Grant: Operating Grant

In developping countries, heart valve diseases such as aortic or mitral insufficiency (AR and MI; regurgitation) are frequent and mostly due to endemic rheumatic fever. Immigrants to Canada from such countries should be considered at high risk of having significant rheumatic aortic or mitral valve disease. Rheumatic fever has declined dramatically in Canada but still accounts for a major percentage of cardiac morbidity in developing countries. Aboriginal Canadians are also at higher risk due to their lower socio-economic status and sometimes improper access to health care. Other causes of aortic or mitral insufficiency are either congenital anomaly, disease of the ascending aorta, degenerative or secondary to an infarct (MI). These valve diseases cause heart dilatation which can sometimes go unnoticed for years before apparition of symptoms such as shortness of breath, fatigability and eventually heart failure if the valve is not surgically replaced by a prosthesis soon enough. Our goal is to better understand in a rat model how the heart adapts to these valve diseases, what are the mechanisms of heart dilatation and why the heart muscle capacity of forming enough energy to fulfill its pump function decrease over time. Our animal model is also unique in giving us the capacity to study a pre-heart failure situation and the slow decline towards this state. It offers us a window to observe over months the mechanisms leading to heart failure in a controlled fashion. In this proposal, we intend to study more in details how the dilated heart manages the formation of its energy to fulfill its function and how lifehabits changes (exercise or diet) can alter positively or not this parameter.