WO2009099437A1

WO2009099437A1 - Apparatus and method for closing an opening in a blood vessel using memory metal and collagen

Info

Publication number: WO2009099437A1
Application number: PCT/US2008/053020
Authority: WO
Inventors: William J. Drasler; Tracee Eidenschink; Joeseph M Thielen; Mark L. Jenson; Anu Sadisiva
Original assignee: Boston Scientific Limited
Priority date: 2008-02-05
Filing date: 2008-02-05
Publication date: 2009-08-13

Abstract

An apparatus and method for closing an arteriotomy site are disclosed The apparatus and method employ the use of a delivery shea within which is provided an anchoring device formed of memory metal The delivery sheath can be inserted through a tissue tract extending from an epidermal layer to the blood vessel wall, whereupon the anchoring device can be extended from the delivery sheat into the blood vessel itself. The memory metal, once freed from the delivery sheath, obtains a nonlinear or coiled configuration which can then be pulled back against the inner surface of the blood vessel to form a backstop A biodegradable plug is then introduced into the tissue tract until it engages the backstop formed by the anchoring device thereby ensuring proper positioning of the biodegradable plug. The anchoring device is then retracted through the biodegradable plug leaving the arteriotomy site substantially closed with hemostasis formed therearound. The various biodegradable plugs disclosed provide for improved retention of the biodegradable plug and proper positioning of the plug within the tissue tract.

Description

APPARATUS AND METHOD FOR CLOSING AN OPENING IN A BLOOD VESSEL USING MEMORY METAL AND COLLAGEN

Cr oss-Reference to Related Application

[0001] This application is a Patent Cooperation Treaty patent application claiming priority undei the Paris Convention to U S piovisional patent application serial no 60/888,211 filed on February 5, 2007

Field of the Disclosure

[0002] The present disclosure generally relates to medical devices and, more particularly, relates to medical devices for closing an arteriotomy

Background of the Disclosure

[0003] In many medical procedures, such as balloon angioplasty and the like, it is known how to create an opening in a blood vessel, known as an arteriotomy, to allow for the insertion of various medical devices which can be navigated through the blood vessel to the site to be treated Typically, the opening is formed in the femoral artery at a point proximate the groin and a series of medical devices are insetted in sequence For example, a guide wire may first be inserted through the tissue tract created between the skin or the epidermis of the patient down through the subcutaneous tissue and into the opening formed in the blood vessel The guide wire is then navigated through the blood vessel to the site of the occlusion, the heart, or any other area to be treated. Once the guide wire is in place, an introducer sheath can be slid over the guide wire to form a wider, more easily accessible, tract between the epidermis and the opening into the blood vessel If an angioplasty needs to be performed, the balloon catheter can then be introduced over the guide wiie again thiough the introducer sheath, thiough the opening in the femoial aiteiy, and then up the blood vessel to the site of the occlusion

[0004] Once the procedure is performed, the guide wire, balloon catheter and any other equipment introduced can be ieti acted thiough the blood vessel, out through the opening in the blood vessel wall, out thiough the introducer sheath, and out of the body entirely The introducer sheath can then be lemoved and the physician or other medical technician is presented with the challenge of trying to close the opening both in the femoral artery and the tissue tract formed in the epidermis and subcutaneous tissue Most importantly, the opening in the blood vessel must be closed as soon as possible

[0005] Over the years that these procedures have been performed, a number of apparatus and methods have been created for closing the opening in the blood vessel Traditionally, and still commonly today, the opening is closed simply by the application of manual pressure If sufficient pressure is applied, the blood vessel is constricted until a clot or thrombus forms whereupon the pressure can be removed and eventually the patient can become ambulatory once again However, a number of drawbacks are associated with such a method For one, the process is very time consuming often taking many hours for the thrombus to fully form, during which time the patient is required to be stationary In addition, the mere application of such significant pressure to the groin is often quite uncomfortable for the patient

[0006] In light of these difficulties, a number of proposals have been introduced to potentially alleviate such drawbacks In one approach, an anchor is inserted thiough the tissue tract and the blood vessel with a filament extending therefiom and connected to a sealing plug by a pulley arrangement Once the anchoi engages an inteiioi surface of the blood vessel the filament can be used to pull the sealing plug securely into the tissue tract While this approach does moie quickly close the opening in the blood vessel than manual piessme application, it also results in the unfavorable characteristic of leaving a foreign body in the patient after the procedure is completed

