Dr. Jean-Francois Légaré
Insidious scarring: Dr. Jean-François Légaré explores blood pressure related heart failure
High blood pressure contributes to many kinds of heart disease in many different ways. This is an enormous concern in Atlantic Canada, where more than a fifth of the adults have known high blood pressure and many more carry this silent risk factor unawares.
Cardiac surgeon and heart researcher, Dr. Jean-François Légaré is exploring a mysterious mechanism that, driven by high blood pressure, leads to heart failure. "The strain of high blood pressure must trigger the heart to release some sort of distress signal," explains Dr. Légaré, director of research in Dalhousie Medical School's Division of Cardiac Surgery. "This signal recruits immune cells to come from the bloodstream to the heart. While these cells normally play an important role in healing, in the heart they keep dividing and promote the formation of more and more scar tissue over time."
Unlike a heart attack, which causes sudden scarring in a defined area of the heart, this slow and steady laying down of scar tissue happens all throughout the heart. Over time this reduces the heart's blood-pumping efficiency and leads to heart failure, the most common form of heart disease in Canada.
Dr. Légaré and his team want to identify and understand the signals that attract immune cells to the heart and keep them proliferating there. They're measuring levels of immune cells in heart tissue samples from patients undergoing heart surgery and searching the patient's blood for signals that could be responsible.
"We're certainly seeing that older patients have higher levels of connective tissue growth factor." notes Dr. Légaré, who collaborates with Dr. Ansar Hassan, Dr. Greg Hirsch, Dr. Rob Rose and Dr. John Sapp and others at Dalhousie Medical School. "This is part of the puzzle we will be exploring in the lab." Ultimately, Dr. Légaré hopes to find a signal that can be blocked or altered with medication to prevent cardiac scarring in people with uncontrolled high blood pressure.