Former Ontario NDP premier and federal Liberal leadership candidate Bob Rae will be entering hospital next week to undergo heart surgery to repair his aorta.

Rae, who is slated to be the Liberal candidate in the Toronto Centre riding in the next federal election, will have an operation to repair his aorta, which is developing a slowly growing aneurysm.

Rae said he doesn't expect the operation to keep him down for long.

"I am in excellent health, and I'm having the operation because I want to stay in excellent health," Rae said in a news release.

"Doctors have determined that surgery now is the wisest treatment. They are very optimistic about a positive outcome, and expect a return to a full and active schedule after surgery and about six weeks of recovery time."

The aorta is the largest artery in the human body.

It originates from the left ventricle of the heart and brings oxygenated blood to the head, neck, arms, major organs in the chest and abdomen, and legs.

An aneurysm is an abnormal widening or ballooning of part of the artery, related to a weakness in the wall of the blood vessel.

Dr. Tirone David at the Peter Munk Cardiac Centre at Toronto General Hospital, will perform the surgery.

Dr. Alan Lossing, a vascular surgeon at Toronto's St. Michael's Hospital, told The Canadian Press that early treatment of the condition is important.

The surgery will take about three to four hours, with a six-week recovery period being typical, he said.

Aortic aneurysm procedures have a success rate in the 98 per cent range, Lossing said.

At 59, Rae is relatively young compared to the typical aneurysm patient, he said.

Politics

Toronto Centre is the former riding of Bill Graham, who served as interim Liberal leader before Stephane Dion took over in December 2006.

Graham resigned as an MP effective July 2. However, Prime Minister Stephen Harper has yet to declare a byelection date for his riding.

The prime minister has up to six months to call a byelection from the time an MP steps down.

Parliament had been scheduled to resume on Sept. 17, but there is speculation the Conservative minority government will progue Parliament and start a new session with a throne speech in October.

Harper has called three byelections in Quebec for Sept. 17. All three ridings had elected opposition MPs in the 2006 election.

Besides Toronto Centre, the Toronto riding of Willowdale, represented by Liberal Jim Peterson since 1988, requires a byelection. Liberal leadership hopeful Martha Hall Findlay is to be the candidate there.

In the West, Desnethe-Missinippi-Churchill River in Saskatchewan had its Liberal MP step down, and Vancouver Quadra's Liberal MP also resigned. As a result, byelections are also required in those two ridings.

Previous reports have indicated Harper will likely call those byelections for some time in November. If Rae's surgery and recovery goes well, he should be ready to campaign by then.

With files from The Canadian Press