Abstract:
A delivery catheter used for the delivery and deployment of self expanding stents. A distal end portion is made rotatable relative to a proximal end portion allowing unwinding of a self expanding stent around the longitudinal axis of the catheter. The rotation of the distal end portion allows for untwisting or partial untwisting of a self-expanding stent which has a torsional pre-load in a compressed state in the catheter.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/858,543, filed Nov. 13, 2006, the entirety of which is hereby incorporated by reference into this application. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to the method of delivery of expandable tubular structures capable of insertion into small spaces in living bodies and, more particularly, concerns a delivery system catheter which has a distal section or tip which can rotate around the catheter&#39;s longitudinal axis. 
         [0004]    2. Description of the Related Art 
         [0005]    A stent is a tubular structure that, in a radially compressed or crimped state, may be inserted into a confined space in a living body, such as an artery or other vessel. After insertion, the stent may be expanded radially to enlarge the space in which it is located. Stents are typically characterized as balloon-expanding (BX) or self-expanding (SX). A balloon-expanding stent requires a balloon, which is usually part of a delivery system, to expand the stent from within and to dilate the vessel. A self expanding stent is designed, through choice of material, geometry, or manufacturing techniques, to expand from the crimped state to an expanded state once it is released into the intended vessel. In certain situations the stent may twist as it is deployed from the delivery catheter. In this case, a delivery system catheter with a rotating tip would enable the stent to untwist or partially untwist before touching the vessel wall. 
         [0006]    Stents are typically used in the treatment of vascular and non-vascular diseases. For instance, a crimped stent may be inserted into a clogged artery and then expanded to restore blood flow in the artery. Prior to release, the stent would typically be retained in its crimped state within a catheter and the like. Upon completion of the procedure, the stent is left inside the patient&#39;s artery in its expanded state. The health, and sometimes the life, of the patient depend upon the stent&#39;s ability to remain in its expanded state while not exerting significant or complex loads on the given vessel or duct (herein “vessel”). 
         [0007]    Conventional delivery system catheters used in the delivery and deployment of self-expanding stents have a distal end which does not rotate significantly relative to the more proximal end. When deploying stents which exit the catheter with a stored energy, especially a stored torsional energy, the stent can twist relative to the catheter, and more importantly, relative to the centerline of the given vessel. If the stent continues to twist but does not completely untwist when it hits the vessel wall, there could be residual load, especially a torsional load, placed on the vessel. This load could potentially injure the vessel wall. 
         [0008]    A similar problem could exist with respect to delivery of stent-like structures. An example of a stent-like structure would be a structure used with other components in a catheter-based valve delivery system. Such a stent-like structure holds a valve which is placed in a vessel. It is desirable to provide a catheter to allow a self expanding stent to unwind or partially unwind prior to deployment from the catheter. 
       SUMMARY OF THE INVENTION 
       [0009]    In accordance with the present invention, a catheter is constructed having a distal end portion that can rotate around its longitudinal axis at least about 45 degrees to more than about 360 degrees relative to a portion of the proximal end in order to allow a self expanding stent to unwind or partially unwind prior to or during deployment from the catheter. In one embodiment, the catheter is comprised of a pusher shaft, an outer sheath, optionally radiopaque markers, a guide wire lumen, appropriate valves and luer fittings as needed, and an end or distal portion capable of rotation about the longitudinal axis of the catheter and relative to the proximal end of the catheter. Alternatively, the end or distal portion of the catheter can be short such as about equal to the length of the crimped stent. The end or distal portion of the catheter can be long such as about nearly the entire length of the catheter. In this latter configuration most of the shaft of the catheter could rotate relative to the most proximal end including any valves or ports. In an alternate embodiment, the end or distal portion could also be any length in between the short and long lengths described above. The distal and proximal sections of the catheter which rotate relative to each other can be connected by for example, flexible sleeve, wires, threads, bearings, by one or more fibers (strings, threads, wires) of single or multiple filaments, or by any number of mechanisms that will allow the relative about 45 to more than about 360 degrees of rotation around the longitudinal axis. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The foregoing description, as well as further objects, features, and advantages of the present invention will be understood more completely from the following detailed description of presently preferred, but nonetheless illustrative embodiments in accordance with the present invention, with reference being had to the accompanying drawings, in which: 
           [0011]      FIG. 1A  is a schematic of a prior art self expanding stent delivery system which includes a section X-X. 
