Single Ventricle: Radiology Primer for Preprocedural Evaluation

Single ventricle is an uncommon congenital abnormality characterized by a single anatomic or functional ventricle that cannot sustain two separate serial circulations. Imaging plays an important role in classifying a single ventricle, quantitating ventricular and valvular function, detecting associated cardiovascular anomalies, and identifying critical factors for management. Echocardiography is the first-line imaging modality. MRI and CT are useful when echocardiography is indeterminate or suboptimal, especially for evaluation of vascular anatomy. Morphologically, two atria can connect to a single ventricle; two atria can connect to separate ventricles with hypoplasia of one ventricle; or both atria and ventricles can be present, but single ventricle physiology exists due to a common atrioventricular canal or decreased function of one ventricle. Common forms of a single ventricle include hypoplastic left heart syndrome, tricuspid atresia, double-inlet ventricle, double-outlet right ventricle, unbalanced atrioventricular canal, and pulmonary atresia with intact septum. Examples of a functional single ventricle include pulmonary atresia with ventricular septal defect, severe Ebstein anomaly, and severe obstructive lesions. Grouping diverse congenital heart defects as "single ventricle physiology" is clinically important due to their shared hemodynamic challenges and management strategy centered on three-stage univentricular palliation. Alternatively, biventricular or one-and-a-half ventricular repair can be performed in select patients, with heart transplant being the last option. Critical imaging parameters for presurgical evaluation include anatomy, atrial septal restriction, ventricular and valvular function, bulboventricular foramen, outlet obstruction, pulmonary vascular resistance, patency of ductus arteriosus, pulmonary artery anatomy, venous connections, and collaterals. ^©RSNA, 2026 Supplemental material is available for this article. See the invited commentary by Kabakus and Baruah in this issue.