Abstract:
A hemostatic plug for sealing wounds in blood vessels comprising a tubular or spring-like body capable of buckling or collapsing upon application of a threshold axial force and having a fretted distal end. A collapsed portion of the plug lodges into the tissue tract and thus acts as a foothold allowing the plug to maintain continuous pressure on the puncture site necessary for a quick effective closure of the wound. Furthermore, collapse of the plug minimizes the chance of arterial penetration.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a method and device for sealing a puncture wound in a blood vessel. More particularly, the invention relates to a collapsible biodegradable collagen plug for sealing a puncture wound in a blood vessel that minimizes the risk of blood vessel entry and that maintains pressure on the puncture site in the blood vessel. 
     2. Description of the Prior Art 
     In certain medical procedures, such as cardiac catheterization, dilation and counterpulsation, a catheter or other device is inserted into an artery, most commonly by percutaneous methods, and then fed through the arterial tree to the site where needed, frequently, the region of the heart. The site usually selected for insertion of the catheter is the groin, because the femoral artery in that region is relatively easy to locate. 
     These procedures are normally initiated by insertion of an angiographic needle, followed by passing a guide wire through that needle into the artery. The needle is then removed leaving the guide wire in place. Next, a sheath-dilator set is passed over the guide wire into the artery in order to enlarge the opening sufficiently to permit entry of the catheter or other device. The dilator is then removed, leaving the sheath or guide cannula in place. The catheter or other device can then be inserted through the cannula with full confidence that when it emerges from the distal end it will be within the lumen of the artery. 
     It should be understood that the subject invention is independent of the blood vessel involved. While it is expected that the femoral artery will be the most commonly used blood vessel, use of other arteries as well as veins is anticipated as well. 
     After a procedure, for example, counterpulsation, has been completed, the sheath must be removed and the wound closed. Often, this can be accomplished simply by the application of digital pressure, generally augmented by the use of a pressure dressing. Customarily, pressure must be applied for at least ½ hour, and frequently for much longer than that. While pressure dressings often suffice, it is not uncommon for additional devices, such as sandbags, to be needed. In addition, during this period the patient must be immobilized, lest movement interfere with the closing process. Because of the pressure required, the time during which it must be applied and the need for immobilization, the procedure is painful and uncomfortable. The procedure also requires prolonged personal attention of a health care professional. Finally, wound closures accomplished in this manner are prone to reopen unexpectedly long after closure appears to have been completed. Patients are therefore often required to remain in the hospital for 24 hours or longer. 
     A device for sealing the wound, overcoming many of the above mentioned problems, is disclosed in U.S. Pat. No. 5,591,204 and is known in the medical field under Datascope Corp.&#39;s VasoSeal® trademark. The VasoSeal® product comprises a charge of hemostatic material and a hollow sheath adapted to pass through the tissue channel of a patient, the sheath having a cross sectional profile larger than the puncture in the patient&#39;s blood vessel. The Vasoseal® product places the hemostatic material in the hollow sheath and advances the hemostatic material through the sheath to the outside of the vessel wall around the puncture. The preferred embodiment of the hemostatic material is a compressed cylinder or plug of collagen in which the distal most portion is fluffed. The plug is designed to mushroom slightly when the plug contacts the exterior wall of the artery and the stiff proximal end lodges in the tissue tract thus holding the expanded distal end in place on the artery. Aside from providing greater puncture area coverage the fluffing of the distal end also serves the purpose of exposing more hemostatic fibers to the blood thus allowing the hemostatic material to react more readily with the blood. 
     U.S. Pat. Nos. 5,330,445 and 5,552,840 disclose a tubular sheath which is slidably disposed over a tubular medical device and which is positioned at a body access site. The sheath is deposited within a patient to assist in sealing the wound caused by the tubular medical device and inhibit internal and external bleeding. Despite the wound sealing assistance provided, these wound sealing sheaths suffer a number of drawbacks, including the possibility of allowing the sheath to enter the artery. The sheath may enter the artery if the distal tip of the sheath does not mushroom out far or is not large enough to engage the puncture site at the exterior wall of the artery. In this instance the proximal end of the plug transmits the insertion force provided by the insertion device to the distal end of the plug allowing the distal tip to penetrate the puncture site and thus enter the artery. Entrance of the plug into the artery is dangerous for a number of reasons. Entrance of the distal tip of the plug, or the entire plug, into the artery obstructs blood passage in the artery and emboli formation on the plug further obstructs blood flow. Furthermore, emboli may break off the distal tip of the plug and flow downstream. Free floating emboli must be removed surgically to prevent decreased circulation to distal extremities. 
