Electrocardiographic findings in patients with complete atrioventricular block.

The introduction of the artificial electrical pacemaker for the treatment of patients with complete A-V block has been accompanied by renewed interest in the pathogenesis of this disorder. It has been considered that most cases of complete block are due to organic or functional lesions either in the A-V node or in the common A-V bundle. Barker and Hirschfelder in 1909 and later Eppinger and Rothberger (1910) demonstrated experimentally that section of both bundle-branches or of the bundle of His could produce a complete A-V block. Wilson and Herrmann in 1921 studied this problem again and concluded that complete block could be due to an interruption of both bundle-branches. They also postulated that in complete block, if the ventricular complexes were of an aberrant type, bilateral bundle-branch block must exist, whereas if the ventricular complexes were of normal contour the interruption must have been above the bifurcation. Yater, Cornell, and Claytor in 1936 published a review of the published reports of 48 patients with pathologically proven complete A-V block due to bilateral bundle-branch block. On the basis of their studies, they concluded that a large number of patients with complete A-V block would have an interruption of both bundle-branches rather than a block above the bifurcation. Rosenbaum and Lepeschkin in 1955 described two cases of bilateral bundle-branch block. By careful analysis of the electrocardiographic tracings, they formulated criteria for the diagnosis of bilateral bundle-branch block. They stated that this diagnosis could be made when one branch was completely interrupted and the other incompletely or intermittently interrupted. Further, bilateral bundle-branch block could be diagnosed when the