Measurement of aortic morphology in a preoperative angiogram, left lateral view, before stage II palliation (bidirectional cavopulmonary shunt): (A) Diameter and length of the native ascending aorta; (B) angle of the native ascending aorta–proximal pulmonary artery anastomosis. The interrupted line with the double arrow in the panel (B) represents the segment of the anastomosis between the pulmonary artery and the patch, through the centre of which the angle with the native ascending aorta is measured.