How can plane travel increase the risk of heart attack?

Cramped airplanes can leave your heart in a tight spot if you don't get up to move. See more heart health pictures.
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When Vice President Dick Cheney was treated for a blood clot in 2007 after a series of long airplane flights, it wasn't all that surprising. Cheney was 66 years old and had a long history of heart disease, and abnormal clotting can be characteristic of that diagnosis. Far more surprising is the fact that 47-year-old former Vice President Dan Quayle developed blood clots after a long plane flight in 1994, and 39-year-old reporter David Bloom died of a blood clot in 2003 after spending days sitting inside a tank.

Bloom's clot was a DVT, or deep vein thrombosis, that became a pulmonary embolism. DVT is a blood clot that forms in the deep veins of the leg or groin. When that blood clot breaks free and travels through the blood to the lungs, it becomes a pulmonary embolism, which can cause a heart attack and can be fatal if it's not treated in time. Bloom's doctors in Iraq did everything right, but by the time Bloom sought treatment, it was too late.


That someone in his 30s can die from a travel-induced blood clot may seem like an anomaly, but it's not. Blood clots that result from long periods of sitting in one place are pretty common -- as many as 600,000 Americans develop this type of clot every year, and perhaps 100,000 of them die from it [source: Ohio]. Most people never even know they have one. The clot often dissolves before it causes any symptoms.

Travel-related DVT is sometimes called economy class syndrome because it's so often linked to long plane flights. This is part of the reason why so many of these clots become fatal pulmonary embolisms. Because they tend to develop during and after long flights, people may assume the leg discomfort they're feeling is just a cramp from sitting for too long, and they don't seek medical attention until it's too late. When clots, and even pulmonary embolisms, are treated in a timely manner -- usually with blood thinners -- they can almost always be resolved [source: CBS]. Recognizing the symptoms early is crucial.

In this article, we'll look at the symptoms of a blood clot and find out why it's linked strongly to plane travel. We'll also discuss who is most at risk, how you can prevent a DVT and what you should do if you think you have one.

The particular circumstances of a plane flight make DVT far more likely. Let's find out why.


Please Do Not Remain Seated

It's a good idea to get up and move around on a long flight -- even if it's a little tricky to maneuver your way out of your seat.
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According to the World Health Organization, sitting on a plane for more than four hours doubles your risk of developing a blood clot [source: Canada]. Researchers estimate that up to 5 percent of all air travelers end up with blood clots [source: IHN]. And airplanes present perfect conditions for DVT: altitude, dehydration and lack of movement.

Airplane cabins are pressurized, but they're pressurized to about 8,000 feet (2,438 meters), not sea level. The higher the altitude, the less oxygen there is in the air [source: Travel Doctor]. Your blood tends to respond to a decrease in oxygen by increasing platelet count. Platelets are the particles in your blood that allow it to clot if you cut yourself. Platelets make the blood more viscous, which increases the chances of forming a clot.


This reduction in oxygen at altitude, along with low moisture content in the air, also leads to dehydration. Dehydration increases the risk of developing a clot because too little water in the body makes the blood thicker. Dehydration is common when traveling because at high altitudes, people usually don't feel thirsty. That, along with the general rush involved in plane travel, leads most people to forgo drinking as much water as they might at home.

High altitude and dehydration are important risk factors, but they're minor compared with lack of movement. Sitting in a car for eight hours -- or in a tank for several days -- is almost as bad as sitting for the same amount of time on an airplane. What we now call economy class syndrome was actually first observed by doctors during World War II in relation to an increase in blood clots following the raid on London, when many people spent hours on end crammed into air-raid shelters [source: WSU]. Lack of movement over a long period of time inhibits circulation, especially in the legs because they're so far from your heart. Blood ends up collecting in the legs. When blood sits too long in one place, platelets can stick together, forming a clot in a vein. If that clots breaks off and starts moving through your system, it can end up in the lungs and cut off oxygen to your heart.

The lack-of-movement problem is made even worse because airline seats are cramped. People can end up with their legs bent for many hours at a time, which further reduces circulation.

Everyone is susceptible to DVT on planes, although older people are more likely to develop it because of general circulation problems, as are people with heart disease, circulation disorders and those who are on drugs that can increase clotting, like birth control pills. But you can lower your risk by developing a few good travel habits:

  • Keep yourself hydrated by drinking lots of water. Avoid caffeinated beverages, because caffeine is a diuretic.
  • Move around on the plane by walking the aisle when you can. When you can't get up, exercise your calves by flexing your feet repeatedly.
  • If you have heart problems, and especially if you've had a recent heart attack or heart surgery, always talk to your doctor before getting on an airplane.

To most of us, drinking water and getting travel clearance seem far less stressful than having to move around on an airplane. Most people don't even want to go to the bathroom on a flight because you've got to wake up the person next to you if you're not sitting on the aisle. But moving around is the most important thing for preventing clots, so go ahead and wake the guy up. Sleeping on a plane can encourage clot formation, anyway. It's about as immobile as you can get.


Lots More Information

Related HowStuffWorks Articles

More Great Links

  • Blood clot risk doubles after four-hour plane trip.
  • Cheney Diagnosed with Blood Clot. CBS March 5, 2007. mostpop_story
  • Compression stockings for preventing deep vein thrombosis in airline passengers. The Cochrane Collaboration.
  • David Bloom's widow: "If one life is saved…" March 6, 2006.
  • Deep Vein Thrombosis in Air Travelers. International Health News.
  • Frequent Flyers Beware: Simple Steps Can Prevent "Economy Class Syndrome." Wright State University School of Medicine.
  • How to Stay Healthy on a Plane. Parade. June 3, 2007.
  • Leg pain can signal dangerous blood clot.
  • New Air Travel Checklist for Heart Patients. WebMD. July 19, 2004. patients?src=rss_foxnews
  • Traveling with Heart Disease. The Travel Doctor.