Variable Ventricular Complexes in Heart Block, and Their Relation to Bilateral Bundle Branch Block

Variable ventricular complexes in heart block have been recorded by a number of writers since they were first described by Mathewson (1913). King (1934) found them in five out of thirty-six cases with the double lesion of complete heart block and bundle branch block. Cohn (1913) noted both left and right bundle branch block and transitional complexes in a case passing from partial to complete A-V block, and he suggested that the changes might be due either to depression of conductivity in both branches alternately or else to a wandering pacemaker. Gilchrist and Cohn (1928) thought the latter explanation the more likely, and attributed the transitional complexes to the almost synchronous discharge of impulses from centres in each ventricle. Similar views have been expressed by Willius (1924), by Coelho (1932), and by Scherf and Schott (1932). On the other hand, Mathewson considered that in his case the impulse was being conducted alternately by each branch.