EFFECTS OF TISSUE CONSTRAINT ON SHOCK WAVE-INDUCED BUBBLE EXPANSION IN-VIVO

The collapse time of lithotripter shock wave-induced cavitation bubble s was found to be significantly reduced from in vitro (133-271 mu s) t o in vivo (34-99 mu s), suggesting that bubble expansion in vivo could be severely constrained by the surrounding tissue. Calculations based on the Gilmore model for bubble dynamics suggest that inertial cavita tion could be induced in blood, provided that appropriate nuclei are p resent. Without tissue constraint, the maximum bubble induced in blood by an HM-3 lithotripter was calculated in the range of 1.3 to 2.3 mm. These results suggest that intraluminal bubble expansion may cause th e rupture of capillaries and small blood vessels during shock wave lit hotripsy, especially when cavitation nuclei are introduced into the ci rculation. (C) 1998 Acoustical Society of America. [S0001-4966(98)0381 1-9].