Architecture of the ventricular mass and atrioventricular valves in complete transposition with intact septum compared with the normal: I. The left ventricle, mitral valve, and interventricular septum.

Venous correction for complete transposition with intact ventricular septum remains the preferred surgical option in most centers (Mustard or Senning procedures). The long-term function of the morphologically right ventricle and tricuspid valve, which continue to sustain the systemic circulation thereafter, remains a matter of concern. Some centers have been performing arterial redirection ("arterial switch") as the surgical treatment of transposition. Consequently, the status of the left ventricle and mitral valve is of equal interest. Yet, detailed morphological studies of the ventricles, atrioventricular valves, and their tension apparatus in "simple" complete transposition are lacking. We have examined the morphology of the left ventricle and the spatial relationships of the component parts of the interventricular septum (part I) as well as the morphology of the right ventricle and the tricuspid valve (part II). A total of 77 specimens with complete transposition and intact ventricular septum were examined and compared with 50 normal hearts. Consistent deformities were noted in relation to the orientation of the ventricular septum. The ratios of ventricular outlet to the inlet lengths were increased in both ventricles and the posterior arterial valve was abnormally related to the atrioventricular valves. These anomalies are similar in some respects to those found in atrioventricular septal defects. Their significance in relation to long-term function remains unclear.