Abstract:
The present invention provides a method and apparatus for sealing a subcutaneous tissue puncture. The method and apparatus reduce the occurrence of anchor shuttling by stiffening a tip or end portion of an insertion sheath that acts as a one-way valve to a closure device anchor. The stiffening of the tip reduces shuttling by reducing or eliminating the tendency of prior insertion sheath tips from puckering and creating a gap into which the anchor may reenter. The method of stiffening may take on many different mechanisms, several of which are disclosed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to medical devices, and, more particularly, to a vascular puncture sealing apparatus with features to aid in anchor function.  
       BACKGROUND OF THE INVENTION  
       [0002]     Various medical procedures, particularly cardiology procedures, involve accessing a corporeal vessel or other lumen through a percutaneous sheath. Insertion of the sheath necessarily requires a hole or opening in the vessel wall so that a medical procedure can be performed through the sheath. After the particular medical procedure has been performed, the sheath must eventually be removed from the vessel and the access hole in the vessel wall must be closed.  
         [0003]     A number of prior vascular closure devices have been developed to close the hole or puncture in the vessel wall. Closing the hole typically involves packing a resorbable sealing plug at the hole or sandwiching the hole between the sealing plug and an anchor. Examples of prior vascular closure devices are described in U.S. Pat. Nos. 6,179,863; 6,090,130; and 6,045,569 and related patents that are hereby incorporated by reference.  
         [0004]     Placing the sealing plug often comprises several steps. First, a puncture site is located. A puncture locator is placed in and through the insertion sheath such that an inlet port in the puncture locator resides outside a distal end of the insertion sheath a predetermined distance. The insertion sheath and puncture locator are inserted through the puncture into a blood vessel. As the distal end of the puncture locator penetrates the blood vessel, blood flows into the inlet port and out of a drip hole via a flow path through the puncture locator.  
         [0005]     Blood exiting the drip hole indicates that the puncture locator and insertion sheath have just penetrated the blood vessel. To ensure proper placement of the insertion sheath and subsequently the closure device, the insertion sheath and puncture locator are normally backed out of the vessel until blood stops flowing from the drip hole. Next, the insertion sheath and puncture locator are re-inserted into the blood vessel until blood starts flowing again from the drip hole. Proper depth of penetration and location of the assembly is established by continuing to insert an additional predetermined distance, for example, an operator often inserts the assembly 1 to 2 centimeters further if the blood vessel is a femoral artery. After the insertion sheath is properly located, the puncture locator is removed and the vascular closure device is inserted through the sheath and into to the blood vessel.  
         [0006]     After the vascular closure device is located in the blood vessel, an anchor at the distal end of the vascular closure device is usually deployed within the vessel. The anchor is initially aligned with a longitudinal axis of the closure device in the sheath. Inserting the anchor out of the distal end of the insertion sheath usually deploys the anchor, allowing it to rotate and align itself with an interior wall of the blood vessel. However, sometimes when the anchor is deployed, it may reenter the sheath instead of rotating and aligning with the blood vessel. This phenomenon is termed “shuttling.” Shuttling disables the function, and negates the benefit, of the device. Therefore, it is desirable to have an apparatus that reduces or eliminates anchor shuttle so that the closure device will function as expected. A failure with the closure device may introduce complications to the closure of the puncture.  
         [0007]     One of the causes of shuttling is “pucker,” or the tendency of an insertion sheath tip to not seal against the closure device as it passes therethrough. If the insertion sheath tip puckers, a gap is formed between the closure device and the insertion sheath, and the anchor may reenter the insertion sheath via the gap. Therefore, it is desirable to have an apparatus reducing the tendency of insertion sheath “pucker” and therefore reduce the occurrence of anchor shuttle so that the closure device is most likely to succeed.  
