Abstract:
Devices, systems, and methods for suturing of body lumens allow the suturing of vascular puncture sites located at the distal end of a percutaneous tissue tract. An elongated articulated foot near a distal end of a shaft is inserted through the penetration and actuated so that the foot extends along the lumenal axis. The foot carries suturing attachment cuffs, and needles are advanced from the shaft through the vessel wall outside of the penetration and into engagement with the needle cuffs after the foot has been drawn proximally up against the endothelial surface of the blood vessel. The cross-section of the shaft within the tissue tract can be minimized by laterally deflecting the needles as they leave the shaft, while tapered depressions within the foot can guide the advancing needles into engagement with the cuffs. The cuffs lockingly engage the needles and can be withdrawn proximally along the needle paths and through the tissue tract so as to form a loop of suture across the puncture. The articulating foot may be realigned with the shaft and withdrawn proximally through the tissue tract without dilating the tissue tract.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation application of and claims benefit of and priority from application Ser No. 10/909,531 filed 2 Aug. 2004, which is a continuation application of and claims benefit of and priority from application Ser No. 09/651,344 (now U.S. Pat. No. 7,001,400) filed 29 Aug. 2000, which is a divisional application of and claims the benefit of application Ser. No. 09/262,402 filed 4 Mar. 1999 (now U.S. Pat. No. 6,136,010). The present application is also a continuation application of and claims benefit of and priority from application Ser No. 11/273,107 filed 14 Nov. 2005, which is a continuation application of and claims benefit of and priority from application Ser No. 10/152,272 (now U.S. Pat. No. 6,964,668) filed 20 May 2002, which is a continuation-in-part of and claims benefit of and priority from application Ser No. 09/651,344 (now U.S. Pat. No. 7,001,400) filed 29 Aug. 2000, which is a divisional application of and claims the benefit of priority from application Ser. No. 09/262,402 filed 4 Mar. 1999 (now U.S. Pat. No. 6,136,010). The disclosures of each of the above mentioned applications are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates generally to apparatus and methods for the suturing of body lumens. More particularly, the present invention relates to techniques for percutaneous closure of arterial and venous puncture sites, which are usually accessed through a tissue tract. 
     2. The Relevant Technology 
     A number of diagnostic and interventional vascular procedures are now performed translumenally. A catheter is introduced to the vascular system at a convenient access location and guided through the vascular system to a target location using established techniques. Such procedures require vascular access, which is usually established during the well-known Seldinger technique, as described, for example, in William Grossman&#39;s “Cardiac Catheterization and Angioplasty,” 3 rd  Ed., Lea and Febiger, Philadelphia, 1986, incorporated herein by reference. Vascular access is generally provided through an introducer sheath, which is positioned to extend from outside the patient body into the vascular lumen. 
     When vascular access is no longer required, the introducer sheath is removed and bleeding at the puncture site stopped. One common approach for providing hemostasis (the cessation of bleeding) is to apply external force near and upstream from the puncture site, typically by manual or “digital” compression. This approach suffers from a number of disadvantages. It is time consuming, frequently requiring one-half hour or more of compression before hemostasis is assured. Additionally, such compression techniques rely on clot formation, which can be delayed until anticoagulants used in vascular therapy procedures (such as for heart attacks, stent deployment, non-optical PTCA results, and the like) wear off. This can take two to four hours, thereby increasing the time required before completion of the compression technique. The compression procedure is further uncomfortable for the patient and frequently requires analgesics to be tolerable. Moreover, the application of excessive pressure can at times totally occlude the underlying blood vessel, resulting in ischemia and/or thrombosis. Following manual compression, the patient typically remains recumbent from four to as much as twelve hours or more under close observation so as to assure continued hemostasis. During this time renewed bleeding may occur, resulting in blood loss through the tract, hematoma and/or pseudoaneurysm formation, as well as arteriovenous fistula formation. These complications may require blood transfusion and/or surgical intervention. 
     The incidence of complications from compression-induced hemostasis increases when the size of the introducer sheath grows larger, and/or when the patient is anticoagulated. It is clear that the compression technique for arterial closure can be risky, and is expensive and onerous to the patient. Although the risk of complications can be reduced by using highly trained individuals, dedicating such personnel to this task is both expensive and inefficient. Nonetheless, as the number and efficacy of translumenally performed diagnostic and interventional vascular procedures increases, the number of patients requiring effective hemostasis for a vascular puncture continues to increase. 
     To overcome the problems associated with manual compression, the use of bioabsorbable fasteners or sealing bodies to stop bleeding has previously been proposed. Generally, these approaches rely on the placement of a thrombogenic and bioabsorbable material, such as collagen, at the superficial arterial wall over the puncture site. While potentially effective, this approach suffers from a number of problems. It can be difficult to properly locate the interface of the overlying tissue and the adventitial surface of the blood vessel. Locating the fastener too far from that interface can result in failure to provide hemostasis, and subsequent hematoma and/or pseudo-aneurysm formation. Conversely, if the sealing body intrudes into the arterial lumen, intravascular clots and/or collagen pieces with thrombus attached can form and embolize downstream, causing vascular occlusion. Also, thrombus formation on the surface of a sealing body protruding into the lumen can cause a stenosis, which can obstruct normal blood flow. Other possible complications include infection, as well as adverse reaction to the collagen or other implant. 
     A more effective approach for vascular closure has been proposed in U.S. Pat. Nos. 5,417,699, 5,613,974; and PCT published Patent Application No. PCT/US96/10271 filed on Jun. 12, 1996, the full disclosures of which are incorporated herein by reference. A suture-applying device is introduced through the tissue tract with a distal end of the device extending through the vascular puncture. One or more needles in the device are then used to draw suture through the blood vessel wall on opposite sides of the puncture, and the suture is secured directly over the adventitial surface of the blood vessel wall to provide highly reliable closure. 
     While a significant improvement over the use of manual pressure, clamps, and collagen plugs, certain design criteria have been found to be important to successful suturing to achieve vascular closure. For example, it is highly beneficial to properly direct the needles through the blood vessel wall at a significant distance from the puncture so that the suture is well anchored in the tissue and can provide tight closure. It is also highly beneficial to insure that the needle deployment takes place when the device is properly positioned relative to the vessel wall. The ease of deployment and efficacy of the procedure can further be enhanced by reducing the cross-section of that portion of the device, which is inserted into the tissue tract and/or the vessel itself, which may also allow closure of the vessel in a relatively short amount of time without imposing excessive injury to the tissue tract or vessel. 
     For the above reasons, it would be desirable to provide improved devices, systems, and methods for suturing vascular punctures. The new device should have the capability of delivering a pre-tied knot to an incision site. It would be particularly beneficial if these improved devices provided some or all of the benefits while overcoming one or more of the disadvantages discussed above. 
     DESCRIPTION OF THE BACKGROUND ART 
     U.S. Pat. Nos. 5,700,273, 5,836,956, and 5,846,253 describe a wound closure apparatus and method in which needles are threaded with suture inside a blood vessel. U.S. Pat. No. 5,496,332 describes a wound closure apparatus and method for its use, while U.S. Pat. No. 5,364,408 describes an endoscopic suture system. 
     U.S. Pat. No. 5,374,275 describes a surgical suturing device and method of use, while U.S. Pat. No. 5,417,699 describes a device and method for the percutaneous suturing of a vascular puncture site. An instrument for closing trocar puncture wounds is described in U.S. Pat. No. 5,470,338, and a related device is described in U.S. Pat. No. 5,527,321. U.S. Pat. No. 5,507,757 also describes a method of closing puncture wounds. 
     SUMMARY OF THE INVENTION 
     The present invention provides improved devices, systems, and methods for suturing of body lumens. The device often allows the suturing of vascular puncture sites located at the distal end of a percutaneous tissue tract with greater ease, in less time, and with less patient trauma than known systems. These improvements are generally provided through the use of shafts having smaller cross-sections than prior suturing systems. In the exemplary embodiment, an elongate articulated foot near a distal end of a shaft is inserted through the penetration and actuated so that the foot extends along the lumenal axis. The foot carries suture attachment cuffs, and can be drawn proximally up against the endothelial surface of the blood vessel. Needles are advanced from the shaft, through the vessel wall beyond the penetration, and into engagement with the needle cuffs. The cross-section of the shaft within the tissue tract can be minimized by laterally deflecting the needles before they leave the shaft, while tapered depressions within the foot can help guide the advancing needles into engagement with the cuffs. The cuffs lockingly engage the needles so that the cuffs can be withdrawn proximally along the needle paths through the tissue tract so as to form a loop of suture across the puncture without having to thread the needles directly with the suture inside the blood vessel. The suture loop may be drawn distally from the shaft, proximally from within the blood vessel, or laterally down one of the needle paths, across the puncture, and out the opposing path. Regardless, the articulating foot may be realigned with the shaft and withdrawn proximally through the tissue tract in a small profile configuration. The use of an articulatable foot in combination with lateral deflection of the needles can avoid dilation of the tissue tract, as was often necessary using known puncture closure systems. 