[0007] Another approach uses a resistive heating coil inserted into the opening in the blood vessel Upon energization of the heating coil, the blood in the vicinity of the opening is caused to coagulate given the rise in temperature This can be accomplished in combination with the introduction of a procoagulant into the site to again expedite the creation of the coagulation While this approach has also met with some level of success, it also results in the introduction of a foreign body and/oi substance into the tissue of the patient

[0008] A still further approach involves the introduction of a collagen plug into the site of the opening Such a plug is sized to be frictionally engaged by the sides of the opening in the blood vessel and thus held in place until coagulation of blood forms around the collagen plug The collagen plug is biodegradable and eventually is dispersed into the blood flow and eliminated from the body However, just the introduction of such a foreign substance into the body can sometimes be, at the very least, inflammatory and uncomfortable for the patient

[0009] In one collagen plug approach, a balloon catheter is inserted into the blood vessel, inflated, and then pulled back against an interior surface of the blood vessel wall to serve as a backstop The collagen plug in such an approach is shaped and sized as to closely match the opening in the blood vessel wall and is pushed down into the tissue tiact until it engages the inflated balloon The inflated balloon can then be deflated and withdiawn leaving the collagen plug in place,

[0010] In another collagen plug approach, a deliveiy sheath wider than the opening in the blood vessel wall is used and then a collagen plug coπesponding to the size of the inner diametei of the deliveiy sheath is pushed through the sheath so as to engage the outer surface of the blood vessel wall The plug can then be tamped oi compiessed down against the exteiioi surface of the blood vessel wall such that a poition of the collagen extends into the opening of the blood vessel wall

[001 1] While each of the foregoing approaches have been met with some level of success, it can be seen that each also has substantial drawbacks Accordingly, it would be advantageous foi the art to provide an apparatus and method which can quickly close the opening in the blood vessel wall, forms a thrombus which reliably remains in place after formation, minimizes patient discomfort, introduces no foreign body or substance into the blood vessel and leaves no foreign bodies behind after the procedure is completed

Summary of the Disclosure

[0012] In accordance with one aspect of the disclosure, an apparatus for¹ closing an opening in a blood vessel is disclosed which comprises an anchoring device having a linear insertion configuration and a non-lineai deployed configuration, as well as a collagen plug adapted to be inserted through a tissue tract against the anchoring device when the anchoring device is in the deployed configuration [0013] In accordance with another aspect of the disclosure, a method of closing an opening in a blood vessel is disclosed which comprises inserting a delivery sheath into a tissue tiact running from an epidermal layer of a patient to an arteiiotomy site in a blood vessel, extending an anchoiing device from the delivery sheath and into the blood vessel, the anchoring device being fbimed of a shape-memory alloy, the anchoring device being held in a lineai configuration when within the delivery sheath and, assuming a nonlinear configuration when extended fiom the delivery sheath, retracting the delivery sheath and anchoiing device a distance sufficient to engage the anchoiing device with an inner surface of the blood vessel pioximate the arteriotomy site, pushing a collagen plug down the tissue tract until the plug engages the anchoiing device, and pulling the anchoiing device from the blood vessel, through the collagen plug and out of the tissue tract

[0014] In accordance with anothei aspect of the disclosure, an appaiatus for closing an opening in a blood vessel is disclosed comprising a deliveiy sheath having a distal end and a pioximal end, the delivery sheath being inseitable into a tissue tract running from an epidermal layer to an arteiiotomy site, and a length of memory-metal positioned within the delivery sheath, the memoiy metal being substantially linear in shape when within the delivery sheath, and being substantially non-lineai in shape when extended from the delivery sheath

[0015] In accordance with another aspect of the disclosure, an appaiatus for closing an opening in a blood vessel is disclosed composing a collagen plug and a thread wrapped around the collagen plug, the collagen plug being compressed when the thread is taut [0016] In accoi dance with yet another aspect of the disclosure, an apparatus foi closing an opening in a blood vessel is disclosed comprising a collagen plug having a relatively dense, haid upper portion, and a relatively malleable, soft lower portion

[0017] These and other aspects and features of the disclosure will become more apparent upon reading the following detailed description when taken in conjunction with the accompanying drawings

Brief Description of the Drawings

[0018] Fig 1 is a sectional view depicting an arteriotomy site with a tissue tract being formed from an epidermal layer to an opening in a blood vessel to be closed;

