Washington, D.C. ? Vice President Dick Cheney, who has a history of heart problems, had surgery Saturday to replace an implanted device that monitors his heartbeat.

Doctors at George Washington University Hospital replaced the defibrillator, a sealed unit that includes a battery. If the device were to sense an abnormal heart rhythm, it would deliver an electronic shock to reset the vice president’s heart to a normal beat.

“The device was successfully replaced without complication,” said Megan McGinn, Cheney’s deputy press secretary.