Pulmonary hypertension

What it is

Pulmonary hypertension is a rise in pulmonary pressures. On the chest film it shows as enlarged pulmonary vasculature. It is not a single disease: five WHO classes are set out, each reaching the same raised pressure by a different road.

Causes and risk

• Class 1, pulmonary arterial hypertension: vascular remodeling of small pulmonary arteries and proliferation of endothelial cells, which increase pulmonary pressures. Idiopathic, familial, HIV, drugs, medications.
• Class 2, due to left-sided heart disease: left-sided heart disease increases pulmonary venous pressures and arterial pressures. Chronic LV heart failure, severe mitral disease, severe aortic disease.
• Class 3, due to lung disease or hypoxemia: chronic lung disease or hypoxemia results in vasoconstriction and loss of pulmonary vasculature. COPD, sleep apnea, obesity hypoventilation syndrome.
• Class 4, due to chronic thromboembolic disease: pulmonary thromboembolism results in increased pulmonary pressures. Prior PE, recurrent PE, large PE, or pulmonary hypertension at time of diagnosis of PE.
• Class 5, miscellaneous: varied conditions result in multiple pathologies, causing increased pulmonary pressures. Connective tissue diseases, sarcoidosis, mediastinal tumors, thyroid disorder.