Pulmonary hypertension, also known as idiopathic pulmonary artery hypertension (IPAH), is a progressive disease that affects the precapillary pulmonary vasculature. The exact underlying risk factors for IPAH are still unknown. The pulmonary artery pressure is persistently more than 25 mmHg at rest and more than 30 mmHg during exercise. IPAH is a rare but fatal disease with a high mortality rate. If left untreated, it may result in increasing back pressures and ultimately right heart failure and death.
Primary pulmonary hypertension is classified in the World Health Organization's (WHO) classification system as part of group 1. The WHO classification of pulmonary hypertension is based on the mechanism or underlying etiology:
Group 1: Pulmonary arterial hypertension (PAH) can be idiopathic (i.e., primary pulmonary hypertension) or due to congenital left to right intracardiac shunts, portal hypertension, persistent pulmonary hypertension of the newborn, collagen vascular diseases, HIV infection.
Group 2: Pulmonary hypertension secondary to left heart disease (pulmonary venous hypertension)
Group 3: Pulmonary hypertension associated with hypoxemia
Group 4: Pulmonary hypertension due to chronic thrombotic disease, embolic disease, or both
Group 5: Miscellaneous
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