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  5. Learn About Pulmonary Hypertension

Learn About Pulmonary Hypertension

Pulmonary hypertension is a serious condition where there is abnormally high pressure in the blood vessels of the lungs.

Key Facts

  • When the arteries in your lungs (pulmonary arteries) narrow (or constrict), the right ventricle of your heart has to beat harder to force blood through the lungs and the blood pressure in your pulmonary arteries gets too high. 
  • There are numerous causes of pulmonary hypertension, which can be inherited or acquired as a result of other medical conditions such as heart disease, lung disease or connective tissue disease.
  • In most cases, pulmonary hypertension cannot be cured, but with proper treatment, you can improve symptoms and slow the disease’s progression. One type of pulmonary hypertension caused by blood clots building up in the pulmonary arteries (called chronic thromboembolic pulmonary hypertension CTEPH) can be cured for some people by surgical removal of the clots.

PH in Children

PH can resemble other conditions, like asthma, making diagnosis difficult. 
Learn More

How Pulmonary Hypertension Affects Your Body

Oxygen-poor blood returning to the heart from all body organs and tissues travels to the right side of the heart which pumps the blood through the pulmonary arteries into the lungs. Within the lungs, these arteries divide into smaller and smaller vessels until the blood reaches the capillaries and takes up oxygen from and delivers carbon dioxide to the alveoli (tiny air sacs). The oxygen-rich blood then returns to the left side of the heart from where it is pumped back to all your organs and tissues.

Normally, the blood pressure in the pulmonary arteries is low (roughly 1/5 of the pressure of blood pumped by your left ventricle) and it flows relatively easily through the vessels in your lungs.  But in PH, the walls of the arteries become stiff, damaged and narrow. This makes blood flow much more difficult and causes the blood pressure in the lungs to rise and the right side of your heart to work harder. Over time, this can cause heart failure. 

Pulmonary hypertension is classified by the World Health Organization according to its causes or associated underlying conditions. There are five groups of PH:

Pulmonary arterial hypertension (PAH) refers to increased blood pressure in the arteries of your lungs caused by obstruction in the small arteries for a variety of reasons. These include "idiopathic" (no known cause or underlying condition), drug-related, HIV infection, connective tissue/autoimmune disorders (such as scleroderma) and others. 

Pulmonary hypertension due to left-sided heart disease. This is when long-term heart disease results in damage to the pulmonary arteries eventually causing PH.

Pulmonary hypertension caused by underlying lung diseases or hypoxemia. The common diseases that cause hypoxia are COPD, emphysema, pulmonary fibrosis, obstructive sleep apnea, lung development abnormalities and chronic high-altitude exposure.

CTEPH (chronic thromboembolic pulmonary hypertension)—In some patients, pulmonary emboli, or blood clots, enter the lung’s arteries and cause PH if they block or narrow too many arteries. Failure of the clots to resolve leads to CTEPH, which happens in a small percentage of patients with blood clots. Some patients with CTEPH can be cured with pulmonary thromboendarterectomy (PTE) surgery.

Pulmonary hypertension from numerous other disorders. This group includes any other cause that doesn’t fit under another heading. Examples are blood disorders, systemic disorders like sarcoidosis, metabolic disorders like thyroid diseases and chronic kidney failure or tumors obstructing pulmonary arteries.

Who is at Risk

Although anyone may be diagnosed with PH, there are several risk factors.

  • People between the ages of 30 and 60 are more likely to be diagnosed and some types of PH are more common in women
  • Family history and genetic disorders
  • Lifestyle habits including tobacco use and illegal drug use
  • Certain prescription medicines
  • Connective tissue disorders
  • Interstitial lung diseases
Next: Pulmonary Hypertension Symptoms and Diagnosis

Page last updated: November 12, 2025

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