Abstract:
A device for introducing an embolic coil into a catheter comprises an elongated body defining a longitudinal passage extending therethrough from a first opening at a proximal end thereof to a second opening at a distal end thereof, the elongated body being including a mating portion for conforming to a size and shape of an opening in a hub of a catheter to mate therewith and an embolic coil introducer sheath including a coil receiving lumen extending therethrough, a distal tip of the introducer sheath being dimensioned to be received within a proximal end of the longitudinal passage. Similarly, a method of implanting an embolic coil, comprises inserting a stabilizer into a catheter hub so that a flexible mating portion substantially conforms to a shape of an inner surface of the hub wherein the stabilizer includes a passage extending therethrough from a proximal opening to a distal opening thereof. An introducer sheath including an embolic coil received in a lumen thereof is inserted into the proximal opening of the passage and through the passage to exit the distal opening thereof so that a distal opening of the lumen is positioned substantially adjacent to a proximal opening of a catheter and an embolic coil is advanced out of the distal opening of the lumen into the catheter and deployed in the body through the catheter.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Embolic coils have been used to stop undesired blood flow, as in, for example, the treatment of aneurysms, arteriovenous malformations, traumatic fistulae and in tumor embolization. These conditions require that the blood flow through a portion of a blood vessel be stopped, for example by introducing an artificial device into the vessel to slow the flow, and by letting the natural clotting process form a more complete blockage of the blood vessel with a clot. 
         [0002]    Embolic coils can be used to form a blockage in a vein or artery to treat conditions like those listed above. These devices have become increasingly common in procedures to block the flow of blood by promoting formation of a clot in a desired location. Embolic coils are made from a bio-compatible material, such as platinum, to minimize the problems associated with tissue irritation and rejection. These coils are often shaped as complex three dimensional curves that fill in portions of the blood vessels and slow blood flow therein. Often, polymeric fibers are added to the metallic coils to enhance the coil&#39;s thrombogenicity, which is the coil&#39;s ability to promote formation of clots. 
         [0003]    Embolic coils are typically introduced into a blood vessel by using a microcatheter which extends from a proximal point outside the patient&#39;s body to a distal point near the embolization site. An introducer sheath containing the coil is used to carry and protect the coil prior to insertion into the patient, and also to transfer the coil to the microcatheter. From the introducer sheath the coil is pushed into the microcatheter and navigated to the embolization site, where it is deployed from the microcatheter. It is often beneficial to pre-hydrate the coil before insertion into the microcatheter to lubricate the coil, so that it travels more easily to the embolization site. In addition, the fluid used to lubricate the coil may be medicated to increase the thrombogenic properties of the coil, reduce infections, or to address other needs. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect, the present invention is directed to a device for introducing an embolic coil into a catheter comprising an elongated body defining a longitudinal passage extending therethrough from a first opening at a proximal end thereof to a second opening at a distal end thereof, the elongated body being including a mating portion for conforming to a size and shape of an opening in a hub of a catheter to mate therewith in combination with an embolic coil introducer sheath including a coil receiving lumen extending therethrough, a distal tip of the introducer sheath being dimensioned to be received within a proximal end of the longitudinal passage. 
         [0005]    The present invention is further directed to a method of implanting an embolic coil, comprising inserting a stabilizer into a catheter hub so that a flexible mating portion substantially conforms to a shape of an inner surface of the hub, the stabilizer including a passage extending therethrough from a proximal opening to a distal opening thereof and inserting an introducer sheath including an embolic coil received in a lumen thereof into the proximal opening of the passage and through the passage to exit the distal opening thereof so that a distal opening of the lumen is positioned substantially adjacent to a proximal opening of a catheter. The embolic coil is advanced out of the distal opening of the introducer sheath lumen into the catheter and deployed in the body via the catheter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a schematic side elevation view showing an introducer sheath stabilizer, according to the present invention, disposed in a microcatheter hub; 
           [0007]      FIG. 2  is an exploded side elevation view of an introducer sheath stabilizer, according to the present invention; 
           [0008]      FIG. 3  is a perspective view of the introducer sheath stabilizer of  FIG. 2 ; 
           [0009]      FIG. 4  is a schematic side elevation view of an introducer sheath stabilizer used in a coil pre-hydration function; 
           [0010]      FIG. 5  is a schematic side elevation view of an introducer sheath stabilizer used in a coil introduction function; 
           [0011]      FIG. 6  is an exploded view showing another embodiment of an introducer sheath stabilizer, according to the present invention, incorporated into an assembly having aspects of a rotating hemostasis valve (RHV); and 
           [0012]      FIG. 7  is an assembled view of the introducer sheath stabilizer of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The present invention is related to medical devices used to introduce an embolic coil into the vascular system of a patient. More specifically, the invention is related to devices used to introduce an embolic coil using a catheter, and to hydrate the embolic coil prior to deployment. 
