Senator Mike Duffy is recovering in an Ottawa hospital from open-heart surgery, the second such operation he's had to clear up blocked arteries.

Dr. Marc Ruel, chief of the cardiac unit at the University of Ottawa's Heart Institute, conducted the procedure, which began at 6 a.m. Tuesday.

Ruel treated the former broadcaster in 2006 for a similar heart problem. Duffy also suffered a minor heart attack in 1992.

Story continues below advertisement

Andree Dumulon, a spokeswoman for the institute, relayed a message from Duffy's wife Heather, saying, "the surgery went well and … he is now resting in recovery."

Duffy was suspended from the upper chamber last month as part of an ongoing controversy over disputed living expenses. Just weeks before, he took sick leave from the Senate, citing his heart condition.

"At the end of August this year I suffered unstable angina at home on PEI, and spent 2.5 days in the Queen Elizabeth Hospital," Duffy wrote in a press release.

"On examination here this week, my Ottawa GP fears the disease has progressed."

Unstable angina refers to chest pains caused by improper blood flow to the heart, and can be a precursor to a full-blown heart attack.

Doctor-ordered scans revealed several blockages in his arteries.

Duffy is the subject of an RCMP investigation into his living expenses and the subsequent repayment of $90,000 in claims. The Mounties are probing an alleged deal with the prime minister's chief of staff to have a third party reimburse Duffy the cost of the repayment, as long as certain conditions were met.

Story continues below advertisement

One of those conditions was that his repayment would put an effective end to an independent audit into his expenses.

No charges have been laid.

That controversy continues to monopolize both Commons and Senate business. As Duffy lay in hospital Tuesday, the Senate was debating a motion that would call a partner from the firm Deloitte to answer questions about alleged interference into the audit.

Duffy took to the Senate floor in October on two occasions to fight back against his suspension, alleging he was the victim of threats and coercion by the prime minister's staff and key senators.