Diagrammatic representation of the configuration of the ductus as demonstrated on the lateral angiogram can be classified as described by Krichenko. Type A or conical duct with well defined aortic ampulla and constriction near the pulmonary artery end. Type B is a large duct with window like structure which is very short in length. Type C is a tubular duct without any constriction. Type D is the complex duct with multiple constrictions and the type E or elongated duct with constriction remote from the edge of the trachea as viewed on lateral angiography (figure adapted from Amplatzer™ manufacturer information).