stents of the invention generally comprise a
 substantially cylindrical body having a longitudinal axis, an open
 proximal end, an open distal end, a lumen therein, and at least one
 deformable section which radially expands to form a flange. The stent,
 with one end of a graft vessel attached thereto, is inserted into an
 incision in a wall of the target vessel with the deformable section in a
 first configuration, and the deformable section is radially expanded to a
 second configuration to deploy the flange. The flange applies an axial
 force, substantially aligned with the stent longitudinal axis, against the
 wall of the target vessel. Additionally, the flange is configured to apply
 a radial force, substantially transverse to the stent longitudinal axis,
 against the wall of the target vessel, to secure the stent to the target
 vessel.
 In one embodiment of the large vessel stent, the stent has a single
 deformable section forming a flange, preferably on a distal section of the
 stent. However, a plurality of deformable sections may be provided on the
 stent. For example, in an alternative embodiment, the stent has a second
 deformable section on a proximal section of the stent. With the proximal
 and distal end flanges deployed, the stent is prevented from shifting
 proximally out of the target vessel or distally further into the interior
 of the target vessel.
 The large vessel stents of the invention are configured to connect to
 target vessels of various sizes having a wall thickness of at least about
 0.5 mm, and typically about 0.5 mm to about 5 mm. In one embodiment of the
 invention, the large vessel anastomotic stent is configured to
 longitudinally collapse as the deformable section is radially expanded.
 The surgeon can control the longitudinal collapse to thereby position the
 distal end flange at a desired location at least partially within the
 incision in the target vessel wall. Moreover, in the embodiment having a
 proximal end flange, the surgeon can control the position of the proximal
 end flange by longitudinally collapsing the stent to a greater or lesser
 degree, to thereby position the proximal end flange at a desired location
 in contact with the target vessel. Thus, regardless of the thickness of
 the target vessel wall, the stent can be longitudinally collapsed to
 position the flanges against the target vessel wall and effectively
 connect the stent thereto. This feature is significant because the stent
 must be connected to target vessels which have a wide range of wall
 thickness. For example, the aortic wall thickness is typically about 1.4
 mm to about 4.0 mm. Therefore, regardless of the thickness of the target
 vessel wall, the degree of deployment of the proximal end flange, and thus
 the longitudinal collapse of the stent, can be controlled by the physician
 to thereby effectively connect the stent to the target vessel. For
 example, the surgeon may choose between partially deploying the proximal
 end flange so that it is positioned against an outer surface of the target
 vessel wall, or fully deploying the flange to. position it in contact with
 the media of the target vessel wall within the incision in the target
 vessel wall.
 In a presently preferred embodiment, the graft vessel is attached to the
 stent before insertion into the patient by placing the graft vessel within
 the lumen of the stent, and everting the end of the graft vessel out the
 stent distal end and about at least the distal deformable section. In a
 presently preferred embodiment, the graft vessel is everted about at least
 the section which contacts the media of the target vessel wall proximal to
 the distal deformable section, to facilitate sealing at the anastomosis
 site.
 In a presently preferred embodiment of the invention, the deformable
 section on the large vessel stent comprises a plurality of helical members
 interconnected and disposed circumferentially around the stent. By
 rotating the distal end and the proximal end of the stent relative to one
 another, the helical members radially expand and the stent longitudinally
 collapses to form the flange. In a presently preferred embodiment, the
 distal flange is configured to deploy before the proximal end flange.
 Another aspect of the invention comprises the applicators designed for
 introducing and securing the large vessel anastomotic stents of the
 invention to the target vessel. One such applicator is configured to apply
 torque and axial compressive load to the large vessel stent, to thereby
 radially expand the deformable section which forms the flange. The
 applicator of the invention may be provided with a sharp distal end, to
 form an incision in the target vessel wall through which the stent is
 inserted or to otherwise facilitate insertion of the stent into the target
 vessel wall. Another embodiment of the applicator of the invention
 includes a catheter member having one or more inflatable members designed
 to expand the incision in the target vessel and introduce the large vessel
 stent therein.
 Another embodiment of the invention comprises small vessel anastomotic
 stents for use on small target vessels such as coronary arteries. The
 small vessel stents generally comprise an outer flange configured to be
 positioned adjacent an outer surface of the target vessel, and an inner
 flange configured to be positioned against an inner surface of the target
 vessel and connected to the outer flange. The outer and inner flanges
 generally comprise a body defining an opening, with one end of the graft
 vessel secured to the outer flange.
