Abstract:
The disclosure pertains to a device for cutting a suture in a fluid environment which isolates a portion of the suture to be cut within a substantially sealed environment and cuts the suture thermally by using an electrically heated element within the chamber. In another embodiment, the disclosure relates to a vascular sealing system including the suture cutting device and a method of use thereof.

Description:
BACKGROUND 
       [0001]    In many medical procedures, such as, for example, balloon angioplasty and the like, an opening can be created in a blood vessel or arteriotomy to allow for the insertion of various medical devices which can be navigated through the blood vessel to the site to be treated. For example, a guidewire may first be inserted through a 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 guidewire is then navigated through the blood vessel to the site of the occlusion or other treatment site. Once the guidewire is in place, an introducer sheath can be inserted over the guide wire to form a wider, more easily accessible, tract between the epidermis and the opening into the blood vessel. The appropriate medical device can then be introduced over the guidewire through the introducer sheath and then up the blood vessel to the site of the occlusion or other treatment site. 
         [0002]    Once the procedure is completed, the medical devices or other equipment introduced into the vessel can be retracted through the blood vessel, out the opening in the blood vessel wall, and out through the tissue tract to be removed from the body. The physician or other medical technician is presented with the challenge of trying to close the opening in the blood vessel and/or the tissue tract formed in the epidermis and subcutaneous tissue. A number of different device structures, assemblies, and methods are known for closing the opening in the blood vessel and/or tissue tract, each having certain advantages and disadvantages. However, there is an ongoing need to provide new and improved device structures, assemblies, and/or methods for closing and/or sealing the opening in the blood vessel and/or tissue tract. 
       SUMMARY 
       [0003]    This disclosure pertains to a device for cutting a suture in a subcutaneous fluid environment which isolates a portion of the suture to be cut within a substantially sealed environment, thereby excluding the surrounding fluid environment, and cuts the suture thermally by using an electrically heated element within the chamber. In a first embodiment, this disclosure pertains to a thermal suture cutting device for use with vascular sealing devices comprising a chamber having a first compression bead defining an first opening for the suture, the opening sized to slidingly receive a suture to be cut; a second compression bead defining an second opening sized and adapted to slidingly and sealingly receive the suture to be cut, an electrically activated heating element within the chamber, said electrically activated heating element being capable of generating a temperature within the chamber greater than the melting temperature of the suture to be cut; and electrical leads at least partially within the chamber capable of supplying sufficient current to the electrically activated heating element to allow the electrically activated heating element to generate a temperature within the chamber greater than the melting temperature of the suture to be cut; a push rod having a proximal end and a distal end, said distal end being attached to the first compression bead component, and one or more lumens extending at least partially between said proximal and distal end; and a source of electrical current sufficient to allow the electrically activated heating element to generate the temperature within the chamber greater than the melting temperature of the suture to be cut. The source of electrical current is connected to the electrical leads and includes a switch capable of controlling the flow of electrical current. The electrical current source is associated with a handle at the proximal end of the push rod. The first compression bead and second compression bead cooperate with the suture to be cut to form a substantially fluid tight chamber within which the suture may be cut, said chamber being capable of excluding a surrounding fluid environment. 
         [0004]    In another embodiment, this disclosure relates to a system for sealing a vascular puncture comprising an anchor deployable adjacent to a vascular puncture; a suture attached to the anchor deployable adjacent to the vascular puncture; a hemostatic material deployed about the suture; and the thermal suture cutting device described herein. 
         [0005]    In yet another embodiment, this disclosure relates to a method of cutting a suture in a fluid environment, such as blood or other body fluid, comprising passing a suture through the thermal suture cutting device described above; positioning the suture and the thermal suture cutting device in the fluid environment; and passing a current through the electrically activated heating element of the device sufficient to allow the electrically activated heating element to generate a temperature within the chamber greater than the melting temperature of the suture to be cut. 
