Patent Publication Number: US-2020289100-A1

Title: Methods and apparatus for fastening and clamping tissue

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATIONS 
     This patent application is a continuation of pending prior U.S. patent application Ser. No. 15/906,763, filed Feb. 27, 2018 which is a continuation-in-part of pending prior U.S. patent application Ser. No. 14/639,814, filed Mar. 5, 2015 by Amsel Medical Corporation and Arnold Miller et al. for METHOD AND APPARATUS FOR OCCLUDING A BLOOD VESSEL AND/OR FOR OCCLUDING OTHER TUBULAR STRUCTURES AND/OR FOR CLOSING OPENINGS IN STRUCTURES AND/OR FOR SECURING AT LEAST TWO OBJECTS TOGETHER, which patent claims priority to prior applications as set forth in the accompanying Application Data Sheet filed herewith, all of which are hereby incorporated by reference, in their entireties. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to surgical methods and apparatus in general, and more particularly to surgical methods and apparatus for fastening or clamping tissue layers together as well as for attaching non-tissue devices or prostheses to tissue and to occlude tubular body structures. 
     BACKGROUND OF THE INVENTION 
     Numerous techniques and devices have been employed by surgeons and clinicians to attach tissue to tissue, to occlude tubular body structures, to attach non-tissue prostheses and devices to tissue, to prevent excess bleeding after tissue resection and the like. A partial list would include sutures, staples, ligating clips, adhesives, clamps, cauterization, among others. The present inventions provide improved methods and devices for performing those and other like functions. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved approaches for fastening tissue to tissue, tissue to non-tissue, for clamping resected tissue and for occluding blood vessels and other tubular body structures. 
     In one aspect, the present invention comprises the provision and use of a novel tissue fastener (sometimes referred to as an “fastener”) that can be used in numerous surgical environments to attach tissue to tissue or to non-tissue prostheses. Fastener may be deployed using a minimally-invasive approach (i.e., either percutaneously or endoluminally), with visualization being provided by ultrasound and/or other visualization apparatus (e.g., CT, MRI, X-ray etc.) or may be used under direct visualization (e.g., during “open” surgery) or under indirect visualization (e.g., during laparoscopic surgery where visualization is provided through the use of a scope, or during percutaneous surgery where visualization is provided through the use of imaging apparatus such as an ultrasound imager, an X-ray imager, etc.). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the invention will be appreciated more fully from the following description of the illustrative embodiments, with reference to the accompanying drawings in which: 
         FIGS. 1-7  are diagrammatic representations of fasteners of the invention; 
         FIGS. 8-24  illustrate an embodiment of the fastener and installation apparatus which may be used to deploy the two-part fastener; 
         FIGS. 25-45  illustrate the sequential steps in deploying the embodiment of  FIGS. 8-24 ; 
         FIGS. 46-49  are schematic views showing a two-part fastener formed in accordance with the present invention; 
         FIGS. 50-53  are schematic views showing still another two-part fastener formed in accordance with the present invention; 
         FIGS. 54-57  are schematic views showing yet another two-part fastener formed in accordance with the present invention; 
         FIGS. 58-61  are schematic views showing another two-part occluder formed in accordance with the present invention; 
         FIGS. 62-70  are schematic views showing an installation apparatus for deploying the two-part occluder shown in  FIGS. 58-61 ; 
         FIGS. 71-77  are schematic views showing another installation apparatus for deploying the two-part occluder shown in  FIGS. 58-61 ; 
         FIGS. 78-80  are schematic views showing another two-part occluder formed in accordance with the present invention; 
         FIGS. 81-83  are schematic views showing means for securing the two-part occluder shown in  FIGS. 78-80  to an installation apparatus; 
         FIG. 84  is a schematic view showing another two-part occluder formed in accordance with the present invention; 
         FIGS. 85-90  are schematic views showing a placement device for facilitating proper placement of an occluder so as to occlude a blood vessel (or other hollow tubular body); 
         FIG. 91  is a schematic view showing a tool for lifting a blood vessel (or other hollow tubular body) away from an underlying anatomical structure so as to facilitate proper placement of an occluder; 
         FIGS. 92-94  are schematic views showing use of an fastener for closing off an organ; 
         FIGS. 95 and 96  are schematic views showing the two-part fastener of the present invention being used to attach hernia mesh to tissue; 
         FIGS. 97-117  are schematic views showing how the distal and proximal legs of the two-part fastener may be aligned with one another, or interdigitated between one another, when the two-part fastener is deployed; 
         FIGS. 118-120  are schematic views showing additional ways in which the interdigitation of legs may be used to occlude a structure; 
         FIGS. 121-124  are schematic views showing a single use delivery device for delivering an fastener; 
         FIGS. 125-128  are schematic views showing how a reusable handle may be used to deploy a plurality of fasteners; 
         FIGS. 129-171  are schematic views showing a multiple fastener delivery device which may be used to deploy a plurality of fasteners; 
         FIG. 172  is a schematic view showing a multiple fastener delivery device where a plurality of fasteners are disposed serially within the delivery device; 
         FIGS. 173-175  are schematic views showing a two-part fastener having asymmetric legs; 
         FIGS. 176-203  are schematic views showing various constructions for separating the tissue to be occluded from the surrounding tissue, and/or for protecting the surrounding tissue from damage during delivery of the fastener; 
         FIGS. 204-214  are schematic views showing another novel fastener formed in accordance with the present invention; 
         FIGS. 215 and 216  are schematic views showing how a substance may be introduced into a vessel between two fasteners or upstream of a single fastener; 
         FIGS. 217-232  are schematic views showing how the fastener may be combined with electrocautery; and 
         FIGS. 233-236  are schematic views showing a handle for deploying a fastener. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     The present invention also provides new and improved surgical methods and apparatus for occluding other tubular structures and/or for closing openings in structures and/or for securing at least two objects together. 
     And the present invention provides new and improved surgical methods and apparatus for fastening mechanical structures to tissues or blood vessels, for example, for drug delivery. 
     More particularly, the present invention comprises the provision and use of a novel fastener which is used to occlude a vein (e.g., the proximal saphenous vein, the small saphenous vein, tributaries, the perforator veins, etc.) so as to restrict blood flow through the vein and thereby treat varicose veins below the point of occlusion. Significantly, the novel fastener is configured to be deployed using a minimally-invasive approach (i.e., either percutaneously or endoluminally), with visualization being provided by ultrasound and/or other visualization apparatus (e.g., CT, MRI, X-ray etc.). As a result, the novel treatment can be provided in a doctor&#39;s office, with minimal local anesthetic, and effectively no post-operative care. 
       FIGS. 1-4  show, diagrammatically, a form of fastener  30  that may comprise a transluminal section  85 , a far side lateral projection  90  and a near side lateral projection  95 , with the far side lateral projection  90  and the near side lateral projection  95  being held in opposition to one another so as to close down a lumen of a blood vessel or attach layers of tissue or non-tissue together. Such an arrangement may be provided by many different types of structures, e.g., such as the “double T-bar” structure shown in  FIGS. 5-7  where the transluminal section  85  of the fastener  30  is formed out of an elastic material which draws the two opposing T-bars  90 ,  95  of the fastener together so as to provide clamping or vessel occlusion. By way of further example but not limitation, far side lateral projection  90  and near side lateral projection  95  may be connected together by a loop of suture, with the loop of suture being lockable in a reduced size configuration with a sliding locking knot. 
     Furthermore, multiple fasteners  30  may be used on tissue or to occlude a blood vessel more completely, or to occlude a blood vessel in multiple regions, or to attach a material (e.g., a drug or cellular delivery element) in multiple places to tissue or to a blood vessel. The fasteners may be coated with a drug-eluting compound, or the fasteners may be electrically charged to enhance or prevent clotting or to deliver a desired compound or agent to the blood vessel, etc. If desired, the location of the occluding or attachment element may be precisely controlled to deliver the desired compound or agent at a specific anatomical location. 
     Drug/Cellular Delivery Applications 
     The fastener  30  may be modified so as to allow drug/cellular delivery at fixed points within or adjacent to the vasculature or other hollow bodily structure. In this form the device may be provided with a drug/cellular delivery body  105  attached thereto, is advanced across a blood vessel  110  or attached to tissue 
     Two-Part Fastener 
     Looking next at  FIG. 8 , there is shown a two-part fastener  200  formed in accordance with the present invention. Two-part fastener  200  generally comprises a distal implant  205  and a proximal implant  210 . 
     Distal implant  205  is shown in further detail in  FIGS. 9-12 . Distal implant  205  comprises a distal implant body  215  and a distal implant locking tube  220 . Distal implant body  215  comprises a tube  225  having a distal end  226 , a proximal end  227 , and a lumen  230  extending therebetween. Tube  225  is slit intermediate its length so as to define a plurality of legs  235 . A set of inwardly-projecting tangs  240  are formed in tube  225  between legs  235  and proximal end  227 . A set of windows  245  are formed in tube  225  between inwardly-projecting tangs  240  and proximal end  227 . Distal implant body  215  is preferably formed out of an elastic material (e.g., a shape memory material having superelastic properties such as Nitinol or superelastic polymers, including superelastic plastics) and constructed so that its legs  235  normally project laterally away from the longitudinal axis of tube  225  (e.g., in the manner shown in  FIGS. 9 and 10 , however, due to the elastic nature of the material used to form distal implant body  215 , legs  235  can be constrained inwardly (e.g., within the lumen of a delivery needle, as will hereinafter be discussed) so that distal implant body  215  can assume a substantially linear disposition. See, for example,  FIG. 12 , which shows legs  235  moved inwardly relative to the position shown in  FIGS. 9 and 10 . However, when any such constraint is removed, the elastic nature of the material used to form distal implant body  215  causes legs  235  to return to the position shown in  FIGS. 9 and 10 . 
     Distal implant locking tube  220  ( FIG. 11 ) comprises a generally tubular structure having a distal end  250 , a proximal end  260  and a lumen  262  extending therebetween. A set of windows  265  are formed in the distal implant locking tube  220 , with windows  265  being disposed distal to proximal end  260 . 
     Distal implant locking tube  220  is disposed within lumen  230  of distal implant body  215 . When distal implant  205  is in its aforementioned substantially linear condition (i.e., with legs  235  restrained in an in-line condition), distal implant locking tube  220  terminates well short of tangs  240  of distal implant body  215 , so that the proximal end  227  of distal implant body  215  can move longitudinally relative to distal end  226  of distal implant body  215 . However, when the proximal end  227  of distal implant body  215  is moved distally a sufficient distance to allow full radial expansion of legs  235  (see  FIG. 8 ), locking tangs  240  of distal implant body  215  will be received within windows  265  of distal implant locking tube  220 , whereby to lock distal implant  205  in its radially-expanded condition (i.e., with legs  235  projecting laterally away from the longitudinal axis of tube  225 , e.g., in the manner shown in  FIGS. 9 and 10 ). Spot welds applied via openings  270  formed in the distal end  226  of distal implant body  215  serve to lock distal implant locking tube  220  to distal implant body  215 , whereby to form a singular structure (see  FIGS. 9 and 12 ). 
     Looking next at  FIGS. 13 and 14 , proximal implant  210  comprises a tube  275  having a distal end  280 , a proximal end  285 , and a lumen  290  extending therebetween. Tube  275  is slit at its distal end so as to define a plurality of legs  295 . A set of inwardly-projecting tangs  300  are formed in tube  275  between legs  295  and proximal end  285 . Proximal implant  210  is preferably formed out of an elastic material (e.g., a shape memory material having superelastic properties such as Nitinol) and constructed so that its legs  295  normally project laterally away from the longitudinal axis of tube  275  (e.g., in the manner shown in  FIG. 13 ), however, legs  295  can be constrained inwardly (e.g., within the lumen of a delivery tube, as will hereinafter be discussed) so that proximal implant  210  can assume a substantially linear disposition. See, for example,  FIG. 14  , which shows legs  295  moved inwardly relative to the position shown in  FIG. 13 . However, when any such constraint is removed, the elastic nature of the material used to form proximal implant  210  causes legs  295  to return to the position shown in  FIG. 13 . 
     As will hereinafter be discussed, distal implant  205  and proximal implant  210  are configured and sized so that tube  225  of distal implant body  215  can be received in lumen  290  of proximal implant  210 , with the expanded legs  235  of distal implant  205  opposing the expanded legs  295  of proximal implant  210  (see, for example,  FIG. 45 ), whereby to impose a clamping action on the side wall of a blood vessel (e.g., vein) disposed therebetween and thereby occlude the blood vessel, as will hereinafter be discussed in further detail (or, as an alternative, the opposing expanded legs of the proximal and distal implants could interdigitate to impose the clamping action). Furthermore, distal implant  205  and proximal implant  210  are configured and sized so that they may be locked in this position, inasmuch as inwardly-projecting tangs  300  of proximal implant  210  will project into windows  245  of distal implant  205 . 
     Two-part fastener  200  is intended to be deployed using associated installation apparatus. This associated installation apparatus preferably comprises a hollow needle  305  ( FIG. 15 ) for penetrating tissue, a distal implant delivery tube  310  ( FIG. 16 ) for delivering distal implant  205  through hollow needle  305  to the far side of the blood vessel which is to be occluded, a composite guidewire  315  ( FIGS. 17-22 ) for supplying support to various components during delivery and deployment, a push rod  320  ( FIG. 23 ) for delivering various components over composite guidewire  315 , and a proximal implant delivery tube  330  ( FIG. 24 ) for delivering proximal implant  210  for mating with distal implant  205 , as will hereinafter be discussed. 
     Hollow needle  305  ( FIG. 15 ) comprises a distal end  335 , a proximal end  340  and a lumen  345  extending therebetween. Distal end  335  terminates in a sharp point  350 . In one preferred form of the invention, hollow needle  305  comprises a side port  355  which communicates with lumen  345 . 
     Distal implant delivery tube  310  ( FIG. 16 ) comprises a distal end  360 , a proximal end  365  and a lumen  370  extending therebetween. 
     Composite guidewire  315  ( FIGS. 17-22 ) comprises a guidewire rod  370  and a guidewire sheath  380 . Guidewire rod  370  comprises a distal end  385  and a proximal end  390 . Distal end  385  terminates in an enlargement  395 . Guidewire sheath  380  comprises a distal end  400 , a proximal end  405  and a lumen  410  extending therebetween. The distal end  400  of guidewire sheath  380  comprises at least one, and preferably a plurality of, proximally-extending slits  415 . Proximally-extending slits  415  open on the distal end of guidewire sheath  380  and allow the distal end of guidewire sheath  380  to radially expand somewhat. As will hereinafter be discussed, guidewire rod  370  and guidewire sheath  380  are configured and sized so that guidewire rod  370  can be received in lumen  410  of guidewire sheath  380 . Furthermore, when guidewire rod  370  is forced proximally relative to guidewire sheath  380 , the proximally-extending slits  415  in guidewire sheath  380  allow the distal end of the guidewire sheath  380  to expand somewhat so as to receive at least some of the enlargement  395  formed on the distal end of guidewire rod  370 . As this occurs, the distal end of guidewire sheath  380  will expand radially. 
