For the 67-year-old Cheney, who canceled a campaign event he was to attend later Wednesday in Illinois, it will be the second time in less than a year that he will have the cardiological procedure.
The vice president's office said that after experiencing a problem, Cheney saw the White House physician. It was discovered there that he was experiencing a recurrence of atrial fibrillation, an abnormal rhythm involving the upper chambers of the heart, said Megan Mitchell, a Cheney spokeswoman.
As a result, Cheney was scheduled to go to George Washington University Hospital in the afternoon for an outpatient procedure -- an electrical shock -- to restore his normal rhythm, Mitchell said. Cheney was remaining at the White House until time for the procedure, and participated in regular morning briefings with President Bush among other duties.
Cheney also experienced atrial fibrillation in November 2007, and doctors also administered an electrical shock then. That irregular heartbeat was discovered while White House doctors were treating the vice president for a lingering cough from a cold.
Cheney has had four heart attacks, starting when he was 37 years old, and many related doctor and hospital visits over the years since. He has had quadruple bypass surgery and two artery-clearing angioplasties. In 2001, he had a special pacemaker implanted in his chest. The pacemaker's battery was replaced last year, and then the entire device was replaced.
In 2005, he had surgery to repair an arterial aneurysm on the back of each knee.
In his checkup in July, doctors said Cheney's heart was beating normally for a man of his age and health history.
The campaign event Cheney will miss is for Marty Ozinga, a wealthy suburban concrete company owner. Ozinga is running for the House against Democrat Debbie Halvorson, a high-ranking Illinois state senator.
About 2.8 million Americans have atrial fibrillation, the most common type of irregular heartbeat, and cases are increasing as the population ages. The episodes are not life-threatening in and of themselves, and patients often aren't even aware when they happen. But if the irregular heartbeat continues, it can increase the risk of the formation of blood clots that can shoot to the brain and cause a stroke, which is life-threatening.
Though the heart sometimes gets back into rhythm on its own, the standard way to restore normal heartbeat is electric shock, a low-risk procedure. If that doesn't work, patients may need to take the blood thinner warfarin to reduce stroke risk.
The type of defibrillator Cheney has is used to prevent sudden death from a very different type of irregular heartbeat, the most serious kind that starts in the bottom of the heart.