         [0006]    In these embodiments, the thermal suture cutting device isolates a portion of the suture to be cut from a surrounding fluid environment and thermally cuts the suture with a minimal consumption of energy. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  illustrates components of an exemplary thermal suture cutting device. 
           [0008]      FIG. 2A  illustrates an embodiment of a portion of an exemplary thermal suture cutting device. 
           [0009]      FIG. 2B  illustrates an embodiment of a portion of another exemplary thermal suture cutting device. 
           [0010]      FIGS. 3A-3C  illustrate configurations of an electrically activated heating element. 
           [0011]      FIG. 4  illustrates elements of a system for sealing a vascular puncture. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The drawings, which are not necessarily to scale, are not intended to limit the scope of the claimed invention. The detailed description and drawings illustrate example embodiments of the claimed invention. 
         [0013]    All numbers are herein assumed to be modified by the term “about.” The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). 
         [0014]    As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include the plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
         [0015]    It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it would be within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described unless cleared stated to the contrary. 
         [0016]      FIG. 1 , illustrates a thermal suture cutting device comprising a first compression bead component  12 , a second compression bead component  14 , an electrically activated heating element  24 ; and a push rod  30 . Compression bead components  12 ,  14  form the distal end of suture cutting device and may be used to position and compress a plug of hemostatic material (not shown) adjacent to a vessel puncture. The first compression bead component  12  defines an opening  16  sized and adapted to sliding receive a suture  50  as well as passages for wires  20  and their insulation  22 . The first compression bead component  12  may be fixedly attached to a push rod  30  which also includes at least one lumen (not shown) for the suture  50 , and optionally additional lumens for wires  20 , and insulation  22 . In some embodiments, the push rod  30  and the first compression bead component  12  may be fabricated from a single piece. In other embodiments, the push rod  30  may be attached to the first compression bead component  12  by a coupling (not shown) which allows a minor amount of deflection therebetween. In yet other embodiments, insulation  22  may be omitted if the push rod  30  is formed from an insulating material. In some such embodiments, the wires  20  may be embedded directly in the material of the push rod  30 . 
         [0017]    Second compression bead component  14  also defines an opening  18  sized and adapted to sliding receive the suture  50 . In some embodiments, opening  18  can also be sized and adapted to sealingly receive suture  50 . The sealing capability, if present, associated with opening  18  may be provided by sizing the opening  18  to lightly compress the suture  50  or may be provided by an elastomeric seal (not shown). In some embodiments the sealing capability may be provided by contact with a cinch button (not shown) associated with the suture  50 . In other embodiments the sealing capability may be provided by a pressure differential between the interior of the device and a fluid of a fluid environment surrounding the first and second compression bead components  12 ,  14 . In yet other embodiments the sealing capability may result from a selection of material for one or both of the second compression bead components  12 ,  14  and the suture such that surface tension of the fluid of the fluid environment substantially prevents the fluid of the fluid environment from entering the opening  18 . Other sealing means may also be used. 
         [0018]    As illustrated in  FIGS. 2A and 2B , first compression bead component  12  and the second compression bead component  14 , in cooperation with suture  50  and any associated sealing elements (not shown), serve to define a chamber  60  within the space between the first and second compression bead components  12 ,  14 , which remains substantially free of the fluid of the external fluid environment at least until the suture  50  has been cut by the electrically activated heating element  24 . 
