VSD: ventricular septal defect; Qp: pulmonary blood flow; Qs: systemic blood flow; LV: left ventricle; PASP: pulmonary artery systolic pressure; SBP: systemic blood pressure; PVR: pulmonary vascular resistance; SVR: systemic vascular resistance; AR: aortic regurgitation; ACHD: adult congenital heart disease; PH: pulmonary hypertension; IE: infective endocarditis. * If the calculated Qp:Qs ≥1.5:1 and the LV size is normal, the Qp:Qs calculation should be rechecked, as it is likely to be incorrect. ¶ Confirmation of Eisenmenger syndrome generally requires cardiac catheterization. Δ Refer to UpToDate content regarding management of patients with VSD with Eisenmenger syndrome. ◊ Refer to UpToDate content regarding choice between surgical or device closure. § In this setting, VSD closure is generally surgical with concomitant aortic valve repair or aortic valve replacement by a congenital heart surgeon. ¥ In this setting, VSD closure is aimed at reducing the risk of recurrent IE. Shared decision making is appropriate if there is no contraindication to closure.