Composite catheter shafts and methods and apparatus for making the same

Abstract

A medical device includes an elongate shaft including a multifilar coil comprising a first strand and a second strand wound in the same winding direction, the multifilar coil comprising a first section having a first end and a second end wherein the first strand and the second strand are wound with identical pitch patterns between the first end and the second end of the first section, the multifilar coil further comprising a second section having a first end and a second end, wherein the first strand and the second strand are wound with different pitch patterns from each other between the first end and second end of the second section, and a polymeric tubular member coextending with the multifilar coil.

What is claimed is: 
     
         1 . A method of making an elongate medical device shaft, the method comprising the steps of:
 (A) providing a first polymeric tubular member having a mandrel extending therein;   (B) fixing a first portion of a first strand in relation to at least one of the mandrel and the first polymeric tubular member;   (C) fixing a first portion of a second strand in relation to at least one of the mandrel and the first polymeric tubular member;   (D) causing relative rotation and relative longitudinal displacement to simultaneously occur between an unsecured portion of the first strand and the first polymeric tubular member and between an unsecured portion of the second strand and the first polymeric tubular member while engaging the unsecured portion of the first strand with a first engagement member and engaging the unsecured portion of the second strand with a second engagement member and maintaining a first longitudinal distance between the first engagement member and the second engagement member, such that a first portion of a multifilar coil is formed over the first polymeric tubular member, the first strand and the second strand having similar pitch patterns along the first portion;   (E) changing the relative orientation between the first engagement member and the second engagement member to a second longitudinal distance therebetween, the second longitudinal distance greater than the first longitudinal distance;   (F) causing relative rotation and relative longitudinal displacement to simultaneously occur between the unsecured portion of the first strand and the first polymeric tubular member and between the unsecured portion of the second strand and the first polymeric tubular member, such that a second portion of the multifilar coil is formed over the first polymeric tubular member, the first strand and the second strand having dissimilar pitch patterns along the second portion; and   (G) removing the mandrel from the first polymeric tubular member.   
     
     
         2 . The method of  claim 1 , wherein step E and step F are performed simultaneously. 
     
     
         3 . The method of  claim 1 , wherein the second portion comprises one wind or less. 
     
     
         4 . The method of  claim 1 , wherein the second portion comprises less than one wind. 
     
     
         5 . The method of  claim 1 , further comprising at least partially embedding the multifilar coil within the first polymeric tubular member. 
     
     
         6 . The method of  claim 1 , further comprising covering the multifilar coil with a second polymeric tubular member. 
     
     
         7 . The method of  claim 6 , wherein covering the multifilar coil comprising overextruding the second polymeric tubular member. 
     
     
         8 . The method of  claim 6 , wherein covering the multifilar coil comprising heat shrinking the second polymeric tubular member. 
     
     
         9 . The method of  claim 1 , wherein the multifilar coil is a trifilar coil. 
     
     
         10 . The method of  claim 1 , wherein the first strand comprises a drawn-filled tube. 
     
     
         11 . The method of  claim 1 , further comprising forming a medical device that includes the medical device shaft. 
     
     
         12 . The method of  claim 11 , wherein the first portion of the multifilar coil is proximal to the second portion of the multifilar coil on the medical device shaft. 
     
     
         13 . The method of  claim 1 , wherein the first and second strands in the first portion are close-wound with a constant pitch pattern. 
     
     
         14 . The method of  claim 1 , wherein the first portion of the multifilar coil has a first end and a second end and the second portion of the multifilar coil has a first end and a second end, the second end of the first portion immediately adjacent the first end of the second portion. 
     
     
         15 . The method of  claim 14 , wherein the first strand and the second strand are longitudinally close to each other at the second end of the first portion, and wherein the first strand and the second strand are longitudinally separated from each other at the second end of the second portion. 
     
     
         16 . The method of  claim 1 , wherein an outer diameter of the first portion of the multifilar coil is the same as an outer diameter of the second portion of the multifilar coil. 
     
     
         17 . The method of  claim 1 , wherein the first strand comprises flat wire having a cross-sectional length L of between about 0.002 inch and about 0.020 inch, and a cross-sectional thickness T of between about 0.0005 inch and about 0.005 inch. 
     
     
         18 . The method of  claim 1 , wherein the first engagement member comprises a first engagement pin and wherein the second engagement member comprises a second engagement pin. 
     
     
         19 . The method of  claim 1 , wherein the first engagement member and the second engagement member are carried on a base, and wherein at least one of the first engagement member and second engagement member is movable in relation to the base. 
     
     
         20 . The method of  claim 1 , wherein causing relative rotation in step D comprises rotating the first polymeric tubular member with a motor. 
     
     
         21 . The method of  claim 1 , wherein step G further comprises removing the mandrel from the first polymeric tubular member while maintaining the pitch patterns of the first strand and the second strand along the second portion.