Bundle of His electrograms in congenital corrected transposition of the great arteries. A study of two adult cases.

His bundle electrograms were recorded in 2 adult cases of congenital corrected transposition of the great arteries. Both patients had prolonged HV conduction and a His potential that was wide. These findings are different from those reported in congenital atrioventricular block without ventricular inversion wherein an abnormality within the AHperiod has been found. It is suggested that these differences reflect different sites of disturbed conduction. In congenital corrected transposition of the great vessels, the abnormality is distal to the atrioventricular node, whereas in congenital atrioventricular block without ventricular inversion it is generally proximal to the atrioventricular node.