     Push rod  320  ( FIG. 23 ) comprises a distal end  420 , a proximal end  425  and a lumen  430  extending therebetween. 
     Proximal implant delivery tube  330  ( FIG. 24 ) comprises a distal end  435 , a proximal end  440  and a lumen  445  extending therebetween. 
     Two-part fastener  200  and its associated installation apparatus are preferably used as follows. 
     First, hollow needle  305  (carrying distal implant delivery tube  310  therein, which in turn contains the composite guidewire  315  therein, upon which is mounted distal implant  205 ) is passed through the skin of the patient, through intervening tissue, and across the blood vessel (e.g., vein  450 ) which is to be occluded. See  FIGS. 25-27 . As this is done, any blood flowing out side port  355  can be monitored—excessive or pulsatile blood flow can indicate that hollow needle has accidentally struck an artery. 
     Next, hollow needle  305  is retracted, leaving distal implant delivery tube  310  extending across the blood vessel. See  FIG. 25 . 
     Then distal implant delivery tube  310  is retracted somewhat so as to expose the distal ends of composite guidewire, or rod,  315  and distal implant  205 . See  FIG. 26 . 
     Next, composite guidewire  315 , push rod  320  and distal implant  205  are all moved distally, so as to advance the distal ends of composite guidewire  315  and the distal implant  205  out of the distal end of distal implant delivery tube  310 . As this occurs, legs  235  of distal implant  205  are released from the constraint of distal implant delivery tube  310  and expand radially. See  FIGS. 27 and 28 . 
     Then, with push rod  320  being held in place against the proximal end of distal implant  205 , composite guidewire  315  is pulled proximally so as to bring the distal end of distal implant  205  toward the proximal end of distal implant  205 , whereby to cause locking tangs  240  of distal implant body  215  to enter windows  265  of distal implant locking tube  220 , whereby to lock legs  235  in their radially-expanded condition (see  FIG. 29 ). 
     At this point, hollow needle  305 , distal implant delivery tube  310  and push rod  320  may be removed ( FIG. 30 ), leaving distal implant  205  mounted on composite guidewire  315 , with the legs  235  fully deployed on the far side of the blood vessel and the proximal end of distal implant  205  extending into the interior of the blood vessel ( FIG. 31 ). 
     Next, proximal implant delivery tube  330  (carrying proximal implant  210  therein) is advanced down composite guidewire  315 , until the distal end of proximal implant delivery tube  330  sits just proximal to the blood vessel ( FIGS. 32-35 ). 
     Then push rod  320  is used to advance the distal end of proximal implant  210  out of the distal end of proximal implant delivery tube  330 . As this occurs, legs  295  are released from the constraint of proximal implant delivery tube  330  and open radially. See  FIGS. 36-39 . 
     Next, using push rod  320 , proximal implant  210  is pushed distally as distal implant  205  is pulled proximally using composite guidewire  315 . More particularly, guidewire rod  370  is pulled proximally, which causes enlargement  395  on the distal end of guidewire rod  370  to expand guidewire sheath  380  to a size larger than lumen  262  in distal implant locking tube  220 , which causes guidewire sheath  380  to move proximally, which causes proximal movement of distal implant  205 . As distal implant  205  and proximal implant  210  move together, their legs  235 ,  295  compress the blood vessel, thereby occluding the blood vessel. Distal implant  205  and proximal implant  210  continue moving together until inwardly-projecting tangs  300  of proximal implant  210  enter windows  245  of distal implant  205 , thereby locking the two members into position relative to one another. See  FIG. 40 . 
     At this point push rod  320  and proximal implant delivery tube  330  are removed. See  FIG. 41 . 
     Next, composite guidewire  315  is removed. This is done by first advancing guidewire rod  370  distally ( FIG. 42 ), which allows the distal end of guidewire sheath  380  to relax inwardly, thereby reducing its outer diameter to a size smaller than lumen  262  in distal implant locking tube  220 . As a result, guidewire sheath  380  can then be withdrawn proximally through the interior of two-part fastener  200 . See  FIG. 43 . Then guidewire rod  370  can be withdrawn proximally through the interior of two-part fastener  200 . See  FIG. 44 . 
     The foregoing procedure leaves two-part fastener  200  locked in position across the blood vessel, with the opposing legs  235 ,  295  compressing the blood vessel, whereby to occlude the blood vessel. 
       FIGS. 46-49  illustrate an embodiment of a two-part fastener  200 A embodying principles of the invention. Two-part fastener  200  generally comprises a distal implant  205 A and a proximal implant  210 A. Distal implant  205 A is shown in further detail in  FIG. 48 . Distal implant  205 A comprises a tubular distal implant body  215 A having a distal end  226 A, a proximal end  227 A, and a lumen  230 A. The distal end of the body  215 A is slit to define a plurality of legs  235 A that can extend generally radially, as shown when the implant is released from its delivery tube. A set of windows  245 A are formed in the tubular body. Distal implant body  215 A is preferably formed out of an elastic material (e.g., a shape memory material having superelastic properties such as Nitinol or superelastic polymers, including superelastic plastics) and constructed so that its legs  235  normally project radially outwardly as shown in  FIGS. 47 and 48 ), however, due to the elastic nature of the material used to form distal implant body  215 A, legs  235 A can be constrained inwardly to a tubular shape containable within the lumen of a delivery needle. When any such constraint is removed, the elastic nature of the material causes legs  235 A to return to their relaxed, expanded position. 
       FIGS. 46, 47 and 49  show proximal implant  210 A comprises a tube  275 A having a distal end  280 A, a proximal end  285 A, and a lumen  290 A. The inner diameter of the lumen  290 A of the tube is greater than the outer diameter of the tubular body  215 A of the distal implant so that it can receive the proximal end of the distal body as shown in  FIG. 47 . The distal implant also is formed from a superelastic material and is slit at its distal end to define a plurality of legs  295 A that will expand to a relaxed, radially extended shape when released from a delivery tube in the same manner as the distal implant. A set of inwardly-projecting tangs  300 A are formed in tube  275 A and are arranged to be received in the windows  245 A of the tubular body of the distal implant when the implants are brought together, this locking the implants together, as shown in  FIG. 47 . Tissue or non-tissue (or both) disposed between the legs of the proximal and distal legs will be clamped with the tubular body of the distal implant extending through an aperture in the tissue and/or non-tissue, transfixing them together (See  FIG. 46 ). In this embodiment, the implants may be formed to have relatively short tubular portions to define a low-profile configuration in which the height of the tubular body of the implant is no greater than about the maximum diameter of its expanded legs. 
     Two-part fastener  200  may be deployed using associated installation apparatus that may comprise a hollow needle  305  ( FIG. 15 ) for penetrating tissue, a retention guidewire  315  ( FIGS. 17-22 ) for temporarily maintaining the position of the distal implant, a push rod  320  ( FIG. 23 ) for controlling the position of the proximal implant 
     Hollow needle  305  ( FIG. 15 ) comprises a distal end  335 , a proximal end  340  and a lumen  345  extending therebetween. Distal end  335  terminates in a sharp point  350 . Hollow needle  305  may have a side port  355  which communicates with lumen  345 . 
     The retention wire may be in the form of a composite guidewire  315  ( FIGS. 17-22 ) that includes an elongated guidewire rod  370  and a guidewire sheath  380  having a lumen that receives the rod. The distal end  385  of the guidewire rod  370  terminates in an enlargement  395 . The distal end  400  of guidewire sheath  380  has proximally extending slits  416  that allow the distal end of guidewire sheath  380  to expand radially when the enlarged end of the rod  370  is drawn into the slit end of the sheath. The expanded end of the sheath can engage the deployed distal implant to retain the distal implant in position while the proximal implant is deployed. 
     In the deployment of the fastener, hollow needle  305 , loaded with the distal and proximal implants arranged in tandem, and with the retention guidewire  315  extending through the implants is advanced to the tissue site to be fastened or occluded with the needle passing through the layers (tissue and/or non-tissue) to be fastened. As this is done, any blood flowing out side port  355  can be monitored—excessive or pulsatile blood flow can indicate that hollow needle has accidentally struck an artery. With the distal tip of the needle located distally of the tissue and with the distal tip of the retention guidewire extended slightly beyond the tip of the needle and in its slightly expanded configuration, the pusher tube is maintained in its position to maintain the positions of the implants and the delivery needle is withdrawn proximally to release the distal implant from the needle and to enable the legs of the distal implant to expand. The retention guidewire maintains the distal implant in its position. Next, with the proximal implant retained within the delivery needle, the needle is withdrawn sufficiently to locate the proximal implant on the proximal side of the layers to be fastened. Then, with the pusher tube in engagement with the proximal end of the proximal implant, the needle is further withdrawn to release the proximal implant. Then, by manipulating the retention guidewire and the pusher tube the implants can be drawn together to lock the implants together and fastening the layers together between the legs of the implants. The retention guidewire then can be configured to a removable state and, together with the pusher, can be removed from the patient. 
       FIGS. 50-53  illustrate another two-part fastener  200 B. Two-part fastener  200 B is generally similar to the aforementioned two-part fastener  200 A, except that distal implant  205 B utilizes a friction fit to lock distal implant  205 B to proximal implant  210 B. 
       FIGS. 54-57  illustrate another two-part fastener  200 C having a distal implant  205 C and a proximal implant  210 C. Two-part fastener  200 C is generally similar to the aforementioned two-part fastener  200 , except that distal implant  205 C comprises a tube  225 C which receives and secures the proximal ends of legs  235 C. Legs  235 C are preferably elongated elements (e.g., bent wires) formed out of a superelastic shape memory material so as to provide the legs  235 C with the desired degree of elasticity. 
     The composite guidewire  315  can be replaced by an alternative guidewire which includes a mechanism for releasably binding the alternative guidewire to distal implant  205 . By way of example but not limitation, such an alternative guidewire may include screw threads, and distal implant  205  may include a screw recess, so that the alternative guidewire can be selectively secured to, or released from, the distal implant  205 , i.e., by a screwing action. 
     Looking next at  FIGS. 58-61 , there is shown another two-part fastener  200 E formed in accordance with the present invention. Two-part fastener  200 E generally comprises a distal implant  205 E and a proximal implant  210 E. 
     Distal implant  205 E comprises a distal implant body  215 E and a distal implant locking tube  220 E. Distal implant body  215 E comprises a tube  225 E having a distal end  226 E and an opposing proximal end. Preferably distal implant  205 E has a lumen  230 E extending distally from its proximal end. Lumen  230 E may extend along the entire length of distal implant body  215 E or it may terminate short of the distal end of distal implant body  215 E. By way of example but not limitation, where two-part fastener  200 E is to be set over a guidewire, lumen  230 E extends along the entire length of distal implant body  215 E. Tube  225 E is slit intermediate its length so as to define a plurality of legs  235 E. Distal implant body  215 E is preferably formed at least in part out of an elastic material (e.g., a shape memory material having superelastic properties such as Nitinol or superelastic polymers, including superelastic plastics) and is constructed so that its legs  235 E normally project laterally away from the longitudinal axis of tube  225 E (e.g., in the manner shown in  FIGS. 58-61 ), however, due to the elastic nature of the material used to form at least the legs  235 E of distal implant body  215 E, legs  235 E can be constrained inwardly (e.g., within the lumen of a delivery needle, as will hereinafter be discussed) so that distal implant body  215 E can assume a substantially linear disposition (in which case the distalmost tips of legs  235 E converge to form the aforementioned proximal end of distal implant body  215 E). However, when any such constraint is removed (e.g., when distal implant body  215  is no longer constrained within a delivery needle), the elastic nature of the material used to form at least the legs  235 E of distal implant body  215 E causes legs  235 E to assume the position shown in  FIGS. 58-61 . 
     In one preferred form of the invention, and as seen in  FIGS. 58-60 , legs  235 E of distal implant  205 E extend at an acute angle to the longitudinal axis of distal implant  205 E, such that legs  235 E collectively define a concave region  236 E. 
     Distal implant locking tube  220 E ( FIGS. 58-61 ) comprises a generally tubular structure having a distal end  250 E and a proximal end  260 E. Preferably distal implant locking tube  220 E has a lumen  262 E extending distally from proximal end  260 E. Lumen  262 E may extend along the entire length of distal implant locking tube  220 E or it may terminate short of the distal end of distal implant locking tube  220 E. By way of example but not limitation, where two-part fastener  200 E is to be set over a guidewire, lumen  262 E of distal implant locking tube  220 E extends along the entire length of distal implant locking tube  220 E. A set of circumferential grooves or recesses  265 E are formed in distal implant locking tube  220 E, with grooves or recesses  265 E being disposed intermediate distal end  250 E and proximal end  260 E. Distal implant locking tube  220 E also comprises a first half  266 E of a mechanical interlock for releasably securing distal implant locking tube  220 E (and hence distal implant  205 E) to a distal implant delivery tube  310 E (see below). Distal implant locking tube  220 E is preferably formed out of a biocompatible material which is relatively inelastic along its length, whereby to minimize lengthwise stretching, although it may be somewhat flexible, whereby to allow it to be delivered over a curved path. By way of example but not limitation, distal implant locking tube  220 E may be formed out of a titanium alloy such as Ti 5 AL-4V. 
     Distal implant locking tube  220 E is disposed within, and extends proximally from, lumen  230 E of distal implant body  215 E. Distal implant locking tube  220 E is secured to distal implant body  215 E in ways well known in the art (e.g., by spot welding, adhesives, mechanical interlocks, etc.), whereby to collectively form a singular structure (see  FIGS. 58-61 ). Note that by forming distal implant body  215 E out of an elastic material, and by forming distal implant locking tube  220 E out of a material which is relatively inelastic along its length, distal implant body  215 E is easily deformable (e.g., so that its legs  235 E can be constrained within a delivery needle) while distal implant locking tube  220 E is fixed in configuration (e.g., so that it can serve to hold proximal implant  210 E to distal implant  205 E, as will hereinafter be discussed). 
