Building a better heart defibrillator
With Canada's aging population, heart failure has become increasingly common. It is estimated that over 500,000 Canadians suffer heart failure each year – a situation that can lead to an increased risk of sudden cardiac death.
For patients at risk of sudden cardiac death, an implantable cardioverter-defibrillator (or ICD) can be inserted into the heart to help regulate the heart beat.
For over ten years, researchers at the Ottawa Heart Institute have been developing and studying a new-and-improved version of this device, which adds insulated wires capable of transmitting electrical impulses to three chambers of the heart. This new addition is called cardiac resynchronization therapy (or CRT) and helps the lower chambers of the heart to beat more strongly and more in unison. In November 2010, a study published in the New England Journal of Medicine revealed that the CRT was found to reduce the risk of death by 24% compared to a traditional ICD.
Co-led by Dr. Anthony Tang and Dr. George Wells at the Heart Institute, the study showed that CRT has the potential to save the lives of thousands of heart patients both in Canada and around the world.
"I've always had a curiosity for wanting to ask and answer questions," said Dr. Tang. "By doing clinical research you can not only help one individual but also get treatments like this one that may make a difference for lots of people. That's the motivation behind it."
In a healthy heart, the muscles all fire at once, pumping blood in a coordinated way. When a dysfunction occurs in the heart, some parts of the organ may contract while others do not.
That's where the CRT comes in – the device helps to synchronize this process, making the heart work in a more coordinated fashion. However, until now, no research had been undertaken to examine the specific benefits and survival rates in heart failure patients who have been implanted with a CRT.
"This particular study is unique in that it actually demonstrated that it keeps more patients out of hospitals for heart failure and also helps them live longer," explains Dr. Tang. "It really translated into meaningful benefits to individuals."
"The patient doesn't really care whether the heart contracts and is coordinating or not," notes Dr. Tang. "What is meaningful for patients is 'Can I live longer?' 'Can I live better?' And we've now demonstrated that this indeed can be the case."
Dr. Wells and Dr. Tang
Dr. Tang is quick to point out that the success of this research trial was due to the collaboration of many individuals and groups all united with a common purpose to improve and extend the lives of
heart patients.
"This is a long-term project that involves a lot of people," said Dr. Tang. "That's an amazing thing that we can do in Canada – the cooperation among all the investigators that are willing to work together on this, and to also involve people in Europe and in Australia. I think that is a manifestation of the eagerness of people to try to find ways to help patients in a cooperative manner. And that is very significant. To me, it's just as significant as the results of the study."
"I'm very grateful that CIHR, with this university-industry program, allowed us to interact with industry to be able to do this kind of work. I think that is huge. This work could not have been done without the support and funding from CIHR but also from industry and the university-based investigators. It's basically three parties able to come together."
The Facts on Cardiovascular Disease
- A conservative estimate: 1.6 million Canadians have heart disease or are living with the effects of a stroke.
- In Canada in 2004, cardiovascular disease was the leading cause of death for Canadians – 72,743 deaths, representing 32% of all deaths.
- In 2000, cardiovascular disease costs in Canada amounted to $22.2 billion – the second highest total cost among all diagnostic categories, only slightly less than musculoskeletal diseases at number one.
- Nine in ten individuals over the age of 20 years have at least one risk factor for cardiovascular disease. Four in ten have three or more of these risk factors. As the number of risk factors increases, so does the risk of cardiovascular disease.
- The risk for developing cardiovascular disease can be reduced by stress management, healthy nutrition, regular physical activity, and maintaining a healthy weight, and by not smoking, avoiding alcohol abuse, and controlling diabetes, hypertension, and high cholesterol.
Source: Public Health Agency of Canada
Cardiovascular Health Research in Canada
The Canadian Institutes of Health Research (CIHR) supports research to prevent and treat cardiovascular disease. In 2009, CIHR invested over $100 million in this field. This work is being carried out by researchers in universities and hospitals across Canada.
The CIHR Institute of Circulatory and Respiratory Health (CIHR-ICRH) helps focus CIHR's work in this area. CIHR-ICRH supports research on heart, lung, brain (stroke), blood, blood vessels, critical and intensive care, and sleep. ICRH's priorities are:
- Obesity, diabetes and cardiovascular complications;
- Technology for diagnostic and therapeutic advances, including imaging technologies for early detection of disease;
- Psychological, social, behavioural and environmental determinants of at risk behaviour for chronic disease, and means of effective interventions;
- Sleep: circadian impact on respiratory and cardiovascular diseases, metabolism and obesity, and means of diagnosis, treatment and prevention;
- Biomarkers for chronic disease, including genetic, proteomic and phenotypic markers for prevention, diagnosis and guidance for therapy;
- Aging and the cardiorespiratory system: changing epidemiology, physiology and means to healthy aging and disease prevention;
- Injury repair and inflammation: mechanisms leading to the development of chronic diseases and their potential prevention; and
- Transplantation-regeneration-cell based therapies to effect cure rather than palliation, including relevant bioethics aspect.
Examples of CIHR-Supported Heart Research in Canada
Dr. Douglas Bradley (University of Toronto) has found evidence that obstructive sleep apnea – a condition that increases risk of heart disease – is linked to fluid retention brought on by a sedentary lifestyle.
Dr. Douglas Lee (Toronto General Hospital) is creating a set of decision guidelines to provide emergency doctors with a better way to decide which patients should be admitted.
Dr. Gregory Miller (University of British Columbia) is examining how depression affects the immune system and hormones and investigating whether the risk of heart disease evolves as depression evolves.
Dr. Alan Katz (University of Manitoba) has found that regular telephone calls to heart failure patients can improve health and reduce long lineups at family doctors' offices.
Dr. Manon Choinière (Montreal Heart Institute) is studying the root causes of chronic post-operative pain after heart surgery, the most comprehensive study of its kind ever conducted in Canada.
Dr. Sandra Davidge (University of Alberta) is investigating whether hormone replacement therapy can increase post-menopausal women's heart health.
Dr. Pamela Ratner (University of British Columbia) is leading several studies looking at how men and women heart attack sufferers experience and respond to their symptoms differently.
Dr. John Rowlands (Sunnybrook Health Sciences Centre) is developing tools that could help surgeons perform open heart surgery more safely – tools may also offer hope to people who are simply too frail to undergo heart surgery.
Nicole Percival, Andrew Mayer, and Jeff Caird (University of Calgary) are evaluating the design features that aid or hinder the use of automated external defibrillators.
Dr. Kathleen Hodgkinson (Memorial University of Newfoundland) is leading research into a rare genetic mutation that causes an irregular heartbeat and sudden cardiac death.
Useful Links
Heart and Stroke Foundation of Canada