Atomic Hearts

The pacemaker, a miniature machine that controls the heart rate by sending out regular electrical impulses, has meant new life for some 70,000 U.S. cardiac patients. But it has also meant a biennial trip to the hospital for surgery. Reason: the conventional pacemaker, implanted under the skin of the chest, must have its battery changed about every two years. For 16 cardiac patients last week, that recurrent surgery became a thing of the past. In operations performed at the Newark Beth Israel Medical Center and the National Heart and Lung Institute in Bethesda, Md., nuclear-powered pacemakers were installed in their chests.

The palm-size pacemakers, developed by the ARCO Nuclear Co. of Leechburg, Pa., with a grant from the Atomic Energy Commission, use no batteries. They contain 400 mg. of the radioactive isotope plutonium 238. As it decays, the plutonium generates heat. That raises the temperature of a thermocouple system, which converts the heat to electrical power for the pacemaker. The device is similar to the nuclear pacemaker inserted in a French patient in 1970 and now used by 24 Americans. Both pacemakers are expected to operate for at least ten years. That is long enough to make the previous chest operation only a memory.

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