         [0014]    Embolic coils have been widely used to treat medical conditions requiring the disruption of the blood flow to specific regions of the body. For example, the treatment of aneurysm, arterial or venous malformations, traumatic fistulae and tumor embolization requires that the supply of blood to the affected areas be interrupted. Aneurysms occur when a portion of an artery&#39;s wall becomes weakened and expands in a balloon-like manner. As more blood flows in, the aneurysm continues to expand and the wall of that portion becomes stretched and thins. If the wall at the aneurysm expands too much, it may burst and cause a hemorrhage. This is a very dangerous condition which may lead to death, coma, paralysis, or other serious medical condition when it occurs in the brain or another vital organ. 
         [0015]    Traditionally, this condition has been very difficult to diagnose, since patients are generally asymptomatic until the aneurysm bursts. At that point, most of the damage has already taken place, and the available medical therapies are limited. Even where the aneurysm is identified prior to bursting, medical options have been limited because aneurysms are often in locations that are difficult to reach by surgery and repairing the damaged blood vessel may be impossible. Recent advances in visualization methods, however, have made the early identification of aneurysms and similar problems more common. Once an aneurysm has been located, it may be possible to block the supply of blood thereto via an embolic coil, even if surgery to repair the blood vessel is not practical. 
         [0016]    Embolic coils may also be used successfully in the treatment of various types of cancer. As tumors often require a large supply of blood to grow, it may be possible to impede further growth by restricting or eliminating this blood supply. Embolic coils may be deployed to shut down blood vessels alimenting the tumor to kill or limit the growth of the malignancy. Deployment of the coil may be aided by various visualization methods, to ensure correct positioning and to evaluate the efficacy of the treatment. The treatment of traumatic bleeding may also benefit from the use of embolic coils. As would be understood by those skilled in the art, damage to blood vessels causing significant blood loss may result in death or a critical condition. This may be especially serious when the injury is internal and the bleeding cannot be controlled without resorting to complex surgical procedures. Embolic coils may be employed to reduce or stop the hemorrhage by blocking the veins or arteries leading to the damaged area(s). 
         [0017]    The deployment of embolic coils into a patient&#39;s vascular system is typically carried out using a catheter. The distal end of the catheter is inserted into a blood vessel and is navigated to the site where the coil is to be deployed with any of various methods of visualization being employed to confirm that a distal end of the catheter is positioned at the proper location. The catheter may be a microcatheter, having a catheter hub at the proximal end which remains outside of the body during the procedure. The embolic coil may be held in an introducer sheath for manipulation prior to insertion, and to insert the coil into the microcatheter after the coil has been prepared. 
         [0018]    Introducer sheaths can be difficult to insert into the catheter hub at the microcatheter&#39;s proximal end. The microcatheter hub is a device adapted to receive attachments to the proximal end of the catheter. If the introducer sheath tip is not fully pressed into the catheter hub during coil delivery, or if there is a space between the sheath tip and the lumen of the microcatheter, the coil may be deployed in the hub causing premature detachment or jamming. For example, interlocking detachable coils feature a coil connected to a drive mechanism, from which it detaches when it is ejected from the catheter. If the introducer sheath is not seated fully in the catheter hub, the arms of the drive mechanism can detach prematurely and cause jamming in the hub. It is thus important to ensure that the coil is passed directly into the catheter lumen from the introducer sheath. 
         [0019]    As described above, prior to insertion in the catheter, it is often necessary to pre-hydrate the coil. This preparatory step consists of irrigating the coil with a saline solution which may contain one or more medical compounds. For example, the coil may be irrigated with a heparin solution to prevent premature coil thrombosis prior to desired final deployment of the coil. Other fluids may also be used to hydrate the embolic coil. For example, compounds adapted to lubricate the coil as it travels through the microcatheter may be used, as well as disinfecting compounds, if needed. 
