ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aPA6. Pressure and cavitation measurements of an intra-arterial angioplasty device.

Inder Raj S. Makin

E. Carr Everbach

Dept. of Eng., Swarthmore College, Swarthmore, PA 19081-1397

Variation of the acoustic field radiated from a low-frequency (22.5 kHz) catheterlike angioplasty device in a relatively large (600 L) tank of water was presented earlier [I. R. S. Makin and E. C. Everbach, 2855(A) (1994)]. The normal volume of the human torso or the human limb into which the ultrasonic wire is inserted during therapy cannot be treated, however, as an infinite medium for the 66.6-mm wavelength (calculated for water) due to the wire source. Therefore the sound field of the device was investigated in a liquid-filled Plexiglas[sup (registered)] cylinder (200-mm diameter, 350-mm height) to simulate anthropometric dimensions. Measurement of pressures along the axis of the cylinder for the wire source positioned axially at one end of the cylinder shows a marked standing wave pattern even up to an axial range of 250 mm. Such strong standing waves could potentially exist far away from the probe tip in vivo. In addition, the occurrence of cavitation at the tip of the wire was confirmed using a 20-MHz passive cavitation detection technique.