THE ASSOCIATION OF TYPE B VENTRICULAR PRE-EXCITATION AND RIGHT BUNDLE-BRANCH BLOCK

Abstract

The scalar lead electrocardiograms and vectorcardiograms of the 2 common types of ventricular pre-excitation are described and illustrated. The problem of the rare association of pre-excitation and bundle-branch block is discussed. Type A pre-excitation has been reported in association with both left and right bundle-branch block. Similarly type B pre-excitation has been reported with left bundle-branch block. Whereas it had previously been argued that type B pre-excitation and right bundle-branch block were incompatible, recent studies have shown that they may alternate or be present together in varying degrees in Ebstein''s anomaly. The constant association of type B ventricular pre-excitation and complete right bundle-branch block has been demonstrated in scalar lead electrocardiograms and vectorcardiograms from a case of Ebstein''s anomaly, and completes the spectrum of possible combinations of pre-excitation with bundle-branch block.