Shocking treatment for kidney stones

Roughly one in ten American males--and perhaps a quarter as many females--will suffer the excruciatingly painful effects of kidney stones at some time in their lives. Some stones will disappear naturally. But government statistics indicate one out of every 1,000 Americans is hospitalized annually for kidney-stone treatment--in many cases, surgery. Now West German researchers offer an apparently painless alternative. In the March JOURNAL OF UROLOGY, Christian Chaussy and colleagues at the Ludwig-Maximilian University of Munich report successful noninvasive destruction of kidney stones using shock waves.

In the procedure (SN: 10/4/80, p. 217), patients in a water bath are subjected to shock waves produced by an underwater high-voltage condenser spark discharge. Each discharge causes an explosive evaporation of surrounding water, which in turn generates shock waves. Spark electrodes are located in the focus of an ellipsoidal reflector. The patient, who has received local anesthesia, is positioned over the ellipsoid so that the stone--monitored with X-ray fluoroscopy--receives the maximum impact from the shock waves.

Roughly 800 spark discharges--kept in phase with the patient's heartbeat, via an electrocardiogram monitor, to prevent arrhythmia--are delivered over the span of an hour and a half. Explains Birdwell Finlayson, a University of Florida urological surgeon who has observed the treatment in Munich, the acoustical transmissivity of water and soft body tissue is lower than that of stone, so shock waves pass through them more slowly. As shock waves attempt to exit a stone, they slow up at the soft-tissue interface and bounce back to collide with fresh, oncoming waves. This collision within the stone results in its shattering.

The procedure itself is as painful "as a haircut," Finlayson says. And most patients are distracted throughout the shocking experience by music piped in over headsets.

Following the treatment, patients remain hospitalized for another five days to await the body's natural elimination of the shattered fragments via the urine. Roughly 15 percent will need treatment for severe abdominal cramps, which may accompany passage of larger stone shards through the ureter (muscular tubes connecting the pelvis of the kidney to the bladder).

Of the 72 patients treated for stones in the renal pelvis during the first year of clinical trials, the researchers report no complications. Two others, whose stones had moved to the ureter, were denied relief because of insufficient stone shattering. Finlayson says that of the 153 patients treated to date, 98 percent have shed their symptoms and roughly 90 percent show total removal of the stone. Stones caused by infection appear most resistant to treatment, probably owing to their density, he notes.

Finlayson cautions American sufferers against rushing off to buy airline tickets for Germany. He says the Munich team is "so overwhelmed by German demand" that all foreigners are being turned away, Meanwhile, Finlayson is in the process of attempting to raise $2.2 million for the purchase of a sister machine from Dornier System GmbH for the University of Florida's medical research center. While there are no such machines in the U.S. yet, the Food and Drug Administration has tentatively okayed the use of up to six for developing further data on the procedure's safety and efficacy. Washington University in St. Louis may be among the first to receive a machine in the U.S., according to William Fair, a urological surgeon at the university Fair says one could be shipped to St. Louis by around the end of the year.

Last updated Dec 12/06