By Dr. Susan Howlett
(Published in The Chronicle Herald, September 19, 2007)
Almost every day, media tell us about new medical discoveries – but the impact of medical research can’t be understood from the results of a single study. Each study builds on years of work. There are only a few ‘eureka’ moments when an entire field moves ahead in a giant leap. Most of the time, we take baby steps. But over fifty years, we can see enormous progress. Consider, for example, what we’ve learned about heart health.
A heart attack occurs when the arteries to the heart are blocked, and heart cells die due to lack of oxygen. This usually happens in people with an artery disease, such as arteriosclerosis. Also called ‘hardening of the arteries,’ it was viewed very differently 50 years ago. According to the 1950 edition of the classic textbook used to educate doctors in Canada, Harrison's Principles of Internal Medicine: “Arteriosclerosis, removing people from active life when the period of maximum fertility has passed, is of benefit to the young if it relieves them of the care of parents, or brings them an inheritance as they enter adult life. But this biologic blessing must be paid for later, for the way to avoid the disease is to have, and to be responsible for, long-lived ancestors.”
Doctors in the 1950s knew high cholesterol levels were involved in hardening of the arteries, but all they could do was advise patients to reduce cholesterol intake. The only ‘treatments’ for high cholesterol were drugs which caused major stomach problems and were unproven to lower cholesterol or prevent heart attacks.
Research has since shown us many different risk factors for arteriosclerosis. We know we can reduce our risk by eating a healthy diet, exercising, not smoking, and maintaining a healthy weight, but we also know that there is more to arteriosclerosis than lifestyle. Even aging marathon runners can develop high cholesterol.
The past fifty years of intensive, worldwide research have helped us understand what leads to hardening of the arteries. As we have learned about the disease process, we have developed drugs to treat the disease. The drugs not only lower cholesterol levels, they decrease the risk of heart attack. Years of laboratory research have also led to techniques for screening people at genetic risk of arteriosclerosis. We can now treat people before they get into trouble.
People in the 1950s also knew high blood pressure leads to heart attacks. Harrison’s recommended salt restriction – but also suggested low doses of a toxic sedative to treat the “dread of the disease.” It mentions other drugs, including a cyanide derivative, which were regarded as too hazardous to be very useful. These days, thanks to research, specific lifestyle changes and safe medications are used to reduce blood pressure and save lives.
If you had a heart attack fifty years ago, most of the now-routine treatments were not available. People knew aspirin relieved headaches, but did not know it could prevent blood clots during a heart attack. They could not treat heart rhythm disorders which kill so many people with heart attacks. They could not prevent the scarring that impairs heart function in people who do survive.
Now, researchers at Dalhousie Medical School are fine-tuning procedures that treat rhythm disorders, and pioneering cellular treatments to repair heart attack damage and prevent scarring and heart failure.
In my laboratory, we are learning how individual cells in the heart respond to changes that take place during a heart attack. We can even reproduce these changes in a petri dish. We want to know if changes that occur in the normal aging process make heart cells more sensitive to a heart attack. These studies may show us how to make the aging heart more resistant to the damaging effects of a heart attack.
The 1950s Harrison's concludes: “Arteriosclerosis and hypertension (high blood pressure) are now the chief factors in determining that we do not overstay our allotted span of life too long.”
Clearly, these days we are doing much better than that. Fifty years of medical research has had a huge impact on our lives. But there is still a long way to go. Cardiovascular disease continues to be the leading killer of Canadians.
Dalhousie Medical Research Foundation has supported my research and that of my colleagues for many years, helping us to build and maintain a thriving cardiovascular research community. This year, the foundation’s annual Molly Appeal is devoted to heart research. Through this appeal, Maritimers can play a direct and vital role in our progress. With continued long-term investment in research, the next fifty years will be even more productive than the past.
Dr. Susan Howlett
Professor, Department of Pharmacology
Dalhousie Medical School
Halifax, Nova Scotia