Misclassification of Pulmonary Hypertension in Partial Anomalous Pulmonary Venous Return.

Partial anomalous pulmonary venous return is a rare congenital heart defect that can escape detection until adulthood and can be misdiagnosed as pulmonary hypertension and managed with vasodilators before the anomaly is identified. This report describes the cases of 3 patients with pulmonary hypertension whose hemodynamics and symptoms improved after repair of anomalous veins. Anomalous pulmonary veins are difficult to identify on a transthoracic echocardiogram, so a high index of suspicion and early use of additional imaging modalities are important to avoid a delayed diagnosis and progression to irreversible disease.