Idiopathic pulmonary arterial hypertension

Patients with idiopathic pulmonary arterial hypertension may have the classic history and physical findings of our patient. It is more common in young women with no previous history of cardiac or pulmonary disease and who have no other demonstrable cause.

Natural history

Idiopathic pulmonary arterial hypertension occurs in patients usually in their third to fifth decades. Average survival is less than five years after the diagnosis is made. The clinical course is one of progressive right ventricular failure leading to death.

Features

Patients with idiopathic pulmonary arterial hypertension have increased pulmonary vascular resistance. Three elements that combine to increase vascular resistance include vasoconstriction, vascular wall remodeling and thrombosis in situ. The result is restricted flow through the pulmonary arterial circulation, ultimately leading to right heart failure.

Normal pulmonary vascular resistance

In normal individuals, a low resistance pulmonary vascular bed results from a delicate balance between endogenous substances that favor vasodilation and antiproliferation and results in no endothelial disruption or thrombosis.

High pulmonary vascular resistance

In contrast, patients with idiopathic pulmonary arterial hypertension have a high resistance vascular bed. In response to some insult, such as endothelial damage, the balance may change to favor vasoconstriction and vascular proliferation and lead to thrombosis in situ. This results in further endothelial damage and a cycle of vasoconstriction, proliferation and thrombosis.

Other etiologies

There are many other etiologies of pulmonary hypertension that can mimic the history and physical findings present in our patient. These include drugs, toxins, connective tissue diseases, HIV, portal hypertension, congenital left-to-right shunts, left heart disease, lung disease and/or hypoxia, chronic thromboembolic disease and sarcoidosis. These must be excluded by subsequent laboratory testing before a definitive diagnosis of idiopathic pulmonary arterial hypertension can be made.