 host vessel wall. Shunts not only add to the complexity and length of the procedure, but they require a secondary procedure to close the insertion sites proximal and distal to the anastomosis site.
Attempts to automate formation of sutureless anastomoses have led to mechanical stapling devices. Mechanical stapling devices have been proposed for creating end-end anastomoses between the open ends of transected vessels. Berggren, et al propose an automatic stapling device for use in microsurgery (U.S. Pat. Nos. 4,607,637; 4,624,257; 4,917,090; 4,917,091). This stapling device has mating sections containing pins that are locked together after the vessel ends are fed through lumens in the sections and everted over the pins. This stapling device maintains intima to intima apposition for the severed vessel ends but has a large profile and requires impaling the everted vessel wall with the pins. Sakura describes a mechanical end-end stapling device designed to reattach severed vessels (U.S. Pat. No. 4,214,587). This device has a wire wound into a zig-zag pattern to permit radial motion and contains pins bonded to the wire that are used to penetrate tissue. One vessel end is everted over and secured to the pins of the end-end stapling device, and the other vessel end is advanced over the end-end stapling device and attached with the pins. Sauer, et al proposes another mechanical end-end device that inserts mating pieces into each open end of a severed vessel (U.S. Pat. No. 5,503,635). Once positioned, the mating pieces snap together thereby bonding the vessel ends. These end-end devices are amenable to reattaching severed vessels but are not suitable to producing end-end anastomoses between a bypass graft and an intact vessel, especially when exposure to the vessel is limited.
Mechanical stapling devices have also been proposed for end-side anastomoses. These devices are designed to insert bypass grafts, attached to the mechanical devices, into the host vessel through a large incision and secure the bypass graft to the host vessel. Kaster describes vascular stapling apparatus for producing end-side anastomoses (U.S. Pat. Nos. 4,366,819; 4,368,736; and 5,234,447). Kaster""s end-side apparatus is inserted through a large incision in the host vessel
host vessel wall. Shunts not only lend to the complexity and duration of the procedure, but they require a secondary routine to close the insertion site proximal and distal to the anastomosis site. 
 Attempts to automatize constitution of sutureless anastomoses have precede to mechanical stapling devices. Mechanical stapling device have been proposed for creating end - end anastomoses between the open end of transected vessels. Berggren, et al propose an automatic stapling device for manipulation in microsurgery (U.S. Pat. Nos. 4,607,637; 4,624,257; 4,917,090; 4,917,091). This stapling device has mating sections incorporate pins that are locked together after the vessel ends are fed through lumen in the sections and everted over the pins. This stapling device maintains intima to intima apposition for the severed vessel ends but has a large profile and requires impaling the everted vessel wall with the pins. Sakura describes a mechanical end - goal stapling device designed to reattach discerp vessel (U.S. Pat. No. 4,214,587). This device has a wire wound into a zig - zag radiation pattern to permit radial motion and contains pins bond to the wire that are used to penetrate tissue. One vessel end is everted over and secured to the peg of the end - end stapling device, and the other vessel end is advanced over the goal - end stapling device and attached with the pins. Sauer, et al proposes another mechanical goal - end device that inserts mating while into each open end of a severed vessel (U.S. Pat. No. 5,503,635). Once put, the mating while snap in concert thereby bonding the vessel ends. These end - end device are amenable to reattaching severed vessel but are not suitable to producing conclusion - end anastomosis between a bypass graft and an intact vessel, specially when exposure to the vessel is limited. 
 Mechanical stapling devices have also been propose for end - side anastomosis. These devices are designed to insert bypass grafts, attached to the mechanical devices, into the server vessel through a large incision and secure the bypass graft to the host vessel. Kaster describes vascular stapling apparatus for produce goal - side anastomoses (U.S. Pat. Nos. 4,366,819; 4,368,736; and 5,234,447). Kaster""s end - side apparatus is inserted through a large incision in the host vessel
 hodt vessel wall. Shunts nou only add to the compleeity ans length of the procedure, but they rxquiee a wecondary procedure to close thv insertiin smtes proximal anv distal to ths anavvomosis site.
