BUNDLE-BRANCH BLOCK UNDER VOLUNTARY CONTROL

Abstract

Bundle-branch block can no longer be considered to result always from a discrete pathological lesion permanently interrupting the ventricular conducting system. Many instances of transient and intermittent bundle-branch block have been reported and the factors responsible for the induction and abolition of conduction defects have been reviewed. Five patients are reported in whom bundle -branch block could be made to appear and disappear at will in 4 this variation was clearly associated with alterations in the heart rate induced by respiration, carotid sinus stimulation, or pharmacological agents. The importance of this observation in the diagnosis of myocardial infarction complicated by left bundle-branch is discussed. It is recommended that an attempt to re-establish normal conduction should be a routine procedure in patients with left bundle-branch block.