referring to fig1 and 1a , an exemplary sealing apparatus 10 constructed in accordance with the principles of the present invention comprises a shaft assembly 70 including an outer tube 71 and an inner rod 76 . an expansible occlusion element 90 is mounted at a distal end ( to the right in fig1 and 1a ) of the shaft assembly 70 and includes a radially expansible mesh 74 covered by an elastomeric membrane 96 . a handle assembly 78 is attached to a proximal end of the shaft assembly 70 and is operatively attached to both the outer tube 71 and inner rod 76 so that the inner rod can be axially advanced and retracted relative to the outer tube . the inner rod 76 and outer tube 71 are coupled together at the distal tip of the sealing apparatus 10 by a plug 77 and a proximal anchor 75 , respectively . the occlusion element 90 is held between the plug 77 and the proximal anchor 75 so that axial retraction of the rod in the proximal direction ( to the left as shown in fig1 and 1a ) foreshortens the occlusion element 90 , causing the occlusion element to expand radially , as shown for example in fig2 . axial advancement and retraction of the rod 76 relative to the outer tube 71 is effected using the handle assembly 78 . the handle assembly 78 includes a cylindrical body 103 attached to the proximal end of the outer tube 71 by a bushing 104 so that the body 103 will remain fixed relative to the outer tube as the inner rod 76 is retracted and advanced . the inner rod is retracted and advanced by a slide assembly 101 which includes a short tube 110 fixedly attached to an endcap 111 and a slide cylinder 109 . the inner rod 76 is secured by tube element 107 which carries locking element 106 and bearing elements 108 and 109 . bearing element 109 is attached to proximal grip 101 and the assembly of the grip 101 and tube element 107 can slide freely within the interior of the cylindrical body 103 so that the rod 76 may be proximally retracted relative to the body 103 and outer tube 71 , as shown in fig2 . once the expansible occlusion element 90 has been radially expanded , the rod 76 will remain retracted and is held in place by locking element 106 which is pulled over a detent 105 , again as shown in fig2 . an alignment bushing 108 is provided in the interior of the cylindrical body 103 to maintain alignment of the slide assembly 101 relative to the cylindrical body . the sealing apparatus of the present invention may optionally include a tensioning mechanism 80 which includes a coil spring 86 , a gripping element 85 , and a coupling element 87 . the tensioning mechanism 80 may be selectively positioned along the length of shaft assembly 70 , and will provide a tension determined by the constant of coil spring 86 to hold the expanded occlusion element 74 against the vascular penetration , as described in more detail in copending , commonly - owned application ser . no . 10 / 974 , 008 , ( attorney docket no . 021872 - 002010us ), the full disclosure of which is incorporated herein by reference . as described thus far , the construction and use of the sealing apparatus including shaft assembly 70 , handle assembly 78 , tensioning mechanism 80 , and expansible occlusion element 90 are generally the same as illustrated in copending application ser . no . 10 / 974 , 008 . the present invention is directed at modifications and improvements to the earlier device for delivering a hemostatic implant into the tissue tract generally above the vascular wall penetration , as will be described in more detail below . as best seen in fig1 a , hemostatic implant 121 , which will typically be a biodegradable polymer as described in more detail above , is carried coaxially or in parallel over the outer tube 71 near the distal end thereof proximal to the expansible occlusion element 90 . while the hemostatic implant 121 is shown to be positioned coaxially over outer tube 71 in fig1 a , it will often be desirable to modify or reposition the implant in order to facilitate release from the sealing apparatus after the implant has been deployed . more simply , the hemostatic implant could be axially split to allow it to partially open after it is rehydrated and facilitate passage of the collapsed occlusion element 74 as the sealing apparatus is being withdrawn . alternatively , the hemostatic implant may be reconfigured and carried laterally ( i . e ., to one side of ) with respect to the shaft of the sealing apparatus , as described in more detail hereinafter with respect to fig9 a and 9c . the hemostatic implant 121 could alternatively be carried on the inner surface of a protective sleeve 123 which is slidably carried over the outer tube 71 . the protective sleeve 123 slides over a backstop 127 which is slidably mounted over the outer tube 71 and which is prevented from moving proximally by stop member 125 which is fixed to the outer surface of the outer tube . backstop 127 has a distal end 128 which engages a proximal end of the hemostatic implant 121 . thus , by proximally retracting the protective sleeve 123 , the hemostatic implant 121 can be exposed to the tissue tract and released from the sealing apparatus . accidental axial retraction of the protective sleeve 123 is prevented by a latch mechanism including a latch element 120 and a key 126 ( fig1 and 2 ). the latch element 120 is typically a spring - loaded component , for example a conical spring having a narrow diameter end attached to the outer tube 71 and a flared or larger diameter end 129 which engages a stop ring 124 formed on the inner surface of the protective sleeve 123 . so long as the flared end 129 of the latch element 120 remains in its flared or open configuration , as illustrated in fig1 a , accidental proximal retraction of the sleeve is prevented . it is further noted