Heart becomes more spherical when exposed to long periods of microgravity in space, a change that could lead to cardiac problems, a new research has found.
The findings from a study of 12 astronauts represent an important step toward understanding how a spaceflight of 18 months or more could affect astronauts' heart health, researchers said.
"The heart doesn't work as hard in space, which can cause a loss of muscle mass," said James Thomas, Moore Chair o f Cardiovascular Imaging an d Lead Scientist for Ultrasound at NASA, and senior author of the study.
"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," Thomas said. The researchers said that knowing the amount and type of exercise astronauts need to perform to keep the heart healthy is going to be very important to guarantee their safety on a long flight like a mission to Mars.
Thomas added that exercise regimens developed for astronauts could also be used to help maintain heart health in people on Earth who have severe physical limitations, such as people on extended bed rest or those with heart failure. The research team trained astronauts to take images of
their hearts using ultrasound machines installed on the International Space Station. Twelve astronauts participated, providing data on heart shape before, during and after spaceflight.
The results show the heart in space becomes more spherical by a factor of 9.4 per cent, a transformation similar to what scientists had predicted with sophisticated
mathematical models developed for the project. By validating those models, the study could also lead to a better understanding of common cardiovascular conditions in
patients on Earth.
"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 working to generalise the models to analyse such conditions as ischemic heart disease, hypertrophic cardiomyopathy and valvular heart disease. The astronauts' more spherical heart shape appears to be temporary, with the hear the returning to its normal elongated
shape shortly after the return to Earth.
The more spherical shape experienced in space may meanthe heart is performing less efficiently, although the long-term health effects of the shape change are not known,