Small device packs a big shock

It’s not even as big as the palm of your hand, but it packs a wallop so powerful that it can knock you over. Some people say that when it fires it’s like having a gun go off in your body or being kicked by a mule. If you have one, you either fear it or love it.

This Implanted Cardioverter Defibrillator (ICD) and patients’ attitudes toward it are what Professor Jane Irvine (BA ’74) in York’s Department of Psychology, Faculty of Health, is investigating.

Right: Professor Jane Irvine

ICDs, implanted underneath the pectoral muscle near the shoulder and connected to the heart by electrodes, monitor fast rhythms in those who have life-threateningly rapid heart beats. "If the rhythms are too fast, they can impair blood circulation to the brain, so typically people will die or be impaired after a few minutes, from lack of oxygen in the brain," explained Irvine. "People at risk who have these smart devices should be able to lead normal lives, because they have their own defibrillators that deliver shocks to correct abnormally fast heart rates."

However, the treatment isn’t that straightforward and Irvine says some people have trouble coping with the tremendous charge when the device kicks in. "It’s fine if they have one or two shocks. That tells them the ICD is working. But if they receive several shocks, some find it traumatizing. They might develop severe avoidance anxiety, and stay away from what they perceive as triggers. For instance, if the ICD kicked in when the person was turning on a tap or a radio, he or she might then avoid those activities," said Irvine.

"There are more extreme cases of avoidance. Sometimes people are embarrassed socially if the shock has caused them to fall down, and they will then stop going out."

As stress producers, Irvine says, shocks are understandably high on the list. They are unpredictable, uncontrollable by the patient and sometimes downright painful.

Left: A graphic showing an Implanted Cardioverter Defibrillator. Graphic courtesy of the Heart Rhythm Society.

Irvine’s current study is an extension of her many years of assessing the psychological aspects and quality of life after someone receives an ICD, which she examined in the large, randomized, contolled Canadian Implantable Defibrillator Trial conducted during the 1990s.

"In that study, we discovered that as long as people didn’t get shocks, their quality of life and psychological adaptation was better than people who took only drugs to control the problem. They had a sense that the ICD was a security blanket – viewed it as life-saving and saw it as a vital part of themselves," said Irvine. 

In some cases, added Irvine, patients positive about their device have gone for the usual twice-yearly ICD check-up [when the doctor sees if it has kicked in and checks the battery], and are surprised to learn that the device has delivered a shock at some point. They hadn’t even noticed.

And, surprisingly, among those who fear ICD shocks, some believe they’ve received them when they have not. Another aspect of Irvine’s current study is looking at these "phantom shocks".

Irvine’s theory is that people who adapt poorly to ICDs want to control the uncontrollable – that is, control when the shocks go off. They become hyper-vigilant and use avoidance behaviour. They often mistakenly think their heart is deteriorating or that the ICD is damaging their heart.

"We believe people do better with ICDs when they are informed about the device in advance, and learn to focus more on controlling their reactions to shocks than controlling the device itself," she said.

The current study comprises 218 patients, looks at the role of counselling half of whom are given interventions in the form of education and counselling about ICDs and what to expect from them, and half who are not.

Irvine and her team of researchers from York University, University of Toronto, Toronto General Hospital and St. Michael’s Hospital in Toronto, have less than a year-and-a-half to go in the five-year Heart and Stroke Foundation of Ontario-funded study. Irvine said that waiting for the final results is tantalizing.

Irvine, who completed a master’s degree at the University of Edinburgh and a PhD at Oxford University, specializes in clinical health psychology. As well as teaching at York and the University of Toronto, she conducts research at the University Health Network of the Toronto General Hospital.