Isomerism in the setting of the so-called "heterotaxy": The usefulness of computed tomographic analysis

The most complex combinations of congenital cardiac malformations are found in the setting of bodily isomerism. The question remains, however, as to whether evidence of cardiac isomerism is always to be found in the setting of bodily isomerism, also known as "heterotaxy." We have previously shown that, when assessed on the basis of the extent of the pectinate muscles relative to the atrioventricular junctions, there is always isomerism of the atrial appendages in this setting. Doubt has been remained, however, as to whether these cardiac features can accurately be recognized during life. We have now encountered two patients showing features of the left and right bodily isomerism. Examinations of these patients made using computed tomography show that all features of isomerism, no matter how complex, can now be visualized during life. The images currently presented show, furthermore, that the features of the so-called "heterotaxy" can be seen during life, not only within the heart but also in all the thoracic and abdominal organs, albeit that the isomeric features are confined to the thoracic organs. Based on the images presented, we argue that if each system of organs is analyzed and described in independent fashion; then it is possible for clinicians to exclude any suggestion of ambiguity and to provide accurate descriptions of the overall arrangement. We further discuss the appropriate terminology to describe the entity we prefer to call isomerism, along with the indications and usefulness of computed tomography in revealing the anatomic features of the congenitally malformed heart.