 The small vessel anastomotic stents of the invention are used on small
 target vessels having a wall thickness of less than about 1.0 mm, and
 typically about 0.1 mm to about 1 mm. For example, small target vessels
 include coronary arteries. Despite the small size of the target vessels,
 the small vessel stents of the invention provide sutureless connection
 without significantly occluding the small inner lumen of the target vessel
 or impeding the blood flow therethrough.
 In a presently preferred embodiment of the invention, the graft vessel is
 received into the opening in the outer flange and everted around the body
 of the outer flange to connect to the outer flange. In another embodiment,
 as for example when the graft vessel is a mammary artery, the graft vessel
 is connected to the outer flange by connecting members such as sutures,
 clips, hooks, and the like.
 The outer flange, with the graft vessel connected thereto, is loosely
 connected to the inner flange before insertion into the patient. The space
 between the loosely connected inner and outer flanges is at least as great
 as the wall thickness of the target vessel so that the inner flange can be
 inserted through an incision in the target vessel and into the target
 vessel lumen, with the outer flange outside the target vessel. With the
 outer and inner flanges in place on either side of a wall of the target
 vessel, tightening the flanges together compresses a surface of the graft
 vessel against the outer surface of the target vessel. This configuration
 forms a continuous channel between the graft vessel and the target vessel,
 without the need to suture the graft vessel to the target vessel wall and
 preferably without the use of hooks or barbs which puncture the target
 vessel.
 In one embodiment of the invention, the inner flange is introduced into the
 target vessel in a folded configuration and thereafter unfolded into an
 expanded configuration inside the target vessel. The folded configuration
 reduces the size of the inner flange so that the size of the incision in
 the target vessel wall can be minimized. Folding the flange minimizes
 trauma to the target vessel and restenosis, and facilitates sealing
 between the graft and target vessel at the anastomotic site.
 In a presently preferred embodiment of the invention, the inner and outer
 flanges are connected together by prongs on one member configured to
 extend through the body of the other member. However, the inner and outer
 flanges may be connected together by a variety of different types of
 connecting members such as sutures, hooks, clips, and the like. In a
 presently preferred embodiment, the flange members are connected together
 by prongs on the inner member configured to extend through the incision in
 the target vessel wall, without puncturing the wall of the target vessel,
 and through prong receiving openings in the body of the outer flange. The
 prong receiving openings in the outer flange may be configured to allow
 for the forward movement of the prong through the opening to bring the
 inner and outer flanges together, but prevent the backward movement of the
 prong out of the opening, so that the inner and outer flanges remain
 substantially compressed together to seal the anastomotic site.
 Another aspect of the invention comprises a small vessel stent applicator
 which facilitates introduction of the inner flange into the target vessel
 lumen, and connection of the inner flange to the outer flange around the
 target vessel. In one embodiment of the small vessel stent applicator, the
 applicator folds the inner flange into the folded configuration for
 introduction into the lumen of the target vessel.
 Anastomotic systems of the invention may comprise combinations of the large
 and small vessel stents of the invention, for connecting one or both ends
 of a graft vessel to target vessels. Typically, in a coronary bypass using
 the anastomotic system of the invention, a large vessel stent connects the
 proximal end of the graft vessel to the aorta, and a small vessel stent
 connects the distal end of the graft vessel to an occluded coronary
 artery. However, it will be apparent to one of ordinary skill in the art
 that various combinations and uses of the anastomotic stents of the
 invention may be used. For example, in patients with an extreme
 arteriosclerotic lesion in the aorta, which may result in serious
 complications during surgical procedures on the aorta, the anastomotic
 stents of the invention allow the surgeon to avoid this region and connect
 the proximal end of the graft vessel to any other adjacent less diseased
 vessel, such as the arteries leading to the arms or head.
 The large and small vessel stents of the invention are provided in a range
 of sizes for use on various sized graft vessels. Thus, the anastomotic
 stents of the invention can be used with venous grafts, such as a
 harvested saphenous vein graft, arterial grafts, such as a dissected
 mammary artery, or a synthetic prosthesis, as required.
 Connection of the large vessel stent does not require the stoppage of blood
 flow in the target vessel. Moreover, the anastomotic stents of the
 invention can be connected to the target vessel without the use of
 cardiopulmonary bypass. Additionally, the surgeon does not need
 significant room inside the patient to connect the anastomotic stents of
 the invention to the target vessel. For, example, unlike sutured
 anastomoses which require significant access to the aorta for the surgeon
 to suture the graft vessel thereto, the anastomotic stents of the
 invention allow the proximal end of the graft vessel to be connected to
 any part of the aorta. All parts of the aorta are accessible to the large
 vessel stents of the invention, even when minimally invasive procedures
 are used. Consequently, the graft vessel may be connected to the
 descending aorta, so that the graft vessel would not be threatened by
 damage during a conventional sternotomy if a second operation is required
 at a later time.
