Neurovascular stent and method

Abstract

A stent designed for catheter delivery to a target neurovascular site via a tortuous path, in a contracted state, and deployment at the target site, in an expanded state, is disclosed. The stent includes a plurality of expandable tubular members, where member is composed of a continuous wire element forming a plurality of wave segments, and segment contains a pair of opposite looped peaks having a wave shape such that the distance between adjacent sides of a wave, on proceeding from a peak toward opposite peaks, increases monotonically with an inflection point therebetween. The expandable tubular members are joined through adjacent peaks by axial connectors. Radial expansion of the stent from a contracted to expanded state is accommodated by movement of adjacent wave-segment peaks away from one another, without significant change in the axial dimension of the stent. Also disclosed are a system incorporating the stent, and a method of treating a neurovascular abnormality.

1 - 17 . (canceled) 
     
     
         18 . A stent having a contracted state and an expanded state, wherein the stent is expandable from its contracted state to its expanded state, comprising:
 a plurality of expandable tubular members, each expandable tubular member comprising a plurality of interconnected strut pairs, each strut pair having a first strut and a second strut adjacent the first strut, the first strut connected to the second strut to form a peak; and   axial connectors joining one or more confronting peaks of adjacent tubular members,   wherein, in the contracted state, a side of each first strut contacts an adjacent side of each second strut near the peak of each strut pair, and   wherein, in the expanded state, a distance between adjacent sides of the strut pair increases from the peak of the strut pair towards the peak of an adjacent strut pair, the distance increasing monotonically with an inflection point therebetween.   
     
     
         19 . The stent of  claim 18 , wherein radial expansion of the stent from its contracted to its expanded state is accommodated by movement of the first strut and the second strut away from one another, without significant change in the axial dimension of the stent. 
     
     
         20 . The stent of  claim 18 , each expandable tubular member being composed of a continuous wire element. 
     
     
         21 . The stent of  claim 20 , wherein the axial connectors are portions of the continuous wire element. 
     
     
         22 . The stent of  claim 21 , wherein the stent is cut from a tube. 
     
     
         23 . The stent of  claim 18 , wherein each expandable tubular member is formed of a NiTi shape memory alloy, and radial expansion is achieved by releasing the stent from a catheter. 
     
     
         24 . The stent of  claim 23 , which has a stress-induced martensite phase at body temperature. 
     
     
         25 . The stent of  claim 23 , which has an austenite phase transition temperature below body temperature. 
     
     
         26 . The stent of  claim 18 , wherein the axial connectors are spaced from one another by intervening, unconnected confronting peaks. 
     
     
         27 . The stent of  claim 18 , wherein the stent in its contracted state has an inner diameter of between 0.5 and 2 mm, and the stent diameter in its expanded state is between 2-9 times that in its contracted state. 
     
     
         28 . The system of  claim 18 , wherein, in the stent's contracted state, the sides have at least two inflection points. 
     
     
         29 . A system for treating a aneurysm or other vascular abnormality in a neurovascular target vessel, comprising:
 a guide wire that can be deployed at the target site,   a catheter having a lumen and a distal end region in the lumen, and adapted to be placed at the target site,   the stent of  claim 18  adapted to be carried in its contracted state within the catheter's distal end region, where the catheter and stent carried therein are adapted to be moved axially along the guide wire, for placing the catheter at the target site, and   a pusher wire movable through the catheter, for forcing the stent out of the catheter into the vascular site, where stent radial expansion to its expanded state is effective to lodge the stent at the target site.   
     
     
         30 . The system of  claim 29 , which further includes a stabilizer attached to the distal end of the pusher wire, engageable with the stent when forcing the same from the catheter. 
     
     
         31 . A method of treating an aneurysm or other vascular abnormality in a neurovascular target vessel, comprising:
 navigating a guide wire to the target site;   moving over the guide wire, a catheter having a lumen and a distal end region in the lumen, and a stent carried in a contracted state within the catheter's distal end region, until the catheter distal end is located at the target site, and being formed of (i) a plurality of expandable tubular members, each expandable tubular member comprising a plurality of interconnected strut pairs, each strut pair having a first strut and a second strut adjacent the first strut, the first strut connected to the second strut to form a peak, a side of each first strut contacting an adjacent side of each second strut near the peak of each strut pair in the contracted state, and (ii) axial connectors joining adjacent expandable tubular members;   replacing the guide wire with a pusher wire; and   using the pusher wire to force the stent out of the catheter into the vascular site, where stent radial expansion to its expanded state is effective to lodge the stent at the target site.   
     
     
         32 . The stent of  claim 31 , wherein, in the stent's expanded state, a distance between adjacent sides of the strut pair increases from the peak of the strut pair towards the peak of an adjacent strut pair, the distance increasing monotonically with an inflection point therebetween. 
     
     
         33 . The stent of  claim 32 , wherein radial expansion of the stent from its contracted to its expanded state is accommodated by movement of the first strut and the second strut away from one another, without significant change in the axial dimension of the stent. 
     
     
         34 . The stent of  claim 31 , wherein the axial connectors join one or more confronting peaks of adjacent tubular members. 
     
     
         35 . The method of  claim 31 , wherein the pusher wire is equipped at its distal end with a stabilizer that is engageable with the stent when forcing the same from the catheter. 
     
     
         36 . The method of  claim 31 , wherein the stent in its contracted state has an inner diameter of between 0.5 and 2 mm, and a diameter in the expanded state of between 2-9 times that in the contracted state. 
     
     
         37 . The system of  claim 33 , wherein, in the stent's contracted state, the sides have at least two inflection points.