Abstract:
A flexible engaging delivery device ( 10 ) for delivery of a vaso-occlusion flexible engaging structure ( 24 ) to a vascular target site via a catheter ( 50 ) is disclosed comprising a catheter ( 50 ) having a lumen ( 52 ) and an introducer ( 48 ) disposed within the catheter ( 52 ). The introducer ( 48 ) comprises an outer sleeve ( 49 ), a shaft ( 12 ) and a wire ( 16 ) that is slidably movable within the shaft ( 12 ). A wire tip ( 22 ) is permanently connected to the wire ( 16 ), wherein the wire tip ( 22 ) is adapted to contact a matted portion ( 20 ) of the vaso-occlusion flexible engaging structure ( 24 ) and is used to deliver said flexible engaging structure from said flexible engaging device ( 10 ) to a vaso-occlusion target site.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 08/998,121, filed Dec. 24, 1997, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     A flexible engaging delivery device for delivery of a vaso-occlusion flexible engaging structure to a vascular target site via a catheter is disclosed comprising a catheter having a lumen and an introducer disposed within the catheter. The introducer comprises an outer sleeve, a shaft, and a wire that is slidably movable within the shaft. A wire tip is permanently connected to the wire, wherein the wire tip is adapted to contact a matted portion of the vaso-occlusion flexible engaging structure and is used to deliver said flexible engaging structure from said flexible engaging device to a vaso-occlusion target site. 
     BACKGROUND OF THE INVENTION 
     In a variety of medical procedures, a physician may need to occlude vessels in order to contain bleeding or reduce the risk of hemorrhaging. 
     There are a variety of devices that have been developed to occlude blood vessels. One of these employs a catheter to deliver one or more vaso-occlusion coils to a vascular target site. The vaso-occlusion coils are typically platinum or other surgical-metal coils that are delivered via a vascular catheter. Typically, the coil is placed in a linear condition in the catheter, and is pushed from the end of the catheter by a pusher wire. As the coil exits the delivery device it assumes a relaxed, convoluted shape at the vascular site. 
     The coil may be deployed simply by ejecting it from the distal end of the catheter. However, this technique may be unsatisfactory where it is desired to better position the coil in the vessel once it has been ejected from the catheter and has assumed its convoluted shape. To overcome this problem, various release mechanisms have been proposed to allow for positive release of the coil from the end of a pusher wire once the coil is properly positioned at the vascular site. Expandable jaw clamps and electrolytically erodible joints are examples of such mechanisms. 
     It would be advantageous to provide a coil delivery device and catheter assembly which provides the combined advantages of (i) a coil release mechanism that allows for simple coil loading and release, (ii) positive release once the coil is properly positioned at the target site, (iii) multiple reloading steps, and (iv) operable with coils having a variety of coil diameters. 
     SUMMARY OF THE INVENTION 
     The invention includes, in one embodiment, a coil-delivery device for delivery to a vascular target site via an inner-lumen catheter, an elongate, flexible vaso-occlusion coil having an end-region inner lumen. The device includes an elongate sleeve, perhaps a catheter, having proximal and distal ends and an inner lumen extending therebetween, and a wire slidably movable within said sleeve. The wire has a distal end region extending beyond the distal end of the sleeve, and a proximal end region that can be manipulated to move the wire between extended and retracted positions with respect to the sleeve&#39;s distal end. A flexible engaging structure in the device extends between the distal ends of the sleeve and the wire, such that movement of the wire between its extended and retracted positions is effective to move the flexible engaging structure between extended and radially expanded conditions, respectively, in which the engaging structure is adapted to be received within and compressionally engage the lumen end region of the coil, respectively. 
     The engaging structure in the device may be braided, generally in the shape of a sock. The structure may be dimensioned, with such in its extended position, to be received in the inner lumen of a coil having an outer diameter as small as 15 mils, and with such in its expanded condition, to compressionally engage the lumen end region of a coil having an outer diameter as great as 35 mils. 
     In another aspect, the invention includes a coil-delivery assembly for delivery of at least one, and preferably a plurality of vaso-occlusion coils to a vascular target site. The assembly includes (a) a catheter having proximal and distal ends, and an inner lumen extending therebetween, (b) an introducer for holding a vaso-occlusion coil in a substantially linear condition, and (c) a coildelivery device of the type described above. The introducer may have an end region adapted to be mated with the proximal end of said catheter, for transferring a coil from the introducer into the catheter. The assembly allows a coil to be frictionally and releasably engaged by the wire, with the coil held in the introducer, transferred from the introducer into and through the catheter, and released from the wire after being advanced across the catheter&#39;s distal end. 
     Also disclosed is a method for releasably engaging a vaso-occlusion coil of the type having an end-region inner lumen. The method involves immobilizing the coil in a substantially linear condition in a tube having an open access end, inserting into the tube, a coil-delivery device of the type described above, and moving the wire in the device to its retracted position to compressionally engage the engaging member with the inner lumen of the coil. 
     These and other objects and features of the invention will become more fully apparent when the following detailed description of the invention is read in conjunction with the accompanying drawings. 
