Vice President Dick Cheney's routine checkup on Friday revealed no new blockages in his heart, but doctors said he needs a new battery for a special pacemaker he has in his chest, a spokeswoman said.

The battery in his implanted cardiac defibrillator is reaching its limit, said Megan McGinn, deputy press secretary for the vice president. She said doctors must replace the entire device to replace the battery, and that the surgery will be scheduled this summer at a convenient time for the vice president.

Cheney underwent his annual physical, which included a stress test, at the George Washington University Medical Faculty Associates near George Washington University Hospital. Doctors also checked out Cheney's cardiac defibrillator, which was implanted in June 2001 to shock his heart if he an irregular heartbeat.

A stress test "showed no evidence of new coronary blockage," McGinn said. She added that doctors said his defibrillator was functioning properly and that they had not had to treat any irregular beating of the vice president's heart.

Cheney, 66, who has a history of heart problems, resumed his normal schedule after the checkup. Doctors did not address the clot Cheney has in his leg.

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

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

He has had four heart attacks, quadruple bypass surgery, two artery-clearing angioplasties and an operation to implant the defibrillator.