Systematization and clinical study of dextroversion, mirror-image dextrocardia, and laevoversion.

; Current embryological and anatomical knowledge makes it possible to systematize, classify, and diagnose the malpositions of the heart by following a logical sequence. (i) The visceral situs is easily established by means of data provided by physical, radiological, and electrocardiographic studies. There is a constant relation between the venous atrium, greater lobe of the liver with suprahepatic segment of the inferior vena cava, and the visceral situs. (2) The direction of the apex: this indicates the heart position in a specific situs, determined by x-rays. Dextroversion is the malposition in situs solitus, as laevoversion is in situs inversus; dextrocardia is the normal position for the latter. (3) Truncoconal morphologies: there are 3 possibilities (a) the vessels derived from the truncus conus are not transposed, (b) the vessels are transposed, or (c) there is a common trunk. Truncoconal morphology is determined in each case by means of a biplane angiocardiogram. (4) The position of the ventricles is deduced from the truncoconal morphology, by applying the rule which establishes whether the anterior vessel or single trunk energes from the ventral ventricle; correlating the position of this ventricle with the situs, we find out whether or not there is ventricular inversion. (5) Associated malformations are diagnosed by clinical as well as haemodynamic studies, completing finally the diagnosis in every case.