Low profile short tapered tip catheter

Abstract

A low profile, short, tapered distal tip catheter and methods for its manufacture are provided. The catheter tip is configured to have a taper over a relatively short length resulting in a low profile that is useful when navigating the catheter tip into tight passages such as the Papilla of Vater. The configuration of the tip and process for making it can be employed in any medical catheter but are found to be most useful in a multilumen papillotome catheter used in biliary procedures.

1 . A method of forming a catheter tapered distal tip comprising:
 providing a polymer catheter shaft having proximal and distal ends,   distal tip adjacent to and including the distal end and a forming region on the distal tip that is to become tapered,
 temporarily placing thermally insulative material segments over regions of the shaft immediately proximal to and distal to the forming region, 
 grasping the shaft at locations proximal and distal to the forming region, heating the forming region sufficiently so that it may be plastically reformed, 
 placing the forming region in tension by pulling axially in opposite directions at the grasping locations, 
 removing the thermally insulative material. 
   
     
     
         2 . A method as defined in  claim 1  wherein the thermally insulative material applies a radial compressive force on the shaft. 
     
     
         3 . A method as defined in  claim 1  wherein the thermally insulative material comprises polyolefin shrink tubing. 
     
     
         4 . A method as defined in  claim 1  further comprising the step of inserting at least one forming mandrel into a lumen of the shaft. 
     
     
         5 . A method as defined in  claim 1  wherein the step of placing the forming region in tension is performed at least in part by an automated mechanical device. 
     
     
         6 . A method as defined in  claim 1  wherein the shaft is placed in tension by moving the grasping locations apart by a known distance at a known rate of travel. 
     
     
         7 . A method as defined in  claim 6  wherein the distance is approximately on the order of 0.72 inch and the rate of travel is in the range of approximately between 0.172 inch per second and 0.414 inch per second. 
     
     
         8 . A method as defined in  claim 1  wherein the catheter is a multilumen papillotome catheter having a cutting wire adjacent to its distal end and further comprising the steps of skiving a hole into the shaft to expose an opening to a lumen of the shaft, placing a cutting wire through a dedicated cutting wire lumen of the shaft and through the skive; securing a distal end of the cutting wire in the cutting wire lumen distally of the skive hole while leaving a portion of the cutting wire exposed from the lumen over the skive. 
     
     
         9 . A method as defined in  claim 8  wherein a thermally insulative material segment is placed over the skive hole during heating. 
     
     
         10 . A method as defined in  claim 8  further comprising installing a radiopaque marker in a lumen of the shaft. 
     
     
         11 . A method as defined in  claim 10  wherein reducing the size of the anchor and marker serve to permit reduction of the length of the distal tip of the catheter. 
     
     
         12 . A method as defined in  claim 1  wherein the heating step comprises applying hot air to the shaft at approximately 700.degree. F. at a flow rate of approximately 20 to 30 cfm and for a time of approximately 40 seconds. 
     
     
         13 . A method as defined in  claim 1  wherein the distal end of the shaft to be tapered has been previously reduced in diameter in a necking process by drawing the shaft through a hot die.