       SUMMARY OF THE INVENTION  
       [0008]     In one of many possible embodiments, the present invention provides a tissue puncture closure assembly comprising a tissue puncture closure device having a distal and a proximal end, a vascular insertion sheath having a distal and a proximal end, where the distal end of the insertion sheath includes a tip portion stiffer than the remainder of the insertion sheath. The tip portion may have a concave fold and may include no more than half of a circumference of the insertion sheath. The tip portion may be stiffened by increasing the wall thickness of the tip portion to something greater than the wall thickness of the remainder of the insertion sheath. Adding a second layer of material or a stiffening ridge may also stiffen the tip portion. In addition, the tip portion may be corrugated or stiffened in other manners. The closure device may include a filament extending from the proximal end of the closure device to the distal end of the closure device, an anchor for insertion through a tissue wall puncture attached to the filament at the distal end of the closure device; and a sealing plug slidingly disposed about the filament at the distal end of the closure device for sealing the puncture.  
         [0009]     Another embodiment provides a vascular insertion sheath including a flexible tubular member having a longitudinal axis, a distal end, and a proximal end; a hemostatic valve coupled to the proximal end of the tubular member, and a fold at the distal end of the tubular member. The fold comprises a higher stiffness coefficient than the tubular member. The higher stiffness coefficient may be provided by the addition of a layer of material over the fold, which may be added only at an edge of the fold. A fold having a thicker wall than the flexible tubular member may also provide the higher stiffness coefficient for the fold. In addition, a stiffening ridge or a corrugation may stiffen the fold.  
         [0010]     The invention also provides a method of reducing anchor shuttle in a tissue puncture closure assembly, comprising stiffening a tip portion of an insertion sheath receptive of a tissue puncture closure device.  
         [0011]     According to another embodiment the invention provides a method of making a vascular insertion sheath, comprising providing a flexible tubular member, tapering an end portion of the flexible tubular member, folding a section of the end portion into a concave depression, and stiffening at least a portion of the concave depression. The tapering may include inserting the flexible tubular member into a heated die and reforming the end portion. The folding may include inserting the flexible tubular member into a heated die and reforming the end portion. The stiffening may include inserting the flexible tubular member into a heated die and reforming at least part of the end portion into a thicker wall or a corrugated section. The stiffening may include applying a layer of material to at least part of the end portion, adding a ridge across the end portion in a direction transverse to a longitudinal axis of the flexible tubular member, or some other stiffening method.  
         [0012]     The present invention also provides a tissue puncture closure assembly comprising a closure device for partial insertion into and sealing of an internal tissue wall puncture. The closure device includes a carrier tube having an anchor nest at a distal end, a filament extending through the carrier tube, an anchor attached to the filament at the distal end of the carrier tube and seated in the anchor nest, and an insertion sheath receptive of the carrier tube of the closure device. The insertion sheath includes a flexible tubular member having a longitudinal axis, a distal end, and a proximal end; a hemostatic valve coupled to the proximal end of the tubular member, and a fold at the distal end of the tubular member. The fold has a higher stiffness coefficient than the tubular member.  
         [0013]     There is also provided a method of sealing a tissue puncture in an internal tissue wall accessible through a percutaneous incision, comprising providing a tissue puncture closure device having a carrier tube with a filament extending therethrough. The filament is connected at a distal end of the carrier tube to an anchor, and the anchor is initially seated in a nest disposed in the carrier tube. The filament is also connected to a sealing plug located proximal of the anchor for disposition and anchoring about the tissue puncture. The method includes inserting the tissue puncture closure device through an insertion sheath having a stiffened tip portion into the percutaneous incision, deploying the anchor into the tissue puncture, withdrawing the closure device from the percutaneous incision, and tamping the sealing plug toward the anchor.  
         [0014]     The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to similar, but not necessarily identical parts throughout, and in which:  
         [0016]      FIG. 1A  is a cut-away assembly view of a tissue puncture closure device and insertion sheath according to the prior art.  
         [0017]      FIG. 1B  is a detail of the cut-away section of  FIG. 1A .  
         [0018]      FIG. 2A  is side view of the tissue puncture closure device of  FIG. 1A  engaged with the insertion sheath in a first position according to the prior art.  
