Coexistence of single ventricle with atresia of one atrioventricular orifice.

SUMMARY A new case of an unusual association of mitral atresia with single left ventricle is reported. The salient anatomic features include: (1) the right atrioventricular valve is atretic; (2) the left atrioventricular valve enters the large ventricle with morpho-logic characteristics of the left ventricle; and (3) this large ventricle communicates by way of an interventricular communication with a smaller left-sided ventricle, but with the morphologic characteristics of the right ventricle. Guidelines for the recognition of these uncommon malformations are given. Additional Indexing Words: Single left ventricle Double-inlet left vei Mitral ateresia L-Loop T HE SINGLE left ventricle' or single (primitive) ventricle2 has been defined as an anomaly of the heart in which both atrioventricular orifices, either separated or fused into a common atrioventricular canal, are received by a left ventricle. The right ventricular cavity, with a more or less pronounced hypoplasia of its sinusal portion, is reduced in some cases to its outflow tract. The term double-inlet left ventricle proposed by Mehrizi et al.3 and de la Cruz and Miller4 defines cases of similar malformations with separate atrioventricular orifices. The latter postulate by their embryologic hypothesis that this malformation could result from an arrest in the normal movement of the atrioventricular canal toward the bulbus cordis. Cases with atresia of one atrioventricular orifice have been excluded from the above-mentioned malformations. 794 Atrioventricular orifice atresia To avoid equivocal reports of the coexistence of the double-inlet left ventricle with atrioventricular orifice atresia, the concept of a "topographically homologous ventricle" was introduced in a recent report.5 (Note: In a heart with atresia of either atrioventricular valve, in which the possible existence of a single left ventricle has to be proved or ruled out, we consider the topographically homolo-gous ventricle to be the one that would be expected to be situated beneath the atretic valve.) A recent contribution6 dealing with these malformations includes cases with mitral atresia without detailed descriptions of the specimens. The following case makes a new observation of this uncommon association. Case Report A 3-month-old female patient expired from cyanosis and congestive heart failure. Chest roentgenograms showed severe cardiac enlargement and increased pulmonary vasculature, and the electrocardiogram revealed right atrial hyper-trophy and a stereotyped rS pattern over the entire precordium.