pulmonary artery" arising from the lateral surface of the common trunk Type II: The branch pulmonary arteries arises separately, but near each other posteriorly off the common trunk Type III: The branch pulmonary arteries arise separately and far apart off the common trunk Type IV: The branch pulmonary arteries arise distally off the aorta, or the lungs are supplied by multiple aortopulmonary collaterals. Type IV is now considered a form of Tetralogy of Fallot and not Common Arterial Trunk. Another well-known classification was defined by Stella and Richard Van Praagh in 1965. In this classification scheme, the preceding letter ("A" or "B") refers to the presence or absence, respectively, of a ventricular septal defect. Type B common arterial trunk is extremely rare; so below, only Type A is considered: Type A1: The branch pulmonary arteries arise from a single "main pulmonary artery" arising from the lateral surface of the common trunk (Collett & Edwards Type I) Type A2: The branch pulmonary arteries arise separately off the common trunk (includes both Collett & Edwards Types II and III). Type A3: One branch pulmonary artery arises off the common trunk, and one branch pulmonary artery is isolated, arising from a patent ductus arteriosus. Type A4: Common arterial trunk in association with interrupted aortic arch. As both of the above schemes involve four numerals, they can be easily confused. For this reason, the Collette & Edwards scheme usually uses roman numerals while the Van Praagh system uses arabic numerals and the preceding "A". Ambiguity as to the system being used can lead to misunderstanding. The classification in the International Paediatric and Congenital Cardiac Code (IPCCC) attempts to eliminate this source of confusion with the following nomenclature scheme, which removes the use of numbered types: Common arterial trunk with aortic dominance and both pulmonary arteries arising from trunk (includes Collette & Edwards Types I, II, and III and Van Praagh types 1 and 2). Common arterial trunk with aortic dominance and one pulmonary artery absent from trunk, isolated pulmonary artery (Van Praagh type 3). Common arterial trunk with pulmonary dominance and aortic arch obstruction (Van Praagh type 4) Treatment Treatment is with neonatal surgical repair, with the objective of restoring a normal pattern of blood flow. The surgery is open heart, and the patient will be placed on cardiopulmonary bypass to allow the surgeon to work on a still heart. The heart is opened