           [0012]      FIG. 1B  is a schematic diagram of detail Portion A shown in  FIG. 1A . 
           [0013]      FIG. 1C  is a schematic diagram of detail Portion B shown in  FIG. 1A . 
           [0014]      FIG. 2A  is a schematic diagram of an embodiment of self expanding stent delivery system in accordance with the present invention which includes a section X-X. 
           [0015]      FIG. 2B  is a schematic diagram of detail Portion A shown in  FIG. 2A . 
           [0016]      FIG. 3A  is a schematic of a second embodiment of self expanding stent delivery system in accordance with the present invention which includes a section X-X. 
           [0017]      FIG. 3B  is a schematic diagram of detail Portion A shown in  FIG. 3A . 
           [0018]      FIG. 4A  is a schematic of a third embodiment of self expanding stent delivery system in accordance with the present invention which includes a section X-X. 
           [0019]      FIG. 4B  is a schematic diagram of detail Portion A shown in  FIG. 4A . 
           [0020]      FIG. 5A  is a schematic of a fourth embodiment of self expanding stent delivery system in accordance with the present invention which includes a section X-X. 
           [0021]      FIG. 5B  is a schematic diagram of detail Portion A shown in  FIG. 5A . 
           [0022]      FIG. 6A  is a schematic of a fifth embodiment of self expanding stent delivery system in accordance with the present invention which includes a section X-X. 
           [0023]      FIG. 6B  is a schematic diagram of detail Portion A shown in  FIG. 6A . 
           [0024]      FIG. 7A  is a schematic representation of a portion of a sixth embodiment of self expanding stent delivery system in accordance with the present invention. 
           [0025]      FIG. 7B  is a section view of  FIG. 7A . 
           [0026]      FIG. 7C  is a schematic diagram of detail Portion A shown in  FIG. 7B . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0027]    Reference will now be made in greater detail to the embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings and the description to refer to the same or like parts. 
         [0028]      FIGS. 1A-1C  are schematic diagrams of conventional self expanding stent delivery system  10  that is well known in the art. Delivery system  10  utilizes outer sheath  11  to hold stent  14  in a crimped (radially compact) state. Pusher assembly  12  positioned at the proximal end of stent  14  and reacts to the forces developed as outer sheath  11  is retracted during deployment of stent  14 . Self expanding stent delivery system  10  typically has inner tube  13  (also known as a guide wire lumen) which goes over a guide wire (not shown), also used during a typical procedure.  FIGS. 1A-1C  also shows distal tip  15  used for delivery. Distal tip  15  is often integral to guide wire lumen  13 .  FIG. 1A  also shows handle/hemostasis valve  17 , which can be coupled to outer sheath  11  and pusher shaft  16  which is coupled to the pusher assembly  12 . Delivery system  10  is designed such that outer sheath  11  and handle/hemostasis valve  17  can move longitudinally along the axis of outer sheath  11  relative to pusher assembly  12  and pusher shaft  16 . 
         [0029]      FIGS. 2A-2B  are schematic diagrams of an embodiment of self expanding stent delivery system  20  in accordance with the present invention. This delivery system includes components of the conventional delivery system shown in  FIGS. 1A-1C , which are labeled in  FIGS. 2A-2B . Outer sheath  21  comprises distal portion  24 , which is connected to proximal portion  22  by torsionally compliant element  23 . Torsionally compliant element  23  allows distal portion  24  to rotate relative to proximal portion  22  and maintain sufficient axially rigidity such that all three elements can move longitudinally relative to pusher assembly  12  and pusher shaft  16 . For example, torsionally compliant element  23  can be any one or combination of the following: a sleeve comprised of filaments, threads, fibers, or wires. The sleeve can overlap a portion of proximal portion  22  or distal portion  24  of outer sheath  21 . A suitable sleeve is made of a flexible polymer or rubber. The individual fibers, threads, filaments or wires can overlap some of proximal portion  22  or distal portion  24  of outer sheath  21 . Distal portion  24  can be short such as about equal to the length of the crimped stent  14 . Alternatively, distal portion  24  can be long such as about nearly the entire length of outer sheath  21 . 
