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Diseases A–Z

Pulmonary hypertension

What’s the Difference between PH and PAH?

Pulmonary Hypertension (PH) is the general term used to describe high blood pressure in the pulmonary arteries. There are many causes of PH.

Pulmonary Arterial Hypertension (PAH) is one category of PH. PAH is due to disease in the pulmonary arteries, which are narrowed and can be scarred to the point of being closed. PAH is an important cause of PH because it is often the most severe, and because many new medications are for patients with PAH.

Types of Pulmonary Hypertension

The World Health Organization (WHO) has grouped Pulmonary Hypertension into five categories

WHO Group 1 is Pulmonary Arterial Hypertension (PAH). This includes

  • PAH that has no known cause (Idiopathic)
  • PAH that is familial or genetically inherited (hereditary)
  • PAH associated with connective tissue disease, congenital heart disease, severe liver disease, HIV infection, or the use of certain diet medications

WHO Groups 2 to 5 PH are linked to other conditions or diseases.

WHO Group 2 is PH due to left-sided heart disease, such as heart failure or high blood pressure.

WHO Group 3 is PH due to lung conditions such as COPD (chronic obstructive pulmonary disease), interstitial lung disease, and sleep apnea.

WHO Group 4 is PH related to multiple or recurrent blood clots (pulmonary embolism) in the lungs.

WHO Group 5 is PH related to other diseases or conditions. Examples include diseases such as sarcoidosis, rare diseases such as lymphangioleiomyomatosis (LAM) and mediastinal fibrosis. This type can also be due to tumors putting pressure on the pulmonary arteries.


Next learn about diagnosing and treatments of Pulmonary Hypertension >>

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