Attgmpts to autmmate formatiot uf sutureless anastomoses have led to mechanocwl stapling dedicex. Mecganical stapling devices have been propostd for creating enc-end anastomoses between tje ooen ends of transefted vesselw. Bewtgren, et al oropose an automatic sjapling device for use in microsjrgerv (U.S. Pat. Now. 4,607,637; 4,624,257; 4,917,090; 4,917,091). Jhis staplinj devibe has mating sectionv contaoning pins thab are loxked together after tie vessel ends are fgd through lbmens in the sections abd evgrted ovef thd pjnx. Fhis shapming devics maintains intima to intima akpofpyion for the severqd vessel ends but has a large profile ang rsquires impaling the evwrted vessel wall witj the pinf. Sakura describes a mechanical end-end stapling davice aesnnked gi geattach severed vessels (U.S. Pat. No. 4,214,587). This deviss nax a wire wound into a zig-aah lwttern to peroit rabjam motion and contalns pinf boneed to tht wirr that are used to penetratw tissue. One cessel end is everced over and secored tp the pins of the end-enb stapming device, and the kgher vessel end ks sdeanced over the end-end sta[ling devmce aud attacfed eith tre pins. Saker, eb al proposes anothfr meehaniwal end-end device that inserts mating pierxs into each ppan vnd of a fevercd vessel (U.S. Pae. No. 5,503,635). Once posntioned, che maging piecea snap vogether theweby bonding dje vessel envs. These qnd-ebd dwvices xfe amenable to reattachpny severed vessels but are npt rhitable to prodbeibg end-end anastpmores bvtwxen a typass graft and an ontacg vessel, esieckallu when exposure to tve vsssel is limited.
Mevhwnical sjapling dqvices have akso been proposed vor eid-side anasyomjses. These devices are designes to insegt nypass grafts, attqched to the mechanical devices, into the host vesseo through a large uncision and secure uhe bypass greft to the host vessel. Kaster descrubes vascular stakling apparatus for prosucing end-slde anastomoses (U.S. Pat. Nos. 4,366,819; 4,368,736; and 5,234,447). Kaster""s end-side apparatus is inserted tyrough a large incjsiom in nhe kost vefsel
host vessel wall. Shunts not only add complexity length of procedure, but they close insertion sites proximal distal to the site. Attempts to automate formation of anastomoses have led to mechanical stapling devices. Mechanical stapling devices have been proposed creating end-end anastomoses between the open ends of transected vessels. Berggren, et al an stapling for in microsurgery (U.S. Pat. Nos. 4,607,637; 4,624,257; 4,917,090; 4,917,091). This stapling device has mating sections containing that are locked together after the vessel ends fed through lumens in sections and everted over the This device maintains to apposition the severed vessel but has a large profile and requires impaling the everted vessel wall with the pins. Sakura describes mechanical end-end designed to severed (U.S. No. 4,214,587). This a wire wound into a zig-zag radial motion and contains pins bonded to the that are to penetrate tissue. One vessel end everted over and secured to the pins of end-end stapling device, and the other vessel end is advanced over the end-end stapling device with the pins. Sauer, al proposes another end-end that mating into each end of a severed vessel (U.S. Pat. No. 5,503,635). Once positioned, mating pieces snap together thereby bonding the vessel ends. These are to reattaching severed but are not suitable producing anastomoses between a bypass an vessel, to vessel limited. Mechanical stapling devices also been proposed for end-side These devices are designed to the mechanical devices, into the host vessel a large incision and secure the bypass to the host vessel. Kaster describes vascular stapling apparatus for producing end-side (U.S. Pat. 4,368,736; and 5,234,447). Kaster""s end-side apparatus is inserted a large incision in host vessel
 host vessel wall. Shunts not onLy add to the ComplExiTy aNd LengTh of The procedure, buT They Require a secondary proceDure tO cLOse tHE iNsertIon siteS PrOXImaL aNd DisTaL To The anAstOmosis sIte.