     In a first aspect, the invention provides a method for suturing a puncture through a vessel wall of a blood vessel. The puncture is disposed within a tissue tract of a patient body, and the method comprises attaching a flexible filament to a first fitting. The first fitting is inserted through the tissue tract and positioned adjacent the vessel wall, and a needle path is formed by advancing a first needle through the vessel wall. The needle is coupled with the first fitting, and the first needle, the first fitting, and at least a portion of the filament are withdrawn through the vessel wall along the needle path. 
     First and second fittings will often be coupled to the flexible filament, and will generally be positioned so that the puncture is disposed therebetween. The flexible filament will often comprise a suture extending between the first and second fittings, with each fitting being drawn proximally by an associated needle so as to form the suture loop. Alternatively, at least one of the needles may include a detachable tip and may advance a suture distally along the needle path as the needle penetrates through the vessel wall. The flexible filament can again couple the first and second fittings, here allowing both fittings to be withdrawn along a single needle path so that the suture advances down along the first needle path, laterally across the puncture, and then out the other needle path. 
     Positioning of the fittings is generally effected by articulating an elongate foot within the blood vessel so that the foot extends along the vessel axis. A confirmation lumen may extend along a shaft supporting the foot to ensure that the foot is positioned within the vessel prior to articulation. Once the foot is properly articulated, it can be withdrawn to firmly engage the endothelial layer of the vessel. The foot will preferably include tapering depressions, which direct the advancing needle toward the fitting, and the suture or other flexible filament adjacent the fittings will often be releasably restrained within a narrow slot extending from the depression. The suture or other flexible filament and its associated slot will preferably be arranged to avoid entanglement of the advancing needle in the suture, and to ensure that the fitting and suture can be withdrawn proximally as the needle is retracted. An atraumatic, flexible monorail guidebody may extend from the shaft and/or the articulatable foot to facilitate alignment of the foot with the vessel, and also to help provide hemostasis while the knot is tied. A wide variety of foot articulation mechanisms may be provided, with deployment preferably being effected when the foot is disposed entirely within the vessel and using an actuator and foot motion that avoid dilation of the puncture. 
     In another aspect, the invention provides a method for suturing an opening in a tissue. The method comprises inserting a distal end of a probe through the opening, the probe defining a probe axis. An elongated foot of the probe is articulated so that first and second ends of the foot extend laterally with the opening aligned therebetween. A first needle path is formed from the probe, through the tissue, and to the first end of the foot. A second needle path is formed from the probe, through the tissue, and to the second end of the foot. Suture is advanced along the first and second needle paths to position a suture loop across the opening. 
     In another aspect, the invention provides a method for suturing a blood vessel. The vessel has a vessel wall, and the method comprises advancing a shaft toward the vessel wall. The shaft has an axis and a plurality of needle guides. A foot is deployed adjacent the vessel wall so that the foot extends laterally from the shaft. A plurality of needles is advanced from the needle guides of the shaft to the foot to form needle paths through the vessel wall. The needle guides deflect the needles laterally so that a needle path width between the needles is greater than a cross-sectional dimension of the shaft. Suture is advanced along the needle paths to position at least one suture loop across the puncture. 
     In yet another method of the present invention, a blood vessel is sutured through a tissue tract of a patient body. The vessel has a vessel wall, and the method comprises inserting a distal end of a probe through the puncture and into the blood vessel. A first end of the suture is advanced from the probe within the tissue tract, through the vessel wall, and into the vessel. The first end of the suture is withdrawn from the vessel through the vessel wall, and through a bight of the suture to form a loop of suture across the puncture. The first end of the suture and a second end of the suture adjacent the bight are tensioned to detach the bight from the probe and form a knot affixing the loop of suture across the puncture. Advantageously, the bight of suture may be pre-tied before the probe is inserted into the tissue tract, the bight optionally being releasably attached to the probe. 
     In a device aspect, the invention provides a system for suturing a blood vessel. The vessel has a vessel wall, and the system comprises a needle having a proximal end and a distal end suitable for forming a needle path through the vessel wall. The needle has a recessed engagement surface adjacent the distal end. The system further comprises a flexible filament and a fitting attached to the filament. The fitting has an opening and a tab extending into the opening, the tab securingly engaging the engagement surface when the needle advances through the vessel wall and into the opening, so that the fitting and at least a portion of the filament can be withdrawn proximally along the needle path by the needle. 
     In a further device aspect, the invention provides a system for suturing a puncture of a blood vessel within a tissue tract. The vessel has a vessel wall and defines an axis, and the system comprises a shaft having a proximal handle and a distal end suitable for insertion along the tissue tract and into the vessel through the puncture. A foot is mounted near the distal end of the shaft. The foot has plurality of needle receptacles extendable laterally from the shaft. A flexible filament extends between the receptacles of the foot. A plurality of needles is advanceable distally and laterally from the shaft, through the vessel wall outside the puncture, and to the receptacles of the foot. 
     In yet another device aspect, the invention provides a system for suturing a puncture of a blood vessel within a tissue tract. The vessel has a vessel wall, and the system comprises a shaft having a proximal handle and a distal end suitable for insertion along the tissue tract and into the vessel through the puncture. A foot is mounted near the distal end of the shaft. The foot has a first needle receptacle and is articulatable from a small profile configuration to a large profile configuration by actuation of the handle. A first fitting is removably mounted adjacent the first needle receptacle. A filament is coupled to the first fitting. A first needle is advanceable from the shaft to the first needle receptacle on the articulated foot. The first fitting securely engages the first needle so that the secured first fitting and at least a portion of the filament can be drawn through the vessel wall by the first needle. 
     In a still further device aspect, the invention provides a probe for suturing an opening in a tissue. The probe comprises a shaft having a proximal end and a distal end and defining an axis therebetween. The shaft has a size and configuration suitable for insertion through the opening in the tissue. An elongate foot is movably mounted to the shaft. An actuator extends along the shaft distally to the foot. Movement of the actuator slides the foot axially and pivots the foot from a low profile configuration to a deployed configuration extending laterally from the shaft. The foot supports a suture, and a needle is advanceable from the shaft, through the tissue, and to the deployed foot. 
     In another aspect, the invention provides a suturing device having a first penetrator and a second penetrator for suturing an incision. The first penetrator is configured to form a first penetration about a periphery of the incision. The first penetrator also carries a pre-tied knot disposed about a periphery of the first penetrator for delivery to the incision. The second penetrator is configured to form a second penetration about the periphery of the incision. The second penetrator also includes suture disposed thereon that is drawn by the first penetrator through the first penetration and through the pre-tied knot during retraction of the first and second penetrators from around the periphery of the incision. The first penetrator draws the suture through the first penetration via a connection between the first penetrator and the suture. Moreover, as the first penetrator draws the suture, the suture delivers the pre-tied knot to the incision for closure of the incision. 
     In another aspect, the invention provides a suturing device for suturing an incision formed in an artery. The suturing device includes a first penetrator, a second penetrator and a receiver. The first penetrator, which forms a first penetration about a periphery of the incision, includes a pre-tied knot disposed about the first penetrator. The second penetrator, which forms a second penetration about the periphery of the incision, has suture disposed thereon, which refracts through the first penetration. The suture retracts through the first penetration into the pre-tied knot during retraction of both the first penetrator and the second penetrator from around the periphery of the incision. In addition, during refraction, the suture delivers the pre-tied knot to the incision for suturing of the incision. The suturing device also includes a receiver for receiving both the first penetrator and the second penetrator upon penetration formation. The receiver connects the suture to both the first penetrator and the second penetrator and allows retraction of the suture through the first penetration as the first penetrator and the second penetrator retract. 
     In another aspect, the invention provides a suturing device for suturing an opening of an artery of a patient during a surgical procedure. The suturing device includes a first penetrator, a second penetrator and a foot. The first penetrator is disposed about a periphery of the suturing device and the second penetrator is located opposite the first penetrator on the suturing device. The first penetrator includes a pre-tied knot configured to receive suture releasably engaged with the second penetrator during suturing of the opening of the artery. The foot, which is movably coupled to the suturing device distal to the first penetrator and the second penetrator, includes a first cuff and a second cuff. The first cuff and the second cuff, which couple to one another via a link, receive the first penetrator and a detachable end of the second penetrator respectively. The first and second penetrators penetrate the artery at a proximal end of the suturing device and couple with the first cuff and the second cuff upon penetration of the artery. The first and second penetrators couple with the first cuff and second cuff such that during retraction of the first penetrator and the second penetrator from the artery, the suture delivers the pre-tied knot to the incision for closure of the incision. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective of a percutaneous blood vessel closure device according the principles of the present invention. 
         FIG. 2  illustrates the vessel closure device of  FIG. 1  in which an elongate foot is shown in a deployed position. 
         FIGS. 2A-C  illustrate actuation of a foot and advancement of needles from a shaft to the articulated foot in a probe similar to the probe of  FIG. 1 . 
         FIG. 3A  is a detailed view showing the foot of the vessel closure device of  FIG. 1  in a parked position prior to deployment. 
         FIG. 3B  is a detailed view showing the foot of the vessel closure device of  FIG. 1  in a deployed position. 
