Insidious scarring:
Dr. Jean-François Légaré explores scarring process that leads to 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 Dalhousie Medical School's Division of Cardiac Surgery. "This signal recruits cells called fibrocytes to come from the bone marrow to the heart. While these cells play an important role in healing wounds, in the heart they keep dividing out of control and form more and more scar tissue."
Unlike a heart attack, which causes rapid scarring in a defined area of the heart, this steady laying down of scar tissue causes pervasive scarring 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 research team want to identify and understand the signals that attract fibrocytes to the heart and that keep them proliferating there. They're measuring the levels of fibrocytes in heart tissue samples from patients undergoing heart surgery and searching the patient's blood for the signals that could be responsible. "We're certainly seeing that older patients have higher levels of connective tissue growth factor." he notes. "This is all part of the puzzle we will be exploring in the lab." Ultimately, Dr. Légaré hopes to find a signal that can be blocked or changed with medication to prevent scarring in people with uncontrolled high blood pressure.