Ventricular Septal Defect and Tetralogy of Fallot: Correlations with the Electrocardiogram and Vectorcardiogram

IN RECENT YEARS the morphological features of the major portions of the atrioventricular (A-V) conduction system of human hearts that were afflicted with various congenital anomalies have been described.1-6 These reports have contrasted the anatomy of the A-V conduction system in examples of ventricular septal defect (VSD) and tetralogy of Fallot with that configuration found in defects of the persistent atrioventricular (A-V) canal type.7 8 The vectorcardiographic (VCG) pattern found in the A-V canal has been considered to be characteristic.9-12 It is now known, however, that various congenital heart defects have a similar vectorcardiographic pattern, including occasional examples of VSD and tetralogy of Fallot.13-l5 Therefore, a study was made of the morphology of the A-V conduction system in instances of VSD and tetralogy of Fallot that had frontal plane VCG patterns similar to those usually found in the A-V canal. An effort was made to find a characteristic or characteristics of the anatomy of the conduction system that might be associated with the unusual VCG pattern observed in these examples.