The effect of extracorporeal shock wave lithotripsy on the microbiological flora of urinary calculi

Effects of Low-energy Shock Waves on Oral Bacteria

We have recently demonstrated that extracorporeal shock-wave therapy (ESWT) is effective in promoting the healing of dermal wounds and in regenerating alveolar bone lost through periodontal disease. The objective of the present study was to determine any antibacterial effect of ESWT on oral bacteria. Monoculture suspensions of 6 bacterial species were treated with 100 to 500 pulses of ESWT at energy flux densities (EFD) of 0.12 mJ/mm2, 0.22 mJ/mm2, and 0.3 mJ/mm2. Following treatment, aliquots were plated for viability determination and compared with untreated controls. ESWT showed a significant microbicidal effect for Streptococcus mutans and an unencapsulated strain of Porphyromonas gingivalis following as few as 100 pulses at 0.3 mJ/mm2 (p ≤ 0.001). In addition, a significant disruption of bacterial aggregates was observed at lower EFDs. No significant reduction in viability was observed for all other bacteria at EFDs and pulses tested (p > 0.05). These findings suggest that low-energy ESWT may be bactericidal for selected oral bacteria.

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.

The effect of isolated high-energy shock wave treatments on subsequent bacterial growth

To determine whether high-energy shock waves possess bactericidal potential, ATCC strains of Escherichia coli, Streptococcus faecalis, Pseudomonas aeruginosa and Staphylococcus aureus were suspended in solution at concentrations approximating 10(6) bacteria per milliliter, placed in polypropylene cryovials, and immersed in the water bath of a Dornier HM3 lithotriptor. Each cryovial was then fluoroscopically guided to the epicenter of the f2 focal point and 2000 shocks at 20 kV applied. Suspensions were then serially diluted and colony counts obtained. The procedure was then repeated with 4000 shocks at 20 kV from the Dornier HM3 and 4000 shocks at intensity level 4 from a Wolff Piezolith 2200 shock wave lithotriptor. Comparison of shock-wave-treated and sham-treated bacterial suspensions revealed no significant difference in bacterial growth according to the colony count technique. We conclude that high-energy shock waves, whether generated by spark gap or piezoelectric array, do not possess significant bactericidal activity.