By Jane Sims Podesta
Updated March 11, 1985 12:00 PM

Wearing only swim trunks, Greg Peters is strapped to a reclining seat and lowered waist-deep into a tub of warm water. As the operating-room lights dim, Dr. Alan Jenkins, a urologist at the University of Virginia Medical Center in Charlottesville, peers intently at a TV monitor flashing X-ray views of Peters. Then, with ear-ringing booms and bams, an immersed electrode sends 18,000-volt shock waves reverberating through the tub.

It looks diabolical, rather like an invitation to an electrocution. But no, this is not another episode in the perils of Greg Peters, who is a 32-year-old lawyer from Dillingham, Alaska. “It’s like you’re sitting in a swimming pool and hearing this loud, heaving pounding,” he says, emerging unscathed from the tub after some 45 minutes and 1,500 boom-booms. In fact, he feels remarkably better, thanks.

What Peters had just undergone is a revolutionary new treatment for kidney stones, an affliction that plagues an estimated half-million Americans. While what causes kidney stones remains a mystery, the ailment in severe forms produces what some sufferers say is the worst pain known to man.

The West German machine, called a lithotripter (from Greek words meaning “stone” and “to crush”), offers a no-knife alternative for 70 to 80 percent of the estimated 100,000 Americans whose condition is serious enough to require surgery. Although the machine cannot reduce some stones that are too large or too hard, it was hailed last December by Margaret Heckler, Secretary of Health and Human Services, as “an authentic modern miracle.”

What the lithotripter does is to create shock waves through brief (one half of one billionth of a second) electrical jolts, which pulverize brittle kidney stones without harming body fat, muscles or bones. The shock waves are aimed precisely by the surgeon with the use of a computerized monitor. After 200 to 400 jolts the stone starts breaking up and is eventually reduced to the consistency of sand, which can then be passed from the body through urine. An anesthetic that numbs the kidney area is given as a precaution, but patients remain conscious throughout the procedure.

To date, the machine has been used on 10,000 patients worldwide, about 2,000 of them in the U.S. “This procedure appears to be vastly safer and more comfortable than surgery,” says the U.Va.’s Jenkins, 35, who has performed 400 such treatments. “Normally a patient is released from the hospital within three days. Only 10 percent of them require some additional procedure, and there have been only three patients where the machine didn’t crush the stone.”

Jenkins’ colleague, Dr. William Arnold, who frequently administers the anesthetic to lithotripter patients at U.Va., experienced the machine himself last December and found it “like a party. I walked in the hospital at about 7 a.m., put on trunks and waited. I was done riding the machine by 9:35. By 10:30 the anesthetic wore off. By 11:15 I was back working on patients. Sure, the machine sounds like focused thunder, but it was a lot better than getting a slash on the side and being laid up for three months.”

U.Va.’s kidney stone crusher is one of six lithotripters now operating in this country. (Others are in Boston, New York City, Houston, Indianapolis and Gainesville.) Its manufacturer, Dornier System of West Germany, expects to sell 20 to 30 machines in the U.S. this year (price: $1.7 million each). Ordinary kidney stone surgery frequently costs more than $10,000, but doctors hope that lithotripter therapy will eventually cost less than $5,000.

Jenkins, who studied physics at MIT and earned his M.D. at Boston University, professes to be unbothered by the jackhammerlike pounding in his operating room. “As the father of four kids, I’m used to a lot of noise,” he says. As with the other two dozen or so American urologists now certified to operate the lithotripter, Jenkins was trained on it by doctors affiliated with Dornier, a firm better known for its military aircraft. “In studying problems of planes flying through rainstorms at supersonic speeds,” Jenkins explains, “Dornier researchers wondered why raindrops were pitting the aircraft. They discovered it was caused by shock waves. Two engineers were working on it when the physician-wife of one asked, ‘Why don’t you do something like break up kidney stones?’ ” Ach so, why not?