     Still looking now at  FIGS. 58-61 , proximal implant  210 E comprises a tube  275 E having a distal end, a proximal end  285 E, and a lumen  290 E extending therebetween. Tube  275 E is slit at its distal end so as to define a plurality of legs  295 E. A set of inwardly-projecting tangs  300 E are formed in tube  275 E, between legs  295 E and proximal end  285 E, for engaging the aforementioned grooves or recesses  265 E in distal implant locking tube  220 E, as will hereinafter be discussed (note that, if desired, the locations and configurations of grooves or recesses  265 E and tangs  300 E can be reversed, i.e., outwardly-projecting tangs  300 E can be provided on distal implant locking tube  220 E and grooves or recesses  265 E can be provided on the inner side wall of tube  275 E, or other means can be provided for connecting tube  275 E of proximal implant  210 E to distal implant locking tube  220 E of distal implant  205 E). Proximal implant  210 E is preferably formed at least in part out of an elastic material (e.g., a shape memory material having superelastic properties such as Nitinol) and constructed so that its legs  295 E normally project laterally away from the longitudinal axis of tube  275 E (e.g., in the manner shown in  FIGS. 58-61 ), however, legs  295 E can be constrained inwardly (e.g., within the lumen of a delivery needle, as will hereinafter be discussed) so that proximal implant  210 E can assume a substantially linear disposition (with the distal ends of legs  295 E collectively forming the distal end of proximal implant  210 E). However, when any such constraint is removed, the elastic nature of the material used to form at least the legs  295 E of proximal implant  210 E causes legs  295 E to return to the position shown in  FIGS. 58-61 . 
     In one preferred form of the invention, and as seen in  FIGS. 58-061 , legs  295 E of proximal implant  210 E extend at an obtuse angle to the longitudinal axis of proximal implant  210 E, such that legs  295 E collectively define a concave region  301 E. 
     Note that the concavity of concave region  236 E of distal implant  205 E is the reverse of the concavity of concave region  301 E of proximal implant  210 E (in other words, and as seen in  FIGS. 58-61 , the concavity of concave region  236 E of distal implant  205 E faces the concavity of concave region  301 E of proximal implant  210 E). 
     As will hereinafter be discussed, distal implant  205 E and proximal implant  210 E are configured and sized so that distal implant locking tube  220 E of distal implant  205 E can be received in lumen  290 E of proximal implant  210 E, with the expanded legs  235 E of distal implant  205 E opposing the expanded legs  295 E of proximal implant  210 E (see, for example,  FIGS. 60 and 61 ), whereby to impose a clamping action on the side walls of a blood vessel (e.g., vein) disposed therebetween and thereby occlude the blood vessel, as will hereinafter be discussed in further detail (or, as an alternative, the opposing expanded legs of the proximal and distal implants may interdigitate so as to further enhance the clamping action. Furthermore, distal implant  205 E and proximal implant  210 E are configured and sized so that they may be locked in this position, inasmuch as inwardly-projecting tangs  300 E of proximal implant  210 E will project into circumferential grooves or recesses  265 E of distal implant locking tube  220 E of distal implant  205 E, whereby to secure proximal implant  210 E to distal implant  205 E. Note that the positions of circumferential grooves or recesses  265 E of distal implant locking tube  220 E and inwardly-projecting tangs  300 E of proximal implant  210 E are coordinated so that when inwardly-projecting tangs  300 E of proximal implant  210 E are disposed in circumferential grooves or recesses  265 E of distal implant locking tube  220 E, legs  235 E of distal implant  205 E and legs  295 E of proximal implant  210 E are sufficiently close to ensure adequate clamping of a blood vessel (or other tubular structure) disposed therebetween. 
     Two-part fastener  200 E is intended to be deployed using associated installation apparatus. In one preferred form of the invention, such associated installation apparatus preferably comprises a hollow needle  305 E ( FIG. 66 ) for penetrating tissue, a distal implant delivery tube  310 E ( FIG. 67 ) for delivering distal implant  205 E through hollow needle  305 E to the far side of the blood vessel (or other tubular structure) which is to be occluded, and a proximal implant delivery tube  330 E ( FIG. 67 ) for delivering proximal implant  210 E for mating with distal implant  205 E, as will hereinafter be discussed. 
     If desired, the associated installation apparatus may be provided in the form of a laparoscopic device  331 E as shown in  FIGS. 62-70 . Laparoscopic device  331 E comprises a handle  332 E, an outer sheath  333 E, a knob  334 E, a first trigger  336 E, a second trigger  337 E and a release lever  338 E, with the functionality hereinafter described. 
     More particularly, hollow needle  305 E ( FIG. 66 ) comprises a distal end  335 E, a proximal end (not shown, but contained within laparoscopic device  331 E) and a lumen  345 E extending therebetween. Distal end  335 E of hollow needle  305 E terminates in a sharp point  350 E. 
     Distal implant delivery tube  310 E ( FIG. 67 ) comprises a distal end  360 E and a proximal end (not shown, but contained within laparoscopic device  331 E). Distal end  360 E of distal implant delivery tube  310 E also comprises a second half  361 E of a mechanical interlock for releasably securing the distal end of distal implant delivery tube  310 E to the proximal end of distal implant  205 E, i.e., by the releasable interconnection of the first half  266 E of the mechanical interlock (carried by the proximal end of distal implant locking tube  220 E) with the second half  361 E of the mechanical interlock (carried by the distal end of distal implant delivery tube  310 E). 
     Proximal implant delivery tube  330 E ( FIG. 67 ) comprises a distal end  435 E, a proximal end (not shown, but contained within laparoscopic device  331 E) and a lumen  445 E extending therebetween. 
     Two-part fastener  200 E and its associated installation apparatus (e.g., laparoscopic device  331 E) are preferably used as follows. 
     First, hollow needle  305 E is passed to the occlusion site, preferably while needle  305 E is contained within sheath  333 E of laparoscopic device  331 E ( FIG. 64 . Then sheath  333 E is retracted, e.g., by turning knob  334 E ( FIG. 65 ), and hollow needle  305 E is passed across the blood vessel (e.g., a vein) which is to be occluded (or passed across another tubular structure which is to be occluded, or passed through tissue or objects to be secured to one another, such as a solid organ, or layers of tissue, etc.). 
     Next, hollow needle  305 E is retracted proximally, back across the blood vessel, e.g., via first trigger  336 E ( FIG. 66 ). This action allows legs  235 E of distal implant  205 E to expand radially on the far side of the blood vessel. At this point, distal implant locking tube  220 E extends proximally through the blood vessel. 
     Then, with distal implant delivery tube  310 E held in place via distal implant delivery tube  310 E and its interlock with distal implant locking tube  220 E (and hence distal implant  205 ), hollow needle  305 E is withdrawn further proximally (e.g., via first trigger  336 E) until proximal implant  210 E is no longer constrained within hollow needle  305 E ( FIG. 67 ). As this occurs, legs  295 E of proximal implant  210 E are released from the constraint of hollow needle  305 E and open radially. 
     Proximal implant delivery tube  330 E is then advanced distally, e.g., using second trigger  337 E, until proximal implant  210 E and distal implant  205 E come together ( FIG. 68 ). As distal implant  205 E and proximal implant  210 E move together, their legs  235 E,  295 E compress the blood vessel therebetween, thereby occluding the blood vessel. Distal implant  205 E and proximal implant  210 E continue moving together until inwardly-projecting tangs  300 E of proximal implant  210 E enter circumferential grooves or recesses  245 E of distal implant  205 E, thereby locking the two members into position relative to one another. 
     At this point, proximal implant delivery tube  330 E is withdrawn ( FIG. 69 ), distal implant delivery tube  310 E is released from distal implant  205 E (i.e., by using lever  338 E to unlock the second half  361 E of the mechanical interlock (carried by the distal end of distal implant delivery tube  310 E) from the first half  266 E of the mechanical interlock (carried by the proximal end of distal implant locking tube  220 E), and then the installation device is withdrawn ( FIG. 70 ). 
     The foregoing procedure leaves two-part fastener  200 E locked in position across the blood vessel, with the opposing legs  235 E,  295 E compressing the blood vessel therebetween, whereby to occlude the blood vessel. 
     In the preceding disclosure, two-part fastener  200 E is discussed in the context of using the elasticity of its legs  235 E,  295 E to cause its legs  235 E,  295 E to reconfigure from a diametrically-reduced configuration (e.g., when constrained within a delivery needle) to a diametrically-expanded configuration (e.g., when released from the constraint of a delivery needle). However, it should also be appreciated that where legs  235 E,  295 E are formed out of a shape memory material (e.g., Nitinol), a temperature change may be used to reconfigure legs  235 E,  295 E from a diametrically-reduced configuration to a diametrically-expanded configuration. By way of example but not limitation, in this form of the invention, legs  235 E,  295 E may be constructed so as to have a diametrically-reduced configuration when maintained at a temperature below body temperature, and legs  235 E,  295 E may be constructed so as to have a diametrically-expanded configuration when maintained at body temperature. As a result, by cooling two-part fastener  200 E to a temperature below body temperature, inserting the two-part fastener into the body, and then allowing the two-part fastener to heat to body temperature, legs  235 E,  295 E can be caused to reconfigure from their diametrically-reduced configuration to a diametrically-expanded configuration. 
       FIGS. 71-77  show an alternative form of installation device. More particularly,  FIGS. 71-77  show another laparoscopic device  331 E. The laparoscopic device  331 E shown in  FIGS. 71-77  is generally similar to the laparoscopic device  331 E shown in  FIGS. 62-70 , except that second trigger  337 E is omitted, and lever  338 E is used to both: (i) advance proximal implant delivery tube  330 E until proximal implant  210 E and distal implant  205 E come together ( FIG. 76 ), and (ii) release distal implant  205 E from distal implant locking tube  220 E ( FIG. 77 ) (i.e., by unlocking the second half  361 E of the mechanical interlock (carried by the distal end of distal implant delivery tube  310 E) from the first half  266 E of the mechanical interlock (carried by the proximal end of distal implant locking tube  220 E)). 
       FIGS. 78-80  show another two-part fastener  200 E also formed in accordance with the present invention. The fastener  200 E shown in  FIGS. 78-80  is substantially the same as the fastener  200 E shown in  FIGS. 58-77 , except that legs  235 E of distal implant  205 E, and legs  295 E of proximal implant  210 E, have their concavity directed in the same direction, so that legs  235 E,  295 E nest with one another rather than confront one another. In addition, as seen in  FIGS. 78-80 , tube  225 E of distal implant  205 E is partially received in lumen  290 E of proximal implant  210 E. 
       FIGS. 81-83  show one preferred construction for releasably securing distal implant  205 E of the two-part fastener  200 E of  FIGS. 78-80  to distal implant delivery tube  310 E. More particularly, in this form of the invention, and looking now at  FIGS. 81-83 , the first half  266 E of the mechanical interlock (carried by the proximal end of distal implant locking tube  220 E) comprises a stepped configuration  433 E, and the second half  361 E of the mechanical interlock (carried by the distal end of distal implant delivery tube  360 E) comprises another stepped configuration  434 E, wherein stepped configuration  433 E and stepped configuration  434 E are inverses of one another so as to mate together. After the second half  361 E of the mechanical interlock (carried by the distal end of distal implant delivery tube  310 E) has been secured to the first half  266 E of the mechanical interlock (carried by the proximal end of distal implant locking tube  220 E), the connection between distal implant delivery tube  310 E and distal implant  205 E can be enhanced, e.g., by telescopically projecting a locking rod  436 E out of a central lumen  437 E of distal implant delivery tube  310 E and into lumen  262 E of implant locking tube  220 E. In this form of the invention, the installation device (e.g., laparoscopic device  331 E of  FIGS. 62-70 , or laparoscopic device  331 E of  FIGS. 71-77 ) include appropriate control means (e.g., release lever  338 E) for telescopically moving locking rod  436 E out of central lumen  437 E of distal implant delivery tube  310 E and into lumen  262 E of implant locking tube  220 E. Alternatively, in another form of the invention, internal locking rod  436 E may be replaced by an overtube (not shown) which telescopically projects over distal implant delivery tube  310 E and distal implant locking tube  220 E of distal implant  205 E, whereby to enhance the connection between the members. 
     It should also be appreciated that other forms of mechanical interlocks may be used for releasably securing distal implant  205 E of the two-part fastener  200 E of  FIGS. 78-80  to distal implant delivery tube  310 E. By way of example but not limitation, a screw interlock may be used, e.g., the first half  266 E of the mechanical interlock (carried by the proximal end of distal implant locking tube  220 E) may comprise a threaded bore, and the second half  361 E of the mechanical interlock (carried by the distal end of distal implant delivery tube  360 E) may comprise a threaded post, wherein the threaded post carried by the distal end of distal implant delivery tube  360 E may be received in the threaded bore of distal implant locking tube  220 E. Alternatively, other configurations of a screw interlock may be used, or other forms of mechanical interlocks may be used. 
     In the constructions shown in  FIGS. 58-80 , a mechanical interlock (e.g., a first half  266 E carried by the proximal end of distal implant locking tube  220 E and a second half  361 E carried by the distal end of distal implant delivery tube  310 E) is used to connect distal implant locking tube  220 E (and hence distal implant  205 E) to distal implant delivery tube  310 E. Alternatively, if desired, distal implant locking tube  220 E can be formed integral with distal implant delivery tube  310 E, with a weakened section disposed at their intersection, and the two members separated by a mechanical breaking action. 
     It will be appreciated that, in certain circumstances, it may be desirable to increase the surface area of those portions of the fastener which contact the tubular structure, in order to better distribute the load applied to the tissue. In this situation, it can be helpful to increase the width of the legs (e.g., legs  235 E and/or legs  295 E of two-part fastener  205 E, etc.), and/or to provide flexible material in the zone between adjacent legs (e.g., in the manner of an umbrella) so that the flexible material can also carry load (i.e., essentially increasing the effective width of legs  235 E and/or legs  295 E). See, for example,  FIG. 84 , which shows flexible material  438 E extending between legs  235 E and legs  295 E. 
       FIGS. 85-90  show a placement device  500  for the facilitating proper placement of the fastener (e.g., the two-part fastener  200 E) so as to occlude a blood vessel (or other hollow tubular body). Placement device  500  generally comprises a blood vessel locator needle  505 , which is a needle of relatively small diameter (e.g.,  21  gauge or smaller), and a guiding component  510  (which may be manufactured from an inexpensive material such as plastic). Guiding component  510  includes a seat  515  for receiving blood vessel locator needle  505 , and an opening  520  for slidably accommodating the shaft of an installation device for setting the fastener (e.g., laparoscopic device  331 E of  FIGS. 62-70 , or laparoscopic device  331 E of  FIGS. 71-77 , etc.). 
     In use, blood vessel locator needle  505  is positioned in seat  515  of guiding component  510 , and then the blood vessel locator needle  505  is advanced through the target blood vessel (e.g., under ultrasound guidance). See  FIG. 86 . Proper placement of blood vessel locator needle  505  is confirmed as blood begins to flow out the proximal end of blood vessel locator needle  505 . Next, the shaft of the installation device for setting the fastener (e.g., laparoscopic device  331 E of  FIGS. 62-70 , or laparoscopic device  331 E of  FIGS. 71-77 , etc.) is advanced through opening  520  of guiding component  510 . See  FIG. 87 . Advancement occurs until a stop  525  on the shaft of the installation device engages the proximal end of guiding component  510 . See  FIG. 88 . When stop  525  on the shaft of the installation device engages the proximal end of guiding component  510 , the distal end of the shaft of the installation device will have passed through the target blood vessel. See  FIG. 89 . At this point, blood vessel locator needle  505  is withdrawn (see  FIG. 90 ) and deployment of the fastener proceeds as previously discussed. 