         [0019]      FIG. 2B  is a detailed cross-sectional view of the tissue puncture closure device and insertion sheath of  FIG. 2A .  
         [0020]      FIG. 3  is a perspective view of a tip portion of the insertion sheath of  FIG. 2A .  
         [0021]      FIG. 4  is a front view of the insertion sheath of  FIG. 3 .  
         [0022]      FIG. 5  is a cross-sectional view of the tissue puncture closure device of  FIG. 1A  in relation to the insertion sheath of  FIG. 2A  in a second position according to the prior art.  
         [0023]      FIG. 6  is a cross-sectional view of the tissue puncture closure devices of  FIG. 1A  in relation to the insertion sheath of  FIG. 2A  in a third position according to the prior art.  
         [0024]      FIG. 7  is a perspective view of the tissue puncture closure device of  FIG. 1A  and insertion sheath of  FIG. 2A  shown in relation to a patient with an anchor deployed according to the prior art.  
         [0025]      FIG. 8A  is a cross-sectional view of the tissue puncture closure device of  FIG. 1A  in relation to the insertion sheath of  FIG. 3  in a fourth position illustrating shuttling according to the prior art.  
         [0026]      FIG. 8B  is a front view of the insertion sheath of  FIG. 3  with the tissue puncture closure device of  FIG. 1A  inside of the insertion sheath.  
         [0027]      FIG. 9  is a front cross-sectional view of a stiffened insertion sheath according to one embodiment of the present invention with a tip portion having a thickened wall.  
         [0028]      FIG. 10  is a front view of a stiffened insertion sheath according to another embodiment of the present invention with a thickened edge tip portion.  
         [0029]      FIG. 11A  is a perspective view of a stiffened insertion sheath according to another embodiment of the present invention with stiffening ridges at the tip portion.  
         [0030]      FIG. 11B  is a cross-sectional side view of the stiffened insertion sheath of  FIG. 1A .  
         [0031]      FIG. 12A  is a perspective view of a stiffened insertion sheath according to another embodiment of the present invention with a second layer added to the tip portion.  
         [0032]      FIG. 12B  is a cross-sectional side view of the stiffened insertion sheath of  FIG. 12A .  
         [0033]      FIG. 13A  is a perspective view of a stiffened insertion sheath according to another embodiment of the present invention with a corrugated section of the tip portion.  
         [0034]      FIG. 13B  is a cross-sectional side view of the stiffened insertion sheath of  FIG. 13A .  
         [0035]      FIG. 14  is a perspective view of the tissue closure device of  FIG. 1A  in relation to a stiffened insertion sheath with an operator tamping a sealing plug according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0036]     As mentioned above, vascular procedures are commonly performed throughout the world and require access to a lumen through a puncture. Most often, the lumen is a femoral artery. To close the puncture, many times a closure device is used to sandwich the puncture between an anchor and a sealing plug. However, there exists a possibility for the anchor to not deploy, disabling the function and negating the benefit of the device. The present invention describes methods and apparatus to reduce or eliminate non-deployment or “shuttle” of a closure device anchor. While the vascular instruments shown and described below include embodiments of particular insertion sheaths and puncture sealing devices, the application of principles described herein to reduce anchor shuttle is not limited to the specific devices shown. The principles described herein may be used to reduce anchor shuttle for any vascular closure assembly. Therefore, while the description below is directed primarily to arterial procedures and certain embodiments of a vascular closure assembly, the methods and apparatus are only limited by the appended claims.  
         [0037]     Referring now to the drawings, and in particular to  FIGS. 1A-1B , a vascular puncture closure assembly including a closure device  100  and an insertion sheath  220  is shown according to the prior art. The vascular puncture closure device  100  includes a carrier tube  102  with a filament or suture  104  extending at least partially therethrough. External to the first or distal end  106  of the carrier tube is an anchor  108 . The anchor is an elongated, stiff, low profile member with a protruding dome  109 . The anchor  108  is typically made of a non-hemostatic biologically resorbable polymer.  
