Right Bundle - Branch Block and Left Anterior

Right bundle-branch block occurred in 42.8% and left anterior hemiblock in 35% of 14 patients after surgical replacement of the tricuspid valve. The combination of RBBB with left anterior hemiblock is caused by injury to the branching portion of the bundle of His or more likely, by a lesion involving the pseudobifurcation. This study provides further proof that left anterior hemiblock may be produced by a "central" lesion of the conduction system. An attempt was made to re-define the relationships of the bundle of His and bundle branches to the membranous septum and septal leaflet of the tricuspid valve and to correlate the site of surgical injury with the type of conduction disturbances produced.