Hemodynamic Unmasking of Atrial Septal Defect After Pulmonary Arterial Hypertension Therapy: A Pathophysiologic Perspective.

Pulmonary arterial hypertension may mask underlying atrial septal defects by reducing left-to-right shunt flow through elevated pulmonary vascular resistance and impaired right ventricular compliance. Targeted therapy may unmask latent defects, emphasizing early multimodality imaging and sustained clinical suspicion for congenital shunts when invasive hemodynamic assessment suggests shunting despite inconclusive echocardiography.