     Another major disadvantage of the above mentioned wound sealing devices is that they rely primarily on the friction force between the patient&#39;s tissue tract wall and the plug and slight swelling of the plug itself to maintain the position of the plug and its pressure on the puncture site. As a result, the plug may be dislodged from the tissue tract with minimal force. Furthermore, the pressure on the artery, required for rapid puncture closure, is lost quickly after the insertion device is removed. 
     While the foregoing wound closure devices may be suitable for the particular purposes employed, or for general use, they would not be as suitable for the purposes of the present invention as disclosed hereafter. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the invention to produce an improved hemostatic plug which quickly seals a puncture in an artery without being prone to entering the artery or being easily dislodged from the artery. 
     It is another object of the invention to produce an improved hemostatic plug which applies a continuous pressure to the arterial puncture site. 
     It is a further object of the invention to produce a economical and efficient method for fabricating an improved hemostatic plug. 
     The invention is a hemostatic plug for sealing wounds in blood vessels comprising a tubular or spring-like body capable of buckling or collapsing upon application of a threshold axial force and having a fretted distal end. A collapsed portion of the plug lodges into the tissue tract and thus acts as a foothold allowing the plug to maintain continuous pressure on the puncture site necessary for a quick effective closure of the wound. Furthermore, collapse of the plug minimizes the chance of arterial penetration. 
     To the accomplishment of the above and related objects the invention may be embodied in the form illustrated in the accompanying drawings. Attention is called to the fact, however, that the drawings are illustrative only. Variations are contemplated as being part of the invention, limited only by the scope of the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, like elements are depicted by like reference numerals. The drawings are briefly described as follows. 
     FIG. 1A is a plan view of an improved hemostatic plug. 
     FIG. 1B is a top view of the proximal non-fretted end of the plug of FIG.  1 A. 
     FIG. 1C is a transverse cross sectional view of the plug taken along lines  1 C— 1 C. 
     FIG. 1D is a bottom view of the fretted end of the plug. 
     FIG. 1E is a longitudinal cross sectional view of the plug in a semi-collapsed form taken along lines  1 E— 1 E in FIG.  1 A. 
     FIG. 1F is a top view of the proximal non-fretted end of the plug in its collapsed form. 
     FIG. 2 is a cross sectional view of a patient&#39;s leg and the plug being inserted over a guide wire into said patient&#39;s leg. 
     FIG. 3 illustrates a cross sectional view of a patient&#39;s leg and the plug in its inserted collapsed form. 
     FIG. 4A illustrates a plan view of an alternate embodiment of the plug comprising helical lacerations. 
     FIG. 4B illustrates a longitudinal cross sectional view of the plug with helical lacerations in its semi-collapsed form taken along lines  4 B— 4 B in FIG.  4 A. 
     FIG. 4C is a transverse cross section of the plug in FIG. 4A in a collapsed state taken along lines  4 C— 4 C. 
     FIG. 5 is a plan view of the plug having two collapsible portions. 
     FIG. 6 is a plan view of collagen sheet of paper, used to fabricate the plug, with lacerations in it and a fretted end. 
     FIG. 7 is a plan view of a smaller sheet of collagen paper laid over a larger sheet of collagen paper. 
     FIG. 8 illustrates the collagen sheet illustrated in FIG. 7 being rolled into a single collagen paper of uniform thickness and varying density. 
     FIG. 9 is a plan view of the plug without lacerations. 
     FIG. 10 is a cross sectional view of a patient&#39;s leg and the plug, as illustrated in FIG. 9, in its collapsed form inserted within the patient&#39;s leg. 
     FIG. 11 is a plan view of a sheet of collagen paper with a removable tube inserted through its center. 
     FIG. 12 is a top view of the sheet of paper illustrated in FIG. 11 with portions of the sheet to the left and right of the removable tube folded. 
     FIG. 13 is a plan view of the sheet of collagen paper illustrated in FIG. 11 rotated ninety degrees. 
     FIG. 14 is a plan view of the sheet of collagen paper illustrated in FIG. 13 with the removable tube piercing the collagen sheet in two locations rather than just one location. 
     FIG. 15 is a plan view of an alternate embodiment of the plug comprising thin strips bundled about the removable tube. 
     FIG. 16 is a plan view of the plug, as illustrated in FIG. 15, in a semi-collapsed form. 
     FIG. 17 is a plan view of an alternate embodiment of the plug comprising a helical filament coiled about the removable tube. 
