A 48-year-old heart patient in New Jersey became the first recipient of a plutonium-powered dual-chamber heart pacemaker designed to last 20 to 40 years, a hospital said. Doctors at Newark Beth Israel Medical Center said John Sniffen of Clifton, N.J., was “doing fine” after a 90-minute operation in which they replaced his old pacemaker with a Pulsar N-1. The new device, designed by Biocontrol Technology Inc. of Indiana, Pa., is powered by plutonium 238 encapsulated in a titanium shell. The device is the first plutonium-powered pacemaker approved for use in maintaining the rhythm of both chambers of the heart, doctors said. It is expected to last three to six times as long as the lithium battery-powered pacemakers now in predominant use.