         [0038]     The suture  104  is also made of a biologically resorbable material and is threaded through the anchor  108  and back to a collagen sponge  110 . The collagen sponge  110  is slidingly attached to the suture  104  as the suture passes distally through the carrier tube  102 . However, as the suture traverses the anchor  108  and reenters the carrier tube  102 , it is securely slip knotted proximal to the collagen sponge  110  to facilitate cinching of the collagen sponge  110  when the closure device  100  is properly placed and the anchor  108  deployed (see  FIG. 5 ).  
         [0039]     A tamping tube  112  is disposed in the carrier tube  102  proximal to the collagen sponge  110 . The tamping tube  112  is slidingly mounted on the suture  104  and may be used by an operator to tamp the collagen sponge  110  toward the anchor  108  at an appropriate time to plug a percutaneous tissue puncture (See  FIG. 14 ).  
         [0040]     At the distal end  106  of the carrier tube  102  is a nest  114 . Prior to deployment of the anchor  108  within an artery, the protruding dome  109  seats outside the distal end  106  of the carrier tube  102 , and one end  116  of the anchor  108  rests in the nest  114 . The nest  114  is typically crushed to a depth such that a surface  118  of the anchor  108  is flush with the outer diameter of the carrier tube  102 . The nest  114  is crushed to a length that is longer than the end  116  of the anchor  108 . The anchor  108  may be temporarily held in place in the nest  114  by a bypass tube  117  disposed over the distal end  106  of the carrier tube  102 .  
         [0041]     The flush arrangement of the anchor  108  and carrier tube  102  allows the anchor to be inserted into an insertion sheath  220  as shown in  FIG. 2A-2B , and eventually through an arterial puncture  701  (shown in  FIG. 7 ). However, the bypass tube  117  includes an oversized head  119  that prevents the bypass tube  117  from passing through an internal passage  221  of the insertion sheath  220 . Therefore, as the puncture closure device  100  is inserted into the internal passage  221  of the insertion sheath  220 , the oversized head  117  bears against a surface  223  of the insertion sheath  220 . Further insertion of the puncture closure device  100  results in sliding movement between the carrier tube  102  and the bypass tube  116 , releasing the anchor  108  from the bypass tube  116 . However, the anchor  108  remains in the nest  114  following release from the bypass tube  116 , limited in movement by the insertion sheath  220 .  
         [0042]     The insertion sheath  220  comprises a generally flexible tubular member  225  and with a hemostatic valve  227  at a proximal end thereof. The insertion sheath  220  includes a fold  224  disposed at a first or distal end  222  thereof. The fold  224  is shown more clearly in  FIGS. 3-4 . The fold  224  acts as a one-way valve to the anchor  108 . As shown in  FIG. 2A-2B  and  3 , the fold  224  is a plastic deformation in a portion of the insertion sheath  220  that elastically flexes as the anchor  108  is pushed out through the first end  222  of the insertion sheath  220 . However, as the anchor  108  passes though and out of the first end  222  of the insertion sheath  220  as shown in  FIG. 5 , the fold  224  attempts to spring back to its original deformed position and a biased tip  226  of the fold  224  engages the nest  114 . As relative movement between the carrier tube  102  and the insertion sheath  220  continues, the biased tip  226  traverses the contour  128  of the carrier tube nest  114  in a proximal direction.  
         [0043]     Typically, after the anchor  108  passes through the first end  222  of the insertion sheath  220  and enters an artery  730  ( FIG. 7 ), the puncture closure device  100  is pulled in a proximal direction with respect to the insertion sheath  220 . The biased tip  226  of the fold  224  again follows the contour  128  and usually slides distally between the anchor  108  and the nest  114 , causing the anchor to rotate as shown in  FIG. 6 . Accordingly, if all goes well, the anchor  108  is deployed within the artery as shown in  FIG. 7  and does not reenter the insertion sheath  220 .  