         [0020]    Conventionally, pre-hydration of the embolic coil is carried out before insertion in the catheter, while the coil is still held in the introducer sheath which can be difficult. However, if the embolic coil is removed from the introducer sheath for pre-hydration, the coil may kink or be deformed when replaced in the introducer sheath. In particular, coils that comprise fibers extending from the coil loops may benefit from being pre-hydrated without removal from the introducer sheath. The fibers are designed to further reduce the flow of blood around the coil, and have a predetermined orientation. Deploying and then re-sheathing these fibered coils for pre-hydration may reverse the direction and change the orientation of the fiber bundles, reducing their effectiveness. 
         [0021]    According to embodiments of the present invention, an introducer sheath stabilizer may be used for both facilitating pre-hydration of an embolic coil and to simplify transfer of the coil from the introducer sheath to a microcatheter. During both steps, the embolic coil is protected from damage. The procedure may be carried out by a single physician, without the need for involvement of assistants.  FIG. 1  shows an exemplary embodiment of an introducer sheath stabilizer according to the invention. In the drawing, a sheath stabilizer  100  is shown in an operative position within a hub  202  of a microcatheter  200 . A distal end  102  of the stabilizer  100  is inserted into the hub  202  of the microcatheter  200 , such that it abuts the proximal end of a catheter lumen  204 . 
         [0022]    During use, an introducer sheath  216  containing an embolic coil  214  is inserted into the proximal end  104  of the stabilizer  100 , and is pushed through the stabilizer  100  until it exits out of the distal end  102  of the stabilizer  100 , as clearly shown in  FIGS. 4 and 5 . The introducer sheath  216  is then further pushed until it contacts the proximal end of the lumen  204 . In this manner the stabilizer  100  helps to maintain the introducer sheath  216  in place preventing premature coil detachment and jamming of the coil  214  in the catheter hub  202 . In the exemplary embodiment, the stabilizer  100  comprises slits  106  formed longitudinally on the walls thereof. The slits  106  facilitate the insertion of the introducer sheath  216  into the stabilizer  100 , prior to attachment to the catheter hub  202 , and also provide a better connection with the catheter hub  202 . In this example, the stabilizer  100  mechanically and frictionally cooperates with the hub  202  to properly position the introducer sheath  216 . 
         [0023]    As will be described below in more detail, the sheath introducer the stabilizer  100  may also be used to facilitate pre-irrigation of the embolic coil  214  prior to deployment. In this function, the stabilizer  100  is used to couple a syringe or other source of irrigating fluid to the introducer sheath  216  containing the embolic coil  214 . The stabilizer  100  thus serves a dual function, facilitating the pre-irrigation of the coil and the insertion of the coil  214  into the microcatheter  200 . The physician performing the embolization procedure thus can carry out two tasks using only one device which can be provided, for example, together with the introducer sheath  216  as part of the packaging for the embolic coil  214 . 
         [0024]      FIGS. 2 and 3  show an exemplary embodiment of the stabilizer  100  according to the invention. In this embodiment, the stabilizer  100  comprises two portions joined to one another. A rigid female luer adapter  112  forms the proximal end  104  of the stabilizer  100  and is designed to provide a means of connecting the stabilizer  100  to another device provided with a luer. A flexible conical section  110  defines the distal portion  102  and completes the stabilizer  100 . The flexible conical section  110  is designed to provide a snug fit with the proximal end of the microcatheter, such as by acting as an adapter fitting into the catheter hub  202 . However, the stabilizer  100  may also be used to facilitate pre-hydration of the embolic coil  214  while still in the introducer sheath  216 . In that function, the distal end  102  of the flexible conical section  110  becomes a receptacle for the distal tip of the introducer sheath  216 . A syringe may then be connected to the luer adapter  112  to provide the irrigation. 
