A woman aged 44 years with no significant medical history presented with increasing exertional dyspnea and fatigue. Transthoracic echocardiography showed an atrial septal defect, and transesophageal echocardiography confirmed a 1.2-cm secundum atrial septal defect with bidirectional shunting without a clear superior rim. A computed tomographic (CT) pulmonary angiogram showed a dilated pulmonary artery consistent with pulmonary hypertension (Figure 1A).