         [0019]    Electrically activated heating element  24  can be positioned within chamber  60  and proximate suture  50 . Electrically activated heating element  24 , capable of generating a temperature within the chamber  60  greater than the melting temperature of the suture  50  to be cut, is connected to electrical leads, or wires  20 , which are connected to a source of electrical current sufficient to allow the electrically activated heating element to generate the temperature within the chamber  60  of greater than the melting temperature of the suture to be cut. The source of electrical current may include a switch  222  ( FIG. 4 ) which is capable of connecting and/or disconnecting the source to the wires  20  and thence to the electrically activated heating element  24  such that when the switch is closed, a current flows through the electrically activated heating element  24 , heating at least a portion of the interior of the chamber  60  to a temperature greater than the melting temperature of the suture  50  to be cut, whereupon the suture  50  melts. In some embodiments melting of the suture  50  not only cuts the suture  50 , but may also result in the formation of a generally ball-shaped tip on the proximal end of the distal portion of the cut suture  50  which may serve as a mechanical stop to prevent the cinch button  120  ( FIG. 4 ), to be discussed further herein, from being displaced when an associated hemostatic plug  100  ( FIG. 4 ) expands. In those embodiments in which a ball-shaped tip is to be formed on the proximal end of the distal portion of the cut suture  50 , it may be desirable to employ a somewhat larger opening  18  to allow the ball-shaped tip to pass through. 
         [0020]    It will be understood that the terms “cut” and “cutting” as used in this disclosure broadly include related terms such as “melting”, “breaking”, “brittle fracture”, and the like which indicate that the suture  50  is severed thereby. Similarly, the term “suture” should be broadly interpreted to include thread, string, monofilament materials, twisted multifilament materials, braided materials, and the like. 
         [0021]    The first and second compression bead components  12 ,  14  may assume a number of geometries in addition to the non-limiting examples provided. For example, the second compression bead component  14  may take the form of an open cup, as illustrated in  FIG. 2A , which mates with and partially surrounds first compression bead component  12  and the electrically activated heating element  24 . The first and second compression bead components  12 ,  14  may form a frictional interference fit, may be bonded together by conventional means, or may be joined by additional joining and/or sealing members (not shown). 
         [0022]    In the embodiment illustrated in  FIG. 2B , the arrangement of  FIG. 2A  is generally inverted such that the first compression bead component  12  is a distally facing cup which receives a second compression bead component  14 . As in  FIG. 2A , first and second compression bead components  12 ,  14  may form a frictional interference fit, may be bonded together by conventional means, or may be joined by additional joining and/or sealing members (not shown). In some such embodiments the second compression bead may be formed of a biodegradable material and may provide the function of and/or replace cinch button  120 . 
         [0023]    The first and second compression bead components  12 ,  14  may desirably be formed from a material or materials which are not adversely affected by exposure to temperatures produced within chamber  60  by the electrically activated heating element  24 . For example, first and second compression bead components  12 ,  14  may be formed from biocompatible metals and/or ceramics. The materials may be cast or machined to their final shapes. In those embodiments in which the second compression bead component  14  also serves as a cinch button  120  which remains after the suture is cut, it may be desirable for the fabrication material to be bioerodible or biodegradable as mentioned above. 
         [0024]    Push rod  30  may be formed integrally with the first compression bead component  12  or may be formed separately and joined to the first compression bead component  12  in a later step. The attachment of the push rod  30  to the first compression bead component  12  may be permanent or temporary. Temporary attachment may be desirable in embodiments in which the push rod  30  and an associated handle  200  ( FIG. 4 ), to be discussed herein, are to be reused. Push rod  30  may be rigid or it may be flexible to allow the thermal suture cutting device to better align with other devices with which it may be used. Push rod  30  may be made from the same material as the first compression bead component  12  or it may be made from a different material. For example, the first compression bead component  12  may be made from a metal or ceramic to better resist damage from the heat produced within chamber  60 , while the push rod  30  may be made from a polymer for lighter weight and/or to impart somewhat greater flexibility. 
         [0025]    Push rod  30  may have one or more partial or complete lumens  32 . The lumens  32  may accommodate the suture  50 , electrical leads, wires  22 , and optionally other devices. Any of the lumens  32  may extend the entire length of the push rod  30  or may terminate along the shaft of the push rod  30 . For example, lumen  32  may terminate near the proximal end of push rod  30  to allow tension to be applied to the suture  50  prior to cutting and to allow the proximal portion of suture  50  to be removed following cutting to confirm that the cut has been successful with a well formed end. Alternatively, lumen  32  may terminate near first compression bead component  12  to allow the suture  50  to lie alongside the exterior of push rod  30  which may allow for the use of a smaller and/or more flexible push rod  30 . 
