The World Health Organization divides pulmonary hypertension (PH) into five groups. These groups are organized based on the cause of the condition and treatment options.
In all groups, the average pressure in the pulmonary arteries is 25 mmHg or higher. The pressure in normal pulmonary arteries is 8–20 mmHg at rest.
(Note that group 1 is called pulmonary arterial hypertension (PAH) and groups 2 through 5 are called pulmonary hypertension. However, together all groups are called pulmonary hypertension.)
Group 1 PAH includes:
Group 2 includes PH with left heart disease. Conditions that affect the left side of the heart, such as mitral valve disease or long-term high blood pressure, can cause left heart disease and PH. Left heart disease is likely the most common cause of PH.
Group 3 includes PH associated with lung diseases, such as COPD (chronic obstructive pulmonary disease) and interstitial (IN-ter-STISH-al) lung diseases. Interstitial lung diseases cause scarring of the lung tissue.
Group 3 also includes PH associated with sleep-related breathing disorders, such as sleep apnea.
Group 4 includes PH caused by blood clots in the lungs or blood clotting disorders.
Group 5 includes PH caused by various other diseases or conditions. Examples include:
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