Potential for cavitation-mediated tissue damage in shockwave lithotripsy.

Area of Science:

• Nephrology
• Urology
• Biomedical Engineering

Background:

• Shockwave lithotripsy (SWL) is a common procedure for kidney stone removal.
• Cavitation is implicated in SWL-induced renal tissue injury.
• Previous studies on SWL-induced cavitation injury primarily used small animals or in vitro models.

Purpose of the Study:

• To investigate the spatial distribution of hemorrhagic lesions caused by SWL in a large-animal model.
• To promote and characterize cavitation during SWL in a porcine model.

Main Methods:

• Utilized a Dornier HM3 lithotripter to target the lower pole calix of porcine kidneys.
• Administered polystyrene microspheres to induce cavitation nuclei in the systemic circulation.
• Performed morphologic analysis of kidneys and inspected abdominal viscera post-SWL.

Main Results:

• Observed extensive hemorrhage on targeted and contralateral kidneys, spleen, intestines, and peritoneum.
• Developed subcapsular hematomas in targeted kidneys.
• Histology confirmed vascular rupture and necrosis of intralobular artery and vein walls in both kidneys.

Conclusions:

• Unfocused shockwaves can damage blood vessels outside the lithotripter's focal zone when cavitation nuclei are present.
• The acoustic field of lithotripters can exceed the cavitation threshold far off-axis.
• Conditions allowing cavitation can lead to significant complications during SWL.