Pathological effects of extracorporeally generated shock waves on calcified aortic aneurysm tissue

This study was done to define further the limits of extracorporeal shock wave lithotripsy (ESWL) in the setting of proximate calcified aneurysms. Calcified aortic aneurysmal tissue was harvested from patients undergoing elective abdominal aneurysm repair. The aneurysmal tissue was divided into control and experimental sections, and then suspended in normal saline at the F2 focal point, and at 2 and 5 cm. away from the F2 focal point in the major parallel axis of an unmodified Dornier HM3 lithotriptor. Shock waves (200, 500 or 1,000) were delivered at 18 kv. at F2, F2 plus 2 cm. and F2 plus 5 cm. The specimens were then analyzed histopathologically first to compare control and experimental sections for differences in preexisting calcification, hemorrhage and inflammation, and then to grade them for overall evidence of tissue disruption. No significant pathological difference was found between control and experimental specimens treated under these parameters. Our study suggests that human aortic aneurysmal tissue undergoes little pathological change when subjected to therapeutic range ESWL. These findings support previous clinical observations that the presence of a proximate calcified aneurysm does not necessarily preclude ESWL for the treatment of renal or ureteral calculi. The spatial and power limits used in this study may help provide a basis for future safe management of renal and ureteral calculi with ESWL in this setting.