         [0030]    Delivery system  20  can include a type of thrust bearing element that allows rotation of the distal portion  24  relative to proximal portion  22  of outer sheath  21  and still transmits the required retraction force. 
         [0031]    Proximal portion  22  of outer sheath  21  is coupled to handle/hemostasis valve  17  as in the conventional delivery system  10 . Additionally, delivery system  20  includes thrust bearing element  25  between pusher assembly  12  and stent  14 . Since stent  14  is in intimate contact with distal portion  24  of outer sheath  21 . Thrust bearing element  25  can further allow stent  14  and distal portion  24  of outer sheath  21  to rotate relative to proximal portion  22  of outer sheath  21  and pusher assembly  12 . For example, thrust bearing element  25  can be a conventionally defined thrust bearing element that reacts to loads parallel to the axis of rotation, but allows rotation along the axis. 
         [0032]      FIGS. 3A-3B  are schematic diagrams of a second embodiment of self expanding delivery system  30  in accordance with the present invention. Delivery system  30  has all the same elements as delivery system  20  shown in  FIGS. 2A-2B , which elements are labeled in  FIGS. 3A-3B , except proximal portion  22  of outer sheath  21  is replaced by proximal outer sheath  31  that extends over torsionally compliant element  23  and part of distal portion  24  of outer sheath  21 . Proximal outer sheath  31  can still rotate relative to the distal portion of the outer sheath, and by covering torsionally compliant element  23  can prohibit the leakage of bodily fluids into outer sheath  21 . 
         [0033]      FIGS. 4A-4B  are schematic diagrams of a third embodiment of self expanding delivery system  40  in accordance with the present invention. Delivery system  40  has all the same elements as delivery system  20  shown in  FIGS. 2A-2B  which are labeled in  FIGS. 4A-4B , except thrust bearing element  25  between pusher assembly  12  and stent  14 . 
         [0034]      FIGS. 5A-5B  are schematic diagrams of a fourth embodiment of self expanding delivery system  50  in accordance with the present invention. Delivery system  50  has all the same elements as conventional delivery system  10  as shown in  FIGS. 1A-1C  which elements are labeled in  FIGS. 5A-5B , but also includes thrust bearing  51  coupling outer sheath  11  to handle/hemostasis valve  17 , such that outer sheath  11  can rotate relative to pusher assembly  12  and pusher shaft  16  but still be longitudinally coupled to handle/hemostasis valve  17  to allow relative longitudinal movement of outer sheath  11  and handle/hemostasis valve  17  to pusher assembly  12  and pusher shaft  16 . Delivery system  50  also includes thrust bearing element  25  between pusher assembly  12  and stent  14 . 
         [0035]      FIGS. 6A-6B  are schematic diagrams of a fifth embodiment of self expanding delivery system  60  in accordance with the present invention. Delivery system  60  has all the same elements as delivery system  30  as shown in  FIGS. 3A-3C  which elements are labeled in  FIGS. 6A-6B , but also includes thrust bearing  51  coupling outer sheath  31  to handle/hemostasis valve  17 , such that proximal outer sheath  31  can rotate relative to pusher assembly  12  and pusher shaft  16  but still be longitudinally coupled to handle/hemostasis valve  17  to allow relative longitudinal movement of proximal outer sheath  31  and handle/hemostasis valve  17  to pusher assembly  12  and pusher shaft  16 . The addition of thrust bearing  51  provides redundancy to delivery system  60 . 
         [0036]      FIGS. 7A-7C  are schematic representations of a portion of self expanding delivery system in an alternate embodiment in accordance with the present invention.  FIGS. 7A-7C  show an alternate version of the handle/hemostasis valve where the handle incorporates nut  77  which is coupled to outer sheath  11 . Pusher assembly  12  incorporates lead screw  72  which is coupled to pusher shaft  16 . In order to retract outer sheath  11 , nut  77  rotates and traverses longitudinally along lead screw  72 . The pitch and direction of lead screw  72  is such that as the stent is deployed, the stent unwinding is counteracted by the rotation of outer sheath  11  in accordance with the interaction of nut  77  and lead screw  72 . 
         [0037]    It is to be understood that the above-described embodiments are illustrative of only a few of the many possible specific embodiments, which can represent applications of the principles of the invention. Numerous and varied other arrangements can be readily devised in accordance with these principles by those skilled in the art without departing from the spirit and scope of the invention.