Pulmonary vascular disease includes a spectrum of conditions or diseases in which the most serious and common complication is pulmonary hypertension. While pulmonary hypertension can occur without any obvious relationship to other diseases ("primary pulmonary hypertension") the majority of cases of pulmonary hypertension are seen in association with a variety of medical conditions and/or toxic exposures. These conditions may include blood clots in the lungs, congenital heart disease, heart and lung diseases which cause low oxygen levels, connective tissue or rheumatologic diseases, sleep apnea, liver disease, HIV infection and exposure to drugs such as amphetamines and diet pills.
There are approximately 32,000 cases new cases of congenital heart disease per year in the United States and 1.5 million new cases worldwide. A large proportion of these patients have abnormalities of the pulmonary vasculature, including pulmonary hypertension. While pulmonary hypertension is now less common with earlier diagnosis of congenital heart disease there still exists a significant population of adults with this debilitating illness.
The estimated annual incidence of primary pulmonary hypertension in the United States and Europe is 1-3 cases per million people per year. The incidence among users of certain diet pills may be as high as 25-50 persons per million per year. Pulmonary hypertension frequently complicates the rheumatologic condition known as scleroderma (which includes patients with the CREST syndrome). In addition, up to 20% of patients with systemic lupus may develop pulmonary hypertension. Pulmonary hypertension can arise in the setting of both acute and chronic pulmonary embolism (blood clots to the lungs) and can represent a fatal complication of this condition. The annual incidence of fatal pulmonary embolism in the U.S. is estimated to be around 200,000, half of which were potentially curable with appropriate treatment. Chronic disease with pulmonary embolism is far less common, but is also often undiagnosed though potentially curable with surgery or other interventions.