Pulmonary hypertension is designated when mean pulmonary artery pressure is greater than 25 mm Hg.
It can be caused by either structural alterations in the lung vasculature (associated with smoking, environmental toxins, left heart failure with pulmonary congestion) or by altered vascular smooth muscle reactivity. Right-sided heart failure resulting from chronic pulmonary hypertension is called cor pulmonale. Although there is a genetic component to its incidence, it seems to be highly correlated with conditions involving chronic hypoxia (e.g., chronic obstructive pulmonary disease, cystic fibrosis, and pneumoconiosis).11 The increased prevalence of obesity with accompanying obstructive sleep apnea may account for a recent increase in reported incidence of this disease. It is relatively hard to diagnose until symptoms appear as the consequences of elevated pulmonary arterial pressures. These symptoms may include systemic edema, pulmonary congestion, shortness of breath, chest pain, and fatigue.