 The anastomotic stents of the invention provide a sutureless connection
 between a graft and a target vessel, while minimizing thrombosis or
 restenosis associated with the anastomosis. The anastomotic stents can be
 attached to the target vessel inside a patient remotely from outside the
 patient using specially designed applicators, so that the stents are
 particularly suitable for use in minimally invasive surgical procedures
 where access to the anastomosis site is limited. The stents of the
 invention allow the anastomosis to be performed very rapidly, with high
 reproducibility and reliability, and with or without the use of
 cardiopulmonary bypass.
 These and other advantages of the invention will become more apparent from
 the following detailed description of the invention and the accompanying
 exemplary drawings.

DETAILED DESCRIPTION OF THE INVENTION
 A presently preferred embodiment of the small vessel stent 10 of the
 invention, for connecting one end of a graft vessel to a small target
 vessel, is illustrated in FIG. 1. The small vessel stent 10 comprises an
 outer flange 11 having a body 12 which defines an opening 13 configured to
 receive the end of the graft vessel 21, and an inner flange 14 having a
 body 15 which defines an opening 16. The inner flange is configured to be
 connected to the outer flange, with the openings 13, 16 at least in part
 aligned. In the embodiment illustrated in FIG. 1, prongs 17 on the inner
 flange are configured to be received within small openings 18 in the outer
 flange, to thereby connect the flanges together. As best illustrated in
 FIG. 2, showing a transverse cross section of the small vessel stent 10
 shown in FIG. 1, taken along lines 2--2, the inner flange 14 is configured
 to be positioned within a lumen 23 of the target vessel 22 against an
 inner surface 24 of the target vessel, and the outer flange 11 is
 configured to be positioned against an outer surface 25 of the target
 vessel 22. In the embodiment illustrated in FIGS. 1 and 2, the inner and
 outer flanges have an arced configuration to facilitate positioning
 against the arced surface of the tubular vessel. The small vessel stent 10
 is preferably used with small target vessels, such as arteries, which
 typically have thin walls and small inner diameters.
 In the embodiment illustrated in FIG. 1, the inner and outer flanges have a
 short dimension and a long dimension, i.e. are substantially oblong. The
 graft receiving opening 13 in the outer flange, and the opening 16 in the
 inner flange, are also substantially oblong.
 FIG. 3 is an exploded view of the inner flange 14, outer flange 11, and a
 graft vessel 21, at an incision 26 in the target vessel 22. In FIG. 4, the
 graft vessel has been connected to the outer flange by inserting the end
 of the graft vessel through the graft receiving opening 13, and everting
 the graft end over the outer flange. Additionally, connecting members such
 as sutures, hooks or clips may be used to fix the graft vessel to the
 outer tubular member (not shown). The prongs 17 on the inner flange pierce
 through the wall of the graft vessel and then through the small openings
 18 in the outer flange. FIG. 4 illustrates the inner and outer flanges
 loosely connected together for positioning at the target vessel, with only
 a partial length of the prongs 17 inserted through the prong receiving
 opening 18, before the flanges are tightened down around the wall of the
 target vessel.
 With the outer flange 11 connected to the graft vessel 21 and the inner
 flange 14 connected to the outer flange 11, the inner flange is introduced
 into the incision 26 in the target vessel 22, and the inner and outer
 flanges are tightened together so that a compressive force is applied to
 the graft vessel against the outer surface 25 of the target vessel. Thus,
 the anastomosis channel is formed from the target vessel lumen, through
 opening in the inner flange, and into the graft vessel lumen. After the
 inner and outer flanges are tightened around the wall of the target
 vessel, in the embodiment having prongs 17, a length of the prongs
 extending above the target vessel can be broken off or otherwise removed.
 FIG. 5 is an elevational view of the small vessel stent shown in FIG. 4,
 connected to the target vessel, with a length of the free ends of the
 prongs 17 removed.
 In one embodiment of the invention, the prongs 17 on the inner flange and
 the prong receiving openings 18 on the outer flange are configured to
 fixedly mate together. FIG. 6 illustrates one embodiment of the prong 17
 and prong receiving openings 18. The opening 18 has deflectable tabs 19
 which deflect to allow displacement of the prong 17 longitudinally into
 the opening from the under side of the outer flange to the upper side of
 the outer flange, but which wedge against the prong to prevent the
 inserted prong from moving out of the opening 18 from the upper side to
 the under side of the outer flange. Additionally, a quick release (not
 shown) may be provided on the prongs to allow the prongs which are only
 partially inserted through the prong receiving opening to be quickly
 released therefrom in the event of an aborted procedure.
