Can We Better Understand the Anatomy of Channels Between the Ventricles on the Basis of Knowledge of Their Development?

Abstract

Surgeons usually close the channels described as “ventricular septal defects.” When both arterial trunks arise from the right ventricle, however, the surgeon will be aware that it is not appropriate to close the channel most frequently described as the “ventricular septal defect.” In this latter setting, furthermore, there is currently no name for the area usually closed during surgery to restore septal integrity. Our previous attempts to emphasize the logical problems created by this situation have not, thus far, been met with uniform approbation. This may reflect the fact that we have not always expressed our concepts using words that are easy to understand. But we continue to believe that words are important if we are to achieve optimal understanding. In this review, therefore, we illustrate those areas that can be closed surgically to restore septal integrity, making a comparison with the defects that provide an outlet for the left ventricle, and hence cannot be closed. To assist understanding, we draw further comparison with the situation in the developing heart, when an area that is initially part of the right ventricle becomes the left ventricular outflow tract subsequent to the completion of septation. We discuss all these features in the setting of the simple perimembranous ventricular septal defect, the defects found in tetralogy of Fallot, and those found in the various forms of double outlet right ventricle. We emphasize the importance to the surgeon of knowing the boundaries around which a patch, or baffle, must be placed to restore septal integrity.