Shortness of breath is the No. 1 complaint of people suffering from heart failure. Now a University of Guelph researcher has discovered its surprising cause – and an effective treatment.
“We have known for decades that heart patients suffer from shortness of breath, but we never really knew why,” says Jeremy Simpson, a professor in the Department of Human Health and Nutritional Sciences.
“It was generally believed that fluid buildup in the lungs made it hard for heart patients to breathe, and assumed it was a side effect of heart disease that couldn’t be directly treated.”
Simpson linked shortness of breath in heart failure to a hormonal imbalance in the brain.
“We may not think of the brain as being the reason why heart failure patients have trouble breathing when they walk up the stairs, especially when the heart is the sick organ,” he says. “But our organs talk to each other and the brain talks to our diaphragm.”
It is already known that people with heart failure have increased levels of the hormones norepinephrine and angiotensin. The imbalance causes high blood pressure and heart failure.
Simpson and his research team discovered these two hormones indirectly affect the diaphragm.
“Essentially these hormones get into the brain and send signals that push the diaphragm into unrelenting overdrive,” says Simpson. “By suppressing these hormones, we can prevent the diaphragm from becoming weak.”
He says beta blockers and angiotensin receptor blockers that can pass through the blood-brain barrier improved both heart and diaphragm function.
The findings, published in the journal Science Translational Medicine, may improve quality of life not just for heart patients but also for people with other diseases involving shortness of breath, he says.