Pulmonary hypertension (mean pulmonary arterial pressure >25mmHg at rest or >30 mm Hg during exercise) is mostly associated with autoimmune disorders involving the lung, interstitial lung disease, chronic pulmonary embolism and end stage COPD. Idiopathic pulmonary (arterial) hypertension (PH) is a rare and progressive disease which involves vasoconstriction of the blood vessels within the lungs. Vasoconstriction or vascular remodelling or loss of vessels results in increased pressure in the pulmonary arteries (from 14 mm Hg normally to 25 mm Hg and higher in PH).
The increased pressure load to the heart causes hypertrophy, a condition called cor pulmonale. Finally dilation of the right ventricle occurs resulting ultimately in heart failure.
The condition of PH and heart failure leads to shortness of breath; initially during exercise, but later also at rest. Other symptoms are fainting (because of oxygen deficiency), edema of the feet, fatigue, liver congestion.