ASD: atrial septal defect; RA: right atrium; RV: right ventricle; PASP: pulmonary artery systolic pressure; SBP: systolic blood pressure; PVR: pulmonary vascular resistance; SVR: systemic vascular resistance; ACHD: adult congenital heart disease; PH: pulmonary hypertension. * Confirmation of Eisenmenger syndrome generally requires cardiac catheterization. ¶ Refer to UpToDate content on medical management of ASD with Eisenmenger syndrome. Δ An ACHD specialist should be consulted prior to ASD closure. Refer to UpToDate content on the choice between surgical or device closure. ◊ Refer to UpToDate content on management of ASD with pulmonary hypertension. § Refer to UpToDate content on diagnosis of platypnea-orthodeoxia and evaluation of its cause. ¥ Refer to UpToDate content on diagnosis and management of paradoxical embolism.