         [0026]    Similarly, electrical leads or wires  20  may be routed either within optional lumens  32 , with suture  50  in a single lumen  32 , or externally along push rod  30 . Electrical leads or wires  20  may optionally be covered by insulation  22  and/or may be embedded in and/or insulated by the material of push rod  30 . 
         [0027]    One or more electrically activated heating element(s)  24  can be located within chamber  60  and proximate suture  50 . Within the chamber  60 , one or more electrically activated heating element(s)  24  can be isolated from the thermal mass of components of the fluid environment outside of the thermal suture cutting device which isolation tends to minimize the energy which would otherwise be required to cut the suture  50 . In addition, isolation of the electrically activated heating element  24  from the fluid of the fluid environment outside of chamber  60  reduces the need for protective coatings or insulation on the electrically activated heating element  24  itself which further reduces the energy which would otherwise be required to cut the suture  50 . 
         [0028]    Electrically activated heating element  24  may be fabricated from any of the high resistance materials commonly employed in electrically activated heating elements such as platinum, nichrome, nitinol, tungsten, thick film resistor or thermistor pastes, and the like. The electrically activated heating element(s)  24  may partially or completely surround the suture  50  to be cut although contact is not necessary and may not be desirable. An electrically activated heating element  24  may take any of a number of shapes such as those of the non-limiting examples of  FIGS. 3A ,  3 B, and  3 C. It will be appreciated that additional mechanical features within chamber  60  may position or stress the suture to facilitate cutting by one or more electrically activated heating elements  24 . In some embodiments, such as that of  FIG. 3B , the electrically activated heating element  24  may include mechanical positioning features such as arm  26 . Other electrically activated heating elements  24  may take the form of coils, such as illustrated in  FIG. 3C , sleeves, parallel bars, and the like.  FIG. 3C  also illustrates an alternate form of mounting the electrically activated heating element  24  in which bent portions of the heating element  24  engage recesses in the first compression bead component  12 . In some embodiments, thermomechanical components of the electrically activated heating element  24  may further serve to cut, melt, or otherwise disrupt the suture  50 . 
         [0029]    The devices of the present disclosure can have associated therewith a source (not shown) of electrical current capable of supplying sufficient current to the electrically activated heating element  24  to generate a temperature within chamber  60  greater than the melting temperature of the suture  50  to be cut. In alternate embodiments in which the thermally mediated cutting of suture  50  is supplemented by other means, a lesser temperature may suffice. For example, it may suffice to soften the suture  50  when the softened suture  50  is in contact with a displacing sharp edge. 
         [0030]    The source  220  of electrical current may include a battery, as illustrated in  FIG. 4 , or an external power supply. In some case, the source  220  may include circuitry to enhance the current which the device is capable of delivering in a short period of time. In addition, the source  220  of electrical current may include a switch  222  or other means of directly or indirectly controlling the flow of current. In some embodiments, a momentary contact switch  222  will allow manual activation of the electrically activated heating element  24 . In other embodiments, the momentary contact switch  222  may activate circuitry which allows current to flow for a specified length of time. In yet other embodiments, switch  222  may be activated by axial pressure applied to one or both of push rod  30  and first compression bead component  12  to ensure that the thermal suture cutting device is properly engaged with a proximal surface of a device to be secured by suture  50 . 
