Medical instrument with controlled torque transmission

Abstract

A medical instrument such as a guidewire that is designed to have controlled torque transmission along its length. Specially treated areas are placed in selected and equal areas along the entire length of the elongated shaft of the medical instrument, and are separated from one another by untreated areas. This process ensures that any torque is transmitted distally, in a smooth manner, regardless of the guidewire position, thus resulting in a substantial reduction in whipping. In one embodiment, a stainless steel guidewire is utilized, and is subjected to annealing heat treatment in selected areas. This annealing process creates a mandrel that has repeated temper properties along its length. Torque applied at one end of this mandrel is transmitted to the opposite end in an even and controlled manner, even when the mandrel is formed into a loop.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . An elongated medical instrument that is subject to torque when in use, comprising: a first plurality of sections that have been subjected to a selected treatment process; a second plurality of sections located between each of the sections of the first plurality of sections, the second plurality of sections not having been subjected to the selected treatment process; and wherein the first plurality of sections and the second plurality of sections have different torque transmission characteristics.