A Case of Atrial Septal Defect Unveiled by the Treatment for Pulmonary Arterial Hypertension.

We present a case of a 51-year-old woman with atrial septal defect (ASD) masked by pulmonary arterial hypertension (PAH). Three months after PAH treatment with a combination of endothelin receptor antagonist and phosphodiesterase five inhibitor, the transthoracic echocardiography revealed left-to-right shunting through a secundum ASD. The pulmonary vascular resistance decreased from 7.4 to 2.6 Wood units. Subsequent transcatheter closure of ASD using Occlutech Figulla Flex II device was successfully performed as a treat-and-repair strategy. Five months later, hemodynamics had normalized. Due to reduced shunt flow caused by PAH, ASD may not be detectable before treatment, so care must be taken not to overlook PAH associated with intracardiac defects.