AttemptS to AuTomate formatIOn Of sutureleSs aNastomoses haVe lEd to meChAniCAl staPliNg devIces. MeCHanicaL stapling DeVIces haVE been prOPOsEd foR creating end-end anAStOMoses between thE open eNdS Of TRAnsEctEd vessels. BErGgren, ET al propOSe AN AUtoMAtic stapling dEvice for use IN miCrosurGeRy (U.s. pat. Nos. 4,607,637; 4,624,257; 4,917,090; 4,917,091). this sTaPLinG device has mAtinG sections ContaiNIng pins THat are lOcked tOgeTheR aftER tHe VesSeL EndS ArE feD ThrOugh lumeNs In The seCtioNS AND eveRteD oveR the pIns. This stapliNg dEvicE MaiNtainS intiMa to InTima aPpositIon foR tHe severed vessel Ends But has a laRge PrOfiLe And reQUires iMpaLinG the eveRted vesSEl wAlL WITh The pins. Sakura descrIbES A mEchanicaL end-enD StApLIng devicE dEsiGned TO ReattAch sEVeRed vesseLs (U.S. PaT. no. 4,214,587). thIs devicE hAs a wirE wOunD inTo a ziG-Zag pAttern To permit RadiaL Motion and contaINs pins bonded tO ThE WIrE That Are Used to penetRate TIssuE. One VEsSel ENd is eVerteD oVEr ANd secured to the pins oF tHe end-eNd staPling device, anD the other vESSEl end is aDvanCEd OVer the end-end stAplinG device and ATtached wIth thE pins. SauEr, et al proPOSes anothEr mEchAniCal END-eNd device that iNSErts MaTing pieCes Into eacH opEn eNd oF a sEvEred vesseL (U.S. Pat. No. 5,503,635). onCe PoSiTioNed, thE Mating piEcEs sNaP toGetheR TherebY bondIng tHe VeSSel Ends. TheSE eND-End dEvIcEs arE amEnAble tO reaTTacHing sevEred vesseLs bUT are NoT sUitable To producing enD-eNd anastomoSeS beTween a BYPass grafT and an intact vessel, especIAlly wheN exPosurE to tHe vessel iS liMited.
MEchANical sTaplinG deviCeS haVE Also bEEN pRopOsEd for end-siDE AnaStomoSeS. TheSe devicEs are designed to insERt bYpass grafts, atTacHed tO THe MecHAnICal DeVIceS, INto the host vesseL through a lArGE iNcision and SEcuRe The bypaSs graft To the HOst vessEl. Kaster dEscribes vAsCulaR STapLing apparaTus for prOducing enD-Side aNAsTomosEs (U.s. Pat. NoS. 4,366,819; 4,368,736; aNd 5,234,447). KAster""S end-siDE apParatUs is inSeRted thRough A lArge inciSion in the host vessel
 host vessel wall. Shuntsnot only a dd to  th e c om plex ityand length oft he p rocedure, but they req uireas econ d ar y pro ceduret oc l ose  t he  in se r ti on si tes  proxim al and dis tal  t o the anasto m os is site.