     FIG. 18 is a cross sectional view of the patient&#39;s leg with the plug as illustrated in FIG. 17 inserted within said patient&#39;s leg. 
     FIG. 19 is a longitudinal cross sectional view of an alternate embodiment of the plug comprising the collagen filament and a collagen sponge filament coiled together about the removable tube. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1A illustrates a plan view of an improved hemostatic plug  11  comprising a tube  10  having longitudinal radial expanding wings  20  extending from a point distal to the proximal end to a point proximal to the distal end of the plug  11 . The wings  20  are formed by longitudinal lacerations  30  extending from a point distal to the proximal end to a point proximal to the distal end of the plug  11 . The distal end of the plug  11  is fretted. 
     FIG. 1B illustrates a top view of the proximal non-fretted end of the plug  11 . A lumen  40  extends from the proximal non-fretted end of the plug  11  to the distal fretted end of the plug  11 . The tube has an inner surface  50  and an outer surface  60 . 
     FIG. 1C illustrates a transverse cross sectional view of the plug  11  taken along lines  1 C- 1 C. The longitudinal lacerations  30  extend depthwise from the outer surface  60  to the inner surface  50  of the tube  10 . 
     FIG. 1D illustrates a bottom view of the fretted end of the plug  11 . 
     FIG. 1E illustrates a longitudinal cross section of the plug  11  in a semi-collapsed form taken along lines  1 E- 1 E in FIG.  1 A. The distance between the proximal and distal ends of the plug  11  has decreased and as a result the wings  20  have buckled and radially expanded. 
     FIG. 1F illustrates a top view of the proximal non-fretted end of the plug  11  in FIG. 1A in its collapsed form. 
     FIG. 2 illustrates a cross sectional view of a patient&#39;s leg  70  and the plug  11 , inserted over a guide wire  80 , into said patient&#39;s leg  70 . FIG. 2 illustrates the result of the first insertion step of the plug  11 . The proximal end of the plug  11  is in contact with an insertion device  90  which provides axial insertion force to the plug  11 . The distal fretted end of the plug  11  has totally covered a puncture  101  in a blood vessel  100  in the patient&#39;s leg  70  and has conformed to the surface of the blood vessel  100 . The collapse of the fretted end and expansion of the plug  11  itself have occluded the lumen  40  (FIGS.  1 B- 1 D). Aside from allowing the distal end of the plug  11  to conform to the surface of the blood vessel  100  and occluding the lumen  40 , fretting the distal end of the plug  11  also serves the purpose of exposing more hemostatic fibers to the blood thus allowing the hemostatic material to react more readily with the blood. 
     FIG. 3 illustrates a cross sectional view of the patient&#39;s leg  70  and the plug  11  in its collapsed form. After the surgeon, via the insertion device  90  (as shown in FIG.  2 ), applies a threshold axial force to the plug  11 , the wings  20  collapse and lodge between the artery and surrounding tissue  110 . The now fixed plug  11  applies continuous pressure to the blood vessel  100 . The plug  11  herein disclosed is more effective in sealing punctures than prior art plugs because of its ability to apply continuous pressure to the puncture  101  in the blood vessel  100 . Prior art plugs rely only on the friction between the outer surface of the plug and the tissue tract to maintain the position of the plug relative to the blood vessel and thus maintain pressure on the blood vessel. Thus the lodging of the wings  20  into the surrounding tissue  110  is an important feature of the present invention. 
     The collapse of the plug  11 , and the resultant lack of axial insertion resistance, indicates to the surgeon that the plug  11  is properly positioned and that he or she should terminate application of axial pressure. Any excessive insertion force, applied after the initial collapse of the plug  11 , is transposed into radial expansion of the wings  20  not linear movement (the distal fretted end remains relatively fixed). Thus, the collapsibility feature of the plug  11  minimizes the potential for arterial insertion of the plug  11 . Furthermore, the radial expansion of the wings  20  makes it more difficult to force the plug  11  into the blood vessel  100 , and therefore, also minimizes the probability of arterial penetration. 
