Routine Echocardiographic Assessments of Single Ventricle Patients Should Include Atrial Strain

The Fontan operation, originally developed as a surgical intervention for tricuspid atresia, has evolved into the preferred palliation method for a variety of univentricular heart defects [1]. The modern Fontan circulation, typically achieved through lateral tunnel or extracardiac conduit modifications, relies on passive systemic venous blood flow from the superior and inferior vena cavaedirectlyintothepulmonaryarteries.Intheabsenceofasub-pulmonary pumping chamber, the Fontan circulation depends on low pulmonary vascular resistance, as elevated pulmonary vascular resistance compromises ventricular preload and cardiac output. Patients with univentricular hearts are particularly susceptible to diastolic dysfunction due to altered hemodynamic loading conditions, myocardial fibrosis from chronic hypoxemia and inflammation, and impaired coronary perfusion [2]. The assessment of diastolic dysfunction in Fontan patients is clinically important as elevated ventricular filling pressures increase common atrial pressure, reduce transpulmonary blood flow, and subsequently decrease cardiac output. This limitation is especially pronounced during exercise—adolescent and early adult Fontan patients