Congenital Heart Disease
| Type of Defect | Mechanism
|
|---|
| 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
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| 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
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| Patent Ductus Arteriosus (PDA) | The ductus arteriosus, which normally closes soon after birth, remains open, and a left-to-right shunt develops
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| Tetralogy of Fallot | Pulmonic stenosis results in right ventricular hypertrophy and a right-to-left shunt across a VSD, which also has an overriding aorta
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| Transposition of Great Vessels | The 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.
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| Truncus Arteriosus | There 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
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| Hypoplastic Left Heart Syndrome | There are varying degrees of hypoplasia or atresia of the aortic and mitral valves, along with a small to absent left ventricular chamber
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| Coarctation of Aorta | Either just proximal (infantile form) or just distal (adult form) to the ductus is a narrowing of the aortic lumen, leading to outflow obstruction
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| 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
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