     FIG. 4A illustrates an alternate embodiment of the improved hemostatic plug  11  identical to the plug illustrated in FIG. 1A except comprising helical lacerations  120  rather than longitudinal lacerations  30 . FIG. 4B illustrates a longitudinal cross section of the plug  11  with helical lacerations  120  in its semi-collapsed form taken along line  4 B— 4 B in FIG.  4 A. The distance between the proximal and distal ends has decreased and the wings  20  have radially expanded. Furthermore, the distal fretted end has mushroomed. FIG. 4C is a transverse cross section of the plug  11  in FIG. 4B in its collapsed state taken along lines  4 C— 4 C. As can be seen in FIG. 4C, in its collapsed form the average distance between the wings  20  in the plug  11  having helical lacerations  120  is less than the averaged distance between the wings  20  in the plug  11  having longitudinal lacerations  30  (as seen in FIG.  1 E). Depending on the insertion site of the plug  11 , a plug having helical lacerations with its tightly spaced wings, may be a more appropriate anchor than a plug having longitudinal lacerations. Note that the number, length, and distance between the longitudinal lacerations, and the pitch, number, and length of the helical lacerations will affect both the anchorability of the plug  11  and also the collapsibility of the plug  11 . Note further that the plug  11  may be designed to have more than one collapsible portion. This may be accomplished by having sets of shorter lacerations with non-laceration portions between them, as illustrated in FIG.  5 . FIG. 5 illustrates the plug  11  having two collapsible portions, a proximal collapsible portion  130  and a distal collapsible portion  140 . The proximal collapsible portion  130  comprises longitudinal lacerations  30  and the distal collapsible portion  140  comprises helical lacerations  120 . Note that both the longitudinal lacerations  30 , as illustrated in FIGS. 1A and 5, and the helical lacerations  120 , as illustrated in FIGS. 4A and 5, do not have to be equally spaced around the plug  11 . Rather the number, length, width, pitch, and spacing of the lacerations may be controlled to created the desired buckling effect. 
     The plug  11  is fabricated by rolling a collagen paper  150 , as illustrated in FIG. 6, having short slits  160  on its distal end and appropriately sized longitudinal lacerations  30  (or alternatively helical lacerations  120 ), around a mandrel (not shown) to form a tube of desired thickness. The collagen paper  150  is made from a thin sheet of collagen. The tighter the collagen paper  150  is rolled the stiffer the plug  11  becomes and the more axial pressure needs to be applied to initiate collapse of the plug  11 . 
     The collagen paper  150  is fabricated to have varying densities by adjusting the amount and position of the raw collagen prior to compressing the material down to a sheet. An example of this is to take a first rectangular sheet  170  of uncompressed collagen, as illustrated in FIG. 7, and lay a second sheet  180  one quarter the size of the first rectangular sheet  170  over it, aligning two edges. Next, compress this substrate to a uniform thickness by passing them through rollers  190 , as illustrated in FIG. 8, to form a sheet of varying density uniform thickness collagen paper  150 . Where the two sheets overlapped the density will be double and the stiffness and blood absorption time will be greater. As discussed above, lacerations are then made in the collagen paper  150 , shown in FIG. 6, and to enhance the mushrooming effect, the distal end of the plug is fretted. This sheet is then used to form a plug by wrapping it around a mandrel with the denser end located proximally. The less dense distal end will be softer and more absorbent than the proximal denser end allowing it to become more compliant and mushroom when contacting the exterior wall of the blood vessel  100  at the puncture  101  (FIG.  2 ). When the fretted end contacts the exterior surface of the artery, as illustrated in FIG. 2, it fans out covering a large surface area. Minimal axial compressive force is required to achieve this mushrooming effect. The length, width, and pitch of the slits  160  (shown in FIG. 6) at the distal end may be varied according to the desired effect. 
     Alternate embodiments of the plug  11  rely on the rolling of the collagen paper rather than the location, spacing, and pitch of lacerations in the collagen paper, to create the collapsibility property. FIG. 9 illustrates the plug  11 , similar to its illustration in FIGS. 1A and 4A, except lacking lacerations. FIG. 10 illustrates said plug  11 , already inserted into a patient&#39;s leg  70 , in its collapsed form. The proximal end of the body of the plug  11  operates as an anchor by lodging between the blood vessel  100  and the surrounding tissue  110 . The plug  11 , if not lodged between the blood vessel  100  and the surrounding tissue  110 , would spring back (by means of a restoring force) to its original shape. This restoring force maintains pressure on the puncture  101  in the blood vessel  100 . The following steps are required to properly position and secure the plug  11 . The plug  11  is inserted into the patient&#39;s leg  70  such that the distal end of the plug  11  contacts the puncture  101  in the blood vessel  100 . Next a threshold force is applied to the plug causing it to buckle. The plug is then bent into a V-shape by forcing the proximal end of the plug towards the distal end. While maintaining this V-shape the proximal end of the plug  11  is lodged between the blood vessel  100  and surrounding tissue  110  so as to fix the proximal end. 
