WASHINGTON (CNN) -- A procedure to restore Vice President Dick Cheney's heart to a normal rhythm went "smoothly and without complication," his spokeswoman said Wednesday.

Earlier, Megan Mitchell said doctors called to Cheney's White House office Wednesday morning found he was experiencing a recurrence of atrial fibrillation, an abnormal rhythm involving the upper chambers of the heart.

Doctors at George Washington University Hospital delivered an electrical impulse to restore Cheney's heart to a normal rhythm, Mitchell said in a statement released late in the day.

After the procedure, Cheney returned home, Mitchell said.

He had spent the morning at the White House, although he did not attend the morning Cabinet meeting. Mitchell said she was unsure what prompted the morning call to physicians.

Cheney also canceled a Wednesday campaign event in Homer Glen, Illinois, for Marty Ozinga, a Republican nominee for a U.S. congressional seat. The vice president instead called and expressed his support for Ozinga, Mitchell said.

Prior to the procedure, Cheney updated President Bush on his health condition, White House Deputy Press Secretary Tony Fratto told reporters.

Fratto said Bush wished the vice president well.

Cheney previously experienced atrial fibrillation last November. George Washington University Hospital doctors also used an electrical impulse then to restore his normal heart rhythm.

Cheney has had four heart attacks dating back to 1978, when he was 37. He suffered his second in 1984 and a third in 1988 before undergoing quadruple bypass surgery to unblock his arteries.

His fourth heart attack occurred in November 2000, after he was elected vice president. At that time, doctors inserted a stent to open an artery.

In 2001, the vice president had a cardiac defibrillator implanted to regulate his heartbeat.

In July, after his annual checkup, doctors said his cardiac status remained stable.

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