 In a presently preferred embodiment of the small vessel stent, the inner
 flange has a folded configuration having a reduced profile to facilitate
 insertion into the incision in the target vessel. In one embodiment, the
 length of the stent is shortened by flexing the short dimensioned sides of
 the stent together, as illustrated in FIG. 7. To hold the inner flange in
 the folded configuration for insertion into the target vessel, a pair of
 inwardly tensioned arms 43, preferably as a part of an applicator, are
 used in one embodiment of the invention. Additionally, the width of the
 stent can be shortened by flexing the long dimensioned sides of the stent
 together, as illustrated in FIG. 8. In the presently preferred. embodiment
 of the folding inner flange illustrated in FIG. 7 and 8, the inner flange
 is formed from a superelastic or pseudoelastic material, such as a NiTi
 alloy, to facilitate folding the inner flange and to provide improved
 sealing against the wall of the target vessel after the inner flange is
 unfolded inside the target vessel lumen. However, other configurations may
 be used, as for example, an inner flange having a collapsible section. For
 example, FIG. 9 illustrates an inner flange having a collapsible section
 27 on the long dimensioned sides of the inner flange, comprising a series
 of short turns in alternating directions. In FIG. 9, the collapsible
 section 27 is shown in a partially collapsed configuration in which the
 length of the inner flange is shortened by collapsing the long dimensioned
 sides of the inner flange. In a presently preferred embodiment, the inner
 flange having a collapsible section 27 is formed of stainless steel.
 FIG. 10 illustrates an applicator 31 used to position the inner flange 14
 within the target vessel lumen 23, and tighten the inner and outer flanges
 together around the wall of the target vessel. The applicator 31 generally
 comprises a shaft 32 with proximal and distal ends, a handle 33 on the
 proximal end, and a connecting member 34 on the distal end for releasably
 attaching to the small vessel stent. In the embodiment illustrated in FIG.
 9, the connecting member 34 comprises an inner compressible member 35
 which is slidably insertable into an outer housing member 36. The
 compressible member 35 has slots 37 configured to receive the prongs 17 on
 the inner flange 14, and an opening 38 configured to receive the graft
 vessel. The free end of the graft vessel, unconnected to the small vessel
 stent 10, is outside of the applicator via the opening 38. The housing
 member 36 has an inner chamber 39 configured to receive the compressible
 member 35. The chamber 39 is smaller than at least a section of the
 compressible member 35, to thereby compress the compressible member 35 to
 a smaller dimension when it is positioned within the chamber 39. The small
 vessel stent is releasably connected to the applicator, after the inner
 and outer flange together with a graft vessel are connected together, by
 inserting the prongs 17 on the inner flange into the slots 37. The
 compressible member 35 clamps onto the prongs 17 as the compressible
 member 35 is positioned within the chamber 39 and the slots 37 are thereby
 compressed. In the embodiment illustrated in FIG. 10, the compressible
 member 35 is partially out of the housing. Additionally, a connecting
 member (not shown) such as a clasp, clamp, or hook on the distal end of
 the applicator may be used to connect the outer flange to the applicator.
 FIG. 10 illustrates, in an exploded view, the positioning of the inner
 flange 14 for releasably connecting to the applicator. Of course, as
 discussed above, the inner flange 14 is typically connected to the outer
 flange with a graft vessel attached thereto before being connected to the
 applicator. The applicator is then used to position the stent in place at
 the incision in the target vessel, with the inner flange inside the target
 vessel lumen and the outer flange against the outer surface of the target
 vessel. To release the small vessel stent 10 from the applicator, the
 compressible member 35 is displaced out of the housing member 36, so that
 the prongs 17 are released from the slots 37 as the slots expand. In the
 embodiment illustrated in FIG. 10, the applicator has a knob 41 for
 turning the shaft 32 to draw the compressible member 35 up into the
 chamber 39. The handle 33 may be used to deploy the small vessel stent by
 squeezing the handle together to displace the compressible member 35 and
 housing member 36 relative to one another. FIG. 11 is a longitudinal cross
 sectional view of an applicator as shown in FIG. 10, with a small vessel
 stent therein, in position at a target vessel.
