Idiopathic dilatation of the pulmonary artery

Thirteen patients with idiopathic dilatation of the pulmonary artery are described and their clinical, roentgenologic, electrocardiographic, and hemodynamic features are elaborated. Absence or mildness of symptoms was the most significant finding in this series. A pulmonic systolic murmur was constantly present. The roentgenogram showed various degrees of dilatation of the pulmonary artery in the presence of normal heart size. The electrocardiogram was normal. The hemodynamic studies showed a mild systolic pressure gradient across the pulmonic valve in some cases in the presence of normal right ventricular pressure. A possible explanation of this finding is discussed. Idiopathic dilatation of the pulmonary artery is a benign lesion and does not affect cardiac function to any appreciable degree.