A System for Describing Congenital Cardiac Malformations and Correlating Them with Abnormal Cardiac Development

This chapter reviews the advances made in analyzing and describing congenitally malformed hearts. It presents how the lessons learned in reaching the current consensus can be used readily by those investigating the structure of the developing normal and abnormal heart to provide a synthesis that, hopefully, will be equally acceptable to clinicians, morphologists and developmental biologists. Many of the difficulties that arose in describing congenitally malformed hearts had their basis in interpretations, rather than in differences in descriptions. The problems with interpretation, nonetheless, frequently reflected the words used in description, or else differences in the definitions used for the various components under discussion. The potential for semantic disagreement is magnified in the setting of the developing heart, since the cardiac components change their positions and relationships with time during the process of development. The system described in this chapter is just as easy to use for complex malformations as for simple ones. The system begins by analyzing the structure of the atrial appendages, recognizing that in most, but not all, instances the arrangement of these structures is in harmony with that of the other lateralized organs of the body. Having established the atrial arrangement, the next step is to analyze the atrioventricular junctions, taking note of ventricular topology and both the type and mode of atrioventricular connections. The same process is then repeated for the ventriculo?arterial junctions, in this instance taking note of connections, infundibular morphology, and relationships of the arterial trunks. Only then, having established the cardiac template, is a catalog made of all the associated malformations, including information on abnormal cardiac position should this be encountered.