Rules for diagnosis of arterioventricular discordances and spatial identification of ventricles. Crossed great arteries and transposition of the great arteries.

Rules are presented for the diagnosis of arterioventricular discordances and the spatial position of the ventricles in these cardiopathies by means of angiocardiography and the position of cardiac catheters. Because these rules are based on previous anatomo-embryological findings, the normal development of the conus and the truncus is briefly analysed. The probable morphogenesis of this group of truncoconal cardiopathies is discussed. The fundamental process required to establish the diagnosis of these cardiopathies is as follows: 1) The truncoconal morphology is identified in the lateral projection. a) The anterior position of the pulmonary artery and its infundibulum with respect to the aorta and its infundibulum is characteristic of crossed great arteries with arterioventricular concordance or discordance. b) The anterior position of the aorta and its infundibulum with respect to the pulmonary artery and its infundibulum is characteristic of transposition of the great arteries with arterioventricular concordance or discordance. 2) Once the truncoconal morphology is identified, the use of the anteroposterior projection allows the establishment of the differential diagnosis between arterioventricular concordances and discordances, and of the spatial location of the ventricles in these entities. a) An anterior pulmonary artery directed from right to left, emerging from an infundibulum placed on the left side (anatomically right ventricle on the left) or an anterior pulmonary artery directed from left to right, arising from an infundibulum located to the right (anatomically right ventricular placed on the right), is the specific image of discordant crossed great arteries. b) An anterior pulmonary artery directed from right to left emerging from an infundibulum placed on the right side (anatomically right ventricle on the right side) or the anterior pulmonary artery directed from left to right arising from a left-sided infundibulum (anatomically right ventricle placed on the left side) is characteristic of concordant crossed great arteries. c) An anterior aorta placed to the right of the pulmonary artery and emerging from a left-sided infundibulum (anatomically right ventricle placed on the left side) or an anterior aorta placed to the left of the pulmonary artery and arising from an infundibulum placed on the right side (anatomically right ventricle placed on the right) is characteristic of discordant transposition of the great arteries. d) An anterior aorta placed to the right of the pulmonary artery emerging from a right-sided infundibulum (anatomically right ventricle placed on the right) or an anterior aorta placed to the left of the pulmonary artery arising from an infundibulum placed on the left (anatomically right ventricle placed on the left) is the specific picture of concordant transposition of the great arteries...