WASHINGTON, United States (AP) – Vice President Dick Cheney’s high-tech pacemaker is working properly and has not been activated by any irregular heartbeats, according to his annual physical on Saturday that showed his overall heart condition was stable.

The 65-year-old Cheney, who has a long history of heart ailments, had an electrocardiogram and imaging to check on repaired aneurysms on the back of his knees, his spokeswoman said.

Doctors also checked the condition of an implantable cardioverter defibrillator, which was placed in his chest in June 2001.

Cheney has had four heart attacks; the first in 1978, when he was 37, and the fourth on November 22, 2000, after the election that made George W Bush president.

“The vice president’s cardiac status remains stable, his ICD is functioning properly and has not treated any arrhythmia,” or irregular heartbeat, according to a statement from his spokeswoman, Lea Anne McBride.

Cheney is scheduled to have a stress test on a treadmill in the fall as part of a comprehensive cardiac evaluation.

Dr Bernadette Aulivola, a vascular surgeon at Loyola University Health System in suburban Chicago, said it was a good sign that Cheney’s defibrillator had not been activated since it was last checked.