[0019] Fig. 2 is a sectional view similar to Fig. 1, but with a delivery sheath and anchoring device being initially inserted;

[0020] Fig. 3 is a sectional view similar¹ to Fig. 2, but with the anchoring device being deployed from the delivery sheath;

[0021] Fig. 4 is a sectional view similar to Fig 3, but with the anchoring device being deployed and retracted against the inner surface of the blood vessel wall;

[0022] Fig. 5 is a sectional view similar¹ to Fig. 4, but with the anchoring device being deployed and a biodegradable plug being inserted;

[0023] Fig 6 is a sectional view similar to Fig. 5, but with the biodegradable plug being tamped down against the anchoring device by a i am rod;

[0024] Fig 7 is a sectional view similar to Fig. 6, but after the anchoring device has been removed, the biodegradable plug has been fully inserted, and a bandage layer¹ has been placed over the epidermal layer; [0025] Pig . 8 is a perspective view of an anchoring device in a deployed configuration;

[0026] Fig. 9 is a sectional view of a blood vessel with an anchoring device being inserted theiein and depicting the pivotable nature of the anchoring device;

[0027] Fig. 10a is a top view of a blood vessel with a top stick;

[0028] Fig 10b is a top view of a blood vessel with a side stick;

[0029] Fig. 10c is a lateral cross-section of the blood vessel of Fig. 10a taken along line c-c;

[0030] Fig. 1Od is a lateral cross-section of the blood vessel of Fig 10b taken along line d-d;

[0031] Fig . 11 a is a sectional view of an alternative embodiment of a collagen plug being inserted;

[0032] Fig. l ib is a sectional view of the alternative embodiment of Fig 11a, but with the collagen plug being fully deployed;

[0033] Fig. 12a is a perspective view of another¹ alternative embodiment of a collagen plug with a thread spiral wound thereabout and in a compressed state;

[0034] Fig. 12b is a perspective view of the biodegradable plug of Fig. 12a, but with the thread being loosened and the collagen plug thereby being expanded;

[0035] Fig. 13 is a perspective view of yet another embodiment of a biodegradable plug including retention barbs; [0036] fig 14a is a peispective view of anothei embodiment showing a plug with slits in an insertion configuiation;

[0037] Fig 14b is a peispective view of the embodiment of Fig 14a in a flared, deployed configuiation;

[0038] Fig 15 is a sectional view of an embodiment having a sepaiate i eti action sheath; and

[0039] Fig 16 is a sectional view of an embodiment having memory metal wire anchoring device with a shaip comei theiein

[0040] While the present disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail It should be understood, however, that there is no intention to limit the invention to these specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the present invention

Detailed Description of the Disclosure

[0041] Referring now to the drawings and with specific reference to Fig 1 , an arteriotomy site 20 is depicted in cross-section As shown therein, a tissue tract 22 is formed extending between an epidermal layer 24 through a subcutaneous layer 25 and a blood vessel 26, As will be readily understood by one of ordinary skill in the art, the arteriotomy site 20 can be formed for any number of different medical procedures including, but not limited to, balloon angioplasty, wherein the aiteiiotomy is typically formed in a femoral artery to allow for the passage of guide wires, balloon catheters, and other medical devices therethrough A balloon catheter can be navigated to the site of the occlusion and expanded to clear the occlusion In addition, othei medical devices can then be insetted and navigated to the site so as to deploy a stent or other similai type of medical device. Aftei the medical procedure is completed, all such medical devices need to be lemoved from the blood vessel and through the tissue tract wheieupon the site of the ar tenotomy must be closed to pi event bleeding

[0042] Turning now to Fig 2, the apparatus for closing the arteiiotomy site is depicted as system 28 As shown therein, the system 28 may include a delivery sheath 30 which could be of a substantially tubular configuration having a distal end 32 and a proximal end 34 The delivery sheath 30 is introduced into the tissue tract 22 until the distal end 32 is proximate an opening 36 formed in a blood vessel wall 38 of the blood vessel 26 An optional circumferential flange 39 or other indicia may be provided on the delivery sheath to inform the physician or other medical technician that the delivery sheath is inserted to the correct depth

