Sass W, Dreyer H P, Kettermann S, Seifert J
Department of Experimental Surgery, University of Kiel, Germany.
J Stone Dis. 1992 Jul;4(3):193-207.
The role of cavitation during shock wave exposure was poorly understood until now. Cavitational activity produces severe damage to nearby surfaces due to multiple high-speed liquid jets resulting from bubble collapse. These jet impacts can be made visible by microscopy. For investigating the presence of cavitational processes by shock waves outside and even inside of targets, we have performed the following experiments. Natural gallstones and artificial targets were examined microscopically with regard to the effects of shock pulses. Scanning electron and light microscopical investigations revealed regularly typical and uniform microjet impacts within the fissures and split lines. Since these experiments are the continuation of high-speed films of 10,000 frames/s of shock wave actions on targets, it is most likely that the shock wave produces at first split lines through the stone. Then liquid occupies these cracks. But the following shock waves create within these liquid-filled fissures cavitation and, therefore, cause the disintegration of the targets. It now becomes understandable why biliary lithotripsy is less effective than renal lithotripsy: bile fluid is a high-viscous liquid and, therefore, hinders the disintegration of stones more than low-viscous urine. Intervals between the application of shock waves in biliary lithotripsy, therefore, should improve the treatment results.
直到现在，人们对冲击波作用过程中空化现象的作用仍知之甚少。空化活动会对附近表面造成严重损伤，这是由于气泡坍塌产生多个高速液体射流所致。通过显微镜可以观察到这些射流冲击。为了研究冲击波在目标外部甚至内部产生空化过程的情况，我们进行了以下实验。对天然胆结石和人造目标进行了显微镜检查，以观察冲击波脉冲的影响。扫描电子显微镜和光学显微镜研究显示，在裂缝和分裂线内有规则地出现典型且均匀的微射流冲击。由于这些实验是对以10000帧/秒的速度拍摄的冲击波作用于目标的高速影片的延续，很可能冲击波首先在结石中产生分裂线。然后液体占据这些裂缝。但随后的冲击波会在这些充满液体的裂缝中产生空化现象，从而导致目标解体。现在就可以理解为什么胆石症碎石术比肾石症碎石术效果差了：胆汁是一种高粘性液体，因此比低粘性的尿液更能阻碍结石的分解。因此，胆石症碎石术中冲击波施加的间隔时间应能改善治疗效果。
