Vice President Dick Cheney on Saturday had minor surgery to receive a new battery for an implanted device that monitors his heart rhythms, his spokeswoman said.

"The device was successfully replaced without complication," Megan McGinn, the vice president's deputy press secretary.

Cheney, who has a history of heart problems, arrived with his wife, Lynne, in the morning for the procedure at George Washington University Hospital, and walked out about four hours later. Cheney returned to his home at the Naval Observatory and then resumed his normal schedule, McGinn said.

Doctors replaced the generator and battery part of the heart defibrillator. That device monitors Cheney's heart and would deliver an electric shock to reset the heart to normal rhythm if the heart ever goes out of rhythm.

Doctors did not replace wires that are attached to the device and are threaded through Cheney's heart. That would have required a much more extensive operation.

During Cheney's annual physical last month, doctors tested his implanted cardioverter-defibrillator and learned that the battery powering the device had reached a level where replacement is recommended, McGinn said Friday.

Dr. John Kassotis, director of electrophysiology at State University of New York's Downstate Medical Center, said doctors typically use a local anesthetic on the chest and shoulder area below the collar bone. They make an incision and remove the defibrillator's generator, detaching it from wires that are connected inside the patient's heart.

"Then, they will reconnect a new battery," Kassotis said. "They will test that everything is working appropriately, then they will suture him closed. What we do is watch the patient for about an hour, make sure that they're doing fine, and send them home."

During his checkup in June, Cheney underwent a stress test, and doctors also checked out the defibrillator, which was implanted in June 2001. The stress test showed no blockages in his heart. Doctors also said then that his defibrillator was functioning properly and that they had not had to treat any irregular beating of the vice president's heart.

Cheney, 66, has a history of heart problems. He has had four heart attacks, quadruple bypass surgery, two artery-clearing angioplasties and an operation to implant the defibrillator.

In March, doctors discovered that he had a deep venous thrombosis in his left lower leg. After an ultrasound in late April, doctors said the clot was slowly getting smaller.

In 2005, Cheney had six hours of surgery on his legs to repair a kind of aneurysm, a ballooning weak spot in an artery that can burst if left untreated.