[0043] Within the delivery sheath 30 is an anchoring device 40 The anchoring device 40 may be of a linear¹ configuration when held within the delivery sheath 30, but be of a non-linear configuration when extended from the delivery sheath as shown in Fig 3 Any number of different materials can be used to form the anchoring device 40 with shape memory metal alloys being one subset of suitable materials Such shape memory metals include, but are not limited to, nickel -titanium alloys (commonly marketed under the Nitinol™ trademark), cobalt-chromium-nickel alloys (commonly marketed under the Elgiloy™ trademark) Such shape memory alloys are often referred to by the acronym SMAs and exhibit two main properties, namely, that they are pseudo-elastic, and have the shape memory effect These features are paiticulaily helpful to the present disclosure in that the anchoring device 40 has sufficient elasticity to be held in a linear configuration depicted in Fig 2, but when freed fiom the delivery sheath 30, reverts to its non-linear or coiled configuration thus serving as an anchoi for the system 28

[0044] Referring again to the drawings and with specific reference to Figs. 3 and 4, it can be seen that once the anchoring device 40 is extended fiom the delivery sheath 30, it fbims the non-linear backstop 41 or configuration of Fig 3. As will be described in further detail herein, that non-linear configuration can result in any number of different shapes with coiled or clover -leaf shapes being two examples In addition, as can be seen from Fig 3, the deployed configuration is formed within the blood vessel 26 itself Accordingly, when the delivery sheath 30 and anchoring device 40 are both retracted within the tissue tract 22, the anchoring device 40 engages an inner¹ surface 42 of the blood vessel wall 38. While such an anchoring device 40 does not seal the tissue tract 22, it does form a sufficient backstop 41 for the introduction of a collagen plug 44 as shown in Fig . 5 As shown, the collagen plug 44 is of a size sufficient to substantially extend across the width 46 of the tissue tract 22 and in the depicted embodiment is substantially cylindrical in shape. The collagen plug 44 can be introduced into the tissue tract 22 itself, through the delivery sheath 30, through an introducer sheath (not shown), or any other suitable mechanism In order to ensure proper placement of the collagen plug 44, it can be seen from Fig. 6, that a ram or tamping rod 48 may be used to compress the collagen 44 down into the tissue tract 22 against the anchoring device 40 By pulling the anchoring device 40 up against the inner surface 42 of the blood vessel wall 38, the backstop surface 41 is formed against which the collagen plug 44 can be pushed [0045] Referring now to Fig 7, when the collagen plug 44 is fully deployed and inserted into the tissue tiact 22 so as to substantially seal blood flow fiom the blood vessel 26 into the tissue tiact 22, the anchoiing device 40 can be ietiacted thiough a apeituie 52 (see Fig 6) formed within the collagen plug 44 In so doing, the collagen plug 44 remains within the tissue tiact 22, and a suitable bandaging mateiial 54 can then be applied across the epidermis 24 allowing for the tissue tract 22 to fully close over time It can theiefore be seen that the apparatus and method disclosed herein provide for a way of closing an aiteiiotomy site 20 which, even during application, results in relatively limited occlusion of blood flow thiough the blood vessel 26 leaving only a biodegradable plug in the tissue tiact 22 It is important to also note that the plug 44 need not be made of collagen, but any other material suitable for sealing such as, but not limited to, fibrin, PLA (polyactic acid), PLGA (poly(actic-co-glycolic) acid), and PEG (polyethylene glycol)

[0046] Referring now to Figs 8 and 9, the anchoiing device 40 is shown in a deployed configuration both in perspective of Fig 8, and in cioss-sectional view shown in Fig 9 It will be readily understood that the anchoring device 40 is naturally in a non- lineai configuration depicted by area 56 of Fig 8 If the entire anchoring device 40 is made of memory metal, the linear configuration of area 58 of Fig 8 is only held in such a state by a delivery sheath 30 or the like as shown in Fig 2 Alternatively, the linear area 58 may be made of tiaditional metal or other static material, with only the non-linear aiea 56 being made of memory metal However, in the depicted embodiment the entire length of the anchoring device 40 is formed of a memory metal having the elasticity and shape memory effect referenced above This is of importance foi many reasons, one of which is depicted in Fig 9

