Cheney Undergoes Heart Treatment

The US vice president, Dick Cheney, has had an electric shock administered to his heart to restore a normal rhythm.

Cheney - who has a long history of cardiac problems - spent more than two hours at a Washington hospital before being sent home last night after the procedure was declared a success.

Tony Blair underwent a similar procedure to correct an irregular heartbeat in 2004.

Cheney's condition was noticed yesterday morning by doctors examining the 66-year-old for a lingering cough.

He remained at work throughout the day, joining George Bush in meetings with Middle East leaders ahead of today's Annapolis peace conference.

"He was found to have an irregular heartbeat which, on further testing, was determined to be atrial fibrillation, an abnormal rhythm involving the upper chambers of the heart," said Cheney's spokeswoman.

Atrial fibrillation, the most common type of irregular heartbeat, occurs when the heart's top chambers, the atria, get out of sync with the bottom chambers' pumping action.

It is not immediately life threatening and the heart sometimes gets back into rhythm on its own.

Patients are often unaware that it is happening but, if the irregular heartbeat continues, it can cause a life-threatening complication: the formation of blood clots that can shoot to the brain and cause a stroke.

The main treatment is to try an electrical shock to restore a normal heartbeat. If that does not work, patients may need to take a blood thinner to reduce the risk of a stroke.

Cheney has suffered four heart attacks and has undergone quadruple bypass surgery, two artery-clearing angioplasties and an operation to implant a defibrillator device to monitor his heartbeat.