    
    
     BREIF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary cross-sectional view of a catheter and coil delivery ice in a coil delivery assembly constructed according to the invention. 
     FIGS. 2A and 2B show, respectively, a fragmentary side view and a sidetional view of a coil-delivery device constructed in accordance with the vention, with its distal end region shown in an extended state. 
     FIGS. 3A and 3B show the distal end of a coil-delivery device of FIG. 2A and 2B with the distal end region in an expanded state. 
     FIG. 4 is a partial cross sectional view of a delivery device and introducer used in transferring a coil from a supply tube to the introducer. 
     FIG. 5 is a partial cross sectional view illustrating transfer of a vaso-occlusion coil from an introducer into a catheter. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates components of one embodiment of a coil-delivery assembly  10  for delivering one or more coils, such as coil  11 , to a vascular target site. The assembly includes a catheter  12  having proximal and distal ends  14 ,  16 , respectively, and an inner lumen  18  extending therebetween. 
     As seen particularly in FIGS. 2A and 2B and  3 A and  3 B, a coil-delivery device  20  in the assembly includes an elongate sleeve  22  having proximal and distal ends  24 ,  26 , respectively, and an inner lumen  28  extending therebetween. A wire  30  in the device is slidably movable within the sleeve. The wire has a distal end  32  extending beyond the distal end of the sleeve, and a proximal end region  33  that can be manipulated to move the wire between extended and retracted positions with respect to the sleeve&#39;s distal end. 
     A flexible engaging structure  35  in the delivery device extends between the distal ends of the sleeve and the wire, such that movement of the wire between its extended and retracted positions is effective to move the flexible engaging structure between extended and radially expanded conditions, indicated in FIGS. 3A and 3B, respectively. 
     Also included in the assembly is an introducer (shown at  34  in FIGS. 4 and 5) for use in introducing a coil, such as coil  11 , carried on device  20  into the catheter, in a manner to be described. 
     Considering now details of the assembly, catheter  12  may be a conventional single-lumen catheter for use in accessing a vascular target site, e.g., along tortuous-path, narrow vessels. The catheter is formed of a flexible tubing  36 , typically about 100-300 cm in length, which may have a reduced thickness and/or stiffness on progressing from the proximal to distal ends, to allow improved target site accessing in deep tissue. The inner diameter of the catheter, i.e., lumen diameter, may vary in size according to the size of the coil to be delivered. Typical catheter cross-sectional dimensions are between about 10-100 mils inner diameter, and between about 5-20 mils tubing wall thickness. The catheter&#39;s inner wall may have a lubricous coating to improve the easy of movement of device  20  and a coil carried therewith, through the catheter. 
     Wire  30  in device  20  may be, for example, a flexible torqueable guide wire having a total length between about 100-300 cm and a maximum diameter of the wire between about 8-40 mils (thousandths of an inch). The body portion of the wire may have a substantially constant diameter along its length, or may contain regions of taper. In one embodiment, the wire has a tapered distal portion of about 5-50 cm in length, and preferably about 15-20 cm in length, with the body portion making up the remainder of the length of the wire. The taper is preferably such as to reduce the diameter of the wire from about 8-40 mils at the proximal end to a minimum diameter of typically 1-5 mils at the distal wire end. Stainless steel wire of suitable for making device  20  type is commercially available, e.g., from Wytech and National Standard. 
     Sleeve  22  in device  20  is formed of a flexible tubing whose inner diameter allows axial movement of wire  30  within the sleeve between the wire&#39;s extended and retracted positions. The tubing may have a reduced diameter and/or stiffness on progressing from the proximal to the distal end. The tubing has a preferred length between about 100-300 cm and a maximum diameter of about 20-50 mils. The outer diameter of the sleeve is dimensioned to allow the wire device, including the sleeve, to be advanced axially through the catheter, to place the distal end region of the device beyond the distal end of the catheter, for coil placement and release at the target site. The outer diameter at the distal end of the sleeve is greater than the inner lumen diameter of a coil, such as coil  11 , to be delivered by the device. 
     Engaging structure  35  is preferably a braided sock formed by braided metal filaments or the like. Such braided sleeves or socks are commercially available in a variety of sleeve diameters, for example, 5-20 mils, from Viamed Corp (South Easton, Mass.), or may be braided using braiders such as supplied by Steeger (Spartanburg, S.C.). 
     The sock is preferably about 1-3 cm in length, and has a “relaxed” diameter similar to that of the outer diameter of the sleeve&#39;s distal end. As will be seen, the sock can be stretched, in its extended condition, to a diameter smaller than its “relaxed” diameter, and in particular, smaller than the inner lumen diameter of a coil to be releasably engaged by the device, e.g., 3-8 mils. At the same time, the sock diameter can be expanded radially, by reducing its length, to a maximum diameter of up to 30-50 mils or more. 
     The braided sock is attached at its proximal end to the distal end of sleeve  22  by conventional methods. For example, the proximal end of the sock may be placed over the distal end of the sleeve, and the interface covered with a layer of a suitable resin capable of bonding to the sleeve. 
