Stent deployment systems and methods

Abstract

A stent deployment system includes a catheter shaft, an expandable member mounted to the catheter shaft, and one or more stents or stent segments slidably positioned on the expandable member. The stent deployment system is adapted for deployment of stents or stent segments in very long lesions and in tapered and curved vessels. The stent deployment system facilitates slidable movement of a stent in a distal direction relative to the expandable member while inhibiting slidable movement in a proximal direction relative to the expandable member.

1 . A method of deploying stent segments in a blood vessel having a luminal taper, the method comprising: 
 transluminally introducing a catheter into the blood vessel, the catheter having an expandable member near a distal end thereof;    positioning a first plurality of independent stent segments over the expandable member such that a first stent segment is on a proximal extremity of the expandable member and a second stent segment is on a distal extremity of the expandable member, the first and second stent segments being independently movable relative to the expandable member; and    expanding the expandable member such that the proximal extremity has a first expanded diameter and the distal extremity has a second expanded diameter smaller than the first expanded diameter, wherein the first stent segment is expanded to a diameter larger than the second stent segment.    
   
   
       2 . The method of  claim 1  further comprising, after expanding the expandable member, slidably positioning a second plurality of independent stent segments over the expandable member with the catheter remaining in the blood vessel.  
   
   
       3 . The method of  claim 1  further comprising constraining a proximal portion of the expandable member from expansion while a distal portion of the expandable member is expanded, the proximal and distal extremities being in the distal portion.  
   
   
       4 . The method of  claim 3 , wherein at least a third stent segment is slidably disposed on the proximal portion.  
   
   
       5 . The method of  claim 3 , wherein the expandable member is constrained by a sheath slidably disposed over the proximal portion of the expandable member.  
   
   
       6 . The method of  claim 2 , wherein the second plurality of independent stent segments is slidably positioned over the expandable member by a pusher slidably coupled to the catheter.  
   
   
       7 . The method of  claim 2 , wherein the second plurality of independent stent segments is slidably positioned over the expandable member by retracting the expandable member relative to the second plurality of independent stent segments.  
   
   
       8 . The method of  claim 1 , wherein the first plurality of independent stent segments is positioned over the expandable member while the catheter is disposed in the blood vessel.  
   
   
       9 . The method of  claim 1 , wherein the expandable member is tapered between the proximal extremity and the distal extremity when expanded.  
   
   
       10 . The method of  claim 9 , wherein the expandable member is tapered when expanded to correspond generally with the luminal taper.  
   
   
       11 . The method of  claim 1 , wherein the proximal extremity has a first axial length of a first constant diameter and the distal extremity has a second axial length of a second constant diameter when the expandable member is expanded.  
   
   
       12 . The method of  claim 11 , wherein the first and second axial lengths are approximately equal.  
   
   
       13 . The method of  claim 11 , wherein the first and second axial lengths correspond to the length of a stent segment.  
   
   
       14 . The method of  claim 1 , wherein the expandable member is expanded to an expanded configuration comprising a plurality of steps of decreasing diameter between the proximal and distal extremities.  
   
   
       15 . The method of  claim 14 , wherein each step has an axial length selected to accommodate a pre-selected number of stent segments.  
   
   
       16 . The method of  claim 14 , wherein the pre-selected number is one.  
   
   
       17 . The method of  claim 1 , further comprising positioning a third stent segment on the expandable member adjacent to the first stent segment and positioning a fourth stent segments on the expandable member adjacent to the second stent segment, the third stent segment being expanded to a diameter larger than the fourth stent segment.  
   
   
       18 . The method of  claim 17 , wherein the third stent segment is expanded to a diameter different than the first stent segment and the fourth stent segment is expanded to a diameter different than the second stent segment.  
   
   
       19 . A stent deployment system comprising: 
 an elongated catheter shaft having a proximal end and a distal end;    an expandable member mounted to the catheter shaft near the distal end, the expandable member having a plurality of surface features projecting outwardly therefrom; and    a stent slidably positionable over the expandable member, wherein the surface features allow sliding movement of the stent distally relative to the expandable member and inhibit sliding movement of the stent proximally relative to the expandable member.    
   
   
       20 . The stent deployment system of  claim 19 , wherein the surface features comprise flexible and resilient projections.  
   
   
       21 . The stent deployment system of  claim 20 , wherein the projections normally point in a distal direction from the expandable member.  
   
   
       22 . The stent deployment system of  claim 20 , wherein the projections are deflectable so the projections point in a proximal direction from the expandable member.  
   
   
       23 . The stent deployment system of  claim 20 , wherein the projections extend from the expandable member at an angle, the angle being variable by manipulating the expandable member.  
   
   
       24 . The stent deployment system of  claim 23 , wherein the angle is variable by inflation of the expandable member.  
   
   
       25 . The stent deployment system of  claim 23 , wherein the angle is variable by tensioning the expandable member.  
   
   
       26 . The stent deployment system of  claim 19 , wherein the surface features comprise flexible and resilient ribs.  
   
   
       27 . The stent deployment system of  claim 26 , wherein the ribs have a curvature so as to be convex on a proximal side thereof, the curvature being selected to allow distal movement of the stent over the rib.  
   
   
       28 . The stent deployment system of  claim 27 , wherein the ribs have a distal side configured to engage the stent to inhibit proximal movement thereof.  
   
   
       29 . The stent deployment system of  claim 27 , wherein the ribs are deflectable to allow proximal movement of the stent over the rib.  
   
   
       30 . The stent deployment system of  claim 19 , wherein the surface features are configured to engage the stent, further comprising means for varying the degree of engagement of the stent by the surface features.  
   
   
       31 . A stent deployment system comprising: 
 an elongated catheter shaft having a proximal end and a distal end;    an expandable member mounted to the catheter shaft near the distal end, the expandable member having an outer surface; and    a stent slidably positionable over the outer surface of the expandable member, wherein the outer surface is configured to allow sliding movement of the stent distally relative to the expandable member and inhibit sliding movement of the stent proximally relative to the expandable member.    
   
   
       32 . The stent deployment system of  claim 31 , wherein the outer surface comprises a plurality of projections projecting outwardly therefrom.  
   
   
       33 . The stent deployment system of  claim 32 , wherein the plurality of projections point generally in a distal direction to facilitate movement of the stent distally relative thereto and to inhibit movement of the stent proximally relative thereto.  
   
   
       34 . The stent deployment system of  claim 33 , wherein the projections are resiliently deflectable so as to point generally in a proximal direction.  
   
   
       35 . The stent deployment system of  claim 32 , wherein the projections project at an angle from the outer surface, the angle being variable in response to tension in the outer surface.  
   
   
       36 . The stent deployment system of  claim 35 , wherein the angle is variable in response to inflation of the expandable member.  
   
   
       37 . The stent deployment system of  claim 32 , wherein the outer surface comprises a plurality of ribs configured to engage the stent.  
   
   
       38 . The stent deployment system of  claim 37 , wherein the ribs are convex on a proximal side thereof.  
   
   
       39 . The stent deployment system of  claim 38 , wherein the ribs have a distal side configured to inhibit proximal movement of the stent.  
   
   
       40 . The stent deployment system of  claim 37 , wherein the ribs are deflectable to allow movement of the stent proximally relative thereto.