Originally published at bhf.org.uk, written by Leanne Grech
Fifty years ago, on 20 July 1969, humans set foot on the moon for the first time and history was made. We now know that weightlessness in space affects both the heart and circulatory system. In microgravity (or very weak gravity), the heart and blood vessels change and the longer spent in space, the more severe the changes.
Houston, we have a structural problem
Both the shape and size of the heart change in microgravity. In fact, studies show that the hearts of astronauts become almost 10% more spherical after long periods of weightlessness in space.
The heart changing shape is not just something that astronauts have to worry about. BHF-funded researchers from Queen Mary University of London found that air pollution, similar to microgravity, changes the structure of the heart.
Professor Steffen Petersen and his team looked at data from around 4,000 participants in the UK Biobank study and showed that even low levels of air pollution can cause serious changes in the heart. They found that people develop larger ventricles if they live near busy, loud roads and are exposed to nitrogen dioxide (NO2) or small particles of air pollution (PM2.5). In addition, they showed that the higher the exposure to the pollutants, the more significant the changes in the structure of the heart. For every 1 extra microgram per cubic metre of PM2.5 and for every 10 extra micrograms per cubic metre of NO2, the heart enlarges by approximately 1%.
While the people monitored in this study had no symptoms, similar heart remodelling is also seen in the early stages of heart failure.
Once in a blue moon…
Abnormal heart rhythms (arrhythmias) have also been observed among astronauts in space. Having an abnormal heart rhythm means that your heart is beating irregularly (atrial fibrillation), too fast (tachycardia), or too slow (bradycardia). A normal heart rate should be 60 to 100 beats per minute. Astronaut Neil Armstrong, spacecraft commander of Apollo 11, had a heart rate of up to 160 beats per minute during his last 20 minutes on the moon.
But tachycardia does not only happen to astronauts after 20+ hours on the moon. For instance, a rare inherited heart rhythm disturbance, known as catecholaminergic polymorphic ventricular tachycardia (CPVT), is found in children and young people. CPVT symptoms include blackouts, dizziness and palpitations. CPVT can also cause the heart to stop beating, leading to sudden death.
BHF-funded researcher Dr Mark Bannister and his team at Cardiff University are studying CPVT. Specifically, they are looking at a protein inside heart cells called the ryanodine receptor which regulates the release of calcium. It is this release of calcium that provides the trigger for each heartbeat. If the ryanodine receptor isn’t working correctly, for example in CPVT, it can lead to a rise in the level of calcium inside heart cells, which can cause arrhythmia.
CPVT could one day be treated using drugs that block the ryanodine receptor. In this project, Dr Bannister wants to find out how a natural blocker of the ryanodine receptor (also called ryanodine) works. In the future, understanding this will help researchers to design new drugs to treat CPVT — a rare but deadly disease.
Skyrocketing blood pressure?
In space, your blood pressure is lower than on Earth, and a study showed that the blood pressure of astronauts was considerably reduced by 10 mmHg, which is just as significant as the reduction you’d normally get from blood pressure medication.
High blood pressure is an extremely common condition in the UK, affecting around one in three adults in England and Scotland. While few have the luxury of going in to space to lower their blood pressure, many are prescribed daily medicines.
BHF-funded researchers are now involving more than 10,000 people with high blood pressure in a 5-year study to answer a simple but important question: when is the best time of day to take blood pressure medicines? Is it in the morning over a bowl of cereal or in the evening over dinner and Netflix?
It’s true that most people tend to take their medicines in the morning. However, there is some evidence that taking blood pressure tablets in the evening lowers blood pressure throughout the whole night, which in turn may have long-lasting benefits on an individual’s overall blood pressure.
In the weightlessness of space, there is also a redistribution of the blood, where more blood goes to the chest and head, causing astronauts to have puffy faces and bulging blood vessels in their necks. The lack of blood flowing to and from the brain can cause astronauts to feel dizzy and sometimes even faint when they return to Earth’s gravity.
On Earth, a decrease in blood flow to the brain is the cause of a condition known as vascular dementia. Because of this, the cells in the affected area of the brain don’t get enough nutrients or oxygen and start to die.
BHF-funded Professor Joanna Wardlaw and her team at the University of Edinburgh are studying vascular dementia which can develop after a stroke and leads to symptoms such as concentration problems and personality changes. In this project, the team will collect biological samples (like blood) and information from hospital records, and perform memory and thinking tests on 2,000 people after they have had a stroke.
In the future, the results from this research will help doctors understand what causes vascular dementia and how to give the best care to people with the condition or at risk of developing it.
It’s not rocket science, or is it?
It took more than 400,000 aerospace engineers and scientists to accomplish the moon landing fifty years ago. Contrary to what their job title suggests, aerospace engineers do not only design and build flying machines. BHF-funded researchers have also been working with aerospace engineers to create a device to assist damaged hearts, which in many ways is just as challenging as landing on the moon 238,855 miles away.
In collaboration with engineers at the Space Research Centre in Leicester, BHF-funded researcher Dr David Adlam has created a prototype for a left ventricular assist device (LVAD) — an artificial heart pump used to treat people with heart failure. Dr Adlam and his team are now hoping to develop it further and be able to test it in humans within the next three years.
Just like the moon landing, scientific breakthroughs take time and effort. Each day spent doing experiments in the lab is a day closer to beating heartbreak forever — each experiment, each result, might well be “one small step for a man, one giant leap for mankind”.
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What can heart researchers learn from astronauts in space? was originally published in British Heart Foundation on Medium, where people are continuing the conversation by highlighting and responding to this story.