Medicine: Implanted Pacemaker

The patients who made the biggest news at last week’s meeting of the American Heart Association in Miami were those who can talk about their “tickers” without being cute. They are the growing number, estimated at 200, whose heartbeats are timed by transistorized pacemakers implanted under the skin of their bellies. Surgeon William M. Chardack told how he and his colleagues at the Veterans Administration Hospital in Buffalo have miniaturized and refined the instruments for internal use since external pacemakers were first shown to be practical (TIME, Jan. 11. 1960), and how they have implanted pacemakers in 30 patients in the last 18 months.

For most heart-disease victims, an internal pacemaker is neither necessary nor suitable. But in some severe cases, the electrical impulses that stimulate the heart’s contractions are blocked so that the heart slows down, beats only feebly, and is in constant danger of stopping, causing spells of unconsciousness.

Working with electronic engineers, the Buffalo doctors devised a transistorized pacemaker, driven by a tiny, long-life mercury battery, cast in epoxy resin and encased in a double coating of silicone rubber. The instrument uses the timing effect of electrical surges in a closed circuit to measure off 60 beats a minute. To carry the impulses to the heart, Dr. Chardack uses two springs of platinum-iridium alloy, attached to the heart muscle.

The implantation is done in one operation. Surgeon Chardack opens the chest to get the electrode into the heart wall and leads the connecting wire through a tunnel under the skin to another incision in the abdomen, just to the left of the navel. He sets the pacemaker on a bed of abdominal muscle. Only 2 by 3 by ½ in., it is so compact that the patient can bend double without feeling it. The battery should last four to five years, and failure is not fatal. The heart jogs along until the battery is replaced.

Some pacemaker experimenters have invented devices to let patients speed up their hearts, by radio signals to the instruments, when exertion demands a greater blood supply. But Dr. Chardack prefers to give the physician this control. In the latest models of the Buffalo pacemaker, there is a second protuberance just underneath the skin. By simply jabbing a triangular needle into this, the physician can adjust the rate.