The variable stiffness heating catheter includes a heating catheter shaft
including at least one electrically conductive member, a reinforcing tube
with apertures formed around the surface of the reinforcing tube, and at
least one coaxial outer layer of a polymer, metal, or both for providing
desired variations in stiffness along at least a portion of the length of
the shaft. The apertures can be formed as axial or helical slits in the
surface of the reinforcing tube, and the reinforcing tube can also be
formed to be tapered at the point where the apertures are formed in the
reinforcing tube to provide a heating catheter that is torqueable and
pushable at the proximal end, yet soft and flexible at the distal end.