         [0031]    In some embodiments, the source  220  of current and/or switch  222  or other means of directly or indirectly controlling the flow of current may be housed in a handle  200  for convenient manipulation of the thermal suture cutting device. The handle  200  may be connected directly or indirectly to push rod  30 .  FIG. 4  illustrates an exemplary system for sealing a vascular puncture which includes handle  200  as well as additional elements of a conventional hemostatic plug  100  and anchor  110  system which may be secured in place by a suture  50 . In  FIG. 4 , elements  100 ,  110 , and  120  are depicted as spread somewhat apart as they might be disposed prior to being urged toward each under the influence of thermal suture cutting device prior to cutting suture  50  proximal of cinch button  120 . 
         [0032]    Anchor  110  may be positioned in a vessel having a puncture to be sealed such that the suture  50  extends through a plug of hemostatic material  100  and a cinch button  120  or other means of securing the combination of anchor  110  and hemostatic material  100  in their respective positions relative to the vessel wall. In prior art systems, the anchor  110  and hemostatic material  100  have been secured by tying a knot in the suture  50  proximal of the hemostatic material  100  with or without an element analogous to cinch button  120 . In systems including a cinch button  120 , the knot may be positioned proximal of cinch button  120 ) which serves to distribute forces generated as the hemostatic material  100  swells in response to contact with blood or other body fluids escaping from the vessel. 
         [0033]    The location of a knot or other securing means within a narrow tissue tract which may be filled with fluid tends to make tying and positioning the knot, as well as cutting the suture  50  adjacent to the knot or cinch button  120  difficult. Further, slippage of the knot or tearing of the hemostatic material  100  may lead to undesirable failure of the vascular sealing system. 
         [0034]    In use, the system may be advanced within a sheath or simply advanced within a tissue tract adjacent to the punctured vessel. Anchor  110  may be positioned within the vessel and tension applied to the suture  50  to seat the anchor  110  against the vessel wall. In some embodiments, anchor  110  may instead be present in another form such as a hook or hooks or even a simple stitch formed by the suture  50 . Hemostatic material, often in the form of a gelatin sponge or pledget, may then be advanced along the suture  50  to a position adjacent to the puncture in the vessel wall. Various means (not shown) may be used to ensure that the hemostatic material  100  is properly positioned relative to anchor  110  and/or the vessel wall. A cinch button  120  may be advanced along the suture  50  and positioned adjacent to hemostatic material  100  where it serves to distribute compressive forces applied by the thermal suture cutting device and/or by the hemostatic material  100  as it expands upon contact with blood or other body fluid. In some embodiments, second compression bead component  14  may provide the function of a cinch button. In such embodiments, the second compression bead component  14  may be formed of a biodegradable or bioerodible material. 
         [0035]    In either event, the thermal suture cutting device is advanced along the suture  50  to position and/or slightly compress hemostatic material  100 . This may be accomplished by advancing push rod  30  and/or handle  200 . It may be desirable to maintain tension on the suture  50  throughout the positioning and cutting processes. This may be accomplished manually by grasping the suture  50  after it exits thermal suture cutting device or additional apparatus (not shown) may apply tension to the suture  50 . 
         [0036]    When it has been determined that the hemostatic material  100  and the thermal suture cutting device are properly positioned, current may be passed through the electrically activated heating element  24  thereby heating a portion of suture  50  within chamber  60  as described above and cutting suture  50 . In some embodiments, cutting the suture may form a ball-shaped tip on the proximal end of the distal portion of the cut suture  50  which may serve as a mechanical stop to prevent the cinch button  120 , or second compression bead component  14 , from being displaced. The formation of a ball-shaped tip on the suture  50  may greatly increase the force required to displace the cinch button  120  from the suture. Following cutting of suture  50 , the thermal suture cutting device and the proximal portion of suture  50  may be removed. 
         [0037]    Although the illustrative examples described above relate to cutting a suture which is a component of a vascular sealing system is also contemplated that devices of this disclosure will be useful in cutting sutures, ribbons, or other similar materials submerged in other fluid environments. 
         [0038]    Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and principles of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth hereinabove. All publications and patents are herein incorporated by reference to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference.