US Vice President Dick Cheney underwent a minor operation on Saturday to get a new device to monitor his heartbeat after a checkup found the battery on the old device was running low.
The device, known as an implantable cardioverter-defibrillator, "was successfully replaced without complication," said Cheney spokesperson Megan McGinn.
The operation "went as well as could have been expected," McGinn said, adding that the vice president was back at his home and had resumed his normal schedule.
Local TV broadcast images of Cheney, 66, entering George Washington University hospital on Saturday morning, then walking out around midday.
Doctors replaced the whole device, which is similar to a pacemaker, except for the attached wires that lead to the vice president's heart, McGinn said.
During his annual physical examination in June, Cheney's doctors found that the battery on the device needed replacing.
The operation required only "a small incision and no anesthesia," but Cheney was sedated during the procedure.
During the June check-up doctors said that otherwise the device was functioning properly and that Cheney showed no evidence of new coronary blockage.
Cheney had his fourth heart attack in 2000, the year he and President George W. Bush won the White House. Cheney underwent an angioplasty weeks after being sworn in as vice president in 2001.
In September 2005 Cheney had an operation for blood clots behind each of his knees, and in January last year he was hospitalized for shortness of breath.
The vice president has been taking blood thinners after doctors discovered a blood clot behind his left knee following a nine-day trip to Asia in March.
Arguably the most powerful US vice president ever, Cheney is one of the least popular members of the Bush administration.
A July 6 survey by the American Research Group found that 54 percent of the public would like to see him impeached. The same poll showed that 45 percent wanted president Bush impeached.
The US Constitution says presidents and vice presidents can be impeached -- that is, formally charged by the House of Representatives -- for "treason, bribery, or other high crimes and misdemeanors" by a simple majority vote.
Conviction by the Senate, which requires a two-thirds majority, means removal from office.
In late April, Representative Dennis Kucinich, a long-shot Democratic presidential hopeful, introduced a resolution calling for Cheney's impeachment.