         FIGS. 4 and 4A  are perspective views illustrating a suture attachment cuff and an associated barbed needle for use in the vessel closure device of  FIG. 1 . 
         FIG. 5  is a cross-sectional view showing the barbed needles securingly engaging the suture cuffs of the deployed foot. 
         FIGS. 6A-C  illustrate one embodiment of a deployable foot, in which the foot slides and pivots when drawn proximally by a tension member. 
         FIG. 7  illustrates the suture cuff positioned within a needle receptacle, and also shows how the suture is releasably secured within a slot extending radially from the needle receptacle. 
         FIGS. 8A-C  illustrate an alternative foot articulation mechanism in which lateral slots on the foot receive pins from the shaft to allow the foot to pivot and slide axially. 
         FIGS. 9A  and B illustrate a still further alternative foot actuation mechanism in which the foot slides axially within a slot. 
         FIGS. 9C  and D illustrate a further foot actuation mechanism in which relative movement between the sides of a two-part shaft actuates the foot. 
         FIGS. 10A-D  illustrate alternative structures and techniques for avoiding entanglement of the needle with the suture. 
         FIGS. 11A-E  illustrate an alternative closure system and method for its use in which a first needle advances the suture to the foot, while a second needle engages and withdraws both the first and second suture cuffs, a flexible filament connecting the suture cuffs, and at least a portion of the suture from within the blood vessel so as to complete a pre-tied knot. 
         FIGS. 12A  and B illustrate an alternative probe having two pairs of needles and a foot with four needle receptacles so as to form two loops of suture across a puncture of a blood vessel. 
         FIGS. 13A-G  illustrate a method for use of a suture system so as to effect hemostasis of a blood vessel puncture through a tissue tract. 
         FIGS. 14A and 14B  are enlarged partial side views of a suturing device in accordance with one embodiment of the present invention. 
         FIGS. 15A through 15F  are enlarged cross-sectional views of the embodiment of the suturing device of  FIGS. 14A and 14B . 
         FIGS. 16A and 16B  are schematic views of a suture bight having a pre-tied knot in accordance with one embodiment of the present invention. 
         FIGS. 17A through 17D  show enlarged partial cross-sectional views of an embodiment of the suturing device in accordance with the invention, in which one embodiment of a penetrator tip and cuff engagement, penetrator tip disengagement, and cuff ejection sequence is illustrated. 
         FIG. 18A  is an enlarged partial cross-sectional view of an embodiment of a foot in accordance with the present invention, showing the link routing through the suture bearing surfaces of the foot. 
         FIG. 18B  is an enlarged partial cross-sectional view of an embodiment of a device in accordance with the present invention, showing the link routing through a suture-bearing surface located distal to the foot. 
         FIGS. 19A and 19B  are enlarged partial cross-sectional views of an embodiment of a foot in accordance with the present invention, showing an alternate penetrator tip and cuff engagement, penetrator tip disengagement, and cuff ejection sequence. 
         FIGS. 20A through 20C  are enlarged partial cross-sectional views of an embodiment of a foot in accordance with the present invention, showing an alternate penetrator tip and cuff engagement, penetrator tip disengagement, and cuff ejection sequence. 
         FIG. 21  is an enlarged perspective view of an embodiment of the pre-tied knot in accordance with the present invention. 
         FIGS. 22A through 22C  show an alternate embodiment of a foot in accordance with the invention. 
         FIGS. 23A through 23C  show another alternate embodiment of a foot in accordance with the invention. 
         FIGS. 24A and 24B  are perspective views of an alternative embodiment of a penetrator tip in accordance with the invention. 
         FIGS. 25A through 25C  are schematic views of an alternate embodiment of a vessel closure device in accordance with the present invention. 
         FIGS. 26A through 26D  are schematic views of alternate embodiments of a vessel closure device in accordance with the invention. 
         FIG. 27  shows a schematic view of one embodiment of a link and cuff assembly in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION 
     A suturing device, which delivers a pre-tied knot to an incision, is disclosed. As an overview, a suturing device in accordance with the present invention includes a first penetrator having a pre-tied knot disposed thereabout and a second penetrator having suture disposed thereon. During operation of the suturing device, the first penetrator and the second penetrator penetrate the tissue about a periphery of an incision in a body lumen. Upon penetration, a penetrator tip releasably engaged with the first penetrator couples with a foot of the suturing device. As the first and second penetrators retract from the body lumen, the penetrator tip and the suture coupled with the penetrator tip retract through a penetration formed in the body lumen by the first penetrator. As will be discussed in greater detail with reference to the accompanying Figures, as the suture retracts, the pre-tied knot receives the suture, forming a knot for suturing the incision in the body lumen. 
     Referring now to  FIG. 1 , a vessel closure device  10  generally has a shaft  12  having a proximal end  14  and a distal end  16 . A proximal housing  18  supports a needle actuation handle  20 . A flexible, atraumatic monorail guidebody  22  extends distally of distal end  16  of shaft  12 . 
     As can be seen with reference to  FIG. 2 , a foot  24  is articulatably mounted near the distal end of shaft  12 . Foot  24  moves between a low profile configuration, in which the foot is substantially aligned along an axis of shaft  12  (as illustrated in  FIG. 1 ), to a deployed position, in which the foot extends laterally from the shaft, upon actuation of a foot actuation handle  26  disposed on proximal housing  18 . 
       FIG. 2A  through C illustrate the structure and actuation of foot  24  of a preferred probe  10 ′ having a modified proximal housing, and also show how needles  38  can be advanced distally from shaft  12  to the foot by depressing needle actuation handle  20 . 
     Actuation of foot  24  is illustrated more clearly in  FIGS. 3A  and B. In the parked position illustrated in  FIG. 3A , foot  24  extends substantially along axis  28  of shaft  12 . Note that the axis of the shaft need not be straight, as the shaft may curve somewhat, particularly adjacent the foot. In the exemplary embodiment, foot  24  is substantially disposed within a foot receptacle  30  of shaft  12  so as to minimize the cross-section of the device adjacent the foot prior to deployment. Advantageously, prior to deployment of the foot, device  10  can have a cross-section adjacent foot  24  of about 7 Fr or less, ideally having a cross-section of about 6 Fr or less for the entire device distally of the proximal end  14  of shaft  12 . 
     Actuation of foot handle  26  slides a foot actuation wire  32  proximally, pulling foot  24  from a parked position to the deployed position illustrated in  FIG. 3B . Once deployed, a first end  24   a  and a second end  24   b  of foot  24  extend laterally from the shaft. Suture  34  here comprises a continuous filament with ends disposed in needle receptacles adjacent each end of the foot. An intermediate portion of suture  34  may extend proximally along a suture lumen of shaft  12  to and/or beyond proximal housing  18 . Alternatively, in preferred probe  10 ′, the length of suture between the ends may extend distally within flexible guidebody  22 , preferably in a dedicated lumen (separate from the monorail guidewire lumen). In still further alternatives described below, a short length of suture or some other flexible filament may extend substantially directly between the needle receptacles. 
     Shaft  12  also includes a foot position verification lumen that extends distally from a position verification port  36  to a position indicator at housing  18 . When the foot is properly positioned within the blood vessel, blood pressure will cause blood to flow proximally through the indicator lumen to the indicator. The indicator may optionally comprise a blood exit port, a clear receptacle in which blood is visible, or the like. In the exemplary embodiment, the indicator of handle  18  comprises a length of clear tubing extending from housing  18  (not shown) in which the blood is clearly visible. It should be understood that a wide variety of alternative position verifications sensors might be used, including electrical pressure sensors, electrolytic fluid detectors, or the like. 
     The structures used in positioning a loop of suture across the puncture can be understood with reference to  FIGS. 4 ,  4 A, and  5 . In general terms, needles  38  extend from shaft  12  into secured engagement with fittings  40  attached to sutures  34 . More specifically, needles  38  include a barbed end  42  defining a recessed engagement surface  44 . Fittings  40  are roughly cylindrical structures having an axial channel  46  that receives barbed end  44  of needle  38  therein. A first slot is cut in fitting  44  so as to define at least one tab  48 . Tabs  48  can be resiliently biased inward into channel  46 . As needle  38  advances into fitting  40 , barbed end  42  resiliently displaces tab  48  clear of channel  46  so as to allow the barbed end to pass axially into the fitting. Once barbed end  42  is disposed axially beyond tab  48 , the tab resiliently flexes back into the channel, capturing needle  38  by engagement between the tab and recessed surface  44 . As each tab can hold the fitting in place on the needle, the use of more than one tab increases the reliability of the system. Ideally, three tabs are provided, as illustrated in  FIG. 4A . 
     To facilitate attachment of fitting  40  to suture  34 , a second slot cut in the tubular fitting structure defines a suture attachment collar  50 . Optionally, collar  50  maybe crimped about suture  34  to mechanically affix the suture to fitting  40 . In addition and/or instead of mechanical crimping, suture  34  may be bonded to fitting  40  using an adhesive, heat, fasteners, knots, or the like. 
