Identification and analysis of left atrial isomerism.

The veno-atrial connections, atrial morphology, atrioventricular (AV) junction, ventricular mass, ventriculoarterial (VA) connection and great arteries in 22 autopsied hearts, diagnosed as having bilateral left-sidedness because of the morphology of the atrial appendages, were studied. The findings were correlated with the arrangement of the thoracic-abdominal organs. A solitary spleen was found in 3 and double spleens in 2 hearts (the remaining 17 hearts had multiple spleens) but left bronchial isomerism existed in all hearts in which bronchial arrangement could be determined. The heart was in the left chest in 14 cases, in the right chest in 5 and midline in 3. The apex pointed to the left in 18 hearts while in 4 hearts it pointed to the right. Fifteen hearts had a biventricular and ambiguous AV connection, 3 hearts had an absent left AV connection and 4 had double-inlet connection via a common valve (to the left ventricle in 3 and the right ventricle in 1). The VA connection was concordant in 14 hearts, discordant in 1, double outlet from the right ventricle in 4, double outlet from a solitary indeterminate ventricle in 1 and single outlet from the right ventricle through a pulmonary trunk with aortic atresia in 2 hearts. Superior caval veins were present bilaterally in 13 hearts. There was interruption of the infrahepatic inferior caval vein with azygos or hemiazygos continuation in 19 hearts while in 3 hearts the inferior caval vein continued upwards to drain into the right-sided morphologically left atrium.(ABSTRACT TRUNCATED AT 250 WORDS)