| abstract |
An apparatus having a steerable distal end portion for insertion in a body lumen comprises a superlastic shape memory member which adopts a memorized shape in an unloaded austenitic state, and stationary heating means for heating at least a portion of the superlastic shape memory member to a temperature above the temperature inside the body lumen. Heating the superlastic shape memory member inside the body lumen causes it to increase in stiffness and tend toward the memorized shape, and subsequent discontinuation of heating causes the superlastic shape memory member to decrease in stiffness, allowing the distal end portion to be deformed from the memorized shape, thereby resulting in movement of the distal end portion which assists in steering it through the body lumen. Preferably, the elongate shape memory member is tubular, having a lumen extending therethrough, and the heating means comprises electrical heating means. In a particularly preferred embodiment, the heating means comprises electrical supply means and electrical conductor means extending through the lumen of the superlastic shape memory member. |