Howard Alliger
MedSonic, Inc., 1938 New Highway, Farmingdale, NY 11735
An ultrasonic wire was developed that can be threaded through the blood vessels to disintegrate or liquefy occlusive material by cavitation. Using an entry point at the groin, the wire, varying in size from 0.018 to 0.032 in., is flexible enough to reach well below the knee as well as the coronary arteries. It is important to prevent transverse whipping motion in the long wire (2--4 1/2 ft.), which reduces the needed linear motion, and tends to break the wire. Here, 110 dB of sound, mostly ultrasound, can be detected coming off the side of the wire at transverse vibration. There is only a small reduction in tip amplitude as the wire is bent. Most heating is at node points when the wire is straight, and at antinodes when the wire rubs against the surrounding catheter. To date, actual in vivo human tests have been more encouraging than in vivo bench top evaluations. There are several interesting reasons for this.