Vice President Dick Cheney had surgery yesterday to replace an implanted device that monitors his heartbeat.
Doctors at George Washington University Hospital replaced the defibrillator, a sealed unit that includes a battery. If the device were to sense an abnormal heart rhythm, it would deliver an electronic shock to reset the vice president's heart to a normal beat.
"The device was successfully replaced without complication," said Megan McGinn, the vice president's deputy press secretary.
Doctors did not replace the wiring attached to the defibrillator. Replacing the defibrillator wires, which thread through the vice president's heart, would have required a much more extensive operation.
Mr. Cheney, wearing a sports jacket and open-collared shirt, smiled and waved as he left the hospital about four hours after he arrived in the morning with his wife, Lynne.
"The vice president feels fine," Miss McGinn said.
She said that the Cheneys returned to their residence at the Naval Observatory and that the vice president would resume his normal schedule.
Dr. Stephen Siegel, a cardiologist at New York University Medical Center, said the device doctors replaced in Mr. Cheney is about the size of a large sports watch.
"It's slipped between muscle and skin in the upper part of the chest," he said. "The area of the wound will be a little sore for a couple of days."
Dr. Siegel said he was not familiar with Mr. Cheney's surgery, but that it was standard procedure to induce an abnormal or fast heart rhythm to test that the new device is working.
Patients who have the same procedure usually do not need anything more than over-the-counter pain relievers afterward. Typically, these patients are told to avoid major exercise for a week or two, he said.
Mr. Cheney has had four heart attacks, quadruple-bypass surgery, two artery-clearing angioplasties and an operation to implant the defibrillator six years ago.
During Mr. Cheney's annual physical last month, doctors tested his implanted cardioverter-defibrillator and learned that the battery had reached a level where replacement was recommended.