     It will be appreciated that, in certain circumstances, the blood vessel (or other tubular structure) to be occluded may be positioned close to an underlying anatomical structure, e.g., an organ, a nerve, another tubular structure, etc. In this situation, it may be helpful to lift the blood vessel (or other tubular structure) upward, away from the underlying anatomical structure, so that the sharp distal tip of the deployment needle does not engage the underlying anatomical structure, and so that the distal end of the fastener (e.g., distal implant  205 E of two-part fastener  200 E) does not engage the underlying anatomical structure, since any such engagement with the underlying anatomical structure could cause trauma to the underlying anatomical structure. To that end, and looking now at  FIG. 91 , clamping forceps  530  (or other tool having a bifurcated distal end) may be placed between the blood vessel (or other tubular structure) and the underlying anatomical structure, and then pulled upwardly, away from the underlying anatomical structure, so as to separate the target blood vessel (or other tubular structure or tissue) from the underlying anatomical structure. The fastener (e.g., two-part fastener  200 E) may then be safely passed through the target blood vessel (or other tubular structure), passing between the bifurcated distal end of the tool, and deployed as previously discussed. 
     Using the Fastener to Occlude Tubular Structures Other than Blood Vessels 
     It will be appreciated that the fastener of the present invention can also be used to occlude tubular structures other than blood vessels. By way of example but not limitation, the temporary fastener of the present invention can be used to occlude other structures within the body (e.g., tubes such as fallopian tubes and/or vas deferens for temporary or permanent sterilization, ducts such as bile ducts and cystic ducts for cholecystectomy, lymphatic vessels, including the thoracic duct, fistula tracts, etc.). 
     Using the Fastener to Close Openings in Structures and/or for Securing at Least Two Objects Together 
     In the foregoing disclosure, the fastener is discussed in the context of occluding a tubular structure (e.g., a blood vessel, fallopian tubes, lymphatic vessels, etc.) by clamping together opposing side walls of the tubular structure in order to occlude the tubular structure. In such an application, the fastener effectively secures one side wall of the tubular structure to the opposing side wall of the tubular structure. However, it should also be appreciated that the fastener of the present invention may be used to close openings in structures and/or to secure two or more objects together for other applications. 
     By way of example but not limitation, the fastener of the present invention may be used to secure two or more portions of tissue together so as to close an incision. 
     By way of further example but not limitation, the fastener of the present invention may be used in a “stomach stapling” procedure to bring together opposing side walls of the stomach in order to reduce the size of the stomach. 
     Furthermore, the fastener of the present invention may be used in an organ resection (e.g., a liver resection), so as to seal the periphery of the resected organ. 
     By way of further example but not limitation, and looking now at  FIGS. 92-94  , the fastener of the present invention can be used for selectively clamping or occluding regions of solid organs so as to selectively stop blood flow or blood loss in various regions through tissue compression. The fastener may be used in solid organ resection of the kidney or liver or other organs. Blood loss and secretion leakage (e.g., bile, urine, etc.) can be problematic in existing solid organ resection procedures. Average blood loss for a liver resection is 700-1200 ml. By clamping desired regions of the solid organ with the fastener of the present invention, it is possible to significantly reduce the amount of undesirable fluid loss (blood loss, secretion leakage, etc.). The fastener of the present invention, can be used to apply pressure selectively to broad areas of the organ and, additionally, may also be used to close off selective tubular structures and vessels connecting the organ with other regions of the body. In one embodiment and method, multiple discrete fastener elements may be individually, selectively deployed across regions of the organ. See, for example,  FIG. 92 , which shows multiple, single, separate puncture placements of the fastener for closing off a resected liver. Note that where multiple, single, separate puncture placements of the fastener are used, different regions of the solid organ may be compressed to different and controllable degrees. 
     In a novel embodiment of the present invention, the length of distal implant locking tube  220 E (of distal implant  205 E) remaining in the body can be determined once clamping of the fastener has been effected, by providing distal implant locking tube  220 E and/or distal implant delivery tube  310 E with weakened (e.g., frangible) sections, and by breaking off distal implant locking tube  220 E from distal implant delivery tube  310 E at a region above proximal implant  210 E. This break can be achieved by incorporating selective weakened regions into the distal implant locking tube  220 E and/or distal implant delivery tube  310 E, so that when a selective weakened region is subjected to twists, or torques, or bending, or pulling, or selective other strains or stresses or the like, distal implant locking tube  220 E will separate from distal implant delivery tube  310 E at a location proximal to proximal implant  210 E. Because clamping is effected across the tissue, distal implant locking tube  220 E connecting distal implant body  215  and proximal implant  210 E will not move, while distal implant delivery tube  310 E will disconnect from distal implant locking tube  220 E. Distal implant locking tube  220 E, which connects distal implant body  215 E and proximal implant  210 E, may be solid or flexible. 
     In other embodiments of the present invention, distal implant locking tube  220 E may be composed of multiple interlocking sections, and constrained by an encasing sheath, or once deployed, by the surrounding tissue. Once clamping of the tissue is achieved, the sheath can be retracted beyond the proximal implant, exposing an interlocking region between the distal implant locking tube  220 E sections and then, with a twist, or appropriate unlocking mechanism, enable the fastener to be disconnected from the distal implant delivery tube  310 E. 
     This construction enables the clamping distance between distal implant  205 E and proximal implant  210 E to be controllable, and allows for significant tissue thicknesses to be clamped. 
     In the embodiment shown in  FIG. 93 , the fasteners are delivered in conjunction with single or multiple compression bands  550 , which may be polymers, or other tissue material or metals or other commonly used materials known in the art. The compression bands  550  may be rolled into the delivery needle or sheath and unfurled prior to delivery of the fasteners. The compression bands  550  extend the pressure across a broader region of the organ or tissue which receives the fasteners of the present invention. 
     In other embodiments, the legs of the fastener may have a thin metallic or polymeric mesh or film that is flexible, yet connects between the fingers, to enable further distribution of pressure on a clamped tissue, vessel, organ or the like. 
     In the embodiment of  FIG. 94 , multiple fasteners can be delivered in parallel to an organ, tissue, tubular structure or the like. In this form of the invention, an installation device  555 , comprising a body  560  having a plurality of deployment needles  565  extending therefrom, can be used for setting the multiple fasteners. Installation device  555  can deliver either single fasteners deployed one at a time, but in a spatially-constrained way, with a pre-defined spacing between the fasteners (determined by the predefined spacing between deployment needles  565 ), or can deliver a plurality of fasteners all at the same time, with a single activation control. This construction can reduce the amount of time required for a procedure such as a resection, by providing for simultaneous fastener deployments. 
     In other embodiments of the present invention, the fasteners can be deployed across multiple tissues, or multiple folds of the same tissue, organ or tubular structure. In certain embodiments of the present invention, the distal implant locking tube  220 E may be elastic, allowing for some movement of the clamped tissue, while still maintaining a desired clamping force or pressure on the tissue. 
     The fasteners of the above invention may also be used for bariatric surgery, or to reduce or plicate the stomach, or to create a gastrostomy sleeve. 
     In another embodiment of the present invention, the unreleased distal implant  205 E can be used as the retractor, and retract the tissue away from any organs or tissues or major blood vessel beneath, enabling subsequent deployment of other fasteners to be placed in a manner that may enable reduction of the size of an organ, joining organs together, closing a tear in the bowel or the like. Once the other desired fasteners have been deployed, the deployment of the first fastener (i.e., unification of the proximal implant  210 E with the distal fastener  205 E) can be completed. 
     Use of the Invention Under Direct Visualization and/or Indirect Visualization 
     Significantly, the present invention may be practiced under direct visualization (e.g., during “open” surgery) or under indirect visualization (e.g., during laparoscopic surgery where visualization is provided through the use of a scope, or during percutaneous surgery where visualization is provided through the use of imaging apparatus such as an ultrasound imager, an X-ray imager, etc.). 
     Enhanced Tissue, Organ, Duct and/or Vessel Clamping or Approximation 
     1. Advantages of Using Two-Part Fastener 
     The present invention relates to, among other things, a novel two-part fastener that clamps hollow tubes, vessels and/or at least two layers of materials (i.e., biological materials or synthetic materials) together, and is an improvement over existing occlusion devices such as clamps or staples, and may connect different or similar tissues together and/or connect tissues to synthetic materials. 
     More particularly, the present invention relates to an apparatus and method for permanently, and controllably, bringing at least two surfaces into at least partial contact or proximity with each other. The present invention can be used for occlusion of tubular structures such as veins, arteries, bile ducts, fallopian tubes, cystic ducts, etc. The present invention can also be used to bring, attach and/or connect at least two folds (e.g., two sides of the stomach, or other parts of the legs, etc.) together so that they are connected. 
     The present invention can also be used to connect tissue with other materials, e.g., graft materials, hernia meshes, drug delivery materials, etc. The present invention is also intended to connect two structures together with or without the need to protect the underlying tissue layers from possible injury by the transfixing needle. 
     2. Drawbacks of Using Staples 
     The advantages of the present invention include, but are not limited to, secure clamping of vessels (or tissues) by transfixing the vessel (or tissue) so that the two-part fastener cannot be dislodged and slip off of the vessels (or tissues) with untoward consequences such as bleeding in blood vessels, and detachment of tissues, etc. Furthermore, compression of the vessel (or tissues) surrounding the puncture hole is accomplished with distributed pressure on the vessel (or tissue) from the two-part fastener preventing any leakage of blood or fluids from the occluded structure. 
     More particularly, two-part fastener  200  is disposed across the vessel which is to be occluded (or across the tissue(s) which are to be clamped together) such that distal implant  205  resides on one side of the vessel and proximal implant  210  resides on the other side of the vessel, with distal implant locking tube  220  passing through the vessel and connecting together distal implant  205  and proximal implant  210 , whereby to generate a clamping force therebetween. This distributed pressure (i.e., compression), around the puncture hole, helps to prevent fluids (e.g., blood or bile) from leaking out of the puncture hole (i.e., the hole in the vessel where distal implant locking tube  220  passes through the vessel) after the aforementioned distal implant  205  and proximal implant  210  are brought together about the tissue to be clamped. Unlike a staple, which may produce bleeding where the legs of the staple pass through the vessel and which can “slip off” of the vessel, distal implant  205  and proximal implant  210  cannot “slip off” of the tissue. The distributed pressure around the puncture hole greatly reduces the possibility of the tissue ripping. 
     Bleeding, “slipping off” of tissue and ripping through tissue are common problems associated with using staples, and with using other clips (such as hemoclips) and clamps. Two-part fastener  200  of the present invention is able to hermetically close a vessel experiencing a pressure of 0 mm Hg up to, and above, 700 mm Hg (i.e., pressures at which the aforementioned issues associated with staples and prior-art clamps occur). 
     The novel two-part fastener  200  of the present invention also eliminates the need for an additional support material when clamping delicate tissue. 
     For example, one prior art medical stapling device requires the provision of additional support material when stapling fragile tissues. More particularly, this prior art medical stapling device uses an additional advanced polymer felt material placed on the tissues and stapled together with the tissues. 
     3. Attaching Two Objects Together Using Two-Part Fastener  200   
     As discussed above, two-part fastener  200  may be used for occlusion of tubular structures such as, veins, arteries, bile ducts, cystic ducts, fallopian tube, etc.). However, it should also be appreciated that two-part fastener  200  may be used to attach a non-tissue element to tissue (e.g., to attach hernia mesh to tissue, or a blood vessel stent-graft to the native vessel). Two-part fastener  200  may also be used to attach a first non-tissue element to a second non-tissue element (e.g., to attach a synthetic hernia mesh to the normal tissues surrounding edges of the hernia site, or to another segment of hernia mesh), e.g., for shaping or reconfiguring a non-tissue element. 
     It will be appreciated from the preceding disclosure that distal implant locking tube  220  of two-part fastener  200  passes through the tubular structure which is to be clamped, however, the entire area around distal implant locking tube  220  is compressed/closed-off so as to prevent any bleeding or leakage of fluids from occurring at the site of the entry/exit point of distal implant locking tube  220  through the side walls of the tubular structure. 
       FIGS. 95 and 96  show two-part fastener  200  being used to clamp, for example, hernia mesh to tissue. 
     4. Two-Part Fastener  200  with Interdigitated Fingers 
     In addition to the foregoing advantages (over prior art clamps and staples) of using two-part fastener  200  to occlude a tubular structure, it should also be appreciated that the provision and use of a two-part fastener  200  having interdigitated legs (i.e., legs  235  of distal implant  205  and legs  295  of proximal implant  210 ) allows a tubular structure to be safely occluded in a way that avoids the problems associated with staples or clips (e.g., hemoclips, Ligaclips, etc.) (see above) and which allows the clamping force which is used to be adjustable. 
     In a preferred embodiment, the present invention generally comprises two compression elements, a proximal implant  210  for compressing the near wall of the vessel, and a distal implant  205  for compressing the far wall of the vessel. Proximal implant  210  and/or distal implant  205  may be made of a shape memory metal (e.g., Nitinol), other biocompatible metals and/or ceramics, and/or various polymers and biodegradable polymers that assume their designated configuration when two-part fastener  200  is used to occlude a vessel. Proximal implant  210  comprises a plurality of legs  295  for applying clamping pressure to the proximal side of a vessel which is to be occluded and distal implant  205  comprises a plurality of legs  235  for applying clamping pressure to the distal side of a vessel which is to be occluded. 
       FIGS. 97 and 98  show two-part fastener  200  being used to occlude a blood vessel (or clamp tissue). In one preferred embodiment of the present invention, distal implant  205  is pre-attached to (or formed integral with) distal implant locking tube  220  (also sometimes referred to herein as the implant locking rod, which also may be made of an organic, ceramic, or biodegradable polymer). In one embodiment of the present invention, distal implant  205  is secured to distal implant locking tube  220  through welding. By way of example but not limitation, distal implant  205  may be welded to distal implant locking tube  220  using a welding material introduced at least in part into a welding hole  600  formed in distal implant locking tube  220  (see  FIG. 102 ). In another embodiment of the present invention, distal implant  205  is secured to distal implant locking tube  220  through a mechanical locking, latching or threaded screw arrangement. In another embodiment of the present invention, distal implant  205  and distal implant locking tube  220  are formed out of one contiguous piece and material. Proximal implant  210  is preferably locked to distal implant locking tube  220  by way of inwardly-oriented flaps (i.e., inwardly-projecting tangs  300 ) which are formed in the body of proximal implant  210  and lock into corresponding openings (i.e., windows  265 ) formed in distal implant locking tube  220 . It should be appreciated that, if desired, flaps (i.e., inwardly-projecting tangs  300 ) may be formed on distal implant locking tube  220  as outwardly projecting tangs, with corresponding openings (i.e., windows  265 ) being formed in proximal implant  210  (i.e., to receive the flaps formed on distal implant locking tube  220 ). There may be one window  265 , or 2 windows  265 , or 3 or more windows  265 . Windows  265  may cover 1%-100% of the circumference of distal implant locking tube  220 , or 1%-95% of the circumference of distal implant locking tube  220  if windows  265  are located on proximal implant  210 . 