     Fitting  40  is quite small in size, and is generally configured to facilitate withdrawing the fitting (and the attached suture) along with needle  38  axially through the vessel wall along the needle path. Needle  38  will generally have a cross-sectional width of between about 0.010 inches and 0.020 inches. Barb  42  will extend laterally so as to define an engagement surface  44  having a protruding length of between about 0.002 inches and 0.005 inches. Fitting  40  will preferably have a cross-sectional size roughly corresponding to or only slightly larger than needle  38 . Fitting  40  will typically have an outer lateral width of between about 0.014 inches and 0.025 inches, and an axial length of between about 0.035 inches and 0.050 inches. Channel  46  will be sized to receive at least a portion of needle  38 , and will generally have a width of between about 0.010 inches and 0.020 inches. Suture  34  will preferably extend axially opposite the open end of channel  46  so as to minimize drag when the suture is drawn proximally along the needle path. In the exemplary embodiment, needle  38  has a diameter of about 0.020 inches, while the fitting comprises a tube having an outer diameter of about 0.020 inches, an inner diameter of about 0.016 inches, and an overall length of about 0.047 inches. The fitting will typically comprise a resilient material, preferably comprising a metal, and in the exemplary embodiment, comprising stainless steel. 
     Needles  38  typically have a length of between about 5.0 inches and 6.0 inches, and will preferably be sufficiently stiff to be advanced in compression through the vessel wall (and adjacent tissues) for up to 0.5 inches when supported in cantilever. Nonetheless, the needles will ideally be flexible enough to be laterally deflected within shaft  12 , as can be understood with reference to  FIG. 5 . Needles  38  generally comprise a high strength metal, ideally comprising stainless steel. Fittings  40  will also preferably comprise a flexible material to allow tab  48  to flex out of the way of barbed end  42 , and to resiliently rebound and engage recessed surface  44 . In the exemplary embodiment, barbed end  42  has a diameter of about 0.015 inches, with the diameter of the needle decreasing to about 0.008 inches proximally of the barb so as to define the recessed engagement surface. 
     As was generally described above, foot  24  includes needle receptacles  52  adjacent the ends of the foot. A fitting  40  (with an associated end of suture  34 ) is disposed within each needle receptacle, and a surface of the receptacle tapers proximally and outwardly so as to guide the advancing needles  38  into engagement with fittings  40  when foot  24  is in the deployed position. As fittings  40  (and associated portions of suture  34 ) are releasably supported in the foot, needles  38  can be withdrawn proximally so as to draw the fittings and suture ends from the foot proximally into (and optionally through) shaft  12 . The needle receptacles of the exemplary embodiment taper outward at an angle between 20 and 35 degrees from the centerline of fitting  40 , and the fitting is held in a recess having a diameter of about 0.0230 inches and a length of about 0.042 inches. A lateral opening or window through the side of foot to the fitting recess may be provided to facilitate needle and/or cuff positioning during assembly of the probe, and a protruding collar near the proximal end of the fitting recess may help keep the fitting in position. 
       FIG. 5  also illustrates the lateral deflection of needles  38  by needle guides  54  of shaft  12 . This lateral deflection of the needles allows the use of a small diameter shaft, while still encompassing sufficient tissue within the suture loop on opposite sides of the puncture so as to effect hemostasis when the suture looped is tightened and secured. In the exemplary embodiment, shaft  12  comprises an outer casing of a biocompatible material such as stainless steel, carbon fiber, nylon, another suitable polymer, or the like. Needle guides  54  may be defined at least in part as lumens formed within the casing of a polymeric material such as nylon or the like. In some embodiments, shaft  12  may comprise a carbon fiber filled nylon, or carbon fiber filled with an alternative material. 
     One example of a suitable structure and articulation motion for foot  24  is illustrated in  FIGS. 6A  and B. Foot actuation wire  32  (see  FIG. 3A ) rides in a lumen of shaft  12 , and draws foot  24  from a parked position (shown in  FIG. 6A ) to a deployed position (shown in  FIG. 6B ) through a combination of sliding and pivoting of the foot. The foot remains supported throughout its range of motion by arms disposed laterally on either side of the foot, the arms defining (at least in part) foot receptacle  30 . Once foot  24  is deployed, needle receptacles  52  and/or the fittings disposed therein will preferably define a lateral suturing width  56  in a range from about 0.260 inches to about 0.300 inches. Foot  24  may be machined or cast from a polymer or metal, but will preferably comprise a polymer such as carbon fiber filled nylon. In some cases, foot  24  may be molded as two separate halves that can subsequently be affixed together. Needles  38  advance from the fixed needle guides  54 , and are laterally directed into fittings  40  by receptacles  52 , as illustrated in  FIG. 6C . In general, a shape memory alloy such as Nitinol™ in its superelastic regime provides a particularly advantageous actuator wire for manipulating foot  24 . 
     Referring now to  FIG. 7 , fittings  40  and suture  34  will be withdrawn proximally by the needles from needle receptacles  52 . To releasably support fittings  40  and suture  34  and avoid entanglement of the suture in the needles, suture  34  is fittingly received within a slot  58  that extends laterally from needle receptacles  52 . As the needles pull the fitting axially from needle receptacles  52 , suture  34  is pulled from slot  58  and free from foot  24 . Bending of the suture proximally within the suture slot can also locally increase the suture width, so that the interaction between the bent suture and the slot can help hold the fitting in the recess. 
     A wide variety of foot actuation mechanisms might be used within the scope of the present invention. A first alternative foot actuation arrangement is illustrated in  FIGS. 8A-C . In this embodiment, a shaft  12   i  has pins  60  which ride in associated slots  62  of a foot  24   i . Proximal motion of an actuation wire causes foot  24   i  to move axially and rotationally, with pins  60  sliding along slot  62 , and the foot pivoting about the pins. In this embodiment, guidebody  22  extends directly from the foot, as illustrated in  FIG. 8C . 
     A still further alternative foot actuation mechanism is illustrated in  FIGS. 9A  and B. In this embodiment, slidable foot  24   ii  is slidingly received within a receptacle  30  of shaft  12   ii . Sliding of the foot  24   ii  from the parked position of  FIG. 9A  to the deployed position of  FIG. 9B  places the needle receptacles  52  in the paths of needles from the shaft  12   ii  without pivoting of the foot. Guidebody  22  (see  FIG. 1 ) will extend here from a distal end of shaft  12   ii  at a fixed angle from the shaft. Optionally, insertion through the tissue tract may be facilitated by including an additional bend in the shaft axis adjacent the guidebody on many embodiments. 
     Yet another foot actuation mechanism can be understood with reference to  FIGS. 9C  and D. Shaft  12   iii  is formed in two parts, which slide axially relative to each other when foot actuation lever  26   iii  moves, using an offset crank arrangement. A similar offset crank supports foot  24   iii , so that the sliding shaft parts cause the foot to pivot as shown. 
     A variety of features may be included in the articulatable foot, the needle receptacle, and/or the needle to avoid tangling of the needle in the suture as the needle is directed to the fitting. As illustrated in  FIG. 10A , a moveable flap  64  may extend over slot  58  so that the advancing needle slides along the flap toward the fitting, rather than entering the slot and engaging the suture directly. Flap  64  may be affixed along one side of the slot, with the other side of the flap flexing into the receptacle to release the suture from slot  58  when the fitting and suture are withdrawn by the needle. 
     An alternative mechanism for avoiding entanglement of the needle with the suture is illustrated in  FIG. 10B . In this embodiment, needle receptacles  52   i  have tangential slots  58   i  which extends substantially tangentially to the surface of the receptacle. As a result of this tangential arrangement, a needle entering the receptacle  52   i  will be directed toward the fitting contained therein, but will generally not be able to enter and advance within the tangential slot  58   i  so as to become entangled with the suture. As illustrated in this embodiment, the slots may optionally extend laterally through the foot so that the loop of suture can be pulled from one side of the shaft without interference. 
     A still further alternative mechanism for avoiding entanglement between the suture and the needle is illustrated in  FIGS. 10C  and D. Two-part needle  38   i  includes an outer sheath  66  and an inner core  68 . The parts of these needles initially advance together into the receptacles with the needle core  68  withdrawn so that the needle presents a smooth tapered tip (the combined tip preferably being larger in diameter than the slot containing the suture) as illustrated in  FIG. 10C . Once two-part needle  38   i  is fully positioned within the needle receptacle, needle core  68  may extend axially to expose barbed tip  42  and recessed engagement surface  44  and to secure the needle to the fitting within the needle receptacle. In the exemplary embodiment of  FIGS. 4 and 5 , barbed tip  42  is formed integrally with the rest of the needle structure, but the tip has a larger cross-section than radial slot  58  containing the suture  34 . As a result, the barbed tip is unable to enter the slot, thereby avoiding entanglement between the needle and suture. 
