Abstract:

The interaction of air bubbles attached to gelatin surfaces, rat's livers, or rat's abdominal aortas with underwater shock waves was investigated to clarify the tissue damage mechanism by cavitation bubbles induced during extracorporeal shock wave lithotripsy. The overpressure of the shock wave was 10.2(plus or minus)0.5 MPa (n=4). The initial bubble radii varied from 0.12-- 3.06 mm. The subsequent collapse of the bubbles was recorded by a high-speed framing camera. The liver cell damage was histochemically evaluated. The bubble attached to the gelatin or rat's liver surface migrates away from the surface with an oscillatory growth/collapse behavior after the shock wave interaction. The penetration depth of the liquid jet into the gelatin and the diameter of the subsequent damage pit on the surface depend on the initial bubble radius. The bubble near the rat's liver surface or aorta surface tends to show the same behavior as for the gelatin. The elongation and split of the nuclei in the liver parenchyma in the direction of the liquid jet and the increase in the cell density within the circumference of the injured region are histochemically revealed.