Canadian Mother Is First North American to Receive MRI-Compatible Defibrillator Implant

Every year, an estimated 1.5 million MRI scans are performed in Canada alone and the number is growing at a rate of approximately 10% per year. At the same time, a mounting number of Canadians who rely on implanted defibrillators to keep their hearts beating are denied this beneficial, life-saving diagnostic test in spite of a 50%–75% probability that they will require one over the lifetime of their defibrillator.

In December 2012, cardiac patient Justine Bovenkerk, a 35-year-old wife and mother from Newmarket (ON, Canada), needed a defibrillator implant to treat a heart disorder, but also required undergoing regular MRI scans to monitor other health conditions. The Heart Rhythm Program at Southlake Regional Health Center (Newmarket, ON, Canada) became the first medical team in North America to insert an MRI-friendly implantable cardioverter defibrillator (ICD) into this patient’s heart.

“We were in a bind,” said Dr. Atul Verma, an electrophysiologist at Newmarket’s Southlake Regional Health Center, noting that there are no MRI-safe defibrillators currently licensed for use in Canada. The drawback is that MRI scans can cause disturbances that affect implanted defibrillators, resulting in potential injury to patients. One alternative would have been to forego the MRI and use computed tomography (CT) scans, which would have been less successful as a monitoring application, and the other was to use an MRI-safe pacemaker that could not have provided the full protection against cardiac arrest that her heart needs. “We didn’t feel good about either option.”

After learning about an MRI-safe defibrillator widely used in Europe—the Lumax ProMRI supplied by Biotronik Canada, Inc. (Etobicoke, ON, Canada)—Southlake’s Heart Rhythm Program applied for and received Health Canada’s approval to use the device to treat Ms. Bovenkerk. The minimally invasive procedure was performed on December 24, 2012, allowing the young mother to be home with her family on Christmas Day. “It was a true team effort, from the triage coordinator who helped to schedule the procedure at the last minute, to the nurses who worked a little later than normal on one of the most popular holidays of the year,” noted Dr. Verma.

The MRI-friendly defibrillator is implanted in the same way as other ICDs, using a small incision near the collarbone. Wires are floated through the veins and attached to the heart while the “brains” of the technology, stored on a small computer chip, are inserted under the skin near the incision. If the patient’s heart starts to beat too rapidly or too slow, the device will readjust the beats to a normal rhythm. If a patient goes into cardiac arrest, it will shock the heart in the same manner as defibrillator panels used outside the body.

“Heart disease is the number one killer of Canadians and defibrillators are increasingly used for anyone who is at risk of cardiac arrest, including people who have had prior heart attacks, people who have advanced degrees of heart failure or people with special inherited conditions as in the case of Justine,” Dr. Verma explained. “Meanwhile, MRI is becoming the diagnostic test of choice. Normally, a radiologist will say no to a patient with an ICD, and now we have a solution.”

Currently, the only MRI-safe device available in Canada is a pacemaker that is different from a defibrillator because it can only speed up the heart when it beats too slowly. It does not have the capability to slow down the heart when it beats too rapidly and cannot shock the heart in the event of cardiac arrest. Last year, 8,300 defibrillator implants were performed in Canada, a number that is growing at a rate of 10%–15% annually.

What sets the Biotronik device apart from other defibrillator implants is a special programming feature that provides an MRI mode, allowing patients to safely undergo an MRI scan with simply the wave of a wand. “There’s a wireless wand we wave over the patient to download information from any implanted defibrillator to a laptop,” explained Dr. Verma. “If you need to program the device differently—or in this case, set the MRI mode—you just type in what you need, wave the wand again, and it automatically updates the device inside the patient.”

Expected to receive Health Canada approval in the spring of 2012, the MRI-friendly defibrillator represents a giant step forward, Dr. Varna added. The MRI-safe mode, for example, alerts the device that it is about to detect an abnormal amount of background noise or disturbance due to the magnetic fields used in an MRI so that it can adjust appropriately. This removes the risk of the MRI interfering with normal performance of the device and possibly causing harm to a patient. MRI-friendly defibrillators also have slight differences in structure and composition that make them safer to operate in magnetic fields.

“At Southlake, our culture is one of innovation,” stated Dr. Dave Williams, Southlake president and CEO. “We relentlessly challenge ourselves to find new ways to achieve more successful outcomes for our patients. The fact that Justine Bovenkerk can now receive the diagnostic testing she needs speaks volumes. As an organization, we could not be more thrilled.”

Related Links:
Southlake Regional Health Center
Biotronik Canada