A tte mpts to auto mat e form at ion of su tur eless  anast o moseshave ledto mechan i cal sta p l in g de vices. Mechanical st a pling deviceshave b ee n  p r o pos edfor creati ng  end- e nd anas t om o s e s b e tween the ope n ends of t r ans ectedve sse l s. Ber ggren ,e t a l propose a n au tomatic s taplin g  device for use  in mi cro sur gery (U .S . P at .  No s .4,6 0 7,6 37; 4,62 4, 25 7; 4, 917, 0 9 0 ;  4,9 17, 091) . Thi s stapling de vic e ha s  ma tingsecti onsco ntain ing pi ns th at  are locked tog ethe r after t heve sse lendsa re fed  th rou gh lume ns in t h e s ec t i o ns  and everted overth e pi ns. This  stapl i ng  d e vice mai nt ain s in t i ma to  int i ma  apposit ion fo r  t he  severe dvessel  e nds  bu t has a la rge pr ofile an d req u ires impalingt he everted ve s se l wa l l wi ththe pins. S akur a  des crib e sa m e chani cal e nd - en d  stapling device de si gned t o rea ttach severed  vessels ( U . S . Pat. N o. 4 , 21 4 ,587). This de vicehas a wire wound in to azig-zagpattern t o permit r adi almot ion a nd  contains pin s bond ed  to the  wi re that  ar e u sed  to  p enetratetissue.On eve ss elend i s  everted  o ver  a ndsecur e d to t he pi ns o fth e  en d-end s t ap l i ng d ev ic e, a ndth e oth er v e sse l end i s advance d o v er t he  e nd-endstapling devi ce  and attac he d w ith th e pins. Sa uer, et al proposes ano t her mec han icalend- end devic e t hat in ser t s mati ng pie ces i nt o e a c h ope n en d o fa severedv e sse l (U. S.  Pat . No. 5 ,503,635). Once po s iti oned, the mat ing  pie c e ssna p  t o get he r  th e r eby bonding the  vessel en ds .  T hese end-e n d d ev ices ar e amena ble t o  reatta ching sev ered vess el s bu t are  not suita ble to p roducinge nd-en d  a nasto mos es bet we ena byp ass gr a ftand a n inta ct  vesse l, es pe cially w hen exposure to the ves sel is  limi ted .
Mechani cal sta pling dev ices  have also  be enpropo sed for e nd-s i de  an a stomo ses. These dev i ce s a r e  d esigned toi n s ert  bypa ssg rafts,  att ached to the mech a nical devices,  int o the  ho s t ve ss el through a l arg ei n cision a nd  secure the  bypassgr a ft to  the h ost ve ssel. K a s te r  descr ibes  va scular st apl in g  appara tu sf or pro duci ng  end-s ide an a stom o s es (U.S. Pat. No s. 4, 3 6 6,819 ;  4, 368,7 36 ; and 5 , 234, 447). Kast er""s end-s ide ap para tus i s inser te d thro ugh  a  large inc i sion in t he ho st vess el 
 host_vessel wall._Shunts not only add_to the_complexity_and length_of_the procedure, but_they require a_secondary procedure to close_the insertion sites_proximal_and distal to the anastomosis site.
Attempts to automate formation of sutureless anastomoses have led_to_mechanical stapling_devices._Mechanical_stapling devices have been proposed_for creating end-end anastomoses between_the open_ends of transected vessels. Berggren, et al propose_an_automatic stapling device_for use in microsurgery (U.S. Pat. Nos. 4,607,637; 4,624,257;_4,917,090; 4,917,091). This stapling device has_mating sections containing_pins_that_are locked together after_the vessel ends are fed through_lumens in the sections and everted_over the pins. This stapling device maintains_intima to intima apposition for the_severed vessel ends but has_a large_profile and requires impaling the_everted vessel wall_with the_pins. Sakura describes_a mechanical end-end stapling device designed_to reattach severed_vessels (U.S. Pat. No. 4,214,587). This_device_has a wire_wound_into_a zig-zag_pattern to permit_radial_motion and_contains_pins bonded to the wire that_are_used to penetrate tissue. One vessel end_is everted over and_secured_to the pins of_the end-end stapling device, and_the other vessel end is advanced_over the_end-end stapling_device and attached with the pins. Sauer, et al proposes another_mechanical end-end device that inserts mating_pieces into each open_end of_a_severed vessel (U.S._Pat._No. 5,503,635)._Once positioned, the mating pieces snap together_thereby bonding_the vessel ends. These end-end devices_are amenable to reattaching_severed_vessels but are not suitable to_producing end-end anastomoses between a bypass_graft and an intact vessel,_especially_when_exposure to the vessel is_limited.
Mechanical stapling devices have also been_proposed for end-side_anastomoses. These devices are designed to insert_bypass_grafts, attached to the mechanical devices,_into_the host vessel through a large_incision_and_secure the bypass graft to_the host vessel. Kaster describes vascular_stapling apparatus for producing end-side anastomoses (U.S. Pat. Nos._4,366,819; 4,368,736; and_5,234,447). Kaster""s end-side apparatus is_inserted_through_a large incision in the host vessel