     Two-part fastener  200  is capable of generating an occlusion pressure (i.e., a clamping force between proximal implant  210  and distal implant  205 ) which is sufficient to clamp a blood vessel with a pressure of at least 100 mm Hg. In another embodiment of the present invention, two-part fastener  200  is capable of withstanding a pressure of up to 300 mm Hg, and in a further embodiment of the present invention, two-part fastener  200  is capable of supporting a pressure of over 700 mm Hg.  FIG. 97  shows the interdigitation (i.e., circumferential offset) of legs  295  of proximal implant  210  and legs  235  of distal implant  205 . 
     5. Adjustable Clamping Force 
     In a further embodiment of the present invention, the amount of pressure (i.e., the amount of clamping force) that two-part fastener  200  applies to the tissues, or across a blood vessel, can be variably controlled. 
     More particularly,  FIG. 99  illustrates how the gap between legs  235  of distal implant  205  and legs  295  of proximal implant  210  can be controlled, effectively controlling the amount of pressure applied to the tissue being clamped, or the degree to which the aperture (i.e., lumen) of the vessel being transfixed by two-part fastener  200  is occluded. 
       FIG. 100  shows one embodiment of the present invention wherein distal implant locking tube  220  comprises a controllable ratcheting mechanism for selectively controlling the spacing between proximal implant  210  and distal implant  205  of two-part fastener  200 . In this form of the invention, legs  235  of distal implant  205  and legs  295  of proximal implant  210  are generally oriented primarily in a parallel orientation to each other, and the distal and proximal fingers are aligned so that they overlapping.  FIG. 101  shows an external view of a ratcheting mechanism of the present invention which allows a variable disposition of proximal implant  210  and distal implant  205  relative to one another. 
     In this form of the present invention, distal implant locking tube  220  comprises a plurality of windows  265  (e.g., a plurality of circular grooves) formed along its length. Proximal implant  210  comprises a plurality of inwardly-projecting tangs  300  formed at a point along its length. As proximal implant  210  is advanced distally towards distal implant  205 , inwardly-projecting tangs  300  enter into windows  265 , thereby locking proximal implant  210  to distal implant  205 . Inwardly-projecting tangs  300  are configured so that proximal implant  210  can only move in a single direction (i.e., distally) relative to distal implant  205 . As proximal implant  210  is advanced distally relative to distal implant  205 , inwardly-projecting tangs  300  can slide out of windows  265  and enter windows  265  located distally. If desired, windows  265  may comprise a chamfered distal edge to facilitate movement of inwardly-projecting tangs  300  out of windows  265  as proximal implant  210  moves distally relative to distal implant  205 . 
     See also  FIG. 102 , and note the “notch-to-notch distance” (i.e., the distance between windows  265 ) which governs the ability to vary the degree of compression established between legs  235  of distal implant  205  and legs  295  of proximal implant  210 . 
     The degree of overlap and/or alignment of legs  235  of distal implant  205  and legs  295  of proximal implant  210  can be controllably adjusted in several ways. First, the locking mechanism (e.g., the inwardly-projecting tangs  300  of proximal implant  210  and windows  265  of distal implant  205 ) may be appropriately positioned relative to one another so as to set the orientation of proximal implant  210  relative to distal implant  205  prior to locking. 
     In one form of the present invention, and looking now at  FIGS. 103-106 , there is provided a mechanism for setting the rotational orientation of proximal implant  210  relative to distal implant  205 .  FIG. 103  shows the mechanism for alignment and orientation control of the proximal implant  210  through an orientation alignment groove (or notch)  605  formed in the proximal end of proximal implant  210 , and a corresponding orientation alignment post (or tab)  610  formed in proximal implant delivery tube  330 . If desired, multiple orientation alignment grooves  605  and multiple corresponding orientation alignment posts  610  may be provided. By controlling the degree of rotation of the proximal implant delivery tube  330  one can vary the rotational orientation of proximal implant  210  relative to distal implant  205  once proximal implant delivery tube  330  is advanced distally so as to engage proximal implant  210  and tab  610  is mated with groove  605 .  FIG. 106  shows how, in one form of the present invention, a rotor knob  615  may be provided which can be used to control the orientation of proximal implant  210  relative to distal implant  205 . Rotor knob  615  exerts a rotary force on proximal implant tube  330  such that when rotor knob  615  is rotated, rotor knob  615  rotates implant tube  330 . By way of example but not limitation, in one form of the present invention, when rotor knob  615  is rotated fully clockwise, legs  235  of distal implant  205  and legs  295  of proximal implant  210  fully overlap and are aligned. Each half-turn increment of rotor knob  615  can be configured to result in a 9-degree orientation difference between legs  235  and legs  295 . Rotor knob  615  may have discrete set points (or stopping points) corresponding to each 9-degree increment of the rotor. Each one of these set points can be configured to correspond to the angles of 9-degrees, 18, 36 degrees (which is the maximal misalignment between the legs), 45, 54, 63, and 72 degrees (corresponding to full overlap of the legs) between two legs  235  and legs  295 . The delivery device may have a display that indicates the angle between legs  235  and  295  that is incremented or decremented by 9-degrees depending on the half rotation of rotor knob  615  in the clockwise or counter-clockwise directions. Other discrete angle steps or increments between legs  235  and legs  295 , or a continuous range of angles are also possible, depending on the particular configuration of the design of rotor knob  615 . 
     The design and mechanism of action of two-part fastener  200  is preferably such that when deployed and locked (e.g., with inwardly-projecting tangs  300  disposed in windows  265 , the individual legs  295  of proximal implant  210  alternate with, and interdigitate with, the individual legs  235  of distal implant  205 .  FIGS. 109-111  are schematic views of a fully-deployed two-part fastener  200  (including a top view) looking down (i.e., looking distally) onto a deployed two-part fastener  200  and with the proximal and distal walls apposed.  FIG. 107  is a photograph of a deployed fastener with offset legs  235  of distal implant  205  and legs  295  of proximal implant  210 . Variable offset between legs  235  and legs  295  allows for the adjustment of clamping tension applied to the tissue. By way of example but not limitation, for delicate or easily damaged or torn tissue (e.g., brain tissue), or tissue that has limited elasticity, it is generally preferable that legs  235  and legs  295  substantially completely oppose one another (i.e., align with one another) so that no lateral tension is applied to the tissue. Similarly, for lung tissue, it may generally be preferable for legs  235  and legs  295  to have a substantial degree of overlap, so as to minimize the tension applied to the tissue. 
     On the other hand, for many vascular applications, maximum interdigitation (i.e., minimum overlap of the legs  235 ,  295 ) is generally preferred (e.g., an angle of 36 degrees between legs  235  and legs  295  may be desired) so as to maximize the tension applied to the tissue whereby to occlude the vessel. 
     With interdigitation of the legs  235  and legs  295  tension is projected across the tissue, with the closing force extending beyond the physical dimensions of legs  235  and legs  295  themselves. 
     Thus it will be seen that the disposition of legs  235  of distal implant  205  relative to the disposition of legs  295  of proximal implant  210  may be controlled so as to apply a desired clamping force according to the type and/or condition of the tissue which is to be clamped. 
       FIG. 112  shows a number of photographs that better illustrate how two-part fastener  200  effectively clamps tissue (in this case a simulated blood vessel). Legs  235  of distal implant  205  and legs  295  of proximal implant  210  are shown interdigitated. This causes ripples, or folds, in the tissue that act to extend the effective closure, and applies the closure force to the vessel well beyond the region directly contacted by the fastener legs  235 ,  295 . By way of example but not limitation, a two-part fastener  200  having a physical occlusion diameter of 5.5 mm is able to close vessels that are over 7 mm (and even equal or greater to 1 cm) in diameter. 
     In one embodiment of the present invention, and looking now at  FIG. 113 , legs  295  of proximal implant  210  and legs  235  of distal implant  205  may be beveled (or rounded) so that legs  295 ,  235  are not sharp, and legs  295 ,  235  may be designed to point away from the tissue to be clamped at the free end of each leg (i.e., on the end of the leg away from the distal implant locking tube  220 ). This is in order to minimize any catching or damage that may be imparted on the tissue by legs  235 ,  295 , whereby to minimize tearing or ripping of the tissue. In other embodiments of the present invention, it may be desirable to provide sharp ends to legs  235 ,  295  so that legs  235 ,  295  catch or pierce the tissue for better gripping. Legs  235 ,  295  may be smooth, or the surface of legs  235 ,  295  may be roughened, e.g., through chemical etching or mechanical means, so as to enhance the reflectivity of the implants, or to provide maximum tissue capture and gripping. 
     Looking at  FIGS. 112 and 113 , it can be seen that (i) legs  295  of proximal implant  210  and legs  235  of distal implant  205  alternate and interdigitate with one another, and (ii) the distal ends of legs  295  of proximal implant  210  pass distally of the proximal ends of legs  235  of distal implant  205 , and vice versa. In effect, when fully deployed on an artery or vein, or duct, or other organ tissue, there is a predominantly circular occlusion of the vessel around distal implant locking tube  220  by legs  235 ,  295  of the distal implant  205  and proximal implant  210 , respectively. This circular occlusion resembles, in some ways, a “pie crust” pattern in which the proximal wall and distal wall of the vessel are brought into apposition with one another, with distal implant locking tube  220  at the center of the “pie”. 
       FIG. 113  shows the shear stress induced between the interdigitation of legs  235  and legs  295 , acting to pull the tubular structure aperture closed. 
       FIG. 114  shows how a plurality of forces may be applied across the vessel using the interdigitation of legs  235 ,  295  of two-part fastener  200  of the present invention. 
       FIG. 115  shows, with the cross-sections a-b and b-c, the strains induced in a vessel by the clamping forces generated by the interdigitated legs  235 ,  295  of two-part fastener  200 . 
       FIG. 116  is a top view showing tissue folding when legs  235  and legs  295  of two-part fastener  200  are interdigitated with one another. The dashed lines show the regions where the tissues are pulled together so as to touch. When legs  235 ,  295  are interdigitated, a force is applied that radiates beyond the physical length of legs  235 ,  295  extending the clamped tissue closure beyond the diameter of the physical legs. 
     Due to the interdigitated mode of operation, the estimated sum of the proximal and distal wall thicknesses of the vessel that is to be occluded does not necessarily determine whether an effective occlusion can be achieved. Since the occlusion components (i.e., legs  235  and legs  295 ) cross each other&#39;s plane when deployed, the proximal and distal walls of the vessel are brought into opposition with one another regardless of their summed wall thickness, i.e., 2.0 mm veins have approximately 0.2 mm wall thickness (0.4 mm combined), as compared to a 3.5 mm muscular artery having approximately 0.6 mm wall thickness (1.2 mm total combined) and even a 7.0 mm muscular artery having approximately a 1.0 mm wall thickness (2.0 mm combined). Each of these vessels, with varying dimensions, can be effectively occluded using two-part fastener  200  due to the way two-part fastener  200  ligates the vessel. The interdigitation of legs  295  of proximal implant  210  and legs  235  of distal implant  205  means effective closure can be realized even with very thin tissue, since legs  295 ,  235  of the fastener components cross each other&#39;s plane when two-part fastener  200  is deployed across the tissue. 
     In one embodiment of the present invention, where legs  295  of proximal implant  210  and legs  235  of distal implant  205  are interdigitated, the force needed to close the vessel disposed between proximal implant  210  and distal implant  205  using two-part fastener  200  is much less than the force needed to close the same vessel with a conventional ligation clip. This is due to the fact that, in the case of two-part fastener  200 , interdigitated legs  295 ,  235  are pushing against tissue, causing the tissue waviness, bending, or folding, but are not pushing up against the full force of counter-set legs  295 ,  235 . This means that vessel closure can be realized with a reduced level of force or pressure on the tissue. 
       FIG. 117  is a histological section showing the residual impact on the vessel cross-section occluded by legs  295 ,  235  after vessel healing of up to 30 days. The vessel is completely occluded and the vessel wall tissue is compressed together and, with early healing, “healed” together. The effect of the sheer forces collapsing the vessel walls together can be seen in  FIG. 117 . The “pie crust” closure may be observed more clearly as well. The arrow indicates the collapsed undulating artery. AVO indicates the location of the interdigitating legs of two-part fastener  200 . 
     The two-part fastener  200  of the present invention may be used to occlude vessels, ducts and/or to compress tissue so it is occluded/compressed at forces less than 700 grams, while the force required to seal off vessels or clamp tissue with a Ligaclip are about 10 times greater. The delivery system for two-part fastener  200  imparts a force which is transferred directly from the operator to two-part fastener  200 . This reduces requirements and levering on the delivery device and the amount of force or pressure an operator may need to apply. The two-part fastener  200  of the present invention, can maintain operation in the elastic regime and does not need to be plastically deformed to realize occlusion. 
     6. Novel Clip with Interdigitated Fingers 
     It should be appreciated that the use of interdigitated legs to occlude a vessel may extend beyond use with two-part fastener  200 . By way of example but not limitation, a novel clip  625  comprising interdigitated and at least in part horizontally spaced legs  630  connected at a common end  635  may be provided. 
       FIGS. 118-120  show a novel ligating clip  625  which uses interdigitation of legs  630  (deployed alternatingly on the proximal and distal sides of the vessel) to create vessel closure. Once again, sheer stress is induced so as to close the vessel or duct. The interdigitation of legs  630  will also reduce the likelihood that the tissue being clamped will slip out, or that the clamp will fall off. In this case, similar to a hemo-clip, legs  630  of ligating clip  625  are “squashed” together across the vessel to be occluded or tissue to be attached. In one embodiment of the invention, legs  630  are pushed so that the tips of legs  630 , deployed on the distal side of the vessel, are now above the tips of legs  630  deployed on the proximal side of the vessel, crossing each others plane, so that the tissue between them is stretched closed. 
     7. Delivery of Multiple Two-Part Fasteners 
     The ability to deploy multiple two-part fasteners  200  during a procedure can be an important advantage in numerous applications. By way of example but not limitation, when treating venous reflux disease, multiple reflux sites may need to be occluded, or a certain length of vessel may need to be occluded, and it may be desirable to utilize multiple two-part fasteners  200  to achieve this. By way of further example but not limitation, when preparing a vein or artery to be used for a bypass procedure, multiple branch or tributary vessels need to be occluded, and multiple two-part fasteners  200  of the present invention may be used. By way of example but not limitation, when it is desired to isolate the region between two parts of a vessel or duct by cutting the region between the two parts (e.g., when removing a bile duct), one two-part fastener  200  may be deployed on either side of the region to be cut, so as to prevent blood loss. For example when desiring to remove a gall bladder the cystic duct needs to be ligated to prevent spillage of bile from the common bile duct or harvesting an organ, such as the kidney, for transplant or removing part or the entire organ, such as the spleen, for therapeutic considerations. 