         [0025]    As would be understood by those skilled in the art, the rigid female luer adapter  112  may be formed of any suitable material compatible with conventional luers (for example, polycarbonate, ABS plastic, Tecoplast). As would be understood, the material selected should be sufficiently resilient to maintain the dimensions of the luer adapter  112  during use of the stabilizer  100 . A lumen  118  extends longitudinally through the luer adapter  112 , and joins a lumen  118 ′ which extends through the flexible conical section  110  to form a continuous passage through the stabilizer  100 . The lumens  118 ,  118 ′ have dimensions adapted to receive the introducer sheath  216  therethrough. The flexible conical section  110  may be formed from polyurethane, santoprene, silicone, natural latex, other thermoplastic elastomers or any material having a suitable flexibility. 
         [0026]    In one embodiment, slits or openings  106  may be formed on shell-like walls of the conical section  110 , to provide additional flexibility. The flexibility of the conical section  110  enables the stabilizer  100  to fit securely in a variety of catheter hubs having different dimensions, to provide a secure and stable interface between the catheter hub and the introducer sheath  216 . In particular, the slitted portion of the flexible conical section  110  allows it to expand and/or contract to fit catheter hubs of different diameters. According to exemplary embodiments of the invention, the flexible conical section  110  forms a catheter hub adapter having outer surfaces which substantially match an inner passage of the hub, and which form a frictional and mechanical connection to the hub. As can be seen in the figures, a radius of the conical section  110  is a minimum at the distal end  102  and a maximum at the proximal end  104 , so that conical section  110  can be inserted into the hub until the connection is made. 
         [0027]    The exemplary flexible conical section  110  comprises a distal opening  114  with a sealing device, which may be a valve  120 . The valve  120  may be of a single slit design, as shown, or may be a dual slit or multi slit design. The valve  120  is designed to accept the coil introducer sheath  216  for pre-hydration of the embolic coil  214  contained therein. In this mode, the tip of the introducer sheath  216  is inserted from the outside into the conical section  110  through the valve  120  which forms a seal around the introducer sheath  216 . Conversely, when the stabilizer  100  is used to facilitate the introduction of the embolic coil  214  into the catheter  200 , the distal tip  206  of the introducer sheath  216  is inserted through a proximal opening  116  of the stabilizer  100  and pushed out of the stabilizer  100  through the valve  120 . The valve  120  thus permits passage of the introducer sheath  216  in both directions, while providing a sealing action around exterior surfaces of the introducer sheath  216 . 
         [0028]    The coil pre-hydration function of the stabilizer  100  is described in greater detail with reference to  FIG. 4 . As shown, an embolic coil  214  is contained within a tubular passage  218  extending through the sheath  216  from a proximal coil receiving opening to a distal coil deploying opening formed in a distal end  206  thereof. In this configuration, the embolic coil  214  is ready for deployment. However, if it is desired to pre-hydrate the coil  214 , this may be done without removing the coil  214  from the passage  218 . According to the invention, the distal tip  206  of the introducer sheath  216  is inserted into the stabilizer  100  via the opening  114  of the distal end  102  so that the distal tip  206  is received within the stabilizer  100  with the distal opening facing the proximal opening  116  in the luer adapter  112 . The valve  120  provides a seal around the outer surface of the introducer sheath  216 , such that a fluid may flow within the lumen  118  to the passage  218  without leaking from the stabilizer  100 . A syringe  210  or other similar source of hydrating fluid is connected to the luer adapter  112  using a conventional luer attachment, such that the nozzle  212  enters the proximal opening  116  of the stabilizer  100 . Fluid such as, for example, a heparinized solution, is then injected into the lumen  118  of the stabilizer  100  from the syringe  210  into the passage  218  of the introducer sheath  216 , to reach the coil  214 . 
         [0029]    After pre-hydration, the stabilizer  100  may be used to assist in introducing the coil  214  into a microcatheter  200  via the coil deploying opening in the distal end  206 . To use the stabilizer  100  in this way, the syringe  210  is disconnected from the stabilizer  100  and the sheath  216  is removed from the stabilizer  100  and reinserted into the stabilizer  100  via the opening  116  at the proximal end thereof. The sheath  216  is extended through the valve  120  so that the distal tip  206  protrudes from the distal end of the stabilizer  100 . 
