8th March 2024

Truncus Arteriosus

This cyanotic birth defect occurs when the embryological truncus arteriosus fails to separate into the pulmonary trunk and aorta. This occurs due to the lack of aortico-pulmonary septum formation and results in a single artery, which arises from both ventricles becoming the aortic and pulmonary vessels. The result is a supply of mixed de/oxygenated blood to the coronary arteries, pulmonary arteries, and systemic circulation. 

The condition occurs spontaneously but is also associated with deletions in chromosome 22q11 (DiGeorge syndrome). Cyanosis presents at birth and heart failure may develop in weeks. On cardiac auscultation, a systolic murmur may be heard at the left sternal edge.

Management is with surgical repair to separate the pulmonary artery from the common artery. Once separated, the common artery functions as the aorta.