CALGARY — At age 37, Melanie Cruise doesn’t fit the usual profile of a pacemaker patient.
She had been suffering heart murmurs from birth and doctors had been unable to diagnose her condition.
It wasn’t until she moved to the Calgary area in 2006 that her physician recommended she have an MRI, which helped identify her specific heart condition and led to the implantation of a pacemaker.
“It was my understanding that cardiac MRIs weren’t done a lot previous to that. But they sent me in for that and that’s when they diagnosed it,” said Cruise of Airdrie, Alta.
It was her faith in the MRI that prompted Cruise to take part in a clinical trial in which she was implanted with the first generation MRI-compatible pacemaker, which has now been approved by Health Canada.
“It was a way for us to treat the issues I was having and gave me a little bit of a safeguard,” she said Tuesday in an interview. “For me, my biggest fear is if something went wrong. What were they going to do if they had to take some sort of emergency treatment?”
In recent years, Health Canada had warned patients with pacemakers of the risks associated with scans using magnetic resonance imaging, or MRI. That included the possibility the device could improperly pace the heart or burn heart tissue at the tip of the pacemaker lead.
“You could do MRIs, but it’s definitely risky and, as a matter of fact, Health Canada has a strict recommendation that MRI imaging should not be performed,” said Dr. Anne Gillis, a professor of medicine at the University of Calgary, who played a key role in the trials.
“It may stop pacing or sometimes it may make the pacemakers pace really fast and precipitate potentially a life- threatening heart-related disorder,” she said. “The lead inside the heart can function as an antenna and conduct a radio frequency wave that can actually heat tissue and damage tissue inside the heart.”
Gillis said the new model, created by Medtronic Inc. of Mississauga, Ont., has components that minimize the magnetic effect and the likelihood that electromagnetic waves can damage the pacemaker.
Magnetic resonance imaging is used in radiology to visualize detailed internal structures and is effective when diagnosing cancer, heart or artery conditions.
The use of MRIs has increased 50 to 70 per cent in Canada in the last five years — it’s estimated that in the pacemaker population, requests for the treatment will continue to grow. At age 65, a person’s chances of needing an MRI doubles.
“Requests for MRI imaging will increase over time, particularly as the population ages,” Gillis said. “The average age of a pacemaker patient is about 73, so you know many of those individuals would be requiring MRI imaging for other health-related conditions as they get older.”
“In the future, patients who receive these types of pacemakers will be able to undergo MRI imaging safely, and what that means in terms of their health is if a doctor feels that is the best test to do to investigate a condition, they’ll be able to undergo it safely.”