The single ventricle and surgical palliation

Abstract

About 10% of patients with congenital heart disease have a univentricular heart, which includes a wide variation of diagnoses. These may occur in the setting of anomalies of cardiac and visceral situs. When considering treatment options, a practical approach has been to define univentricular heart disease as the heart in which just one ventricle is present that can sustain the circulation, whether anatomically or functionally. Treatment consists of staged palliation, starting with an aortic-to-pulmonary anastomosis, if required, and of stepwise separation of the systemic and pulmonary circulation, culminating in a total cavopulmonary connection where caval return passively flows into the lungs, bypassing the heart (called the Fontan procedure). Detailed anatomic, haemodynamic, and functional imaging is required throughout the staged treatment and during long-term follow-up. Cardiovascular magnetic resonance (CMR) is a widely recommended tool for this purpose. CMR imaging should include assessment of the pulmonary artery, the aortic arch to assess for arch obstruction, the ventricular outflow tract, systemic-to-pulmonary collaterals (aortic–pulmonary, veno-veno), anomalous venous structures, pulmonary or systemic veins, systemic venous return, ventricular size/function and blood flow, and tissue characterization for myocardial scarring. The focus of imaging may shift, depending on the stage of treatment. During staged palliation, CMR can be used to detect residual findings requiring additional interstage interventions. CMR is recommended after Fontan completion for serial follow-up of ventricular function, haemodynamics, physiology, and anatomical assessment of the Fontan pathway.