“Heart Selfies” Reveal What Happens to Your Heart in Space

Your heart stays strong by pumping against gravity

International Space Station

With all the perils Sandra Bullock’s character faced in the movie “Gravity,” heart health probably wouldn’t rank high on her list of worries. But space travel can reshape your heart and possibly weaken it as well.

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At the 63rd Annual American College Of Cardiology’s Scientific Session and Expo, scientists presented evidence that microgravity can affect your heart.

Data from research NASA conducted with funding from the National Space Biomedical Research Institute shows that during extended stays on the International Space Station, astronauts’ hearts changed shape, becoming more spherical (round).

Though striking, the results are no surprise to NASA scientists. They confirm the predictions made by mathematical models created for the study.

Results confirm 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,” says James Thomas, MD, Lead Scientist for Ultrasound to NASA and senior author of the study.

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Lower gravity or a gravity-free environment lessens the effort your heart has to make in order to pump blood through your body. And, like any less-exercised muscle, it can lose strength after a long visit in space.

Twelve astronauts took ultrasound heart “selfies” at all stages of their space travel. That gave scientists before, during and after images of astronauts’ hearts.

Changes to heart structure

The images proved mathematical predictions made prior to the study. The normally slightly longish-shaped heart became more spherical, becoming rounder by almost 10 percent.

Typical earthbound hearts are longer than wide. Researchers theorize the change might involve function as well as structure. Dr. Thomas explains, “The heart doesn’t work as hard in space, which can cause a loss of muscle mass. That can have serious consequences after the return to Earth, so we’re looking into whether there are measures to take to prevent or counteract that loss.”

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Hearts bounce back

Luckily, it seems the physical changes are temporary. The astronauts’ hearts returned to their normal, slightly elongated shape once their owners returned to Earth. Space travelers also experience other symptoms after long trips including dizziness or fainting upon getting up or changing position (orthostatic hypotension).

Other potential heart health risks occur during space travel. Exposure to radiation might accelerate atherosclerosis. Some space travelers also experience increased incidence of arrhythmias, according to previous research done by NASA.

More research needs to be done before the exact toll space travel takes on the heart becomes clear, Dr. Thomas says. Information collected from extraterrestrial travels and microgravity’s influence on heart function can inform the mechanics and stresses back on planet Earth.

Scientists theorize that study of heart function in space might lead to better understanding and treatment of heart failure and valvular disease, as well as developing ways of keeping future travelers healthy during long space flights.

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