that the stop ring 124 engages stop member 125 of the backstop 127 preventing accidental distal movement of the protective sleeve 123 . thus , when the sealing apparatus 10 is introduced to a tissue tract , as described in more detail below , movement of the protective sleeve 123 in either the distal or proximal direction is inhibited . to allow selective proximal refraction of the protective sleeve 123 , the key 126 ( fig1 and 2 ) may be axially advanced to engage the latching element 120 , as illustrated in fig3 . the key 126 fits inside of the protective sleeve 123 and depresses or radially contracts the latch element 120 so that it fits within the interior circumference of the stop ring 124 , thus allowing proximal retraction of the protective sleeve 123 , as shown in fig4 . once the key 126 has engaged and constrained the latch element 120 , as shown in fig3 , the protective sleeve 123 may be proximally withdrawn past the hemostatic implant 121 and the backstop 127 , as shown in fig4 . thus , the hemostatic implant 121 will be released from constraint and exposed to the environment in the tissue tract . the environment in the tissue tract will include blood and other body fluids which can hydrate the hemostatic implant 121 , causing swelling as shown in fig4 . the swelling will continue , as shown in fig5 , and the radially expanded occlusion element 90 can be collapsed using the handle assembly , as shown in fig5 . the collapsed occlusion element 90 can then be proximally withdrawn into and through the backstop assembly 127 , as shown in fig6 ( where an annular space may be provided to accommodate the occlusion element ). when the occlusion element has been fully withdrawn within the backstop 127 , the hemostatic implant is completely released , as shown in fig6 , and the remaining portions of the sealing apparatus can be pulled away from the hemostatic implant , as shown in fig7 . referring now to fig8 a - 8i , deployment and use of the sealing apparatus 10 of the present invention through an introducer sheath 40 will be described in more detail . introducer sheath 40 will typically be in place within a blood vessel lumen 41 passing from the skin surface 46 through tissue 45 in a tissue tract . a vascular wall penetration 42 will thus be present in the vascular wall 43 , all as shown in fig8 a . the sealing apparatus 10 is then introduced through the access sheath 40 so that the expansible occlusion element 90 passes out through the distal end of the sheath , as shown in fig8 b . handle assembly 78 will remain outside of the sheath and accessible to the user so that the slide assembly 101 may be pulled relative to the cylindrical body 103 to radially expand the occlusion element 90 , as shown in fig8 c . the vascular access sheath 40 may then be withdrawn over the exterior of the sealing apparatus 10 while the sealing apparatus is simultaneously withdrawn to seat the expanded occlusion element 90 against the vascular penetration 42 , as shown in fig8 d . at that point , the protective sleeve 123 and key 126 become exposed and available to the user for manipulation . the key may then be distally advanced over the outer tube 71 so that the key engages and depresses the latch 120 ( fig1 a ) as illustrated in fig8 e . the key 126 and protective sleeve 123 may then be manually pulled in a proximal direction over the outer tube 71 to release the hemostatic implant 121 , as shown in fig8 f . the expandable element 90 may then be collapsed , as shown in fig8 g , and the collapsed element withdrawn into the distal end of the sealing apparatus , as shown in fig8 h . the entire sealing apparatus 10 , except for the hemostatic implant 121 , may then be withdrawn from the tissue tract , leaving the hemostatic implant 121 in place over the now closed vascular wall penetration , as shown in fig8 i . the hemostatic implant , which may optionally carry the anti - proliferative , coagulation promoting , and / or radiopaque substances described above , will remain in place inhibiting bleeding through the upper portions of the tissue tract and allowing the vascular wall penetration to heal . over time , the hemostatic implant 121 will preferably biodegrade , leaving a healed tissue tract and vascular wall penetration which are usually suitable for re - entry at a subsequent time . referring now to fig9 a - 9c , a protective sleeve 123 ′ comprises an outer sleeve 150 and an inner release sheath 152 . the outer sleeve 150 and inner release sheath 152 are separately retractable so that the outer sleeve may first be retracted relative to the hemostatic implant 121 ( fig9 c ) while the inner release sheath initially remains over the implant . the release sheath 152 will thus provide an anti - friction interface so that the outer sleeve 150 slides over the implant 121 with reduced sticking the inner release sheath 152 is preferably formed from a relatively lubricious or slippery material and will preferably include an axial opening or slit 158 which permits the distal portion thereof to partially open after the outer sleeve 150 has been retracted , as shown in fig9 b . once the outer sleeve 150 has been retracted to relieve constraint over the hemostatic implant , the inner sleeve may then be retracted to completely release the hemostatic implant , as shown in fig9 c . conveniently , the outer sleeve 150 may be coupled to the inner release sheath 152 so that proximal retraction of the outer sleeve will automatically retract the inner release sheath at the proper point in travel . for example , a cavity or channel 154 may be formed in an inner surface of the outer sleeve 150 and a ring or other engaging element 156 may be formed on the outer surface of the inner release sheath 152 . initially , the ring 156 will be positioned