Recovery of Impulse Propagation in the Bundle Branches of the Human Heart

Abstract

During the study and follow up of a large series of cases of intermittent bundle branch block (BBB), we observed that recovery of impulse propagation may occur in many different forms, encompassing a wide spectrum of quantitative and qualitative variations. In some cases, there is a greatly prolonged range of complete BBB, followed by a short range of incomplete BBB. In others, the dominant feature is a disproportionately wide range of incomplete BBB; and still in others, a pure prolongation of the complete BBB range with disappearance of the incomplete BBB becomes apparent. These disparate forms of abnormal conduction are further complicated by the fact that the prolongation of recovery may vary from a few milliseconds to several seconds and, even more, by the fact that adaptation to changes in heart rate may also exhibit unexpected responses, including cases in which the duration of recovery is totally unaffected by variations of the cardiac cycle length.