         [0044]     However, because the end  116  of the anchor  108  normally bears directly against the nest  114 , sometimes the biased tip  226  of the fold  224  slides over the anchor  108  as shown in  FIG. 8A  when the closure device  100  is pulled proximally with respect to the insertion sheath  220 , instead of sliding between the end  116  and nest  114 . Thus, rather than deploying properly within the artery, the anchor  108  is sometimes reinserted into the insertion sheath  220 , and the puncture closure device  100  fails.  
         [0045]     One reason the anchor  108  sometimes slides back under the fold  224  is the tendency of the typical fold  224  to pucker as the closure device  100  is inserted through the fold  224 . Referring to  FIG. 8B , when the closure device  100  or other instrument passes through the insertion sheath  220 , it is possible for the tip  226  of the conventional fold  224  to pucker and create a gap  830  between the carrier tube  102  and the insertion sheath  220 . The gap  830  is sometimes wide enough to allow reentry of the anchor end  116  ( FIG. 1B ), and the fold thus no longer acts as a one-way valve.  
         [0046]     Therefore, according to some embodiments of the present invention, a tissue closure assembly includes a modified insertion sheath  920  as shown in  FIG. 9 . The modified insertion sheath  920  includes a flexible tubular member  925  (and in some embodiments a hemostatic valve  227  at a proximal end thereof as shown in  FIG. 1A ) and a tip portion  932 . According to principles described herein, the tip portion  932  is rendered stiffer than the tubular member  925 . As shown in  FIG. 9 , the tip portion  932  comprises a concave fold  924  with an edge section  934 . According to the embodiment of  FIG. 9 , the concave fold  924  comprises no more than about half of a circumference of the insertion sheath  920 .  
         [0047]     Stiffness is a characteristic of the resistance of a material or object to deformations. Therefore, the stiffness of the tip portion  932  may be characterized by a stiffness coefficient k. The stiffness coefficient k is commonly used as an experimental value to characterize elastic and viscoelastic materials. The coefficient k is normally expressed by k=∂F/∂x, where F is the applied load and x is the relative displacement. Stiffness is not conservative and depends on geometry as well as the material. Accordingly, the stiffness of the tip portion  932  or a segment of the tip portion  932  may be increased in a number of ways. Some exemplary methods of stiffening the tip portion  932  are described and illustrated below. However, it will be understood by those of skill in the art having the benefit of this disclosure that many other stiffening methods may also be used, and that the methods and apparatus described and illustrated below are not an exhaustive set. The present invention contemplates any stiffening of the tip portion  932  or a sub-part of the tip portion  932  of an insertion sheath with respect to the generally flexible tubular member  925 .  
         [0048]     According to the embodiment of  FIG. 9 , the fold  924  of the tip portion  932  is stiffened by a greater wall thickness T 1  than a wall thickness T 2  of the tubular member  925 . The greater wall thickness T 1  may continue throughout the entire fold  924 , the entire tip portion  932 , or a sub-part of the fold  924 . In addition, the greater wall thickness T 2  may be variable or constant across the tip portion  932 . An increase in the wall thickness T 1  results in a higher stiffness coefficient for the fold  924  (or other segments of the tip portion  932 ) and therefore a reduced tendency to pucker when the closure device  100  is passed therethrough. A reduction in pucker tendency results from stiffening because instead of puckering, a stiffened fold  924  will tend to move as a single rigid unit as the closure device  100  passes therethrough.  
         [0049]     Similarly, in some embodiments only the edge section  932  of the fold  924  is stiffened by the greater wall thickness T 1  as shown in  FIG. 10 . Increasing the wall thickness of just the edge section  932  may sufficiently stiffen the fold  924  to prevent pucker.  
         [0050]     Turning next to  FIGS. 11A-11B , another stiffening mechanism according to the present invention is illustrated. As shown in  FIGS. 11A-11B , the tip portion  932  comprises at least one stiffening ridge  1136 . The stiffening ridge is arranged substantially orthogonal to a longitudinal axis  1142  of the insertion sheath  920 . The stiffening ridge  1136  is shown at the edge  934  of the fold  924  and reduces or eliminates the tendency of the fold  924  to pucker. There may also be additional stiffening ridges to increase the stiffness coefficient of the fold  924 , such as the two additional stiffening ridges  1138 ,  1140  shown. The stiffening ridges  1136 ,  1138 ,  1140  are generally parallel to one another in the embodiment shown, but this is not necessarily so.  