 In addition, the applicator 31 may be provided with a insertion member for
 holding the inner flange in the folded configuration facilitating
 introduction into the target vessel lumen through the incision in the
 target vessel. In one embodiment, the applicator insertion member
 comprises a pair of inwardly tensioned arms 43 extending past the distal
 end of the shaft for releasably holding the inner flange in the folded
 configuration, as illustrated in FIGS. 7 and 8.
 In the method of the invention, the small vessel stent connects one end of
 a graft vessel to a target vessel to form an anastomosis. The target
 vessel is incised, and balloons on occlusion catheters positioned against
 the target vessel are inflated to occlude blood flow upstream and
 downstream of the anastomosis site. The outer flange is attached to one
 end of a graft vessel as described above, and, in the embodiment
 illustrated in FIG. 1, the prongs on the inner flange are inserted through
 the graft vessel and into the prong receiving openings in the outer
 flange. The graft vessel may be occluded with a temporary clamp on the mid
 portion of the graft, to prevent blood loss through the graft vessel
 during the procedure. The inner flange is inserted into the target vessel
 lumen, and the inner and outer flanges are tightened together to compress
 the graft vessel against the outer surface of the target vessel. After the
 inner and outer flanges are tightened together, the free end of each prong
 is broken off to decrease the length of the prongs left inside the
 patient. The prongs are typically provided with a weakened point 42 near
 the body of the inner flange to facilitate breaking of the prong by
 tensile forces or by fatigue failure due to strain hardening. The
 occlusion balloons are deflated and the occlusion catheters removed, with
 the stent connected to the target vessel and the graft vessel in fluid
 communication with the target vessel lumen.
 In the embodiment illustrated in FIG. 1, the outer flange is longer and
 wider than the inner flange. The outer flange has a length of about 4 mm
 to about 12 mm, preferably about 7 mm to about 9 mm, and a width of about
 1 mm to about 5 mm. The wall thickness of the body of the outer flange is
 about 0.10 mm to about 0.30 mm. The inner flange has a length of about 4
 mm to about 12 mm, preferably about 7 mm to about 9 mm, and a width of
 about 0.5 mm to about 5 mm, and preferably about 2 mm to about 4 mm. The
 wall thickness of the body of the inner flange is about 0.10 mm to about
 0.25 mm. The inner and outer flanges are preferably formed of stainless
 steel, preferably 316 stainless steel, although, as previously discussed
 herein, superelastic or pseudoelastic materials such as nickel titanium
 alloys, titanium, or tantalum, may also be used. Additionally, advanced
 polymers which can be plastically deformed, such as polyetheretherketone,
 may be used.
 FIG. 12 illustrates a presently preferred embodiment of the large vessel
 stent 110 of the invention, for connecting one end of a graft vessel 125
 to a large target vessel 127. The large vessel stent 110 comprises a
 substantially cylindrical body 111 having an open proximal end 112, open
 distal end 113, a lumen 114 extending therein configured to receive the
 end of the graft vessel 125. FIG. 13 illustrates a transverse cross
 section of the large vessel stent 110 shown in FIG. 12, taken along lines
 13--13. FIG. 14 illustrates a flattened view of the large vessel stent 110
 shown in FIG. 12.
 The cylindrical body has a distal deformable section 115 and a proximal
 deformable section 116. The deformable sections 115, 116 have a first
 configuration for insertion into the target vessel, and a radially
 expanded second configuration for connecting to the target vessel. In the
 embodiment illustrated in FIG. 12, the distal and proximal deformable
 sections 115, 116 comprises a plurality of helical members 123, 124,
 respectively. In the embodiment illustrated in FIG. 12, each helical
 member has a proximal end radially spaced on the stent body relative to
 the helical member distal end. The helical members are radially spaced
 around the circumference of the cylindrical body between longitudinally
 spaced portions of the cylindrical body. In FIG. 12, the helical members
 forming the deformable sections are shown in the first configuration prior
 to being radially expanded to the second configuration. As illustrated in
 FIG. 15, the distal deformable section 115 radially expands to the second
 configuration to form a distal end flange 121, configured to apply a force
 radial to the cylindrical body 111 longitudinal axis against the target
 vessel and thereby connect the stent to the target vessel. Similarly, the
 proximal deformable section 116 radially expands to the second
 configuration to form a proximal end flange 122, as illustrated in FIG.
 20. The flanges 121, 122 are deployed by circumferentially rotating the
 proximal end of the stent body relative to the distal end of the stent
 body. Such rotation causes the stent body to longitudinally collapse as
 the helical members radially expand from the first to the second
 configuration. FIG. 16 illustrates a transverse cross section of the large
 vessel stent 110 shown in FIG. 15, taken along lines 16--16.