[0047] As shown therein, with the blood vessel 26 depicted in a lateral cross- section, if the opening 36 is formed in a side of the blood vessel (known in the medical arts as a "side-stick"), the anchoring device 40 is sufficiently elastic so as to allow for the pivoting of a linear area 58 relative to a non-lineai aiea 56 As an aside, it is important for the reader to understand the difference between a "side-stick" and a "top-stick" Referring to Figs 10a-d, that difference is explained As shown therein, the blood vessel 26 includes a longitudinal axis denoted by the Greek letter α If the physician is accurate when making the incision in the blood vessel 26, the opening 36 will be formed such that the longitudinal axis α extends substantially through the center of the opening 36 This is known as a "top-stick" and is shown in top view in Fig 10a and in lateral cross-section in Fig 10c If, however, as is often the case, the incision is made to the left or right of the longitudinal axis α anywhere from immediately next to the longitudinal axis α to tangential to the blood vessel 26, the opening 36 is known as a "side-stick" This is of importance for anchoring and closing purposes in that as best shown in the sectional views of Figs 10c and 1Od, with a "top-stick" the opening is relatively uniform and symmetrical, but with a "side-stick", the opening extends down and away relative to the skin of the patient Accordingly, to best close such an opening, the anchor must move to be aligned with both sides of the opening, and the collagen plug or other form of closure must be shaped or compressed to fill that resulting shape of the opening 36 This challenge is made even more difficult when it is considered that the tissue tract 22 meets the blood vessel 26 at an acute angle (typically 45°) thus often resulting in a compound angle, and the closure pioceduie is performed without the physician oi other medical technician being able to physically see the opening 36

[0048] The present disclosure aids in these respects however Moie specifically, when the physician or other medical technician deploys the anchoring device 40 and retracts the backstop 41 against the inner surface 42 of the blood vessel wall 38, the anchoring device 40 is able to pivot to a degree sufficient to allow for adequate contact of the backstop 41 against both sides 63a and 63b of the blood vessel wall 38 proximate to the opening 36 as shown in Fig 9 A suitable backstop 41 is thereby formed allowing for proper insertion of the collagen plug 44 While not depicted, it can be readily understood that the teachings of the disclosure are equally applicable to side- sticks which would be provided on the opposite side oi left side of Fig 9, as well as the aforementioned top-sticks, wherein the insertion would be formed in the top of the blood vessel with respect to Fig 9

[0049] Another feature of the pending disclosure is the ability of the collagen plug 44 to remain within the tissue tract 22 Three embodiments of a collagen plug having such enhanced features are depicted in Figs 1 Ia through 13 Starting with Figs 1 Ia and b, one example of such a collagen plug is depicted as a plug 64 As shown first in an intermediate insertion stage of Fig 11a, the plug 64 may be formed entirely of collagen, but may include an upper portion 66 and a lower portion 68 The upper portion 66 may have a relatively high density so as to be relatively hard, while the lower portion 68 may have a relatively low density so as to be relatively malleable or soft The plug 64 may be a composite of collagen and a hardening agent The difference in hardness levels is of importance in that, as can be seen in a comparison between Figs 11a and 1 Ib, as the plug 64 is insetted through the tissue tiact 22, the relatively hard uppei portion 66 serves to grasp inner surfaces 70 of the tissue tract 22 In so doing, tissue 72 is gathered between the upper portion 66 and lower poition 68 thereby increasing the surface area of tissue being held and increasing the frictional interference between the plug 64 and tissue tract 22 In addition, by providing the lower portion 68 of relatively soft or malleable collagen, it can better conform to the shape of the opening 36 formed in the blood vessel wall 38. For example, if the opening 36 is a side-stick as depicted in Figs 9 and 10, such a soft, malleable portion 68 can, upon application of adequate insertion force, alter its shape to best fill the shape of the side-stick opening

[0050] Referring now to Figs 12a and 12b, another alternative embodiment of the collagen plug is depicted by element 74 As shown therein, the plug 74 includes a substantially cylindrical body 76 of collagen with a vicryl thread or¹ filament 78 spirally wound thereabout When the filament or thread 78 is pulled taut, the plug 74 maintains the cylindrical shape depicted in Fig 12a, and when the thread is relatively loose about the plug 74, the plug 74 obtains the relatively bulbous shape depicted in Fig 12b The applicability of this plug to such an arteriotomy closure application can be readily understood More specifically, the tight configuration depicted in Fig 12a could be used when the plug 74 is being inserted through the tissue tiact 22 and then once it reaches its deployment location, i e , proximate the blood vessel wall itself, the string or filament can be loosened thereby allowing the plug to expand and increase the frictional engagement between the plug 74 and the tissue tract 22

