Stent installation method using balloon catheter having stepped compliance curve

Abstract

A balloon catheter suitable for deploying a stent utilizes a balloon molded with a stepped diameter profile.

We claim:  
     
         1 . A balloon for a medical catheter, the balloon having a molded configuration with a longitudinal axis, the balloon configuration, when viewed in longitudinal quarter section, comprises: 
 first and second waist segments spaced longitudinally apart from each other and defining a longitudinally intermediate region therebetween, each waist segment being bonded to the catheter,    first and second step segments within said intermediate region and spaced longitudinally apart from each other, each being and spaced radially from the longitudinal axis and from said waist segments, the second step segment being spaced radially from the longitudinal axis a greater distance than the first segment,    a first diverging portion extending between the first waist segment and the first step segment,    a second diverging portion extending between the first step segment and the second step segment, and    a transition portion extending between the second step segment and the second waist segment.    
     
     
         2 . A balloon as in  claim 1  wherein said balloon transition portion comprises 
 a third step segment, within said intermediate region and spaced longitudinally apart from the second step segment and from the second waist segment in a region therebetween,  
 a third diverging portion extending between the second step segment and the third step segment, and  
 a fourth diverging portion extending between the third step segment and the second waist segment.  
 
     
     
         3 . A balloon as in  claim 1  wherein said balloon transition portion consists of a third diverging portion extending between the second step segment and the second waist segment and which, when moving from the second step segment to the second waist portion, continuously decreases in distance from the longitudinal axis.  
     
     
         4 . A balloon as in  claim 1  wherein said step portions extend generally parallel to the longitudinal axis.  
     
     
         5 . A balloon catheter assembly comprising a an elongate tubular body, a distal end and a balloon as in  claim 1  mounted thereon near the distal end thereof.  
     
     
         6 . A balloon catheter as in  claim 5  wherein the balloon is mounted on the catheter with the first step segment located proximally along the catheter relative to the second step segment.  
     
     
         7 . A balloon catheter assembly as in  claim 5  wherein the balloon is mounted on the catheter with the first step segment located distally along the catheter relative to the second step segment.  
     
     
         8 . A balloon catheter as in  claim 5  wherein said balloon transition portion consists of a third diverging portion extending between the second step segment and the second waist segment and which, when moving from the second step segment to the second waist portion, continuously decreases in distance from the longitudinal axis.  
     
     
         9 . A balloon catheter assembly as in  claim 5  wherein said balloon transition portion comprises 
 a third step segment, within said intermediate region and spaced longitudinally apart from the second step segment and from the second waist segment in a region therebetween,  
 a third diverging portion extending between the second step segment and the third step segment, and  
 a fourth diverging portion extending between the third step segment and the second waist segment.  
 
     
     
         10 . A balloon catheter assembly as in  claim 5  further comprising an expandable stent mounted on the catheter over the balloon.