     An alternative vessel closure probe  70  will be explained with reference to  FIGS. 11A through 11E . This embodiment include an articulatable foot  24  having a pair of needle receptacles  52 , as described above. Although each needle receptacle  52  contains a fitting  40  for coupling a flexible filament to a tip of an associated needle, the filament in this case comprises a temporary connecting filament  74 , as shown schematically in phantom in  FIG. 11A , spanning directly between the needle receptacles. Rather than pulling the two ends of an extended loop through the needle paths and proximally out the tissue tract for tying, closure system  70  advances a single end of the suture distally along one needle path, across the puncture, and then proximally along the other needle path. To provide this interaction, at least one needle include means for attaching a suture  34  to connecting filament  74 , herein the form of a detachable coupling structure carried on the at least one needle. This structure facilitates the use of a pre-tied knot. 
     Referring now to  FIGS. 11A  and B, the distal end of probe  70  advances distally through skin S and into a tissue T of the patient while the probe is in the small profile configuration with foot  24  aligned along the axis of the probe. Here, however, an end  76  of suture  34  is affixed to a detachable needle tip  78  of a hollow needle  38 ′. Detachable tip  78  comprises a fitting having an opening receiving an end of suture similar to fitting  40 , attached to a barbed needle end (similar to that of needle  38 ). Suture  34  may extend proximally within hollow needle  38  where the needle has an open channel along its length, may exit the hollow needle just proximally of detachable tip  78 , or may be disposed alongside a solid needle. Needle  38  (opposite hollow needle  38 ′) has a fixed barbed tip, as described above, and a bight of suture  80  is releasably attached to the probe shaft encircling the opening of needle guide  54  of the fixed tip needle. The bight of suture may be releasably disposed within a slot of the probe, may be temporarily held in place by a weak adhesive or coating, or the like. A second end  82  of suture  34  extends proximally along the shaft of the probe, the second end of the suture optionally also being releasably held along the shaft. 
     Bight  80  will define a knot when first end suture passes therethrough, as can be understood with reference to FIGS.  11 Ai and  11 Aii. Bight  80  will often include more than one loop, and may be pre-arranged so as to define a square knot (using the layout schematically illustrated in FIG.  11 Ai), a clinch knot (FIG.  11 Aii), or a variety of known or new surgical knots. 
     Probe  70  advances along tissue tract TT to puncture P in blood vessel V. Once foot  24  is disposed within a blood vessel V, a pull wire moves the foot proximally and pivots the foot laterally so that the foot extends along an axis A of the vessel, as illustrated in  FIG. 11B . The foot can then be pulled proximally against an inner surface of the vessel wall W to ensure that the needle receptacles  52  are properly positioned. 
     As can be understood with reference to  FIGS. 11C  and D, hollow needle  38 ′ and needle  38  advance to engage fittings  40  within receptacles  52 . Hollow needle  38 ′ draws first end  76  of suture  34  distally through vessel wall W, and detachable tip  78  is secured into an associated fitting  40  using the barb and tab interaction described above. As connecting filament  74  extends between fittings  40 , and as detachable tip  78  can pull free of hollow needle  38 ′ when the needles are withdrawn, this effectively couples needle  38  to first end  76  of suture  34 . The detachable tip riding partially within the hollow needle (or vice versa) so that the assembly remains together under compression. Hence, needle  38  can pull the suture distally along the needle path formed by hollow needle  38 ′, across the puncture P, and proximally along the needle path formed by needle  38 , as illustrated in  FIG. 11D . 
       FIGS. 11D  and E show that the knot can be completed by pulling needle  38 , connecting filament  74 , and first end  76  of suture  34  (together with the fittings  40  and detachable needle tip  78 ) proximally through bight  80 . Second end  82  of suture  34  can be pulled to free bight  80 , and the ends of the suture can be tightened and the probe removed to provide permanent hemostasis. 
     It will be recognized that removal of probe  70  can be facilitated by coupling first end  76  to bight  80  over an outer surface of the probe, and by arranging suture  34  and hollow needle  38 ′ so that the suture can pull free of the needle when detachable tip  78  is released, for example, by having the suture exit the needle proximally of the tip through a channel that extends to the tip so that the needle does not encircle the suture. By including such provisions, after foot  24  is returned to the narrow configuration, the probe can be pulled proximally from the tissue tract leaving the pre-tied knot in place. 
     Alternative arrangements (using the detachable needle ends of probe  70 ) are possible to provide the benefit of a pre-tied knot and the like for closure of a vessel puncture. For example, a probe having a pair of needles in which each needle included a detachable tip might be used to pull first end  76  through a bight, so that the bight need not encircle the needle path of one of the needles. 
     In some cases, particularly for closure of large punctures, it may be advantageous to provide multiple suture loops across the puncture, either in parallel, in an “X” pattern, or the like. As illustrated in  FIGS. 12A  and B, the present invention encompasses the use of more than two needles and associated receptacles, fittings, sutures, and the like. Multiple loop systems may have four, six, eight, or more needles, or may even have odd numbers of needles and fittings, particularly where one or more fittings have a plurality of suture ends extending therefrom. This allows a wide variety of stitching patterns to be provided by such multiple loop probes. 
     The method of use of the probes of  FIGS. 1-7  can be understood with reference to  FIGS. 13A-G . After accessing a blood vessel V (often using the Seldinger technique), a guidewire GW is left extending into skin S and down through tissue T along tissue tract TT. Guidewire GW enters vessel V through a puncture P in vessel wall W, and extends along the vessel throughout many endovascular procedures. As illustrated in  FIG. 13A , distal guidebody  22  is advanced over the guidewire GW in a monorail fashion, so that the guidewire helps to direct the probe along the tissue tract TT and into the vessel through puncture P.  FIG. 13B  shows that when sensor  36  is disposed within the vessel, blood can flow from the sensor port and through a lumen in shaft  12  to the proximal handle to notify the operator that foot  24  has been advanced far enough for deployment. 
     Deployment of the foot is effected by actuation of the foot deployment handle, as described and illustrated above with reference to  FIGS. 2 and 2B . As described above, guidebody  22  helps to align the probe with the axis of vessel V. Guidebody  22  may be set at an angle and/or offset relative to shaft  12  as appropriate to aid in alignment with a particular vessel access technique. As shown in  FIG. 13C , the deployed foot  24  extends laterally from the shaft, so that foot  24  adjacent receptacles  52  can be drawn up against vessel wall W by gently pulling shaft  12 . Hence, the foot helps to accurately position the needle guides  54  at a distance from the vessel wall. 
     Referring now to  FIG. 13D , flexible needles  38  are deflected laterally by needle guides  54  toward receptacles  52  of the deployed foot. As a result, the needles advance in cantilever both distally and laterally when needle actuation handle  20  is pressed (see  FIG. 2C ), and the tapering surfaces of receptacles  52  help to push the needles back into alignment with the fittings so as to overcome any unintended deflection of the needles by tissue T or vessel wall W. This ensures that needles  38  securingly engage fittings  40  within receptacles  52 , thereby coupling the ends of suture  34  to the needles. While suture  34  is here illustrated running along the side of shaft  12  outside foot receptacle  30  to a lumen within guidebody  22 , it should be understood that the suture loop might instead extend proximally in a lumen of shaft  12 , might be routed through the foot and/or foot receptacle, and/or might be stored in a spool adjacent foot  24 . Regardless, suture  34  should able to pull free of the probe between its ends to form a continuous loop across puncture P. 
     Referring now to  FIGS. 13E  and F, fittings  40  and the ends of suture  34  are drawn proximally through the vessel wall W along the needle paths formed by needles  38 . Optionally, the needles may be withdrawn proximally out of the tissue tract and clear of shaft  12 , or they may remain coupled to the shaft within needle guides  54 . The foot actuator is moved to store foot  24  along shaft  12 , and the shaft can then be pulled proximally from the tissue tract. Guidebody  22 , which may comprise a soft, compliant polymer, may temporarily extend at least partially into tissue tract TT and through puncture P to help reduce the loss of blood until the loop is secured. 
     Now referring to  FIG. 13G , once shaft  12  has been withdrawn sufficiently to expose needle guides  54 , the ends of the suture loop can be grasped by the operator. Tying of a knot in suture  34  can then proceed in a conventional manner. The use of a clinch knot may facilitate gradual tightening of the knot while removing guidebody  22 , although a wide variety of knot and knot advancing techniques might be used. 
       FIGS. 14A and 14B  show an embodiment of a vessel closure device  100 . This embodiment includes an articulatable foot  114  ( FIG. 14B ) having a pair of penetrator receptacles (described below). Although each penetrator receptacle contains a fitting (or cuff) for coupling a flexible filament to a tip of an associated penetrator, the filament in this case may be a short length of suture such as a link  112  spanning directly between the penetrator receptacles. Rather than pulling the two ends of an extended loop through the needle paths and proximally out the tissue tract for tying, closure system  100  advances a single end of the suture distally along one needle path, across the puncture, and then proximally along the other needle path. To provide this interaction, at least one needle includes means for attaching suture  102  to the link  112 , here in the form of a detachable coupling structure carried on the at least one needle. This structure facilitates the use of a pre-tied knot. 
