The Diagnostic Approach to Truncus Arteriosus: Medical Aspects

Summary

Truncus arteriosus, a rare congenital anomaly, usually presents in severe congestive heart failure in the first few weeks of life. If untreated, mortality in the first year is 78% from congestive heart failure, intercurrent infections, or pulmonary vascular disease. The defect represents partial or total absence of the aorticopulmonary septum, that is, complete absence of fusion of the truncal swellings and the conal ridges that normally join to form the arterial valves and the distal infundibulum. The accepted classifications are those of Collett and Edwards (1949) and Van Praagh and Van Praagh (1965). The clinical picture and natural history of truncus arterious in infants and children are largely determined by the size of the pulmonary blood flow, pulmonary vascular resistance, any narrowing of the pulmonary arteries, or the degree of truncal valve regurgitation. Electrocardiograms and chest X-rays help in making a diagnosis with the clinical picture, but the echocardiogram gives a strong indication of truncus arteriosus. If in doubt, cardiac catheterization and angiocardiography may be necessary before any surgical correction. The prognosis is poor because of the early onset of intractible congestive heart failure, pulmonary edema, and progressive pulmonary vascular disease beginning around 6 months of age. Cardiac failure is managed aggressively with digoxin, diuretics, vasodilators, and angiotensinconverting enzyme (ACE) inhibitors. At present, total correction is performed after stabilizing the patient at the time of diagnosis or between 1 and 3 months of age. The most optimistic aspect of early correction in the truncus anomalies is related to the absence of pulmonary vascular disease and to the growth of the pulmonary arteries. Besides pulmonary vascular disease and significant truncal valve regurgitation, an interrupted aortic arch is the most significant factor contributing to surgical mortality. Coronary artery anomalies and repair at ages greater than 3–6 months, however, may also contribute to surgical mortality.