This diagram depicts the classification of truncus arteriosus devised by Van Praagh:
- type A1: aorta and main pulmonary artery share a common arterial trunk
- type A2: separate origins of the branch pulmonary arteries from the left and right lateral aspects of the common trunk
- type A3: origin of one branch pulmonary artery (usually the right) from the common trunk, with other lung supplied either by collaterals or a pulmonary artery arising from the aortic arch
- type A4: coexistence of an interrupted aortic arch
(AA - ascending aorta; DA - descending aorta; MPA - main pulmonary artery; RPA - right pulmonary artery; LPA - left pulmonary artery; PDA - patent ductus arteriosus; VSD - ventricular septal defect; RA - right atrium; LA - left atrium; RV - right ventricle; LV - left ventricle)