WASHINGTON, July 28 (Reuters) - U.S. Vice President Dick Cheney resumed his normal schedule shortly after doctors implanted a new internal heart defibrillator on Saturday, a spokeswoman said.

Cheney returned home after the procedure at George Washington University Hospital, spokeswoman Megan McGinn said.

"The device was successfully replaced without complication," McGinn said in an e-mailed statement.

Implanted cardioverter defibrillators monitor the heart and shock it back into a normal rhythm if abnormal beating occurs.

After Cheney's annual checkup last month, his doctors advised him to have the defibrillator replaced because the battery was wearing down. The device was implanted in 2001.

His office previously said the device was functioning properly and had not treated any abnormal heart beats.

Cheney, 66, has had four heart attacks but none since becoming vice president in January 2001. The most recent attack, shortly after the November 2000 election, was considered mild.

The vice president, one of President George W. Bush's closest advisers, also had a blood clot in his leg discovered earlier this year after a nine-day trip through Asia and the Middle East. It was treated with blood-thinning medication.

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