Morphological changes induced in the pig kidney by extracorporeal shock wave lithotripsy: Nephron injury

Abstract

While shock wave lithotripsy (SWL) is known to cause significant damage to the kidney, little is known about the initial injury to cells along the nephron. In this study, one kidney in each of six juvenile pigs (6 -7 weeks old) was treated with 1,000 shock waves (at 24 kV) directed at a lower pole calyx with an unmodified HM-3 lithotripter. Three pigs were utilized as sham-controls. Kidneys were fixed by vascular perfusion immediately after SWL or sham-SWL. Three of the treated kidneys were used to quantitate lesion size. Cortical and medullary samples for light (LM) and transmission electron microscopy (TEM) were taken from the focal zone for the shock waves (F2), the contralateral kidney, and the kidneys of sham-SWL pigs. Because preservation of the tissue occurred within minutes of SWL, the initial injury caused by the shock waves could be separated from secondary changes. No tissue damage was observed in contralateral sham-SWL kidneys, but treated kidneys showed signs of injury, with a lesion of 0.2% Ϯ 0.1% of renal volume. Intraparenchymal hemorrhage and injury to tubules was found at F2 in both the cortex and medulla of SWL-treated kidneys. Tubular injury was always associated with intraparenchymal bleeding, and the range of tissue injury included total destruction of tubules, focal cellular fragmentation, necrosis, cell vacuolization, and membrane blebbing. The initial injury caused by SWL was cellular fragmentation and necrosis. Cellular vacuolization, membrane blebbing, and disorganization of apical brush borders appear to be secondary changes related to hypoxia. Anat Rec Part A 275A: 979 -989, 2003.

Shock-induced bubble jetting into a viscous fluid with application to tissue injury in shock-wave lithotripsy

“…The tubules on the other side of this line and a few isolated in the disrupted region appear intact, but when examined in greater detail the cells there show blebbing and enlarged electron-clear vacuoles suggestive of localized ischemic injury. 46 The cells and tubules near this borderline also seem to show more injury on sides adjacent to the disrupted area, 46 which is consistent with the apparent spreading character of the injury. Within about three tubules from the disrupted region, the tissue appears completely normal.…”

“…8, suggest that injury spreads in sharp fronts behind which the tissue appears utterly disrupted. 46 The tissue in this image was fixed by vascular perfusion immediately following the delivery of 1000 shock waves. This rapid fixing and relatively short treatment time was done so that the primary mechanical shock-wave injury could be distinguished from any subsequent injury due to hypoxia or other mechanisms.…”

“…͑7͒ leads to a spreading that is consistent with the observations in lithotripsy. It should take around 1000 shocks before widespread injury is observed, 2,46 yet upon reaching a typical clinical dose of 2000 shocks the injury should have an ϳ1 cm scale, 46,47 whatever its actual shape. Lesion geometric effects will be grouped into an undetermined efficiency parameter g.…”

Suppression of shocked-bubble expansion due to tissue confinement with application to shock-wave lithotripsy

“…Pooling of blood in lesions, whatever their cause, is potentially a route to reduced viscous confinement. Similarly, examination of kidney tissue injured by shock-wave lithotripsy shows that the entire microstructure is disrupted, 36 which will also tend to reduce its viscosity and thereby perhaps also facilitate bubble growth and spreading cavitation damage.…”

Using 300 Pretreatment Shock Waves in a Voltage Ramping Protocol Can Significantly Reduce Tissue Injury During Extracorporeal Shock Wave Lithotripsy

“…The design of the extracorporeal shock wave lithotripsy (SWL) experiment and all surgical procedures used during the experiment followed the same methods used in previously published studies. [6][7][8] Fifteen female farm pigs, weighing &15 kg each (Hardin Farms, Danville, IN), were anesthetized, and each animal was placed in an unmodified Dornier HM-3 lithotripter (Dornier Medical Systems, Kennesaw, GA). A lower pole calix of the left kidney of each animal was targeted for lithotripsy treatment by retrograde infusion of X-ray contrast (Isovue-300; Bracco Diagnostics, Princeton, NJ) and imaging with the biplanar X-ray system of the HM-3.…”