Vice President Richard Cheney

U.S. Vice President Dick Cheney left a hospital in Washington Saturday following a scheduled operation to replace a battery in a device that monitors his heart.

Mr. Cheney has a history of heart trouble. He has suffered four heart attacks, the most recent in 2000.

An internal defibrillator was implanted in his chest in 2001. The device monitors his heartbeat and administers an electric shock to the heart muscle to correct irregular beats.

During Cheney's routine physical examination last month, his doctors noticed the defibrillator's battery had weakened to the point that it should be replaced.

Cheney's office said the device had been operating normally and had not had to correct any irregular heartbeats.