Pulmonary Hypertension

Last Updated 05/08/2020

Authors:Sandeep Sahay, MD, FCCP; Yi Chun Yeh, MD

About Pulmonary Hypertension

Key facts about Pulmonary Hypertension

Pulmonary hypertension happens when the blood pressure in the blood vessels that carry blood from the heart to the lungs (called pulmonary arteries) gets too high. This high pressure causes arteries in the lungs to become narrower (or constrict). Less blood flows through the lungs, which lowers how much oxygen gets into your blood. n Pulmonary hypertension has many causes. You can inherit it from your parents or get it because of another medical condition, such as heart disease, lung disease, or connective tissue disease. n Many cases of pulmonary hypertension have no known cause. n Pulmonary hypertension can be treated but not cured. The disease can cause heart failure.

What is Pulmonary Hypertension

Pulmonary (meaning “having to do with the lungs”) hypertension is a serious condition where the pressure in the blood vessels between your lungs and heart is too high.

In healthy people, blood returns to the heart after carrying oxygen to all their organs and tissues. The heart pumps this blood from its right side (the right ventricle), through the pulmonary arteries, into the lungs. In the lungs, these arteries split into smaller blood vessels. There, the blood picks up oxygen and releases carbon dioxide. The oxygen-rich blood then flows to the left side of the heart (the left atrium). The left ventricle then pumps this blood out to all body organs and tissues.

High blood pressure in the lungs happens because:

  • The blood vessels have become narrower (a lung problem); or
  • The pressure in your left atrium is higher (a heart problem).

Either problem backs blood flow into your lungs. Over time, the right side of your heart must pump harder to get the blood through its vessels and the lungs. This can cause heart failure.

How Pulmonary Hypertension affects your body

The World Health Organization sorts cases of pulmonary hypertension into 5 groups. Which group your pulmonary hypertension falls into depends on its cause or other diseases you may have (called underlying conditions):

  • Group 1. Pulmonary arterial hypertension is higher pressure in blood vessels caused by a blockage (or obstruction) in the small arteries in the lung. Blockages can happen for many reasons:
    • Using recreational drugs
    • Having HIV, the virus that causes AIDS
    • Diseases of your connective tissue
    • Autoimmune disorders, such as scleroderma or rheumatoid arthritis
      Blockages can also occur for no clear reason, in which case they’re called idiopathic.
  • Group 2. Pulmonary hypertension caused by left-sided heart disease (left heart failure, valve disease).
  • Group 3. Pulmonary hypertension caused by lung diseases or having a condition that causes your blood oxygen to be low (called hypoxemia). These conditions include:
  • Group 4. Chronic thromboembolic pulmonary hypertension, which means that blood clots in your lungs block blood flow.
  • Group 5. Pulmonary hypertension from many other problems with your metabolism, blood, or whole system.

No matter what group your case falls into, blood flow through your lungs to the left side of your heart is lower and blood pressure inside your vessels is higher. This may cause the vessel walls to get thicker within your lungs. The higher pressure then strains your heart as it works harder to pump blood through your lungs.


The American Lung Association recommends that patients and caregivers join its Living with Lung Disease support community to connect with others facing this disease. To talk to a trained lung professional, call the American Lung Association’s Lung Helpline at 1-800-LUNGUSA. They can help answer your questions and connect you with additional support.