     There are several ways in which multiple two-part fastener&#39;s  200  can be delivered. 
     8. Reusable Handle with Disposable Tip 
     Looking next at  FIGS. 121 and 122  multiple two-part fasteners  200  may be delivered using a plurality of single use disposable delivery devices  640 , wherein each single use delivery device  640  contains a single two-part fastener  200 . With this form of the present invention, each single use disposable delivery device  640  is used to deploy a single two-part fastener  200 , and then the single use disposable delivery device  640  is disposed of after use. Multiple single use disposable delivery devices  640 , each incorporating a two-part fastener  200 , may be packaged as a single sterile package (e.g., 3 or 6 single use delivery devices to a sterile package). After a sterile package is opened and some (or all) of the single use delivery devices are used, all single use delivery devices must be discarded. Alternatively, each single use disposable delivery device  640  may be packaged in its own sterile package. 
     Looking now at  FIG. 122 , in one form of the present invention, there is provided a disposable delivery device for delivering a single two-part fastener  200 .  FIGS. 123 and 124  show the deployment steps for an embodiment of the delivery device.  FIG. 124  shows: (a) hollow needle  305  passing through the blood vessel, (b) deployment of distal implant  205 , (c) retraction of hollow needle  305  and deployment of proximal implant  210 , (d) using push rod  320  to lock proximal implant  210  and distal implant  205  together. The next steps (not shown), involve retraction of proximal implant delivery tube  330 . Exposing the junction between distal implant locking tube  220  and distal implant delivery tube  310 , and rotating a knob  620  ( FIG. 122 ) which rotates distal implant delivery tube  310  and releases it from distal implant locking tube  220 , releasing two-part fastener  200  from the delivery device. The delivery device is then removed leaving two part fastener  200  deployed. 
     In another embodiment of the present invention, and looking now at  FIG. 125 , hollow needle  305  of the delivery device may contain two-part fastener  200 , and once deployed, hollow needle  305  may be removed from the handle of the delivery device, and a new hollow needle  305  (containing a two-part fastener  200  disposed therein) may be affixed to the delivery device and used to deploy a second two-part fastener  200  during a given procedure. As such, the handle and delivery element are retained throughout the procedure, while the hollow needle  305  (and hence the two-part fastener  200  contained therein) is replaced. This form of the invention enables the delivery device to be reused multiple times during a procedure, while the individual two-part fasteners  200  are deployed and the plurality of hollow needles  305  are discarded. Hollow needle  305  can be attached to the handle (which is pre-loaded with a two-part fastener  200 ) prior to delivery of a two-part fastener  200 , and detached following delivery of the two-part fastener  200 , and replaced with a new hollow needle  305  (which is pre-loaded with another two-part fastener  200 ). This approach enables the delivery of multiple two-part fasteners  200  during a single procedure, and reduces the cost of the system, since the handle and delivery element is generally more costly than a hollow needle  305  which is pre-loaded with two-part fastener  200 . 
     In one form of the present invention, the handle and delivery element can be sterilized and reused for multiple procedures. 
     In one form of the present invention, hollow needle  305  is configured to be threaded and screwed into the delivery device. See  FIG. 125 , which is a cross-section of two-part fastener  200  pre-loaded in a hollow needle  305  which is attached to the delivery device using a releasable locking mechanism  645 . 
       FIG. 126  shows a cross-section of hollow needle  305  with two-part fastener  200  pre-loaded inside, and a releasable locking mechanism  645  for attaching hollow needle  305  to the delivery device.  FIG. 127  is an external view of hollow needle  305  showing releasable locking mechanism  645 . See also  FIG. 128 , which shows the reusable delivery device. 
     9. Rotating Barrel 
     In still another form of the present invention, multiple two-part fasteners  200  can be disposed within a single delivery device. In one preferred form of the present invention, and looking now at  FIGS. 129-139 , multiple two-part fasteners  200 , each contained within their own hollow needle  305 , may be loaded into chambers  650  in a barrel-like cartridge  652 , which in turn is mounted to a housing  665 , whereby to be deployed one after another as will hereinafter be discussed. In other words, in this form of the present invention, rather than having a hollow needle  305  that is pre-loaded with a two-part fastener  200  and attached to the same delivery device, the multiple two-part fasteners  200  are each loaded into their own hollow needle  305  and into chambers  650  of cartridge  652 , whereby to allow the delivery of multiple fasteners deployed one at a time, each through its own corresponding hollow needle  305 . 
     In one preferred form of the present invention, cartridge  652  rotates, and plungers are used to first deploy the pre-loaded hollow needle  305  contained within cartridge  652  across the tubular structure (or tissue) to be occluded (or clamped), and then used to deliver the pre-loaded two-part fasteners  200  contained within the hollow needle  305 . 
       FIGS. 129-139  show the device and delivery mechanism for deploying multiple fasteners in greater detail.  FIG. 129  shows six hollow needles  305 , each contained within their own chamber  650  within cartridge  652 . Cartridge  652  is controllably rotatable via rotation of a knob  653 . Rotating knob  653  rotates rotator element  654  which serves to rotate barrel  652  to the next stop notch  655 , which stop notch  655  corresponds to the next chamber  650  of barrel  652 . A needle push rod  660  is actuated by a lever  656 , proximal implant delivery rod  680  is actuated by lever  657 , and proximal implant delivery tube  690  (or  330 ) is actuated by a lever  658 . When actuated, the levers move corresponding support posts  659 ,  661  and  662  forward towards barrel  652 . Note, needle push rod  660 , has a reversible latching mechanism  663  provided on the distal end of needle push rod  660  which is similar to releasable locking mechanism  645  of single use delivery device  640  in that reversible latching mechanism  663  allows needle push rod  660  to reversibly latch onto hollow needle  305  so that needle push rod  660  can push or pull hollow needle  305 . 
     In use, in order to deliver two-part fastener  200  across a tubular structure, and looking now at  FIGS. 130-133 , lever  656  is activated and pulled proximally to move needle push rod  660  distally into chamber  650  so that needle push rod  660  latches onto hollow needle  305  and pushes hollow needle  305  at least partially out of cartridge  652 . Hollow needle  305  (and the delivery device), are then positioned so as to transect the tubular structure to be occluded. Next lever  657  is pulled proximally, whereby to push proximal implant delivery rod  680  distally so that proximal implant delivery rod  680  locks onto a hook formed on the proximal end of distal implant locking tube  220 . Next, lever  658  is pulled proximally so as to deliver proximal implant delivery tube  690  so that it covers the clasping or locking region between distal implant locking tube  220  and proximal implant delivery rod  680 . Next lever  657  is pulled back further proximally, whereby to deploy distal implant  205 . See  FIG. 135 . Then levers  658  and  657  are pulled back further proximally, deploying proximal implant  210  and locking distal implant  205  and proximal implant  210  together via distal implant locking tube  220 . Next, and looking now at  FIG. 137 , levers  657  and  658  are pushed forward distally so as to retract proximal implant delivery tube  690  proximally, and to release implant  220  from the delivery device and hollow needle  305 . Lever  656  is then pushed forward distally so as to retract deployed hollow needle  305  into barrel  652 . See  FIG. 138 . Barrel  652  is then rotated to the next chamber  650  location containing a new hollow needle  305  pre-loaded with a two-part fastener  200 . Cartridge  652  is rotated by rotating knob  653  of the delivery device. The delivery device is now ready for delivering another two-part fastener  200  in the same manner as discussed above. Note that after two-part fastener  200  has been deployed, the empty hollow needle  305  is retracted proximally and contained in cartridge  652 , as shown in  FIG. 139 . 
       FIGS. 140 and 141  are top views of a delivery device wherein cartridge  652  (sometimes also referred to herein as a “barrel”) contains multiple two-part fasteners  200 , wherein each two-part fastener  200  comprises a pair of clamping elements (e.g., distal implant  205  and proximal implant  210 ) and an associated hollow needle  305 . In this form of the present invention, all two-part fasteners  200  disposed in cartridge  652  are delivered one at a time through separate hollow needles  305 . In this form of the present invention, while multiple hollow needles  305  are used, only a single delivery mechanism is required. The advantage of using multiple hollow needles  305 , wherein each two-part fastener  200  is deployed via a separate hollow needle  305 , is that each hollow needle  305  is sharp and is not dulled by multiple penetrations through tubular structures, organs or tissues. With the embodiment shown in  FIGS. 140-143 , hollow needle  305 , proximal implant delivery tube  690  and proximal implant delivery rod  680  are pre-loaded into chamber  650 . Each two-part fastener  200  is deployed in a manner similar to that discussed above (i.e.,  FIGS. 129-139 ), however, proximal implant delivery rod  680  does not require a hook in this case. Therefore, the delivery mechanism of the delivery device may be simplified over the delivery device shown in  FIGS. 129-139 . 
     As seen in  FIGS. 144-148 , in another preferred form of the present invention, multiple two-part fasteners  200  are contained within a cartridge  652  and are delivered through the same hollow needle  305 . Since there is only a single hollow needle  305 , the two-part fasteners  200  contained in cartridge  652  are loaded one-by-one from cartridge  652  into a single hollow needle  305  disposed in the center of the delivery device for deployment. 
       FIG. 148  shows a top view of the multi-fastener single needle device shown in  FIGS. 144-147 , wherein hollow needle  305  is located in the center of cartridge  652 . In this form of the invention, each two-part fastener  200  is contained in a tube  664 . A plurality of tubes  664 , each containing a two-part fastener  200 , are loaded into the cartridge  652 , and into the pre-deployment clamp region  666 , where a spring pushes them towards and into hollow needle  305 . Once each two-part fastener  200  has been deployed, a lever or button is pressed allowing the empty container  667  to be pushed into the post deployment waste receptacle  668 . The push rods to deploy two-part fastener  200  are located perpendicular to the shown clamp deployment region and can be operated in the same manner shown for the multi-needle deployment device discussed above. 
       FIGS. 149-171  show another operating concept of a multi-fastener delivery device formed in accordance with the present invention, wherein two-part fastener  200  is delivered through the same hollow needle  305 . A barrel  670 , having multiple chambers  675  which can be loaded with multiple two-part fasteners  200 , is plugged into a delivery device, so that multiple two-part fasteners  200  can be delivered one after the other through a single hollow needle  305 , without having to withdraw hollow needle  305  from patient body or from a laparoscopic port. 
       FIG. 150  shows multi-fastener barrel  670  loaded with two-part fasteners  200 . The number of two-part fasteners  200 , and which chambers  675  are loaded with two-part fasteners  200 , may be selected and controlled by the user. 
       FIG. 151  shows one embodiment with two-part fasteners  200  being pre-loaded into the replaceable barrel  670  of delivery device. 
       FIG. 152  shows a side view of multiple fastener delivery device  665 . 
       FIGS. 153-156  show a proximal implant delivery rod  680  and hook  685  locked onto the distal implant locking tube  220  hook of two-part fastener  200 . Proximal implant delivery tube  690  covers the latching region of the two hooks, thereby securing the connection. 
       FIGS. 157-161  show how proximal implant delivery rod  680  and proximal implant delivery tube  690  are pushed in a coordinated fashion (e.g., together) downward (i.e., distally) so as to push two-part fastener into (and through) hollow needle  305 . 
       FIGS. 162-166  and  FIGS. 167-171  show how hollow needle  305  transfixes a tubular structure (or blood vessel or tissue) and two-part fastener  200  being deployed across a vessel or duct, in a similar manner and with similar steps to those shown in  FIGS. 63-77 . Once distal implant  205  is deployed, hollow needle  305  is retracted, deploying proximal implant  210 . Proximal implant delivery tube  690  is then pushed down (i.e., distally), so as to push and lock proximal implant  210  onto distal implant locking tube  220 , which is disposed between proximal implant  210  and distal implant  205 , thereby compressing and securing the tubular structure between proximal implant  210  and distal implant  205 . Proximal implant delivery tube  690  is then raised (i.e., moved proximally), exposing the clamping region between proximal implant delivery rod  680  and distal implant locking tube  220 . Proximal implant delivery rod  680  is then rotated, unlocking it from the distal implant locking tube  220 . The delivery device, together with hollow needle  305  is extracted, leaving the implanted transfixed two-part fastener  200  disposed across the tubular structure, blood vessel or clamped tissues. 
     10. Serial Deployment of Two-Part Fastener  200   
     In another form of the present invention, multiple two-part fasteners  200  may be disposed in the same hollow needle  305 , and deployed one after another in a serial fashion. See  FIG. 172 . 
     11. Occlusion Using Asymmetric Legs  235 ,  295   
       FIG. 173  shows the two-part fastener  200  of the present invention preventing hemorrhaging caused by the transfixing rod (i.e., distal implant locking tube  220 ). There are many applications for which such a device could prove useful, e.g., in aortic aneurysm repair, particularly in the thoracic aorta, where, after removal of the aneurysm, the edge of the vessel is fragile and attaching a necessary synthetic graft to close the gap in the vessel by suture is complicated by bleeding from the needle entry points. This may result in clinical failure, endangering the patient or resulting in a complications. Another example is the resection and suturing of the atrial appendage of the heart which may be resected in patients who have an anthemia with clot embolising from this appendage. Suturing the atrial appendage wall even with the buttress synthetic material often results in significant bleeding from the entry points of hollow needle  305 . 
       FIG. 173  also shows two-part fastener  200  and the surrounding effective pressure zone. Note that the different overlaps between legs  295  of proximal implant  210  and legs  235  of distal implant  205  are controllably adjustable to provide the desired pressure zone and occlusion level. 
     In one form of the present invention, the pressure zone generated by two-part fastener  200  is a circular area extending around the entry point of the transfixing distal locking tube  220  ( FIG. 174 ), but in other embodiments the pressure zone may be non-circular, meaning that the lengths of legs  235  of distal implant  205  and legs  295  of proximal implant  210  are not equal along one axis relative to another, so as to permit two-part fastener  200  to be positioned proximal to a branched vessel or tissue, as shown in  FIG. 175 . 
     More particularly,  FIG. 175  shows a two-part fastener  200  where the legs  235  of distal implant  205  and the legs  295  of proximal implant  210  are not symmetric, but rather are oval (i.e., shorter) in one dimension than the other, allowing placement proximite to interconnection regions. In one form of the present invention, the orientation of the two-part fastener  200  can be determined using markings disposed on the delivery device handle (e.g., an arrow which indicates the long direction of legs  235 ,  295 ). In laparoscopic or open procedures, the orientation of two-part fastener  200  can also be visually confirmed. In percutaneous applications, ultrasound, or CT imaging can be used to further determine orientation of two-part fastener  200  relative to vessels, ducts, organs, tissue that is are to be clamped or occluded. 