     The distal end of the sock is attached to the distal end of wire  30 , such that movement of the wire between its extended and retracted positions is effective to move the sock between its extended and radially expanded conditions, respectively. The attachment of the wire to the distal end of the sock may be, for example, by a solder joint or other suitable bonding agent. 
     The coil-delivery device just disclosed, as embodied in device  20 , also forms one aspect of the invention. 
     As indicated above, assembly  10  further includes an introducer for use in transferring a coil from the introducer into the catheter in the assembly. FIG. 4 illustrates such an introducer, indicated here at  34 . The introducer defines an inner cylindrical cavity  50  which is open at both ends. The introducer is dimensioned to receive a vaso-occlusion coil, such as coil  52 , within the cavity. The introducer&#39;s distal end, indicated here at  54 , has a flange  56  for releasably engaging annular groove  62  in the open end of a coil-supply tube  58 . 
     In a typical embodiment, where multiple coils are to be delivered, each coil is supplied in a tube, such as tube  58 , which is closed at one end, and open at its opposite end, here indicated at  60 . The open end has an annular groove  62  for receiving flange  56 , to engage the introducer by snap-fit, and anchor the introducer releasably to the coil-supply tube during a coil-transfer operation. 
     A variety of coils, such as coil  52 , may be suitable. One example of a coil  52  for delivery by the present invention is “flower coil” available from Target Therapeutics (Fremont, Calif.). This coil can be easily constrained to a linear condition, but will “fold” into a convoluted vaso-occlusion condition when released from its linear constraints. Typical coil lengths are between about 1-50 cm. Typical outer coil diameters are between about 15-35 mils. As seen in FIG. 5, the coil includes an inner lumen extending the length of the coil. This lumen has typical diameters between and 5 and 25 mils. 
     Operation of the assembly will now be described. Initially, catheter  12  in the assembly is directed to a selected vascular target site, e.g., using a conventional guide wire to guide the catheter through a vessel path. The guide wire is then removed, leaving the catheter in place to serve as a conduit for delivering coils from the proximal, accessible catheter end to the target site adjacent the catheter&#39;s distal end. 
     With respect particularly to FIGS. 4 and 5, to supply the first coil to the target site, a vaso-occlusion coil having a selected length and diameter is transferred from a supply tube, via the introducer, into the catheter. This is done by attaching the distal introducer  34  end, by snap-fit engagement, to a coil-supply tube, such as tube  58 . Device  20  is then inserted through the introducer  34  and into the coil-supply tube  58 , with the braided sock in its extended, small-diameter condition, allowing the sock to be received in the inner lumen of the open end region of the coil. That is, wire  30  (see FIG. 2A) in the device  20  is moved to its extended condition and held in this condition as the wire device  20  as a unit is advanced axially into the introducer  34 . The sock is inserted substantially all the way into the coil lumen, this advancement being arrested when the coil end abuts the distal end of sleeve  22  (FIG. 2A) in the device. The wire  30  in the device  20  is now moved toward its retracted position, causing the sock to expand radially and to compressionally engage the lumen of coil  64 . With the wire held in its retracted position, the coil  64  may now be removed from its supply tube  58  and drawn completely into the introducer cavity  44  by retracting the device  20  into and substantially through the introducer  34 . 
     As shown in FIG. 5, the introducer  34  is now disengaged from the supply tube and snap-fit engaged with catheter  12  which has an end groove  66  (similar to groove  62  in supply tube  58  in FIG.  4 ). The coil-delivery device assembly, as depicted in FIG. 5, may be advanced in the direction of the catheter&#39;s  12  distal end, ultimately until the attached coil is discharged from the distal end of the catheter, where the coil assumes its convoluted, vaso-occluding condition. The delivery device may be further manipulated at this stage, until the coil is optimally positioned at the target site. When this positioning is achieved, the wire ( 30  in FIG. 2A) in the device  20  is extended to extend the braided sock in its small-diameter condition, allowing the coil  64  to released from the delivery device  20  by retracting the braided sock, e.g., into the catheter. 
     The coil-delivery device  20  is then withdrawn from the catheter  12  and a new coil may be (i) transferred from its supply tube to the introducer, (ii) transferred from the introducer to catheter, and (iii) released from the wavy segment at a selected position at the target site, as described above. This reloading and new coil placement at the target site is repeated unto a desired number of coils have been placed at the site. 
     From the foregoing, it will be appreciated how various objects and features of the invention have been met. The delivery device allows a coil, e.g., supplied in a supply tube, to be releasably engaged by inserting the braided sock in the device into the supply tube until the sock is inserted into an end region of the coil&#39;s inner lumen, and retracting the device wire to produce a compressional engagement of the device with the coil. Once releasably attached to device, the coil can be positively manipulated into and through a catheter and released at a selected vascular site, simply by retracting the wire in the device. This allows for simple reloading and release of multiple coils during a coil vaso-occlusion procedure. 
     Further, the engagement structure in the device, e.g., a braided sock, is adapted to compressionally engage coils having a variety of different lumen sizes, and thus the physician can select a range of coil sizes to be placed without replacing any of the assembly components. 
     While this invention has been described in reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.