Anatomic types of congenital dextrocardia Diagnostic and embryologic implications

The anatomic findings in 51 necropsied cases of congenital dextrocardia are presented. The diagnostic and embryologic implications of these findings are assessed. A new general anatomic classification is proposed which is equally applicable to right-sided and to left-sided hearts, either with two well-developed ventricles or with single (common) ventricle. The proposed classification, which is specifically designed to facilitate accurate diagnosis of the relative locations of the cardiac chambers by current investigative methods, is based upon two considerations: (1) the type of viscero-atrial situs present, and (2) the type of cardiac loop which coexists. The type of visceral situs, established radiologically, always is the same as the atrial situs. Thus, the visceral situs indicates the atrial locations with virtually complete accuracy. The type of relationship between the great arteries at the semilunar valves, determined angiocardiographically, indicates the type of cardiac loop present and, hence, the relative location of each ventricle. Thus, the great arteries identify the ventricles with great accuracy. Three types of relationship are considered, an appreciation of which greatly simplifies and clarifies one's understanding of congenital heart disease: (1) viscero-atrial; (2) bulboventricular (great arteries to ventricles); and (3) bulboventriculovisceral (types of cardiac loop relative to types of viscero-atrial situs). The malformation which recently has been regarded as “classic dextroversion” very probably is nonexistent. The incidence of the tetralogy of Fallot in dextrocardia has been greatly overestimated, probably because of confusion with transposition, pulmonary stenosis and ventricular septal defect. The mirror-imagery of inversion is considered to be a biologic illusion. Rudimentary spleen (polysplenia) appeared to be a forme fruste of asplenia. Posterior transposed aorta is described.