ABOUT PH
Types of PH
Pulmonary hypertension (PH) is not a single disease. In fact, the World Health Organization (WHO) has identified five distinct groups based on the different causes of pulmonary hypertension, and how it is treated.
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Pulmonary arterial hypertension is a type of pulmonary hypertension that is specifically due to narrowing of the pulmonary arteries (blood vessels) that carry blood to the lungs.
The exact cause of pulmonary arterial hypertension is not well understood. Narrowing of pulmonary arteries in PAH is due to multiplication and growth of cells in the walls of the pulmonary arteries, as well as scar tissue formation in the pulmonary arteries. Tremendous ongoing research has identified many biologic abnormalities in pulmonary arterial hypertension, including genes, proteins, and small chemicals in the body.
Pulmonary arterial hypertension is a broad category which includes many patients with different types of PAH. These include:
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Idiopathic
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Heritable (genetic)
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Associated with connective tissue disease
WHO Group 1: Pulmonary Arterial Hypertension (PAH)
Diseases of the left side of the heart result in failure to properly pump blood to the rest of the body. This causes a back-up of blood in the lungs, resulting in pulmonary hypertension.
What causes pulmonary hypertension due to left-sided heart disease?
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Left-sided congestive heart failure
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Mitral valve disease
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Other heart diseases
WHO Group 2: PH Associated with Left-Sided Heart Disease
Lung diseases can lead to lower blood oxygen levels (hypoxia). Hypoxia causes the pulmonary arteries to spam and narrow (vasoconstriction), resulting in pulmonary hypertension.
What causes pulmonary hypertension due to lung disease?
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COPD
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Pulmonary fibrosis
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Sleep apnea
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Other lung diseases
WHO Group 3: PH Associated with Lung Disease
WHO Group 4: Chronic Thromboembolic Pulmonary Hypertension (CTEPH)
Pulmonary hypertension can sometimes be caused by various other diseases. The exact mechanisms of PH in most of these conditions are unclear.
What are some examples?
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Certain lung diseases (e.g. sarcoidosis, others)
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Certain blood diseases (e.g. sickle cell anemia, others)
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Chronic renal failure
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Vasculitis