         [0030]    The coil introduction function of introducer sheath stabilizer  100  is described in more detail with reference to  FIG. 5 . In this configuration, the smaller diameter distal end of the cone-shaped stabilizer  100  is inserted into the catheter hub  302  of a catheter  300 . The flexible conical section  110  is formed of a pliable material to mate with a tapered inner surface  303  of the catheter hub  302  to form a stable, temporary frictional and mechanical connection with the catheter  300 . The introducer sheath  216  is then inserted into the stabilizer  100  through the proximal opening  116  and is pushed through the passage  118  until its distal end  206  emerges from the distal opening  114  through the valve  120 . The introducer sheath  216  is further pushed longitudinally until the coil deploying opening of the distal tip  206  seats in the tapered inner surface  303  substantially adjacent to a proximal opening of the catheter lumen  304 . Thus, the coil  214  may be transferred directly from the passage  218  to the lumen  304  without unwanted movement of the tip  206  relative to seating surfaces of the catheter hub  302 . This reduces the chances of premature detachment, damage or entrapment of the coil  214  in the microcatheter hub  302 . 
         [0031]    The exemplary multi functional introducer sheath stabilizer according to embodiments of the present invention allows for embolic coil pre-hydration without removal from the sheath as well as greater ease of coil insertion in a delivery catheter, by using a single device. The exemplary device may be used for multiple types of coils, including pushable coils and fibered coils for which pre-deployment and re-sheathing risk reversing or altering the fiber&#39;s orientation. The inclusion of a luer adapter allows for in line attachment of a rotating hemostatic valve (RHV) for continuous or intermittent heparinized saline flush of the microcatheter lumen. 
         [0032]    In a different exemplary embodiment, the introducer sheath stabilizer may be incorporated into an RHV.  FIGS. 6 and 7  show a stabilizer  400  adapted to fit in an RHV placed on the proximal end of a microcatheter  300 . In this configuration, a distal male luer  406  is adapted to lock to the proximal end of a catheter hub  302  of the microcatheter  300 . The distal male luer  402  doubles as a valve housing and serves as the bottom valve housing for a valve  402 . The valve  402  may be a conventional valve used in conjunction with catheters. The stabilizer  400  fits through a passage  408  which extends through the valve  402  and through the male valve housing  406  and further extends beyond the RHV to protrude into the microcatheter hub  302 . The distal end  410  of the stabilizer  400  protrudes sufficiently to engage the tapered portion  301  of the hub  302  and thus seal against any reflux of blood or other fluids from the microcatheter  300 . A threaded closure may be used to join the male valve housing  406  to a female luer adapter  404 , which allows mating to an external device for flushing the microcatheter  300  prior to introducing the coil  214  thereinto. 
         [0033]    The assembly of the male valve housing  406  and the female luer adapter  404  forms a structure which contains the valve  402  and defines a passage  408  containing the stabilizer  400 . The assembly may be designed so that the valve  402  can be closed by the user, for example by tightening the threads of the assembly. Placing the stabilizer  400  within the RHV provides several advantages. Seating the stabilizer  400  in the microcatheter hub  302  helps prevent the occurrence of retrograde blood flow up the sheath  216  reducing the possibility of thrombus build up in the interface between the two parts and reducing friction in the sheath  216 . As in the embodiments described above, the stabilizer  400  maintains the introducer sheath  216  (not shown in  FIG. 6 ) centered within the microcatheter hub  302 , resulting in a smoother introduction of the embolic coil  214  into the microcatheter  300 . The valve  402  prevents kickback of the sheath  216  and together with the stabilizer  400  reduces coil jamming and premature detachment. 
         [0034]    As described above, the distal portion of the sheath  216  may be formed of a compressible material adapted to conform to the inner surfaces of a variety of microcatheter hubs. This universal compatibility of the stabilizer  400  with different catheters and hubs may be enhanced by slots  412  formed in the conical portion of the stabilizer  400 . The slots  412  help the proximal portion of the stabilizer  400  to widen or narrow to fit different size passages, so that the stabilizer  400  provides a properly sized passage to an introducer sheath  216  containing a coil  214  regardless of the size of the catheter or hub. 
         [0035]    The present invention has been described with reference to specific embodiments, and more specifically to a stabilizer used to facilitate introduction of an embolic coil into a microcatheter hub. However, other embodiments may be devised that are applicable to other procedures and devices, without departing from the scope of the invention. Accordingly, various modifications and changes may be made to the embodiments, without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.