       FIG. 15A  shows a side, cross-sectional view of the device  100  in a position prior to deployment of the foot  114 . The device  100  has been advanced through the incision  105  in the arterial wall W. For ease of description, reference numeral  122  indicates the anterior side of the device, and reference numeral  124  denotes the posterior side of the device. Device  100  has a rigid shaft  118  that has channels defined therein to carry the elongate bodies or penetrators  106  and  106 ′. Penetrator  106 ′ may also be referred to as the anterior penetrator, and penetrator  106  may be referred to as the posterior penetrator. For purposed of description and not limitation, the anterior penetrator  106 ′ carries the pre-tied knot  104 , and posterior penetrator  106  carries the detachable coupling structure or penetrator tip  108 . Anterior penetrator  106 ′ defines a penetrator tip  108 ′ at its distal end. 
     The articulatable foot  114  includes anterior and posterior penetrator receptacles  116 ′ and  116 , respectively. These receptacles are also referred to as cuff pockets. Cuffs  110  are shown positioned in cuff pockets  116 ′ and  116 . A link  112  extends between the cuffs  110 . 
       FIG. 15B  shows the foot  114  deployed so as to position the cuff pockets  116  to receive the first and second penetrators  106 ′ and  106 . As shown in  FIG. 15B , the anterior penetrator  106 ′ has the pre-tied knot  104  disposed about a proximal portion of its length. Alternatively, the pre-tied knot  104  may be disposed about the periphery of a knot tube, through which the anterior penetrator  106 ′ may pass (as described in further detail below). 
       FIG. 15B  illustrates the suturing device  100  deployed within a lumen  107  in accordance with an embodiment of the present invention. As may be seen with reference to the Figure, the suturing device  100  includes an elongate body  106 ′ having a penetrator tip  108 ′. The elongate bodies  106  and  106 ′ deploy to form penetrations  109  and  109 ′ within the vessel wall W. The configuration of the penetrator tip  308  allows penetration of the vessel wall W immediately surrounding the incision  105  to form the penetration  309 . As such, the penetration of the penetrator tip  108  through the tissue wall W allows for passage of the elongate body  106  through the tissue and into the lumen  107 . The elongate body  106  holds the suture  102  as the elongate body  106  passes through the tissue wall W immediately adjacent the incision  105  and into the foot  114 . 
     As may be seen with reference to  FIG. 15B , in this embodiment, the foot  114  has a single unit design where the cuffs  110  and  110 ′ are disposed on opposite sides of the suturing device  100  and the foot  114 . This orientation allows balance of forces during the deployment of the elongate bodies  106  and  106 ′, thereby allowing precise suturing and minimizing the possibility of incorrectly suturing the incision  105 . Also, as may be seen with reference to the Figure, the suturing device  100  delivers the suture longitudinally relative to the lumen  107 , thereby minimizing arterial diameter constriction. Likewise, in this embodiment, the foot  114  is positioned at an angle “Q” relative to the shaft  118  of the suturing device  100 . Preferably, the angle “Q” is in a range between about 20 degrees and about 60 degrees and more preferably is about 40 degrees. The angle “Q” approximates the puncture angle commonly used to access the femoral artery. The angle Q and the rigid character of the shaft  118  serve to provide accurate, virtually simultaneous “cuff capture” by both the anterior and posterior penetrators. Moreover, since the device  100  is preferably used without an introducer sheath, the rigid nature of the shaft  118  provides the control of the travel of penetrators as they move distally to engage the cuffs. The device  100  can therefore be used in the same femoral artery access puncture without disturbing the existing tissue tract and causing undue discomfort to the patient. 
     When both the elongate bodies  106  and  106 ′ and the suture  102  pass through the lumen wall W and into the lumen  107 , the elongate bodies  106  and  106 ′ engage with the foot  114 . The penetrator tip  108  and anterior penetrator tip  108 ′ of the elongate bodies  106  and  106 ′ engage with cuffs  110  and  110 ′ of the foot  114 . The cuffs  110  and  110 ′ include a link  112  that connects the cuffs  110  and  110 ′ to one another. It should be noted that the cuffs  110  and  110 ′ facilitate connection of the penetrator tip  108  with the anterior penetrator tip  108 ′ such that the penetrator tip  108  and the anterior penetrator tip  108 ′ are coupled to one another via the link  112 . 
       FIGS. 16A and 16B  show the suture bight in the pre-deployed state ( FIG. 16A ) and the deployed state ( FIG. 16B ). The suture  102  is arranged to provide the pre-tied knot  104  that automatically travels down from the shaft of the device where it is stored prior to delivery to the tissue wall. The loop  104  of suture  102  serves to pull the knot  104  down the rail portion  140  of the suture during deployment. It should be noted that it would-be desirable to be able to distinguish the ends  140  and  150  of the suture  102  during deployment so that the correct end is pulled by the operator to advance the knot. Should the non-rail end be pulled, the knot may be prematurely tightened before it is advance to its deployed position at the wall of the vessel. 
     The ends of the suture may be distinguished from each other by changing the color of one end (e.g. with dye), providing an attachment on one end (e.g. shrink wrap tubing, a bead, etc.) or with the suture itself (e.g. tying a knot in one end). 
       FIG. 15C  shows the penetrator tips fully deployed into and engaged with the cuffs  110 .  FIG. 15D  shows the penetrators being retracted after the tips have engaged the cuffs  110 . On the anterior side  122 , the penetrator  106 ′ is pulling the anterior cuff  110  distally. On the posterior side  124 , the penetrator tip  108  has been disengaged from the penetrator  106 , via a mechanism described below. As shown in  FIG. 15D , the link  112  is now coupled to one end of the suture via posterior cuff  110 . Suture  102  is also shown exiting the posterior penetrator shank via an opening in the side of the penetrator shank. 
     Referring to  FIG. 15E , after deployment of the foot  114 , the suture  102  moves as indicated by directional arrows X 1 . As the suture  102  moves, a suture loop  103  also moves in a direction indicated by directional arrow X 2  towards the foot  114  and the incision (not shown). The suture  102  moves through the foot  114  and through an opening distal to the foot  114  that defines a suture-bearing surface  111 . The suture-bearing surface  111  is disposed at a distal end of the suturing device  100  separate from the foot  114 , in this embodiment. The suture bearing surface  111  bears forces placed on the suture  102  during suturing. As such, the suture-bearing surface  111  minimizes forces placed on an incision during incision tensioning, thereby minimizing the possibility of damaging tissue immediately surrounding the incision. In this embodiment, the suture bearing  111  is a slot disposed at a distal end of the suturing device  100 , which includes a passage for the suture  102  during incision suturing as shown with reference to the Figure. 
     As the suture loop  103  and the suture  102  move, the pre-tied suture knot  104  also moves in the same direction as the suture loop  103  towards the foot  114  and the incision. The suture loop  103  continues to move the pre-tied suture knot  104  towards the incision until the suture  102  and the pre-tied suture knot  104  suture the incision formed in the arterial wall. It should be noted that a suture trimmer might be used to assist the delivery of the knot  104  to an arteriotomy. The suture trimmer may be any device suitable for pushing the knot towards the arteriotomy and trimming suture immediately adjacent the knot  104  once the knot is tightened. 
     Now making reference to  FIG. 15F , the suturing device  100  delivers the pre-tied suture knot  104  to the incision and the foot  114  is returned to its non-deployed position. The penetrators (not shown) have been retracted, the link has been fully refracted through the knot, and the knot has been advanced to the vicinity of the arterial wall. When the body of the device is removed, a stitch will remain in place across the incision in the artery. It should be noted that embodiments of the device described herein place a stitch of suture in a longitudinal orientation with respect to the vessel so as to minimize transverse vessel constriction and also to take advantage of the transverse orientation of the fibers of the vessel tissue. 
       FIGS. 16A and 16B  show the suture bight in the pre-deployed state ( FIG. 16A ) and the deployed state ( FIG. 16B ). The suture  102  is arranged to provide the pre-tied knot  104  that automatically travels down from the shaft of the device where it is stored prior to delivery to the tissue wall. The loop  104  of suture  102  serves to pull the knot  104  down the rail portion  140  of the suture during deployment. It should be noted that it would be desirable to distinguish the ends  140  and  150  of the suture  102  during deployment so that the correct end is pulled by the operator to advance the knot. Should the non-rail end be pulled, the knot may be prematurely tightened before it is advanced to its deployed position at the wall of the vessel. 
     The ends may be distinguished from each other by changing the color of one end (e.g. with dye), providing an attachment on one end (e.g. shrink wrap tubing, a bead, etc.) or with the suture itself (e.g. tying a knot in on end). 
       FIG. 17A  shows an enlarged detail of the posterior portion of the foot of one embodiment of suturing device  300 . In an accordance with an embodiment of the present invention, the elongate body  306  may be any type of structure capable of penetrating the wall of a lumen, such as an artery, a blood vessel, or the like. In addition to the penetration capability, the elongate body  306  may be a hollow tube capable of holding suture. Examples of such structures may include a hypodermic needle or the like. The suturing device  300  stores the elongate body  306  within its shaft (not shown). As previously described with reference to  FIGS. 2A through 2C , a user deploys a handle (not shown) of the suturing device  300  thereby deploying the elongate body  306  and the penetrator tip  308 . During deployment, the elongate body  306  and the penetrator tip  308  penetrate the lumen wall W immediately surrounding the incision  305  and enter the lumen  307  of a patient, as shown with reference the following  FIG. 17B . 