     12. Tissue Protection 
     It should be appreciated that it is often desirable to stabilize (e.g., via clamping) the vessel (or other tubular structure) that is to be occluded using two-part fastener  200 . In addition, it is often desirable to provide a “needle shield” under the vessel (or other tubular structure) which is to be occluded so that hollow needle  305  does not damage underlying tissue as it pierces the vessel (or other tubular structure) which is to be occluded. 
       FIG. 176  shows a delivery device comprising a gripper (or dissector)  695  that holds the vessel (or tissue) in place while it is transfixed, while also protecting the underlying tissue, (i.e., tissue which is not to be transfixed), via a needle stop, from being injured by hollow needle  305  as it pierces the vessel. The needle stop can also have a sharp knife-like edge, to help first dissect out the tissues to be occluded from the tissues to be protected. 
     13. Lift to Protect 
       FIGS. 177-179  show examples of prior art dissectors for use in open and laparoscopic surgery. 
     Looking next at  FIGS. 180 and 189 , under certain conditions (e.g., when hollow needle  305  is being used to transfix a vessel that is in proximity to tissue, organs, or other vessels) it is desirable to deploy a device  700  that can be positioned between the tip of hollow needle  305  and the vessel to protect, for example, the tissues, organs, nerves, or other biological materials and vessels that may otherwise come in contact undesirably with the tip of hollow needle  305 . Other applications for which the present invention is used, may require a needle (or other sharp element) to penetrate tissues, or an organ, and the envisioned devices of the invention may act as a “shield” (or stop) to protect any tissue or biological material not desired to be penetrated beyond the desired penetration site or depth. 
       FIGS. 180 and 181  show dissection of a tubular structure which has been “lifted” so as to be free from surrounding tissue prior to penetration of the tubular structure by hollow needle  305  and delivery of two-part fastener  200 .  FIG. 181  shows counter traction by elevation of “dissector limbs”  705 ,  710  which allows easy penetration of the tubular structure by hollow needle  305  but does not control depth of penetration by hollow needle  305 , thereby allowing underlying tissues to be penetrated and/or injured by hollow needle  305 . 
       FIG. 182  shows another form of dissector formed in accordance with the present invention which may be used for dissection of the tubular structure so as to free the tubular structure from the surrounding tissues. Dissector  715  provides for elevating and counter-traction as well as providing a shield  720  to limit the penetration of hollow needle  305  into the surrounding (i.e., underlying) tissues, structure or viscera. More particularly,  FIG. 182  shows dissector  715  in the closed neutral position. The dissector preferably comprises two limbs  705 ,  710  having curved distal tips  725 . One distal tip  725  of dissector  715  comprises two superimposed curved blades  730 ,  735  connected to a controlling rod  740 .  FIG. 183  shows how depressing controlling rod  740  moves the two curved blades  730 ,  735  of dissector  715  apart. Rotation of controlling rod  740  rotates the movable portion of the dissector tip (i.e., curved blades  730 ,  735 ). If desired, the second limb  710  of dissector  715  has of a single, fixed curved blade  730 . In another embodiment of the invention, the dissector tips  725  can be flat, and can be controllably rotated outward protruding away from the blades. 
       FIG. 184  shows the closed neutral position of the adjustable limbs  705 ,  710  wherein the two curved blades  730 ,  735  lie in apposition (i.e., lying on top of each other). The movable curved blade  735  is connected to controlling rod  740  which can be depressed and rotated. In this embodiment, dissector  715  is designed such that limbs  705 ,  710  can overlap, so that they can be easily delivered through, for example, a standard cannula for laparoscopic procedures.  FIG. 185  shows that, by rotation of limbs  705 ,  710  of the dissector the dissector can be brought into an operational configuration. 
       FIG. 186  shows another form of dissector  745  formed in accordance with the present invention now opened and comprising two “limbs” a first limb  750  having a single tip  755 , and a second limb  760  having a double adjustable tip  765 . A rod  770  is mounted to the movable component of the double dissector tip element  765 .  FIG. 187  shows the vessel (or tubular structure) to be penetrated by hollow needle  305  and the surrounding or underlying tissues. 
       FIG. 188  shows the vessel (or tubular structure) has been dissected from the surrounding tissues and elevated by the two distal tips (or blades)  755 ,  765  and the hollow needle  305 , is being readied to penetrate the vessel (or tubular structure). 
       FIG. 189  shows rod  770  being depressed and separating the two elements  775 ,  780  of double adjustable tip  765 . 
       FIG. 190  shows the extended distal blade (shield)  780  of the dissector tip being rotated by rotating rod  770  so that the extended distal blade points toward the second dissector tip  755 . 
       FIG. 191  shows shield  780  in place as hollow needle  305  penetrates the vessel (or tubular structure). Shield  780  limits the distal penetration of hollow needle  305  and protects the surrounding tissues, organs and structures (e.g., nerves, arteries, veins, etc.). While the embodiment of  FIG. 191  shows the needle separate from the dissector  745 , in another embodiment of the present invention, the needle may be connected to dissector  745  in a way that, once dissector  745  is deployed and shield  780  is positioned, the hollow needle  305  can be positioned to transect the vessel, tissue, duct or organ for deployment of the two-part fastener  200  that clamps the vessel, tissue, duct, organ. 
     14. Dissector 
     In yet another form of the present invention, and looking now at  FIGS. 192-194 , a needle stop (or “shield”)  785  may comprise an integral part of dissector  695  support, and the two-part fastener  200  delivery device, and/or hollow needle  305  of the delivery device, may be attached to dissector  695  support. Needle stop  785  may be sharp so that needle stop  785  functions as a dissector, separating tissue located above the stop from tissue located below the stop. In one embodiment of the present invention, supports  790  are provided on dissector  695  for supporting the tissue so that it is elevated above needle stop  785 . The gap between needle stop  785  and the supports  790  is preferably 1 cm or more, in another embodiment of the present invention, the gap between needle stop  785  and supports  790  is equal to, or greater than, 0.25 cm; and in another embodiment, needle stop  785  is movable and/or controllable to the point of having needle stop  785  and supports  790  in contact. 
       FIG. 192  shows hollow needle  305  attached to dissector  695 . If desired, needle stop  785  can serve as a dissector, and may be configured to “fold up” (or roll up, in a similar way to dissector shown in  FIGS. 182 and 183 ) so as to minimize the cross-section of needle stop  785  prior to deployment (e.g., so that needle stop  785  can be delivered via a cannula). 
       FIG. 193  shows a vessel or tissue held in place by supports  790  which create a gap between the vessel and needle stop  785 . By virtue of the foregoing construction, in one embodiment of the invention, dissector  695  may be used to provide sufficient space for deploying two-part fastener  200 . 
       FIG. 194  shows another embodiment of the present invention, wherein additional supports  790  are provided, and further wherein supports  790  are movable relative to one another, whereby to act as clamps to compress the tissue together and thereby facilitate penetration of the vessel by hollow needle  305 . 
     In yet another form of the present invention, where the tissue holder element and the protective stop can be pulled together (or pushed apart) so as to create a gap sufficient for hollow needle  305  to be delivered past the vessel, organ or tissue to be penetrated by hollow needle  305 , distal implant  205  may be deployed into the gap. The protective stop and tissue holder can be sized so as to easily pass through a laparoscopic cannula. 
       FIG. 195  shows one embodiment of the present invention wherein the protective needle stop  785  may be used as a dissector, whereby to separate a biological element of interest from other biological material, and wherein the protective needle stop  785  can serve to protect the biological material from being penetrated by hollow needle  305  when hollow needle  305  is used to deliver two-part fastener  200 . The gap between protective needle stop  785  and the tissue holder is preferably adjustable, and can be controlled by pushing down or pulling up lever  786 , which either (i) moves needle stop  785  distally when lever  786  is pushed distally, in either a discrete or continuous manner, so as to increase the gap between the tissue holder element and protective needle stop  785 , or (ii) reduces the gap between the tissue holder element and protective needle stop  785  when lever  786  is pulled proximally. 
     15. “J”-Shaped Needle Stop Deployed Parallel to Hollow Needle  305   
     In another form of the present invention, and looking now at  FIGS. 196-199 , hollow needle  305  and a novel needle stop  795  contained in a sheath  800  may be configured to run parallel to each other such that, once hollow needle  305  is deployed out of a sheath  805 , needle stop  795  can bend and align under hollow needle  305 , whereby to prevent contact between hollow needle  305  and the tissue underneath needle stop  795 . In one embodiment of the present invention, hollow needle  305  and needle stop  795  are used in conjunction with forceps (or a dissector) that supports the tissue to be transfixed by hollow needle  305 . 
       FIG. 196  shows how hollow needle  305  and needle stop  795  may be deployed using a cannula (e.g., a laparoscopic cannula)  810  so as to facilitate delivery through a laparoscopic port. This approach may be used in conjunction with separate dissectors (not shown) and may also comprise a housing rather than a cannula. 
       FIG. 197  shows another embodiment of the present invention, wherein hollow needle  305  and needle stop  795  comprise a deformable material or a shape memory material or a material that has been cut so as to allow needle stop  795  to curve (e.g., stainless steel that has been laser machined). Needle stop  795  may comprise a tubular structure, ribbon or solid rod. 
       FIG. 198  shows deployment of needle stop  795 . Once at the desired location, the needle stop is pushed out of its sheath  800  and delivered, deploying underneath the structure which is to be pierced by hollow needle  305  (to set two-part fastener  200 ). The depth, length and rotation angle of needle stop  795  is typically pre-set so as to locate needle stop  795  under and around where the tip of hollow needle  305  will be located. 
       FIG. 199  shows how, once transfixion is completed, hollow needle  305  is first removed from the vessel (i.e., withdrawn proximally) and then needle stop  795  is removed. In another embodiment of the present invention, needle sheath  805  and the needle stop sheath  800  are not connected together. 
     As discussed above, hollow needle  305  and needle stop  795  are preferably disposed as two separate parallel elements, with needle stop  795  attached to a hollow tube (or entirely made from the hollow tube) preferably comprising a shape memory or superelastic material (e.g., Nitinol). However, it should also be appreciated that, if desired, needle stop  795  and hollow needle  305  may be arranged, at least in part, co-axially. 
     16. Push Away Tissue 
       FIGS. 200 and 201  show a tissue spacing mechanism  815  which may be used to push tissue located near the distal tip of hollow needle  305  away from hollow needle  305  so as to enable deployment of distal implant  205  of two-part fastener  200 , with tissue spacing mechanism  815  being used to form a gap between the target tissue, vessel or organ and the underlying tissue of a desired distance. This form of the invention may be used to simplify robotic surgical procedures, since it may eliminate the need for a separate instrument to dissect, and create the safe space for, deployment of two-part fastener  200 . See  FIGS. 202 and 203 . 
     In another embodiment of the present invention, a ratchet and locking mechanism may be deployed so as to limit movement of hollow needle  305  to only a fixed amount beyond the end of a sheath or the end of a laparoscopic cannula, thereby limiting the depth of deployment of hollow needle  305  beyond a vessel, tissue or organ to be transfixed. 
     In another embodiment of the present invention, hollow needle  305  is spring-retractable, so that as soon as hollow needle  305  pierces the vessel, hollow needle  305  immediately retracts, thereby protecting tissue beneath. 
     17. Two-Part Fastener which Pierces Vessel from Bottom 
     In the foregoing disclosure, two-part fastener  200  is delivered through a hollow needle  305  that pierces the vessel (or other tubular structure which is to be occluded). More particularly, with two-part fastener  200 , distal implant  205  is delivered through hollow needle  305  such that when distal implant  205  is disposed on the distal side of the vessel (or other tubular structure) which is to be occluded, distal implant locking tube  220  extends through the vessel (or other tubular structure) which is to be occluded when hollow needle  305  is retracted proximally. However, if desired, hollow needle  305  may by omitted and distal implant locking tube  220  may be configured to pierce the vessel which is to be occluded in a distal-to-proximal direction (i.e., so as to pierce the tissue from the distal side of the vessel to the proximal side of the vessel). 
     Another embodiment of the present invention is shown in  FIG. 204 . In this form of the present invention, a delivery device  825  comprises a holder  830  for distal implant  205 , and proximal implant  210  is then slid down on top of distal implant  205  after distal implant  205  has been deployed such that distal implant locking tube  220  pierces the vessel (or other tubular structure) which is to be occluded, as will hereinafter be discussed. In this form of the invention, distal implant  205  comprises a distal implant locking tube  220  having a sharp end  835  which pierces the vessel (or other tubular structure) which is to be occluded, while proximal implant  210  comprises a cap  840  that caps sharp end  835  and protects adjacent tissue from inadvertent injury due to the sharp end  835  of distal implant locking tube  220 . This configuration of two-part fastener  200  is especially advantageous for use in open surgical procedures, but may also be used in laparoscopic and other procedures. 
     More particularly,  FIGS. 204 and 205  show distal implant  205  having a spiked distal implant locking tube  220  (i.e., a distal implant locking tube having a sharp end  835 ) and mounted onto deployment delivery device  825  (e.g., a clamp or forceps). 
       FIGS. 206 and 207  show delivery device  825  and distal implant  205  being positioned beneath the vessel to be occluded, and shows the delivery device when delivery device  825  is moved into contact with vessel so that distal implant locking tube  220  pierces the vessel from the distal side of the vessel in a distal-to-proximal direction and distal implant locking tube  220  penetrates through the vessel, whereby to exit the far (i.e., proximal) wall of the vessel (or other tubular structure), or the tissue to be clamped, so that the sharp end  835  of distal implant locking tube  220  is exposed on the proximal side of the vessel. 
       FIGS. 208 and 209  show a proximal implant  210  mounted to delivery device  825  with cap  840  extending through a hole  845  formed in a holder  850 , such that proximal implant  210  is releasably retained on the distal side of holder  850 . Note that proximal implant  210  comprises a locking shaft (i.e., tube  275 ) extending somewhat perpendicular to legs  295  of proximal implant  210 . Tube  275  also comprises cap  840  for locking proximal implant  210  to distal implant locking shaft  220 . 
       FIGS. 210 and 211  show proximal implant  210  and distal implant  205  being brought into contact with one another by aligning distal implant  205  and proximal implant  210 . Tube  275  (and cap  840 ) of proximal implant  210 , which is hollow, is locked to distal implant locking tube  220  (which may or may not be hollow) of distal implant  205 . Tube  275  (and cap  840 ) and distal implant locking tube  220  may be made of different materials (e.g., titanium and stainless steel) or the tube  275  (and cap  840 ) and distal implant locking tube  220  may be made of the same material. If desired, distal implant locking tube  220  and proximal tube  275  may be configured such that they are contiguous with legs  235  of distal implant  205  and legs  295  of proximal implant  210 , respectively. 
