Researchers found that astronaut's hearts become spherical when exposed to long periods of zero gravity.
The finding could help scientists gain insight into health risks associated with space travel, an American College of Cardiology news release reported.
"The heart doesn't work as hard in space, which can cause a loss of muscle mass," James Thomas, M.D., Moore Chair of Cardiovascular Imaging and Lead Scientist for Ultrasound at NASA, and senior author of the study, said in the news release. "That can have serious consequences after the return to Earth, so we're looking into whether there are measures that can be taken to prevent or counteract that loss."
Knowing how much energy it takes to keep the heart healthy could help better-protect astronaut's health in the future.
The researchers trained 12 astronauts aboard the International Space Station (ISS) to examine their hearts using an ultrasound machine. The team found the astronauts' hearts grew spherical by a factor of 9.4, which was consistent with mathematical predictions.
"The models predicted the changes we observed in the astronauts almost exactly. It gives us confidence that we can move ahead and start using these models for more clinically important applications on Earth, such as to predict what happens to the heart under different stresses," Thomas said.
The team is now generalizing the models to reflect "ischemic heart disease, hypertrophic cardiomyopathy and valvular heart disease," the news release reported.
"The models could help us simulate those pathologies to understand the impact on cardiac function," Thomas said.
The heart returns to its normal "elongated" shape after returning to Earth.
"The more spherical shape experienced in space may mean the heart is performing less efficiently, although the long-term health effects of the shape change are not known," the news release reported.
Upon returning to Earth astronauts often feel lightheaded and some even pass out from a drop in blood pressure.