[0051] With respect to Fig 13, a still further embodiment of a plug is depicted by element 80 As opposed to the collagen plugs previously depicted, an exterior surface 82 of the plug 80 can be formed with a series of barbs 84 oi othei protrusions In the depicted embodiment, it can be seen that the baibs 84 are formed with angled surfaces 86 with some of the angled surfaces 86 extending upwardly and some the angled surfaces 86 extending downwardly In so doing, the baibs 84 prevent movement in both directions along the longitudinal axis of the plug 80 More specifically, the barbs 84 engage the tissue of the tissue tract 22 thereby increasing the factional interference between the two and substantially preventing movement

[0052] With respect to Figs 14a and 14b, a plug 100 is depicted having a plurality of slits 102 or other incisions therein As shown, in an insertion configuration (Fig 14a) the plug 100 is substantially cylindrical However, in the deployed configuration (Fig 14b), the plug 100 is flared on buckled at distal end 104 This configuration may be reached by applying compressive force in the distal direction, thereby causing the individual legs 106 to buckle and the slits 102 allowing such motion In so doing, the distal end 104 has a much larger diameter to facilitate retention in the tissue tract or blood vessel wall

[0053] Referring now to Figs 15, another embodiment is depicted which employs an anchoring device having a circular deployment configuration and a retraction sheath 200 separate from the delivery sheath 230 As shown therein the retraction sheath 200 houses a circular memory wire 202 with four retention loops 204 A first thread or filament 206 is strung through a pair of opposed loops 204, while a second thread or filament 208 is strung through a second pair of opposed loops 204 If each set of opposed loops 204 is held together, the circular wire 202 will not deform and a plug 210 can be pushed against it and serve as an anchor In such an embodiment, the plug 210 can be annulai in shape and be slid through the delivery sheath, but ovei the ieti action sheath 200 Aftei the plug is deployed, the threads 206 and 208 can be pulled to compiess the wiie 202, and the wiie 202 can then be ieti acted out of the blood vessel through the ieti action sheath 200 The plug 210 may have a thread wound through it to compiess the plug while being pushed down the blood vessel, but allow the plug to expand when positioned appropriately

[0054] In another embodiment, depicted in Fig 16, a memory wiie 300 with a sharp corner 302 (peihaps, a 90° turn) is used As shown, when inserted, the wiie 300 can be positioned such that the coinei 302 is positioned directly below the tissue tract 304, thereby foiming an anchoring device oi shouldei against which a biodegiadable plug 306 can be pushed A distal end 308 of the wiie 310 can have a ietiaction thread oi filament 312 attached thereto After the plug 306 is positioned, the filament 312 can be pulled thereby pulling the wiie with it out of the patient

[0055] Fiom the foiegoing, it can be seen that the pending disclosure provides an apparatus and method foi closing an arteriotomy site The appaiatus and method provide foi a minimally invasive procedure which has a relatively low degree of blood occlusion thr ough the blood vessel dur ing the application Using memoiy metals, a suitable backstop foi the introduction of a collagen plug is easily formed and easily retracted after the collagen plug is deployed In addition, by providing collagen plugs of specific shapes, densities, and exterior configurations, the fiictional interference between the collagen plug and tissue tiact itself is increased thereby increasing the piobability that the collagen plug will remain in place for a time duration sufficient to fully and enduiingly foim hemostasis at the aiteiiotomy site

Claims

What is claimed is:

1 An apparatus foi closing an opening in a blood vessel, compiising: an anchoiing device having a linear insertion configuration and non-linear deployed configuration; and a biodegradable plug adapted to be inserted through a tissue tract against the anchoring device when the anchoring device is in the deployed configuration

2 The apparatus of claim 1, wherein the anchoring device is a material having shape memory

3 The apparatus of claim 2, wherein the anchoring device is made of a nickel-titanium alloy

4 The apparatus of claim 2, wherein the anchoring device is made of a cobalt-chromium-nickel alloy

5 The apparatus of claim 1, wherein the anchoring device forms at least one loop when deployed

6 The apparatus of claim 1 , wherein the anchoring device forms a continuous loop when deployed

7 The apparatus of claim 1, wherein the anchoring device forms an oval when deployed

8 The apparatus of claim 1, further including a delivery sheath, the anchoring device being fully received within the delivery sheath when in the insertion configuration and being partially extended from the delivery sheath when in the deployed configuration

9 The appaiatus of claim 1, wherein the anchoring device is removable after the biodegradable plug is deployed

10 The appaiatus of claim 1, fuithei including a tamp rod adapted to compact the biodegradable plug against the anchoring device