       FIGS. 212 and 213  show how delivery device  825  is removed after distal implant  205  and proximal implant  210  are locked together. 
     More particularly,  FIG. 214  shows the delivery devices removed, leaving the vessel occluded using two-part fastener  200 . Tube  275  (which may be only part of proximal implant  210 , and made of Nitinol or titanium or other metals) of proximal implant  210  not only serves to lock with distal implant locking tube  220  of distal implant  205 , but also protects surrounding tissue by covering the sharp end  835  of distal implant locking tube  220 . 
     18. Exemplary Uses of the Two-Part Fastener 
     By way of example but not limitation, two-part fastener  200  of the present invention may be used for, and in, procedures such as left arterial appendage occlusion. It should also be appreciated that the two-part fastener  200  may be used in cardio-thoracic-vascular applications such as internal mammary artery bypass surgery where the secure ligation of branches is critical to the prevention of bleeding and for the treatment for dissecting aneurysms of the aorta (which is generally performed by sewing patches onto the native artery so as to allow suture attachment to an interposition graft). With such a procedure, one problem is typically bleeding through the needle holes of the transfixing sutures. The present invention can be used so as to pressurize the tissue around the point of transfixion and prevent bleeding. 
     In a similar fashion, when occluding the atrial appendage to prevent clot formation and embolization during surgery, the atrial appendage tends to bleed around the needle hole when sutured using a needle. The novel two-part fastener  200  of the present invention can mitigate this bleeding by providing sealing pressure where two-part fastener  200  pierces the atrial appendage. 
     It should be appreciated that two-part fastener  200  may be used as a vessel anastomotic device for mechanically joining various vessels together. 
     In addition, two-part fastener  200  may be used so as to allow the reliable fixation of covered stents to the aortic wall in the endovascular treatment of aortic aneuryms, particularly where the stent attachment zone is short and uneven. This may be performed percutaneously or through a catheter-directed endo-vascular approach. 
     It should also be appreciated that two-part fastener  200  may be used in applications involving solid organs where the use of staples may be undesirable or unacceptable. 
     For example, solid organs do not generally accept conventional staplers since solid organs bleed through the staple entry points. The two-part fastener  200  of the present invention avoids these issues, and is suitable for parenchymal resection of organs such as the liver, spleen, kidney and lung. The pressurized zone around the transfixing point wound prevents the bleeding that occurs with standard suture technique through the needle entry points. 
     For such applications, it may be desirable to modify the two-part fastener  200  of the present invention so as to form a multi-vessel fastener capable of deploying a row of clips simultaneously, and/or to apply clips laterally to the solid tissue edges. 
     The two-part fastener  200  of the present invention may also be used for other applications. By way of example but not limitation, the two-part fastener  200  of the present invention may be used in general surgical applications, e.g., occlusion of the spermatic cord as an alternative to vascectomy in male sterilization; cystic and bile duct occlusion; bowel fistula or other fistulous tracts, etc. Or the present invention may be used for attachment of tissues, e.g., during hernia repair where synthetic materials (e.g., hernia mesh) are used to reinforce the site of the hernia repair. The two-part fastener  200  of the present invention may also be used for secure ligation of the fallopian tube for sterilization procedures. This can be accomplished by the simple application of the two-part fastener  200  of the present invention to the fallopian tube, using open, laparoscopic or robotic surgery. 
     It should also be appreciated that two-part fastener  200  may be used for orthopedic applications, e.g., as anchors in joint surgery or repair of tendons or ligaments. 
     And two-part fastener  200  may be used for interventional radiologically-directed procedures performed under imaging (e.g., ultrasound, CT, fluorosocopy, etc.), including, but not limited to, the ligation of tubular or vascular structures or the coaptation of tissues 
     When using conventional staples, it is common to also use a buttress, integrating tissue stapling with a buttress provides surgeons with both greater functionality and efficiency. The present invention does not require the use of a buttress, or support material, as in the case of the Endo GIA product, thereby simplifying two-part fastener  200 , avoiding the need for additional materials in the body, and reducing the cost and complexity of these procedures. If desired, however, in certain instances, the present invention could also be used in conjunction with similar supporting or buttressing materials. 
     The present invention can be used in a fashion similar to a stapler for open surgery procedures (e.g., an open anastomosis). 
     By way of example but not limitation, two-part fastener  200  may be used for the prevention of, or treatment of, blood clot embolization in the pulmonary or peripheral systemic circulation. The present invention may be used to percutaneously (or laparoscopically or even in open surgery) occlude a vein, in the presence of a vein (superficial or deep) that has a clot where there is the possibility of propagation and dislodgment of the clot into the blood stream in the large veins returning the blood to the heart and lungs. Two or more two-part fasteners  200  can be placed on either side of the clot, thereby trapping and containing the clot, or the occlusion elements may be deployed upstream from the clot, thus preventing propogation of the clot toward the heart or lungs. 
     19. Ligation and Injection of Sclerosant or Glues such as Those Containing Cyanoacrylate 
     When a long segment of vein is to be occluded safely, the two-part fastener  200  of the present invention may be used as a clamp at the most proximal end of the vein, thereby preventing chemical substances (i.e., a sclerosant or glue containing cyanoacrylate) from directly flowing into the general circulation of the bloodstream. This allows safer use of either sclerosant or glues, which may be injected in the intervening venous segment with occlusion in place. See  FIG. 215 . Large tributaries in an isolated vein segment can also be occluded by placing two-part fastener&#39;s  200  at the origin of these tributaries. For injection of sclerosant or glue to occlude a segment of a vessel, only a single two-part fastener  200  (i.e., only a single occlusion site) is necessary to prevent the sclerosant from spilling over into the more proximal vessel and into the general circulation. See  FIG. 216 . 
     In one embodiment of the present invention, there is provided a method and apparatus for occluding vessels that uses the two-part fastener of the present invention and comprises a protruding side needle to deliver sclerosant or glue. In this form of the present invention, an fastener (e.g., two-part fastener  200 ) may be delivered in an upstream region of a vein, and another fastener (e.g., two-part fastener  200 ) may be delivered downstream. The sclerosant or glue is then injected between these fastener elements. 
     20. Two-Part Fastener Utilizing Electro/RF Cautery 
     In another form of the present invention, a modified form of two-part fastener  200  may be used to cauterize a vessel, tubular structure, and/or to bond different tissues. More particularly, in this form of the present invention, at least a portion of two-part fastener  200  connects to an electrical cauterizing unit (e.g., monopolar, bipolar, etc.) which is preferably built into the delivery device. 
     In one form of the present invention, two-part fastener  200  is connected to an energy source (or energy sources) and the vessel or duct or tissues may be occluded (or attached, fused, or connected to each other) by the application of RF energy. The RF energy may be applied between two-part fastener  200  and an electrode located in, or on, the patient at another location (e.g., a patient return electrode), or an electrode located between proximal implant  210  and distal implant  205  of two-part fastener  200 . The same potential may be applied to both proximal implant  210  and distal implant  205  in a monopolar electro-surgery mode, or a potential difference may be applied between the proximal implant  210  and distal implant  205  in a bipolar electrosurgery mode. The energy source may produce an RF current, where the currents and voltages may be monitored and controlled and with controllable duty cycles at frequencies from 200 Khz-3.3 MHz that, so as to optimize the attachment of the tissues or occlusion of the vessels and ducts, and/or the denaturing of collagen and other proteins to produce fusion or binding, or coagulation or blending. Once the energy is delivered to the tissues, the occlusion elements (e.g., distal implant  205  and proximal implant  210 ) and the delivery device are removed. See  FIG. 226 . In one form of the invention, distal implant  205  and proximal implant  210  may be held at the occlusion site for a controllable amount of time after application of the energy and before removal, so as to help ensure better occlusion. Distal implant  205  and proximal implant  210  approximate the various tissues to a controllable degree, whereby to reduce the amount of energy needed to be imparted to the tissues and vessels, thus reducing damage and maximizing binding. In this form of the invention, distal implant  205  comprises a plurality of legs  855 , and proximal implant  210  comprises a plurality of legs  860 . Legs  855  of distal implant  205  and legs  860  of proximal implant  210  provide significant surface area, or contact area, between an occlusion element electrode and the tissue. As such, binding or sealing or connecting of tissue or occlusion of vessel or duct can occur over a large surface area. This area can be much larger than the cross-section of the delivery element probe or device that penetrates the patient skin. See  FIGS. 223 and 224 . In one embodiment of the present invention, the effective ratio of the diameter of distal implant  205  and proximal implant  210  to the diameter of the delivery element probe or device may be greater or equal to 2:1 (and may be up to 10:1 or more). Furthermore, the surface area of tissues that can be connected can be large, depending upon the dimension of legs  860  of proximal implant  210  and legs  855  of distal implant  205 . These legs are the functional equivalent of legs  235  and  295  of the two-part fastener  200 . 
     When distal implant  205  and proximal implant  210  are removed, a hole may remain which is sealed around the edges in the segment of the occluded vessel duct or tissue. However, if desired, various coagulants or sealants or glues (e.g., cyanoacrylate) may be injected through the needle or delivery device or a separate different delivery device (injected through a second needle placed near the site) so as to close the hole in the tissue, and/or to promote healing. 
     In one embodiment of the present invention, distal implant  205  and proximal implant  210  are extracted through the same hollow needle  305  that delivered them. 
     In one form of the present invention, distal implant  205  and proximal implant  210  may be decoupled from the electrical energy source once they have delivered the electrical energy to the tissue, and then locked together and decoupled from the delivery device so as to remain implanted, sandwiching the tissue that has been treated with RF energy. This approach may transform (or enhance) the integrity of the tissue (e.g., in bowel or stomach tissue) so as to reduce the likelihood that two-part fastener  200  will migrate through the tissue. 
       FIG. 217  shows a preferred embodiment of the present invention with the distal implant  205 , proximal implant  210  and the insulating element  865  being shown before being deployed.  FIG. 218  shows an embodiment of the present invention where the occlusion elements are deployed. All three elements are generally contained within a delivery device and a needle (e.g., hollow needle  305 ) that controls their deployment and delivery of two-part fastener  200  through multiple tissue layers or a vessel, duct or fallopian tube. 
     More particularly,  FIG. 217  shows individual electrode elements (i.e., distal implant  205  and proximal implant  210 ) and insulating element  865 , prior to deployment. 
     And  FIG. 218  shows distal implant  205  and proximal implant  210  and the insulating element  865  after deployment. 
       FIG. 219  shows the delivery device with hollow needle  305  attached. 
       FIG. 220  shows the delivery device with hollow needle  305  penetrating through a vessel or tissues. 
       FIG. 221  shows advancement of distal implant  205 . 
       FIG. 222  shows deployment/opening of distal implant  205  so as to cause legs  855  of distal implant  205  to extend radially outward. 
       FIG. 223  shows raising of hollow needle  305  and deployment of proximal implant  210  beyond the tip of hollow needle  305 . 
       FIG. 224  shows legs  860  of proximal implant  210  opening (or in its open condition) once released from hollow needle  305 . 
       FIG. 225  shows proximal implant  210  and distal implant  205  being connected to an electrical energy source  870 . In the embodiment shown in  FIG. 225 , there is a potential difference between the proximal implant  210  and distal implant  205 . In other embodiments of the present invention, the potential difference between both proximal implant  210  and distal implant  205  may be the same, and another electrode may be placed in or on the patient. 
       FIG. 226  shows the application of energy to tissue, e.g., by the application of radio-frequency (RF) current and voltage between the electrodes (i.e., legs  855  of distal implant  205  and legs  860  of proximal implant  210 ) which penetrates through the tissue. The duty cycle and frequency of the RF energy can be adjustably controlled so as to optimize sealing of the tissue or vessel, while minimizing any burning of the tissue. 
       FIG. 227  shows that, after application of the RF energy to the sandwiched tissue, distal implant  205  is retracted first. In this case, distal implant  205  is retracted into the insulating element  865 . 
       FIG. 228  shows the fully retracted distal implant  205 . 
       FIG. 229  shows the assembly being raised a little relative to the tissue, with hollow needle  305  being pushed down so that it begins to compress legs  860  of proximal implant  210 . 
       FIG. 230  shows how hollow needle  305  compresses the legs  860 , or fingers (e.g., legs  295 ) of proximal implant  210 , while proximal implant  210  is raised relative to hollow needle  305 . 
       FIG. 231  shows how hollow needle  305  (and assembly) are extracted from the body, leaving the vessel or tissue sealed. 
       FIG. 232  shows the sealed tissue region, with the possible needle hole sealed around its perimeter. 
     In another embodiment of the present invention, legs  235  of distal implant  205  are placed at the tip of hollow needle  305 , and then opened and deployed by withdrawal of hollow needle  305 , while distal implant  205  remains in the same location. 
     In another embodiment of the present invention, two-part fastener  200  is used in conjunction with a robotic arm for robotic surgery. The ability to deliver two-part fastener  200  through a needle reduces the number of steps and maneuvers that the surgeon must perform, thereby simplifying occlusion of vessels and/or attachment or approximation of tissues. Also, the amount of surrounding tissue required to be cleared around the vessel is reduced. 
     21. Novel Handle 
     The sequence of events required to deliver the occlusion device, as described above, may be automated using a system of motors and springs, and may be powered by a power supply or battery that may or may not be rechargeable. It should also be appreciated that, if desired, the device may be powered by a solar cell built into the system. In one embodiment of the invention, the entire delivery may be activated through a single button. 
       FIG. 233  shows an ergonomic design for a novel handle  875  formed in accordance with the present invention that may contain a battery (not shown) in order to provide the necessary energy to seal tissue or automate various delivery device actions or alternatively, the present invention could be connected to a transformer and/or electrical outlet. In other embodiments, the present invention is simply a mechanical device and not connected to any energy source such as AC or DC voltage and current. 
       FIGS. 234 and 235  show a refined handle design of a delivery device for fastener implant  200 . The refined handle design uses sliders to actuate deployment of proximal implant  210  and distal implant  205  and lock them together. 
     In practice, a vessel is occluded by sliding handle  875  aside, and then sliding it all the way down, as seen in  FIG. 234 . This brings proximal implant  210  and distal implant  205  together, whereby to occlude the vessel. 
     Removal of the delivery device is accomplished by rotating handle  875  counterclockwise, until the delivery device detaches from the clip, as shown in  FIG. 235 . The delivery device is then withdrawn and retrieved ( FIG. 236 ). 
     Among other things, (i) handle  875  is designed to provide tactile feedback upon closing of the clip; (ii) the ratcheted control of two-part fastener  200  deployment provides precise and controlled deployment of two-part fastener  200 ; and (iii) the design of handle  875  provides stability and secure holding of two-part fastener  200 , and the solid feel provides physician comfort. 
     Modifications of the Illustrative Embodiments 
     It should be understood that many additional changes in the details, materials (e.g., shape memory polymers that are permanent or that dissolve over time, or carbon nanotube based), steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.