Which of the following statements about truncus arteriosus are true?

B. Most infants present with cyanosis.

C. Most infants present with congestive heart failure.

D. Repair requires a conduit from right ventricle to pulmonary arteries. 

DISCUSSION: While an occasional child survives to age 3 or 4 years, without either palliative or totally corrective surgical treatment few live past early infancy. The lesion is one of excessive pulmonary blood flow because of the origin of the pulmonary arteries from the truncus arteriosus; physiologically, the pulmonary arteries arise directly from the aorta. Although the aortic saturation can never be 100% because of some element of bidirectional shunting at the VSD, the physiologic manifestations are congestive heart failure and excessive pulmonary blood flow rather than cyanosis. The congestive heart failure becomes severe as pulmonary vascular resistance drops. If congestive heart failure later improves spontaneously, it is because of the development of pulmonary vascular disease. Complete repair always requires closure of the VSD, detachment of the pulmonary arteries from the common trunk, and re-establishment of an outflow tract from the right ventricle to the pulmonary artery. This conduit usually contains a valve and can be either a homograft or a synthetic conduit containing a porcine valve.