The mechanical properties of guidewires. Part I: Stiffness and torsional strength.

The stiffness of guidewires varies in accordance with the fourth power of the core diameter. Titanium wires with the same core diameters have one-quarter the stiffness of steel wires. The torsional strength shows the same correlation with the 4th power of the diameter of the core in solid wires. With a few exceptions, spring wires do not have a usable torsional strength. The differences in the stiffness of the wire tips, and the different kinds of transition to the stiff shaft can be explained by differences in the construction of the wires and their tips.