 FIG. 17 illustrates the large vessel stent shown in FIG. 12 with a graft
 vessel 125 attached thereto. The graft vessel is attached to the large
 vessel anastomotic stent by inserting one end of the graft vessel into the
 proximal end of the cylindrical body and, in a preferred embodiment,
 everting the graft end 126 out the cylindrical body distal end. The graft
 vessel may be everted over all or only a section of the outer surface of
 the large vessel stent 110. In the embodiment illustrated in FIG. 17, the
 graft is everted over the distal deformable section 115 which is in the
 first configuration prior to being radially expanded to the second
 configuration.
 FIGS. 18-20 illustrate the large vessel stent shown in FIG. 17 within a
 wall of the target vessel 127 before and after deployment of the distal
 flange 121 and proximal flange 122. In FIG. 18, the stent has been
 inserted into an incision in a wall of the target vessel, with the distal
 end of the stent within the lumen 128 of the target vessel 127 and the
 proximal end 112 of the stent extending outside of the target vessel. In
 FIG. 19, the distal deformable section 115 has been radially expanded to
 form the distal end flange 121. During deployment of the distal end
 flange, the stent body longitudinally collapses, and the distal end flange
 is positioned at least in part within the wall of the target vessel, so
 that the flange applies a force radial to the stent longitudinal axis,
 illustrated by the arrow R, against the wall of the target vessel defining
 the incision therein. Additionally, an axial force, illustrated by the
 arrow A, is applied against the target vessel wall, compressing the target
 vessel wall. The final position of the distal end flange may vary, with
 the distal end flange being completely within the target vessel wall as
 shown, or, alternatively, partially within the target vessel lumen (not
 shown). In FIG. 20, the proximal deformable section 116 has been radially
 expanded to form the proximal end flange 122. The proximal end flange
 positioned against the outer wall of the target vessel produces an axial
 force, illustrated by the arrow A, against the target vessel. In the
 embodiment illustrated in FIG. 20, the proximal end flange is in contact
 with an outer surface of the target vessel wall. Alternatively, the
 proximal end flange may be in contact with the media of the target vessel
 between the inner and outer surface of the target vessel wall, and
 preferably with the proximal end of the stent flush with the outer surface
 of the target vessel (not shown). The degree to which flange is deployed
 may be varied to control how and where the flange contacts the target
 vessel wall. Thus, depending on the thickness of the target vessel wall,
 the proximal deformable section can be radially expanded and
 longitudinally collapsed to a greater or lesser degree, so that the
 proximal end flange is in contact with the target vessel either on an
 outer surface of the target vessel or within the incision therein in
 contact with the media of the target vessel wall.
 Although the large vessel stent 110 is shown in FIG. 12 with a proximal
 deformable section and a distal deformable section, forming proximal and
 distal flanges, respectively, the large vessel stent may have one or more
 deformable sections. For example, an intermediate deformable section (not
 shown) between the proximal and distal end deformable sections may be
 provided for additional sealing and securing force against the media of
 the target vessel wall.
 In the large vessel stent illustrated in FIG. 12, the intermediate section
 of the body is solid. FIG. 21 illustrates an alternative embodiment in
 which voids or openings 129 are provided in the body wall which allow for
 tissue ingrowth, to thus facilitate sealing and securing of the
 anastomosis. In another embodiment of the large vessel stent, illustrated
 in FIG. 22, a peripheral edge on the distal end of the large vessel stent
 is curvilinear, so that deployment of the distal end flange increases the
 diameter of the open distal end. The generally sinusodial edge increases
 the diameter of the opening in the distal end as the distal deformable
 section 115 is longitudinally collapsed.
 An applicator 131 is typically used to deploy the flanges and connect the
 large vessel stent 110 to the target vessel 127, as illustrated in FIG.
 23. In the embodiment illustrated in FIG. 23, the applicator 131 comprises
 an elongated stent delivery member comprising a shaft 133 having an outer
 tubular member 134 having a lumen 135 therein, an inner tubular member 136
 having a lumen 137 configured to receive the graft vessel 125 and being
 rotatably located within the lumen of the outer tubular member, a handle
 138 on the proximal end of the shaft, and connecting members 141 on the
 distal end of the inner and outer tubular members which releasably secure
 the large vessel stent 110 to the applicator 131. The distal and proximal
 ends of the large vessel stent 110 releasably secure to the inner and
 outer tubular members, respectively, and the inner and outer tubular
 members are rotatable relative to one another, so that the distal end of
 the stent can be rotated relative to the proximal end of the stent and the
 flanges thereby deployed. In the embodiment illustrated in FIG. 23,
 longitudinal openings 139, preferably coextensive with one another, in the
 inner and outer tubular members are provided to facilitate positioning the
 graft vessel, and large vessel stent connected thereto, on the applicator
 131. FIG. 24 illustrates an enlarged view of the distal end of an
 applicator as shown in FIG. 23, with a large vessel stent 110 and graft
 vessel 125 thereon. FIGS. 26 and 27 illustrate transverse cross sections
 of the applicator shown in FIG. 24, taken along lines 26--26 and 27--27,
 respectively.