at the distal end of the cavity or channel 154 , as shown in fig9 a . after the outer sleeve 150 has been retracted so that it no longer lies over the implant 121 , the ring may then engage a distal end of the cavity or channel 154 , as shown in fig9 b , and engage the ring 156 , allowing the outer sleeve to then pull the inner sleeve proximally , as shown in fig9 c , to fully release the hemostatic implant 121 . referring now to fig1 a - 10c , it is also possible to selectively couple the key 126 ′ to a protective sleeve 123 ′. the key 126 ′ has a coupling element , such as plurality of proximally disposed barbs 160 at its distal end . the key 126 ′ may be advanced into the protective sleeve 123 ′ where a distal end 162 of the key 126 ′ engages latching element 120 ′ on the outer tube 71 ′. latching mechanism 120 ′ may conveniently comprise a plurality of barbs so that advancement of the key 123 ′ radially closes the barbs along the protective sleeve 123 ′ to be proximally retracted relative to the tube 71 ′. once the key 126 ′ is fully distally advanced , as shown in fig1 b , the proximally disposed barbs 160 will engage an inner lip 164 at the proximal end of the protective sleeve 123 ′. thus , as the key 126 ′ is proximally retracted , as shown in fig1 c , the key will pull the protective sleeve 123 ′ in a proximal direction , thus exposing the implant 121 . a further aspect of the present invention is illustrated in fig1 a and 10b . radiopaque marker bands 170 and 172 may be provided at the proximal and distal ends of the implant 121 , respectively . usually , these bands will be disposed on the outer tube 71 ′, but they could also be disposed on or incorporated within the hemostatic implant 121 . in either case , they are useful to evaluate positioning of the hemostatic implant prior to deployment , as described in more detail below in fig1 a , 13 b , 14 a , and 14 b . referring now to fig1 a and 11b , the hemostatic implant 121 may be disposed coaxially over the outer tube 71 and in a rod 76 . by then proximally retracting the protective sleeve 123 , the implant 121 is released and can hydrate as shown in fig1 b . as described previously , however , it will still be necessary to withdraw the outer tube 71 as well as the collapsed occlusion element 90 past the hemostatic implant 121 . when the hemostatic implant 121 fully circumscribes the outer tube 71 , however , both the tube 71 and the collapsed occlusion element 90 can tend to dislodge the implant within the tissue tract . therefore , in some instances , it will be desirable to modify the geometry of the implant to facilitate withdrawal of the outer tube and the collapsed occlusion element . for example , as shown in fig1 a and 12b , hemostatic implant 121 ′ can be formed with a crescent - shaped cross - section so that it does not fully circumscribe the outer tube 71 which carries it . by laterally displacing the outer tube 71 an inner rod 76 within the protective sleeve 123 , as shown in fig1 a , the volume of the hemostatic implant 121 will be generally the same as that shown in fig1 a . when the protective sleeve 123 is withdrawn , however , as shown in fig1 b , the hemostatic implant 121 will hydrate and expand laterally on one side of the outer tube 71 , as shown in fig1 b . by disposing the outer tube 71 and collapsed occlusive element 90 to one side of the implant , it is much easier to withdraw the apparatus and collapsed occlusion member past the implant without dislodging the implant within the tissue track . referring now to fig1 a and 13b , the radiopaque markers 170 and 172 can be used to determine whether the hemostatic implant 121 is oriented properly prior to deployment . for simplicity , the protective sleeve and other components of the deployment system are not shown in fig1 a and 13b ( or in 14 a and 14 b as described below ). the radiopaque markers 170 and 172 may be formed as part of the deployment instrument , for example being placed on outer tube 71 , and / or may be formed as part of the hemostatic implant 121 . in either case , when the deployment apparatus is properly oriented as shown in fig1 a , the radiopaque markers 170 and 172 will appear to be stacked generally vertically when viewed in an anterior view , as shown in fig1 b . in contrast , if the apparatus has been improperly deployed so that the hemostatic implant has been advanced into the vessel lumen past the tissue tract tt as shown in fig1 a , then the radiopaque markers 170 and 172 will be spaced apart in the anterior view as shown in fig1 b . as these views will be readily distinguishable by the physician using conventional fluoroscopy , the radiopaque markers provide a convenient and reliable indicator of when it is acceptable to deploy the hemostatic implant . while the above is a complete description of the preferred embodiments of the invention , various alternatives , modifications , and equivalents may be used . therefore , the above description should not be taken as limiting the scope of the invention which is defined by the appended claims .
apparatus for sealing a vascular wall penetration disposed at the end of the tissue tract comprises a shaft , an occlusion element , a hemostatic implant , and a protective sleeve . the apparatus is deployed through the tissue tract with the occlusion element temporarily occluding the vascular wall penetration and inhibiting backbleeding therethrough . the hemostatic implant , which will typically be a biodegradable polymer such as collagen carrying an anti - proliferative agent or coagulation promoter , will then be deployed from the sealing apparatus and left in place to enhance closure of the vascular wall penetration with minimum scarring . the implant may be radiopaque to allow observation before release .