What Is Pulmonary Embolism (PE)?

A pulmonary embolism, or PE, is a potentially life-threatening blood clot that starts out as a deep vein thrombosis (DVT). A DVT is a blood clot that occurs in a vein, usually in the leg. A vein is a type of blood vessel that carries oxygen-poor blood back to the heart (versus arteries, which are blood vessels that carry oxygen-rich blood throughout your body). Sometimes, a DVT blood clot breaks off and travels through the bloodstream to the lungs, where it becomes a pulmonary embolism.

How does a blood clot become a PE?

Watch a short video to see how a clot formed somewhere else in your body can cause a PE, and the symptoms to look out for.

More people die of DVT/PE each year than
breast cancer, traffic accidents, and HIV combined.

DVT/PE 100,000
Breast Cancer, Traffic Accidents, and HIV 82,840

DVT and PE blood clots may also be referred to as venous thromboembolism (VTE). It is estimated that between 300,000 and 600,000 Americans per year are affected by DVT or PE. These conditions are the third-most-common diagnoses related to blood vessels after heart attack and stroke.

What causes a pulmonary embolism?

A PE begins as a DVT blood clot, usually in the leg. Because nearly half of all people with a DVT are not diagnosed, it can go untreated long enough for a piece of the clot to break free and travel through the bloodstream to the lungs. Once there, it blocks blood flow and oxygen, which not only damages lung tissue, but also may affect other organs due to reduced oxygen in the blood.

Is a pulmonary embolism life threatening?

PEs affect more than just your lung function. They can have other serious effects on your health because your lungs are part of your cardiovascular system. Cardiovascular means “having to do with the heart and blood vessels."

Your cardiovascular system is also known as the circulatory system. Your heart, arteries, veins, and lungs are all equally important in moving nutrients and oxygen-rich blood to every single part of your body. Because this network connects everything from your brain to your toes, a problem—like a PE blood clot—in one part of your body can cause problems somewhere else.

For example, when you have a PE, not only is there a risk of it permanently injuring your lung, it often results in decreased oxygen in your blood, which could then starve your other organs of oxygen. In the most serious cases of pulmonary embolism (also called massive pulmonary embolism), the blood clot is large enough to block blood flow between the heart and the lungs, putting extreme strain on the heart, which can lead to sudden death. This is why it's so important to pay attention to potential symptoms of a PE and seek treatment right away.

In addition to following the treatment plan laid out by your healthcare professional, having a heart-healthy lifestyle can help lower your risk for other cardiovascular diseases. Learn more about living well after a PE.

Infographic showing the cardiovascular system and how blood flows from the heart to body to lungs