     The plug  11 , illustrated in FIG. 9, is formed by rolling collagen paper about a removable tube  200 , as illustrated in FIG.  11 . The removable tube  200  is inserted through the middle of a collagen sheet  210  having a left side  220  and a right side  230 . The collagen sheet  210  is folded such that the left side  220  and the right side  230  are in contact. Next the collagen paper is rolled about the removable tube  200 . Alternatively, the paper on both sides of the collagen sheet  210  can be folded resulting in a plug having a top view as illustrated in FIG. 12. A collapsible plug  11  having different properties can be formed by rotating the collagen paper ninety degrees (or a different angle) before rolling or folding, as illustrated in FIG. 13, or by having the removable tube  200  pierce the collagen paper  150  in two or more locations before rolling or folding, as illustrated in FIG.  14 . Each of the above described plug fabrication schemes will produce plugs with varying collapsibility and blood saturation rate properties. The removable tube  200  is use as a mandrel to maintain the shape of the plug  11  during fabrication. A preliminary step to insertion of the plug  11  involves inserting the guide wire  80  through the removable tube  200  and then removing the removable tube  200  by pulling it away from the patient toward the proximal end of the guide wire  80 . 
     FIG. 15 illustrates yet another alternate embodiment of the plug  11 . The plug  11  comprises thin parallel strips  240  of collagen which are bundled about the removable tube  200  by wrapping a distal portion and a proximal portion of the thin strips  240  with a band  250 . The plug  11  resembles a broom except that only one end of the bristles are attached to the handle of a broom. After a threshold axial insertion force is applied to the plug  11  the thin strips  240  collapse and anchor between the blood vessel  100  and surrounding tissue  110 , similar to the collapsed plug  11  with lacerations illustrated in FIG.  3 . FIG. 16 illustrates the plug  11  in a semi-collapsed state. Note that the filaments have buckled and radially expanded and that the distance between the distal and proximal ends has decreased. The collapsibility of the plug  11  may be controlled by varying the width, thickness, or diameter (if circular strips are used) of the strips  240 . Furthermore, the width, thickness, or diameter of the thin strips  240  may vary along the length of the strips  240 . Also note that the lengths of the strips  240  may be controlled so as to create a distal end that is contoured to the shape of the punctured artery, thereby optimizing arterial surface area coverage. Similarly, the diameter or thickness and width of the distal end of the strips  240  may be made smaller, making the plug  11  more pliable, so as to allow the distal end of the plug  11  to conform to the shape of a blood vessel upon contact. Similar to the insertion procedure described above for the other alternate embodiments of the plug  11  described the removable tube  200  is removed prior to insertion of the plug  11 . 
     FIG. 17 illustrates another alternate embodiment of the plug  11 . The plug  11  comprises a collagen filament  260  wrapped around the removable tube  200  in a rope like manner. Once inserted into the tissue tract, the plug  11  may be unraveled at the distal end by twisting the proximal end and thus cover a larger surface area at the puncture  101 . FIG. 18 illustrates a cross sectional view of the plug  11  inserted into the patient&#39;s leg  70 . Insertion of the plug  11  comprises the following steps. First, the guide wire  80  is inserted through the removable tube  200  and the removable tube  200  is removed. Next the plug  11  is advanced forward into the patient&#39;s leg  70  such that the distal end contacts the puncture  101  in the blood vessel  100  and force is applied until the plug  11  buckles. At this point the force is relieved so as to allow the plug  11  spring back into its original shape. The plug  11  is then unraveled at the distal end by twisting the proximal end. The distal end is lodged in surrounding tissue  110  directly above the arterial puncture  101  and therefore remains fixed. The purpose of unraveling the plug  11  is to increase the diameter of the distal end of the plug  11 , and therefore, allow for greater surface area sealing coverage of the puncture  101 . The unraveling torque applied to the distal end of the plug  11  is maintained as axial force is applied once again to buckle the plug  11 . After buckling the proximal end becomes lodged into the surrounding tissue  110  thereby keeping the proximal end of the plug  11  fixed and thus maintaining continuous pressure on the puncture  101 . 
     Alternatively, the rope-like plug  11  may be made up of collagen filaments  260  and compressed collagen sponge filaments  270  coiled together, as illustrated in FIG.  19 . FIG. 19 illustrates a longitudinal cross section of such a plug  11 . The collagen filaments  260  are useful for puncture  101  closure because of their hemostatic properties. The collagen sponge filaments  270  expand upon exposure to blood and are therefore useful to provide continuous pressure on the puncture  101 .