pediatrics
Persistent Truncus Arteriosus
Classification
There are several classification systems in use. An earlier classification, by Collett and Edwards, is Type I: The main pulmonary artery arises from the truncus and then divides into the right and left pulmonary arteries. Type II: The right and left pulmonary arteries arise separately (but adjacent to each other) from the posterior aspect of the truncus. Type III: The right and left pulmonary arteries arise from the lateral aspects of the truncal root reasonably distant from each other. Type IV: Both pulmonary arteries are supplied by collateral vessels from the descending aorta. (Type IV is now reclassified as Tetralogy of Fallot with pulmonary atresia.) Ventricular Septal Defect (VSD) [VSD]) and the very rare type B (truncus arteriosus Type A1: The main pulmonary artery arises from the truncus and then divides into right and left pulmonary arteries. Type A2: The right and left pulmonary arteries arise separately from the posterior aspect of the truncus. Type A3: One lung is supplied by a pulmonary artery branch that arises from the truncus and the other lung (usually the left) is supplied by a ductus-like collateral artery Type A4: The truncus is a large pulmonary artery and the aortic arch is interrupted or coarctation is present. The truncal valve may be quite abnormal and manifest with stenosis, regurgitation, or both. The valve is tricuspid in 69%, quadricuspid in 22%, and bicuspid in 9%. Other anomalies (eg, right aortic arch, interrupted aortic arch, coronary artery anomalies) may be present and may contribute to the high surgical mortality rate. A Patent Ductus Arteriosus (PDA) is exceedingly rare in Collett and Edwards types I, II, and III defects or in Van Praagh types A1 and A2 but is present in about half of patients with truncus arteriosus, most notably those with types A3 and A4 defects. Physiologic consequences of truncus arteriosus include mild cyanosis, significant pulmonary overcirculation, and Cyanotic heart anomalies . 