March 31, 2014
Hearts Become Spherical When Astronauts Go To Space: Study
Lawrence LeBlond for redOrbit.com - Your Universe Online
When astronauts go to space, they are not only affected by a loss of muscle mass, but new research shows that their hearts are also at risk, particularly in the fact that they tend to form more spherical shapes while in outer space.
Previous studies have shown that astronauts are exposed to a range of health issues when taking prolonged trips into space, including losses in bone density and muscle mass and vision anomalies. The new heart health findings, based on a study of 12 astronauts, is to be presented at the upcoming American College of Cardiology’s 63rd Annual Scientific Session.
The new findings bolsters the evidence that even longer periods in space, as would occur on a mission to Mars, is associated with increased dangers on human health. The results of the astronaut study will help scientists better understand how a spaceflight lasting 18 months or longer could affect heart health.
"The heart doesn't work as hard in space, which can cause a loss of muscle mass," senior study author James Thomas, MD, Moore Chair of Cardiovascular Imaging and Lead Scientist for Ultrasound at NASA, said in a statement. "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."
In order to keep the heart healthy in space, astronauts will need to know the amount and type of exercise they need to perform to guarantee their safety on prolonged spaceflights. Thomas noted that exercise regimens developed for astronauts could also help people on Earth who have physical limitations also maintain good heart health.
For the study, the researchers trained astronauts to take images of their hearts using ultrasound machines installed on the International Space Station. The 12 participating astronauts provided data on heart shape before, during and after space missions.
The results show that the heart becomes more spherical by a factor of 9.4 percent. This is on board with what scientists had predicted using mathematical models developed for the project. The team believe the models, developed specifically for the study, could also give doctors a better understanding of common cardiovascular conditions for ground-based patients.
"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.
With the new findings in hand, the team now wants to generalize the models to analyze other heart problems that may occur in space, such as ischemic heart disease, hypertrophic cardiomyopathy and valvular heart disease.
"The models could help us simulate those pathologies to understand the impact on cardiac function," Thomas said.
Thomas maintained that the spherical form is only temporary and returns to a normal shape shortly after astronauts return to Earth. But while in space, a spherical shape may mean the heart is performing less efficiently, although long-term health effects are currently unknown.
However, it has been previously found that some astronauts do suffer a variety of cardiac effects upon returning to Earth. Orthostatic hypotension, where the astronaut becomes lightheaded or passes out, occurs when the body experiences a sudden drop in blood pressure when an astronaut tries to stand up. Arrhythmias can also occur during space travel, and there is concern that radiation exposure may accelerate atherosclerosis.