Human sex hormones play a role in improving the function of the right ventricle (RV) of the heart.
The researchers found that in women receiving hormone therapy, higher estrogen levels were associated with higher RV ejection fraction and lower RV end-systolic volume - both measures of the RV's blood-pumping efficiency - but not in women who were not on hormone therapy, nor in men.
Conversely, higher testosterone levels were associated with greater RV mass and larger volumes in men, but not in women, and DHEA, an androgen which improves survival in animal models of pulmonary hypertension, was associated with greater RV mass and volumes in women, similar to the findings with testosterone in men.
For the study, researchers used blood samples and magnetic resonance imaging (MRI) of the heart and measured sex hormones and RV structure and function in 1957 men and 1738 post-menopausal women.
"One of the most interesting things about this research is that we are focusing on individuals without clinical cardiovascular disease so that we may learn about determinants of RV morphology before there is frank RV dysfunction, which is an end-stage complication of many heart and lung diseases," said Steven Kawut of the University of Pennsylvania School.
"When we study people who already have RV failure from long-standing conditions, the horse has already left the barn. We are trying to assess markers that could one day help us identify and intervene in individuals at risk for RV dysfunction before they get really sick," he said,
Because the RV plays a critical role in supplying blood to the lungs and the rest of the body, RV function is closely tied to clinical outcomes in many diseases where both the heart and lungs are involved, such as pulmonary hypertension, COPD and congestive heart failure.
However, the RV is more difficult to study and image than the left ventricle and comparatively little is known about its structure and function and how to treat or prevent right heart failure.
Sex hormone levels could help explain a key paradox in pulmonary arterial hypertension (PAH), where the RV response is an important determinant of survival. While women are far more likely to develop PAH, they also have better RV function and may have a better survival than men.
"It is possible that hormone balance could predispose them to developing PAH, but confer a protective benefit in terms of RV adaptation," explained Kawut.
"We have shown differences in RV structure that go beyond the sexes and may depend on specific hormone levels," he concluded.he study was published online in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.