     Once the penetrator tip  308  engages with the cuff  310 , the elongate body  306  and the penetrator tip  308 , along with the cuff  310 , proceed through the foot  314  and into the lumen  307 . As may be seen with reference to  FIG. 17B , the cuff  310  is pushed through the foot  314 , such that the cuff  310  is pushed out of a pocket  316  and through the foot  314  into the lumen  307 . Once the cuff  310  and the elongate body  306  enter the lumen  307 , the penetrator tip  308  detaches from the elongate body  306  via a push mandrel  315  as shown with reference to  FIG. 17C . 
       FIG. 17C  illustrates the detachment of the pentrator tip  308  from the elongate body  306  in accordance with one embodiment of the present invention. Upon engagement of the penetrator tip  308  with the cuff  310 , the push mandrel  315  is further advanced such that it contacts a proximal surface  308   b  of the penetrator tip  308 , and further still until the penetrator tip  308  detaches from the elongate body  306 . Upon detachment of the penetrator tip  308  from the elongate body  306 , the push mandrel  315  and the elongate body  306  retract from the foot  314 , as shown with reference to  FIG. 17D . 
     As shown in  FIG. 17D , after the penetrator tip  308  detaches from the elongate body  306 , the elongate body  306  retracts from the penetrator tip  308  and cuff  310 . Meanwhile, on the anterior side of the device (not shown in  FIG. 17D ), the elongate body  306 ′ also includes the needle tip  308 ′ which engages with the cuff  310 ′ as previously described with reference to  FIG. 15C . The needle tip  308 ′ does not disengage from the elongate body  306 ′ upon engagement with the cuff  310 ′. Therefore, during refraction of the elongate body  306 ′ from within the lumen  307 , the needle tip  308 ′ also refracts from the lumen  307  through the penetration  309 ′. As the needle tip  308 ′ retracts through the penetration  309 ′, the elongate body  306 ′ also retracts the cuff  310 ′. As previously described, the cuff  3   10 ′ couples with the cuff  3   10  via the link  312 . During refraction of the cuff  310 ′ through the penetration  309 ′, the cuff  310  and the suture  302  also retract through the penetration  309 ′, thereby drawing the suture  302  through the penetration  309 ′. It should be noted that the foot  314  may provide suture bearing surface for the suture  302  during operation of the suturing device  300 , as shown with reference to  FIG. 18A . 
       FIG. 18A  shows an embodiment of the present invention illustrating the passage of the suture  302  through the lumen  307  and the passageways  309  and  309 ′. As may be seen with reference to the Figure, the cuff pockets  316  of the foot  314  provide a suture-bearing surface for the suture  302  as the suture  302  is drawn through the passageways. The suture bearing surfaces of the foot  314  minimize the possibility of the suture  302  damaging tissue surrounding the incision  305 . 
     In another embodiment shown in  FIG. 18B , the suturing device  300  also provides a suture bearing surface for the suture  302 . During retraction of the elongate bodies  306  and  306 ′ from the lumen  307 , the suture  302  refracts through the foot suture bearing surfaces  314   a  and the suture-bearing surface  311  formed distally of the foot. The distal suture bearing surface  311  and the foot suture bearing surfaces  314   a  guide the suture  302  in order to minimize the possibility of the suture  302  damaging the patient during retraction of the elongate bodies  306  and  306 ′ from the lumen  307 . In this embodiment, suture-bearing surface  311  is a slot defined in the body of the device distal of the foot. The slot includes a passage for the link and suture, and an edge  311   a . It is contemplated that the edge  311   a  may contact the edge of the incision in the artery and become caught on the adventitia of the blood vessel. Various devices may be provided, such as flaps, o-rings, etc., that provide a smoother transition over the slot and edge  311   a  as the device is inserted through the incision. 
       FIGS. 19A and 19B  illustrate an alternative embodiment of the present invention for releasing the cuff  310  from the foot  314 . In this embodiment, the foot  314  includes link passageway  313  through which the link  312  passes. After the elongate body  306  engages the penetrator tip  308  with the cuff  310 , the elongate body  306 , during refraction from the foot  314 , removes the cuff  310  and the penetrator tip  308  from the foot  314 . The force holding the penetrator tip  308  on the elongate body  306  overcomes the force holding the cuff  310  in the cuff pocket  316 . Once the cuff  310  clears the foot  314  and attains the orientation shown with reference to  FIG. 19B , the previously described push mandrel (not shown) detaches the penetrator tip  308  from the elongate body  306 . Upon detachment of the penetrator tip  308  from the elongate body  306 , the link  312 , along with the cuff  310  and the penetrator tip  308 , retracts through the passageway  313  via the link  312  and the elongate body  306 ′. In an alternate embodiment, the cuff  310  and pentrator tip  308  maybe pulled off the elongated body  306  by tension in the link  312 . 
     In yet another alternate embodiment shown in  FIGS. 20A through 20C , the cuff  310  and penetrator tip  308  may be detached from the elongate body  306  before being removed from the cuff pocket  316 . In this embodiment, after the elongate body  306  and the penetrator tip  308  engage with the cuff  310 , the push mandrel  315  detaches the penetrator tip  308  from the elongate body  306 , leaving it in the cuff pocket  316  to be removed by tension in the link  312 , as shown in  FIG. 20C . 
     It should be noted that other methods might be used to detach the penetrator tip  308  from the elongate body  306 . These methods include, but are not limited to, detachment through friction or tension. Making reference to  FIG. 20B , in an embodiment where friction between the cuff pocket  316  and the cuff causes detachment of the penetrator tip  308  from the elongate body  306 , a surface  308   c  of the penetrator tip  308  frictionally engages with a cuff surface  316   a  of the cuff pocket  316 . During refraction of the elongate body  306  from the foot  314 , the frictional engagement between the cuff surface  316   a  and the penetrator tip surface  308   c  causes detachment of the penetrator tip  308  from the elongate body  306 . In an embodiment where link tension causes detachment of the penetrator tip  308  from the elongate body  306 , the link  312  is tensioned such that the link  312  is taut between the cuffs  310  and  310 ′. As such, the tension of the link  312  prevents movement of the cuff  310  out of the foot  314  along with the elongate body  306  during retraction of the elongate body  306  from the foot  314 , thereby causing detachment of the penetrator tip  308  from the cuff  310 . 
     After detachment, during retraction of the elongate body  306  and the elongate body  306 ′ (not shown), the link  312  may draw the cuff  310  and the penetrator tip  308  from the cuff pocket  316 . As discussed earlier, the cuff  310 ′ engages with the elongate body  306 ′ and pulls the cuff  310  via the link  312  as the elongate body  306 ′ refracts from the lumen  307 . As such, retracting the link  312  pulls on the cuff  310 , thereby pulling the cuff  310  from the cuff pocket  316  and through the lumen  307  along with the suture  302 , as shown with respect to  FIG. 20C . 
       FIG. 21  shows the pre-tied suture knot  304  disposed about a periphery of a knot tube  301 . In this embodiment, the knot tube  301  includes a hollow center  301   a  configured to allow passage of an elongate body (not shown) as the suturing device  300  sutures the incision. However, it should be noted that in an alternative embodiment of the present invention, the elongate body (not shown) might also store the suture  302 . In the alternative embodiment, the suture  302  and the pre-tied suture knot  304  are disposed about a periphery of the elongate body where the pre-tied suture knot  304  may reside within a pocket (not shown) of the elongate body. 
     Embodiments of the suturing device of the invention may also include additional configurations for a foot, as shown with reference to  FIGS. 22A through 22C . In this embodiment, the suturing device  300  includes a foot  319  having cuff pockets  319   a  and  319   b . The configuration of the cuff pockets  319   a  and  319   b  allow the foot  319  to hold the cuffs  310  and  310 ′ during use of the suturing device  300 . The foot pivots from a first orientation shown with reference to  FIG. 22A  to a second orientation shown with reference to  FIG. 22B  via a hinge  320  as shown in  FIG. 22C . 
       FIG. 22C  shows the hinge  320 , which allows rotation of the foot  319  in a direction indicated by directional arrow Y. The hinge  320  may be any device capable of rotatably coupling the foot  319  to the suturing device  300 , such as pin assembly or the like. In addition to the hinge  320 , the foot  319  includes a connector  322  that couples the cuffs  310  and  310 ′ with one another. The connector  322  also includes a flexible portion  322   c  (shown with respect to  FIG. 22C ) that allows flexing of the connector  322  as the connector  322  resides within passage  317  of the foot  314 . The connector also includes ends  322   a  and  322   b  that facilitate connection with the penetrator tip  308  and the needle tip  308 ′ of the elongate bodies  306 ′ and  306 . 