 FIG. 27 illustrates an enlarged view of the distal end of the applicator
 131 shown in FIG. 23. In the embodiment illustrated in FIG. 27, the
 connecting members 141 on the outer tubular member 134 comprise tabs 142
 configured to mate with slits 143, as illustrated in FIG. 12, on the
 proximal end of the stent. The connecting members 141 on the inner tubular
 member 136 comprise angular slits 144 which slidably receive tabs 145, as
 illustrated in FIG. 13 on the distal end of the stent. The tabs on the
 distal end of the stent are introduced into the slits on the applicator
 inner tubular member and a slight twisting motion releasably secures the
 tabs therein. A variety of suitable connection members can be used
 including releasable clamps, clips, hooks, and the like.
 In one embodiment of the invention, the applicator 131 includes a vessel
 penetrating member 146, as illustrated in FIGS. 24 and 28, for forming an
 incision in the target vessel. Additionally, the applicator may be
 provided with one or more inflatable members for enlarging the incision,
 and/or drawing the applicator and stent into the incision. For example, in
 the embodiment shown in FIG. 28, a vessel penetrating member 146 having
 proximal and distal ends, a piercing member 147 on the distal end, and at
 least one inflatable member on a distal section of member 146, is
 configured to be received in the inner lumen of the inner tubular member
 136. In the presently preferred embodiment illustrated in FIG. 28, a
 proximal balloon 148, which is preferably formed from noncompliant
 material, is provided on the outer tubular member for expanding the
 incision in the target vessel, and a distal balloon 151, which is
 preferably formed from compliant material, is provided distal to the
 noncompliant balloon 148, for drawing the vessel penetrating member 146
 into the target vessel lumen 128. However, the distal balloon may be
 omitted and the catheter advanced through the incision and into the target
 vessel lumen physically or by other suitable methods, as when the proximal
 balloon is shaped to advance into the target vessel lumen during
 inflation. Additionally, the target vessel may be held to resist the force
 of inserting the stent into the aortal wall, as by a suction applicator
 (not shown) positioned against an outer surface of the target vessel,
 which pulls the target vessel toward the applicator.
 In the method of the invention, the large vessel stent, with a graft vessel
 connected thereto, is introduced into the patient, inserted into the
 target vessel and connected thereto by deployment of the flange. FIGS.
 28A-28H illustrate the connection of the large vessel stent to a target
 vessel. The stent 110, with an everted graft vessel 125 thereon, is
 releasably secured to the distal end of the applicator. The graft vessel
 is within the lumen of the inner tubular member, and the vessel
 penetrating member 146 is within the lumen of the graft vessel 125. As
 shown in FIG. 28A, the applicator 131 and stent 110 assembly is introduced
 into the patient and positioned adjacent the target vessel 127. An
 incision in the target vessel wall is formed by inserting the piercing
 member 147 into the target vessel, and the incision is enlarged by
 inflating the proximal balloon 148 on the vessel penetrating member 146,
 see FIGS. 28B and 28C. The distal end of the applicator is then displaced
 distally into the target vessel lumen 128 by inflating the distal balloon
 151, see FIG. 28D. With the stent in position within the incision in the
 target vessel, the applicator inner tubular member is rotated relative to
 the applicator outer tubular member, so that the distal end of the stent
 rotates relative to the proximal end of the stent, and the distal end
 flange is deployed, see FIG. 28E. In the embodiment illustrated in FIG.
 28D, the distal end of the stent is positioned within the target vessel
 lumen before the distal end flange 121 is deployed, to facilitate
 deployment thereof. In a presently preferred embodiment, the distal
 deformable section is positioned at least in part within the target vessel
 lumen before the distal flange is deployed. However, it is not required
 that the deformable sections are outside of the incision in the target
 vessel wall for the flanges to be deployed. The proximal end flange 122 is
 deployed by further rotating the applicator tubular members as outlined
 above for the distal end flange, see FIG. 28F. The balloons 148, 151 on
 the vessel penetrating member 146 are then deflated and the applicator 131
 removed from the target vessel 127, leaving the graft vessel 125 connected
 thereto, see FIGS. 28G and 28H.
