Former president Bill Clinton is undergoing heart surgery at a New York City hospital.

Doctors began a multiple-bypass operation on the former president early Monday.

Mr. Clinton checked into the hospital late last week, complaining of shortness of breath and chest pains. Doctors scheduled the surgery after tests showed blockages in at least three arteries around his heart.

The Clinton family has received tens of thousands of goodwill messages from supporters. During the weekend, Mr. Clinton told CNN's Larry King that he is looking forward to the surgery so he can feel well enough to jog again. He also reportedly gave campaign advice to presidential candidate John Kerry from his hospital bed.

New York senator Hillary Rodham Clinton says her husband is in good spirits

"He is going to be fine, and he will be back in fighting form before very long, after the surgery and the period of necessary recovery passes," Mrs. Clinton says.

About 250-thousand heart bypass surgeries are performed each year in the United States. The rate of unexpected death is less than four-percent.

Heart bypass surgery involves taking blood vessels from elsewhere in the body and using them to redirect blood flow around the vessels that have become clogged.

Dr. Frank Dorsa is a cardiologist at Westchester Medical Center, where the initial tests were done. He says the recovery period varies, but should be relatively short for Mr. Clinton, who is 58 and generally in good health except for his high cholesterol.

"Older patients tend to stay in the hospital longer, but in general across the board there has been a decline in the amount of time spent in the hospital after routine bypass surgery," Dr. Frank Dorsa says.

Doctors say if all goes according to plan, Mr. Clinton could be out of the hospital in less than a week. Rehabilitation from bypass surgery normally takes about two months.