         [0051]     The tip portion  932  of the insertion sheath  920  may also be stiffened by the addition of a second layer of material  1244  as shown in  FIGS. 12A-12B . According to the embodiment of  FIGS. 12A-12B , the second layer  1244  coincides with, and therefore stiffens, the fold  924 . The second layer  1244  may be of the same or a different material than the tubular member  925 . The second layer  1244  may be of uniform or varying thickness. However, according to the embodiment shown, the second layer  1244  is thicker at the fold edge  934  where pucker is a problem than it is at a second end  1246  of the fold  924 . According to some embodiments, the second layer  1244  is only added to the fold edge  934 .  
         [0052]     Referring next to  FIGS. 13A-13B , another stiffening mechanism for the tip portion  932  of the insertion sheath  920  is shown according to the present invention. As shown in  FIGS. 13A-13B , the tip portion  932  includes a corrugated section  1350  in the fold  924 . According to  FIGS. 13A-13B , the corrugated section is disposed transverse to a longitudinal axis  1342  of the insertion sheath  920 , stiffening the fold  924  against pucker when the puncture closure device  100  ( FIG. 1A ) is inserted therethrough.  
         [0053]     The various embodiments of the insertion sheath  920  shown and described above may be made by any of a number of ways. For example, the insertion sheath  920  may be made by providing the flexible tubular member  925 , tapering the end portion  932  of the flexible tubular member for ease of insertion into a percutaneous incision, folding a section of the end portion  932  into a concave depression or fold  924 , and stiffening at least a portion of the fold  924 . The tapering, folding, and stiffening may each be accomplished by inserting the flexible tubular member  925  into one or more heated dies that reform the end portion  932 . Reforming the flexible tubular member  925  to any of the configurations described above, or others, stiffen the end portion  932  and reduce the possibility of anchor shuttle.  
         [0054]     The various modifications to the insertion sheath  920  may be implemented with any tissue puncture closure assembly, such as a tissue puncture closure assembly  1400  shown in  FIG. 14 . The tissue puncture closure assembly  1400  includes the closure device  100  for partial insertion into and sealing of an internal tissue wall puncture  1452 . The closure device  100  is shown inserted through the insertion sheath  920 , which has the stiffened tip portion  932 . The stiffened tip portion  932  may be stiffened according to any of the embodiments described above or others.  
         [0055]     An operator may seal the internal tissue wall puncture  1452  by inserting the tissue puncture closure device  100  through the insertion sheath  920  and into a percutaneous incision  1454 . The anchor  108  is inserted through the puncture  1452  and into a lumen  1456 . The anchor may be deployed in part by pulling the closure device  100  proximally back through the insertion sheath  920 . The tip portion  932  of the flexible tube  925  acts as a one-way valve and forces the anchor  108  to rotate rather than allowing it to reinsert itself into the insertion sheath  920 . Further, because the tip portion  932  is stiffened to reduce the occurrence of pucker, the chance of a reinsertion of the anchor  108  into the insertion sheath  920  is also reduced. The closure device  100  and insertion sheath  920  are then withdrawn from the percutaneous incision  1454  together, exposing the suture  104  and the tamping tube  112 . The tamping tube  112  is then used to tamp the collagen sponge  110  or other sealing plug toward the anchor  108 , such that the anchor  108  and the collagen sponge  110  sandwich and seal the puncture  1452 . The suture  104  is then cut, leaving the anchor  108  and the collagen sponge  110  at the puncture  1452  site.  
         [0056]     The words “including” and “having,” as used in the specification, including the claims, have the same meaning as the word “comprising.” 
         [0057]     While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made without departing from the scope of the invention.