Truncus Arteriosus

Truncus arteriosus is a rare congenital cardiac lesion characterized by failure of embryonic truncal septation resulting in a single semilunar valve and single arterial trunk providing both pulmonary and systemic circulations. Systemic venous blood and pulmonary venous blood mix at the ventricular septal defect level, and the resulting desaturated blood is ejected into the single outflow tract. Because the pulmonary arteries arise directly from the truncus, the pulmonary vascular resistance will determine the pulmonary blood flow, which is usually torrential. Without surgical intervention, death in infancy is the rule. Surgery for truncus arteriosus has evolved over the past 50 years. Current management involves total repair during the neonatal period with excellent expected results. The presence of truncal valve insufficiency or interrupted aortic arch may increase the surgical risk for morbidity and mortality. Current therapy and management continue to evolve. This chapter will focus on the morphology, pathophysiology, and management of truncus arteriosus.