1 1 The appaiatus of claim 1, wherein the biodegradable plug is substantially cylindrical in shape, with a relatively rigid upper portion and a relatively malleable lower portion

12 The appaiatus of claim 1, wherein the biodegradable plug is substantially cylindrical with a plurality of exterior barbs

13 The appar atus of claim 1 , wherein the biodegradable plug further includes at least one thread wrapped therearound, the thread compressing the size of the collagen plug when pulled taut, the collagen plug expanding when the thread is released

14 The apparatus of claim 13, wherein the thread is wound around an exterior suiface of the plug and thereby adds fiictional interference with the tissue tract when deployed

15 The appaiatus of claim 1, wherein the biodegradable plug is made of collagen

16 The appaiatus of claim 1, wherein the biodegradable plug is made of polyactic acid

17 The appaiatus of claim 1, wherein the biodegradable plug is made of poly(actic-co-glycolic) acid

18 Ihe apparatus of claim 1, wherein the biodegradable plug is made of polyethylene glycol

19 The apparatus of claim 1, wherein the biodegradable plug has different pioperties in a distal end than a proximal end

20 The apparatus of claim 1, wherein the biodegiadable plug includes a plurality of slits

21 A method of closing an opening in a blood vessel, compiising: inserting a delivery sheath into a tissue tract extending from an epideimal layer of a patient to an arteiiotomy site in a blood vessel; extending an anchoring device from the delivery sheath and into the blood vessel, the anchoring device being formed of a shape memory alloy, the anchoring device being held in a linear configuration when within the delivery sheath and assuming a nonlinear configuration when extended from the delivery sheath; retracting the delivery sheath and anchoring device a distance sufficient to engage the anchoring device with an inner surface of the blood vessel proximate the arteriotomy site; pushing a biodegradable plug down the tissue tract until the plug engages the anchoring device; and retracting the anchoring device from the blood vessel, through the biodegradable plug and out of the tissue tract

22 The method of claim 21 , wherein extending the anchoring device causes a distal end of the anchoring device to coil

23 The method of claim 21, wherein extending the anchoring device causes a distal end of the anchoring device to form a cloverleaf

24 The method of claim 21, further including driving a ram rod down the tissue tract to compress the biodegradable plug against the anchoring device

25 The method of claim 21 , wherein the biodegradable plug has at least one thread wrapped therearound, and the method further includes releasing tension in the thread once the biodegradable plug is in engagement with the anchoring device, the biodegiadable plug thereby expanding against inteiioi surfaces of the tissue tiact

26. An apparatus for closing an opening in blood vessel comprising: a delivery sheath having a distal end and a proximal end, the delivery sheath being inseitable into a tissue tract extending from an epidermal layer to an ar tenotomy site; and

a length of memory metal positioned within the delivery sheath, the memory metal being substantially linear in shape when within the delivery sheath and being substantially non-linear when extended from the delivery sheath

27 The apparatus of claim 19, wherein the memory metal is a nickel- titanium alloy

28 The apparatus of claim 19, wherein the memory metal is a cobalt- chromium-nickel alloy

29. The apparatus of claim 26, further including a sealing plug adapted to be pushed down the tissue tract and into engagement with the memory metal when in the substantially non-lineai configuration

30. The apparatus of claim 29, wherein the sealing plug is made of collagen.

31 The apparatus of claim 30, wherein the collagen plug includes a plurality of external barbs

32 The apparatus of claim 30, wherein the collagen plug includes a relatively hard upper portion, and a relatively soft lower portion 33 , The apparatus of claim 30, wherein the collagen plug fmthei includes at least one thread wrapped theieaiound, the thiead compiessing the size of the collagen plug when pulled taut, the collagen plug expanding when the thiead is ieleased

34 The appaiatus of claim 33, when the thread is wrapped aiound an exteiioi surface of the collagen plug

35 An appaiatus foi closing an opening in a blood vessel, composing: a collagen plug; and

a thiead wiapped around the collagen plug, the collagen plug being compiessed into a fust, lelatively small dimension when the thiead is pulled tight, the collagen plug expanding into a second lelatively laige dimension when the thiead is loose

36 An apparatus foi closing an opening in a blood vessel compiising a biodegiadable plug having a relatively dense, hard upper portion and a relatively malleable, soft lower portion.