Researchers Get it “Right” in the Study of Heart Failure
By Sidra Sarfaraz
August 30, 2018
When it comes to studying heart failure, clinicians and researchers have long assumed that what happens in the right ventricle (chamber) is similar to what happens in the left. Now, research from the Department of Human Health and Nutritional Sciences has found that changes in the right ventricle follow a pattern over time that is unique from the left ventricle, an important finding when it comes to understanding heart failure.
“Looking at heart failure with a left ventricular focus is insufficient. Both ventricles need to be evaluated simultaneously to understand how the heart is functioning,” says Prof. Jeremy Simpson, who led the study.
Heart failure affects over 600,000 Canadians and occurs when the heart can no longer pump enough blood to meet the needs of the body. Traditionally, cardiac research has focused on the left ventricle, which pumps oxygenated blood out to the rest of the body. The long-standing assumption is that the right ventricle - which pumps blood to the lungs – responds only to the changes in the left ventricle, and not in its own way or its own timeline.
Simpson and senior PhD students Mathew Platt and Jason Huber used a mouse model of heart failure to study how the condition progresses over time in both ventricles. High pressure was induced by surgically constricting the main blood vessel leading out of the heart, the aorta. The reduced size of the aorta creates a back-up of blood, increasing blood pressure and eventually leading to heart failure. While this model is commonly used, no one has characterized the temporal changes occurring in BOTH ventricles.
Platt and Huber collected data on heart function in both ventricles at multiple time points (2, 4, 9 and 18 weeks) to gain better insight into how the heart responds to stress as a whole. They were surprised to find that although it is the left ventricle that is first affected by the increased blood pressure, important changes still occurred in the right ventricle.
Most notably, the right ventricle differed from the left in terms of both the timeline and severity of its response to stress. For example, the left ventricle grew in width whereas the right ventricle grew in length several weeks into the study.
The researchers also found that this model of heart failure developed secondary pulmonary hypertension, which is high blood pressure in the lungs and a common condition in late stage heart failure patients. This means that researchers can use the same animal model to study both heart failure and the associated lung problems, and gain a better understanding of heart failure as a whole.
These findings have important implications for patients. Recent studies suggest that poor right ventricular function and high pressure in the lungs both lead to higher mortality in heart failure patients. Assessing and treating these patients with both ventricles in mind is the next logical step in clinical practice.
“I’m hoping this paper will remind both cardiac researchers and clinicians about the importance of the right ventricle,” says Platt.
Nadya Romanova (University of Guelph) and Keith Brunt (Dalhousie University) were also involved in the study. The study was funded by the National Science Research Engineering Council, Canadian Institutes of Health Research, and the Heart and Stroke Foundation of Canada.
Read the full study in the journal Frontiers in Physiology.
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