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New implantable defibrillator device offers certain patients a safer alternative

Toronto, August 25, 2016

By Kendra Stephenson

Dr. Victoria Korley performs the second subcutaneous defibrillator procedure on a candidate patient at St. Michael’s Hospital
Dr. Victoria Korley performs the second subcutaneous defibrillator procedure on a candidate patient at St. Michael’s Hospital. (Photo by Yuri Markarov)

Approximately 40,000 Canadians die of sudden cardiac arrest each year, often with little or no warning. Many are young, otherwise healthy individuals with undiagnosed heart conditions that are difficult to catch without extensive screening or genetic testing.

St. Michael’s cardiologist Dr. Victoria Korley treats patients who were able to be diagnosed with these types of conditions before a fatal event, usually with defibrillators, which are battery-powered devices placed under the skin to detect and correct potentially lethal irregular heart rhythms.

In April, she began placing a new device – the subcutaneous implantable cardioverter defibrillator, or S-ICD – in patients who aren’t good candidates for the standard defibrillator. The standard device, called a transvenous defibrillator, is smaller but sits just under the collarbone with the leads fed through the central vein and attached directly to the heart.

The presence of the transvenous leads within the heart tissue can sometimes cause serious complications, including lead displacement or fracture, as well as blood infections. These infrequent but serious complications could require removal of the leads or device, possibly causing hospital readmission or increased risk of death.

“Although effective, the transvenous device is not ideal for certain patients, especially those prone to infections, on dialysis or already using a central line for administering medications,” said Dr. Korley. “The new S-ICD has a much lower risk for infection and is easier to remove in case of an infection because it lives outside the chest cavity.”

   
Did you know?
In Ontario, 200 young people – between ages two and 40 – die from sudden cardiac arrest each year, many of which have an undiagnosed heart condition.

The S-ICD leads sit by the left breast bone, under the skin but over the chest cavity and connected to the device located just under the left armpit. The device is larger than other defibrillators to deliver a strong-enough shock to be effective from outside the chest wall.

Patients are screened to identify their particular condition or arrhythmia and must fit specific criteria. For example, patients who have a condition requiring a pacemaker cannot receive the S-ICD as it does not have pacing capabilities.

“In addition to being equally effective in these patients, the S-ICD is well-received among younger patients because it is more aesthetically appealing,” said Dr. Korley. “Despite its bigger size, the outside scarring is minimal and the leads are not visible beneath the skin. The defibrillator itself also sits in a location that is usually covered by clothing or the patient’s left arm.”

Dr. Korley has performed two S-ICD procedures at St. Michael’s, and both patients are doing well.

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.