Not Just Big Kids

Abstract

Atrial septal defects (ASDs), allowing blood to directly communicate between systemic and pulmonary arterial circulations at the atrial level, are among the most common congenital cardiac anomalies seen in the adult population. The degree of shunting across an ASD is directly related to the area of the ASD and inversely related to the compliance of the combined atrial-ventricular chambers on either side of the heart. Under normal physiological conditions, there is net left-to-right shunting across an ASD, as the left ventricle is far less compliant than the right ventricle. This shunt of fully oxygenated blood back to the right atrium results in a volume load to the right-sided heart chambers and to the pulmonary vasculature; if left untreated, large-volume left-to-right shunting can result in atrial arrhythmias, right ventricular diastolic and systolic failure, worsened functional class, decreased exercise capacity, left ventricular diastolic failure, and, uncommonly, development of pulmonary arterial hypertension.1 The indication to treat an ASD is typically related to its hemodynamic significance and its effects on the right ventricle. National care guidelines denote ASD closure with class IA recommendation in patients with evidence …