Congenital Heart Disease
Type of DefectMechanism
Ventricular Septal Defect (VSD)There is a hole within the membranous or muscular portions of the intraventricular septum that produces a left-to-right shunt, more severe with larger defects
Atrial Septal Defect (ASD)A hole from a septum secundum or septum primum defect in the interatrial septum produces a modest left-to-right shunt
Patent Ductus Arteriosus (PDA)The ductus arteriosus, which normally closes soon after birth, remains open, and a left-to-right shunt develops
Tetralogy of FallotPulmonic stenosis results in right ventricular hypertrophy and a right-to-left shunt across a VSD, which also has an overriding aorta
Transposition of Great VesselsThe aorta arises from the right ventricle and the pulmonic trunk from the left ventricle. A VSD, or ASD with PDA, is needed for extrauterine survival. There is right-to-left shunting.
Truncus ArteriosusThere is incomplete separation of the aortic and pulmonary outflows, along with VSD, which allows mixing of oxygenated and deoxygenated blood and right-to-left shunting
Hypoplastic Left Heart SyndromeThere are varying degrees of hypoplasia or atresia of the aortic and mitral valves, along with a small to absent left ventricular chamber
Coarctation of AortaEither just proximal (infantile form) or just distal (adult form) to the ductus is a narrowing of the aortic lumen, leading to outflow obstruction
Total Anomalous Pulmonary Venous Return (TAPVR)The pulmonary veins do not directly connect to the left atrium, but drain into left innominate vein, coronary sinus, or some other site, leading to possible mixing of blood and right-sided overload