     In an embodiment of the present invention where the suturing device  300  employs the foot  319 , during use of the suturing device  300 , upon insertion of the suturing device  300  within the lumen  307 , a user deploys the foot  319  as shown with reference to  FIG. 22A . Upon deployment of the foot  319 , the user deploys the elongate body  306  (not shown) that engages with the cuff  310  (not shown) as previously described. Once the penetrator tip  308  detaches from the elongate body  306  via the push mandrel  315 , or other means previously described, the user rotates the foot  319  into the orientation shown with reference to  FIG. 22B . Upon orientation of the foot  319  as shown with respect to  FIG. 22B , the user deploys the elongate body  306 ′ (not shown) which engages with the cuff  310 ′ (not shown). After the elongate body  306 ′ engages with the cuff  310 ′, the user retracts the elongate body  306 ′ along with the cuffs  310  and  310 ′ and the suture  302  to suture an incision as previously described. 
     Another embodiment of the suturing device  300  includes feet  324  and  328  as shown with reference to  FIG. 23A .  FIG. 23A  illustrates an embodiment of the present invention in which the suturing device  300  includes the feet  324  and  328 . As may be seen with reference to  FIG. 23B , the foot  324  is hollow such that the foot  328  fits within the foot  324  during both insertion and retraction of the suturing device  300  within the lumen  307 . The feet  324  and  328  also include cuff pockets  324   a  and  328   a  and cam surfaces  324   b  and  328   b . The configuration of the cuff pockets  324   a  and  328   a  allow placement of the cuffs  310  and  310 ′ within the feet  324  and  328  during use of the suturing device  300 ; allowing engagement of the elongate bodies  306  and  306 ′ during suturing. The cam surfaces  324   a  and  328   a  contact cam surfaces  326   a  in order to deploy the feet  324  and  328 . Once the feet  324  and  328  deploy, the suturing device  300  attains the configuration shown with reference to  FIG. 23C . 
     During use of a suturing device implementing the feet  324  and  328 , a user inserts the suturing device into an incision as the foot  328  resides within the foot  324 . Upon insertion of the suturing device within the incision, the user deploys the feet  324  and  328  by moving the feet  324  and  328  towards the cam surfaces  326   a , in order to deploy the feet  324  and  328 , as previously described. After deployment of the feet  324  and  328  within a lumen, the user deploys the elongate bodies  306  and  306 ′ whereby the penetrator tip  308  and needle tip  308 ′ engage with the cuffs  310  and  310 ′ residing within the cuff pockets  324   a  and  328   a . Upon engagement with the cuffs  310  and  310 ′ the user retracts the elongate bodies  306  and  306 ′ and sutures the incision. 
     In addition to the alternative configurations for the foot of the suturing device  300 , the suturing device  300  may also include alternative cuff configurations that allow engagement of the elongate bodies  306  and  306 ′ with the link  312 . An example of such an alternative configuration is shown with respect to  FIG. 24A .  FIG. 24A  illustrates a perspective view of an alternative embodiment of the penetrator tip  330 . In this embodiment, a penetrator tip  330  includes mating surfaces  330   a  which engage with the previously described cuff tabs  310   a  of the cuff  310  when the penetrator tip  330  engages with the cuff  310 , as shown with reference to  FIG. 24B . As such, a user detaches the elongate body  306  from the penetrator tip  330  with the push mandrel  315  after engagement of the penetrator tip windows  330   a  with the cuff tabs  310 , as discussed with reference to the penetrator tip  308  and the cuff  310 . The mating surfaces  330   a  may be cut-outs, such as windows, formed within the penetrator tip  330 . The elongate bodies  306  and  306 ′ may also engage with the link  312 . 
       FIG. 25A  shows an alternative method of coupling the elongate bodies  306  and  306 ′ with the link  312 . In this embodiment, the elongate body  306 ′ includes a loop  332  (shown in  FIG. 25B ) which engages with the link  312  as the elongate body  306 ′ enters the foot  314 . In this embodiment, the link  312  is constructed of a resilient material capable of flexing in response to the loop  332  contacting the link  312 , such as polypropylene or any other material having spring-like characteristics. The elongate body  306 ′ moves in a downward direction as indicated by directional arrow A until the loop  332  comes into contact with an end  312   a  of the link  312 . When the loop  332  contacts the end  312   a , the loop  332  moves the end  312   a  in a direction F 1  indicated by directional arrow F 1 . The catch  332  continues to move the end  312   a  of the link  312  in the direction F 1  until the loop  332  contacts the end  312   a , as shown with reference to  FIG. 25B . 
     Referring to  FIGS. 25A-C , the link  312  is constructed of a material having spring like properties. Therefore, when the loop  332   a  comes into contact with the end  312   a , the resilient properties of the link  312  move the end  312   a  in a direction F 2 , as indicated by directional arrow F 2  in  FIG. 25A . The end  312   a  moves in the direction F 2  such that the end  312   a  moves into the loop  332   a , as shown with reference to  FIG. 25B . Once the end  312   a  moves into the loop  332   a , a user retracts the loop  332  along with the end  312   a  and the link  312  in a direction B as indicated by directional arrow B of  FIG. 25C . As the loop  332   a  and the catch  332  move in the direction B, the loop  332   a  clamps the link  312  against a surface  306 ′ a  of the elongate body  306 ′. Thus, during retraction of the suturing device  300  from the foot  314 , the link  312  remains engaged with the elongate body  306 ′, as shown with reference to  FIG. 25C . As the elongate body  306 ′ and the catch  332  retract from the foot  314 , the catch  332  pulls the link  312  through the foot  314 , also as shown with reference to  FIG. 25C . While the catch  332  pulls the link  312 , the cuff  310  (not shown) and the suture  302  (not shown) move through the foot  314  in order to enable suturing of an incision. 
     In another embodiment, the suturing device  300  may also employ a clip and ring assembly  338  which couples the elongate bodies  306  and  306 ′ with the link  312 , as shown with reference to  FIG. 26A .  FIG. 26A  illustrates a schematic view of the clip and ring assembly  338  for coupling the elongate bodies  306  and  306 ′ with the link  312  in accordance with an embodiment of the present invention. The elongate bodies  306  and  306 ′ include a clip  336  in place of the penetrator tip  308  and the needle tip  308 ′ where the clip  336  has a configuration as shown with reference to the Figure. The clips  336  include flexible arms  336   a  and a passageway  336   b.    
     The clip and ring assembly  338  also includes a ring  334  that engages with the clip  336 . The link  312  couples with the ring  334  using any suitable technique, such as tying or the like. The ring  334  has a circular configuration as shown with respect to  FIG. 26B  such that as the elongate bodies  306  and  306 ′ engage with the foot  314 , the clip  336  couples with the ring  334 . As the clips  336  engage with the ring  334 , the flexible arms  336   a  flex in a direction indicated by directional arrows Y and Z thereby increasing a width W i  of the passageway  336   b  in order to allow passage of the ring  334  through the clip  336  as shown with regards to  FIG. 28C . 
     Referring to  FIG. 26D , there is shown a top view of the foot  314  where the foot  314  includes cuff pockets  314   b - 1  and  314   b - 2 . The cuff pocket  314   b - 1  holds the ring  334  prior to engagement with the clip  336 . The cuff pocket  314   b - 2  is configured such that as the elongate bodies  306  and  306 ′ enter the foot  314 , the clips  336  enter the cuff pocket  314   b - 2  and engage with the ring  334  as shown with reference to the Figure. Once the clip  336  engages with the ring  334 , the clip  336  coupled with the elongate body  306  detaches from the clip  336  while the elongate body  306 ′ remains engaged with the clip  336 . During retraction of the elongate bodies  306  and  306 ′ from the foot  314 , the elongate body  306 ′ pulls the link  312  and the suture  302  through the foot  314  in order to suture an incision. 
       FIG. 27  shows an embodiment of a cuff  410  and link  412  assembly that maybe provide with the various embodiments of the present invention. Cuff  411  has a penetrator tip receiving end  434  and a tapered end  432 . Link  412  has two ends  442  (only one shown in  FIG. 27 ). An example of a preferred link material is expanded Polytetrafluoroethylene (ePTFE). PTFE is commonly referred to as Teflon. ePTFE is particularly suited for use as the link material in the vessel closure devices described herein because of its low friction, high strength properties. 
     To assemble the link and cuff assembly, a length of link material is first threaded through the cuff. The end of the link material extending from the penetrator tip receiving end  434  of the cuff  410  is then heated so that it expands. The link is then pull through the cuff  410  such that the expanded end portion  442  is seated in the interior tapered end  432  of the cuff  410 . 
     The present invention offers surgeons an automated method for delivering a pre-tied knot to an incision formed in a lumen. The present invention minimizes the problems associated with a surgeon manually delivering a knot to an incision site. Thus, the present invention reduces the time required to accurately and precisely place a suture knot in close proximity to an incision formed in a lumen, thereby decreasing both the overall time a patient spends in surgery and the costs associated with spending time in surgery. 
     While illustrative embodiments of the invention are disclosed herein, it will be appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. For example, the various features of each embodiment may be altered or combined to obtain the desired device or method characteristics. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments that come within the spirit and scope of the present invention.