 In a presently preferred embodiment, the distal end flange is configured to
 deploy at lower torque than the proximal end flange. A deflecting section
 153 is provided on the helical members 123, 124, which bends during the
 deployment of the flanges. In one embodiment of the invention, illustrated
 in FIG. 14, the deflecting section 153 is formed by at least one notch in
 each helical member, having a depth which decreases the transverse
 dimension of the helical members at the notch. In the embodiment of the
 large vessel stent illustrated in FIG. 14, the a deflecting section is
 formed by two opposed notches 154 on opposite sides of the helical
 members. The notches on the distal helical members have a depth that is
 greater than the depth of the notches on the proximal helical members.
 Consequently, the transverse dimension of the deflecting section on the
 distal helical member is smaller than that of the proximal helical
 members, so that the distal flange will deploy before the proximal flange.
 Thus, the distal section helical members radially expand at lower torque
 than the proximal helical members, so that rotating the proximal and
 distal ends of the stent body relative to one another causes the distal
 end flange to deploy first, followed by the proximal end flange.
 In the embodiment illustrated in FIG. 14, the helical members have
 deflecting sections 153 on the proximal and distal ends, and an
 intermediate deflecting section located substantially centrally along the
 length of the helical member between the proximal and distal ends of the
 helical member. In the deployed flange, the intermediate deflecting
 section is thus located on a peripheral extremity of the deployed flange
 and the flange is substantially perpendicular to the stent longitudinal
 axis. Alternatively, the intermediate deflecting section may be located
 distally or proximally along the length of the helical member, so that the
 flange is angled relative to the longitudinal axis of the stent. For
 example, where the intermediate deflecting section is located between the
 center point and the distal end of the helical member, the flange is
 angled toward the distal end of the large vessel stent 110, as illustrated
 in FIG. 29.
 In the embodiment of the large vessel stent illustrated in FIGS. 18-20, the
 length of the large vessel stent before deployment of the flanges is
 greater than the width of the target vessel wall, so that the deformable
 sections are on either side of the target vessel, at least in part outside
 of the incision in the target vessel wall. The length of the stent after
 the flanges are deployed, as illustrated in FIG. 20, is substantially
 equal to the width of the target vessel wall. The length of the stent 110
 is about 0.5 mm to about 5 mm, and the diameter is about 4 mm to about 10
 mm. The large vessel stent is preferably formed from stainless steel.
 However, other suitable materials may be used, including tantalum,
 titanium, and alloys thereof. The large vessel stent wall thickness is
 about 0.10 mm to about 0.20 mm.
 The anastomotic stents of the invention may be used for a variety of
 anastomosis procedures, including coronary bypass surgery. For example,
 the distal end of a dissected mammary artery can be connected to a
 coronary artery, using a small vessel stent of the invention. Typically,
 one or more slices are made in the end of the mammary artery in order to
 increase to diameter of the mammary artery to facilitate its connection to
 the outer flange of the small vessel stent. FIG. 30 illustrates a heart
 160 on which a coronary bypass has been performed using the anastomotic
 stents of the invention. The distal end of a harvested vein graft 125 is
 connected to the coronary artery 161 using a small vessel stent of the
 invention, and the proximal end of the graft vessel is connected to the
 descending aorta 162 using a large vessel stent of the invention.
 In an anastomotic system using the large vessel stent in combination with
 the small vessel stent, the large vessel stent would preferably be
 connected to the target vessel first, so that the lumen of the graft
 vessel would be accessible through the other end of the graft vessel, to
 thereby provide access for a catheter which incises and expands the aortal
 wall. The small vessel stent would be connected next, because it requires
 no access through the lumen of the graft vessel.
 Although principally discussed with respect to coronary bypass surgery, the
 anastomotic stents of the invention may be used in a number of anastomosis
 procedures. For example, the other types of anastomosis procedures
 include, femoral-femoral bypass, vascular shunts, subclaviancarotid
 bypass, organ transplants, and the like.
 It will be apparent from the foregoing that, while particular forms of the
 invention have been illustrated and described, various modifications can
 be made without departing from the spirit and scope of the invention. For
 example, those skilled in the art will recognize that the large and small
 vessel stents of the invention may be formed of wound or bended wire,
 filaments and the like. Other modifications may be made without departing
 from the scope of the invention.