Bundle-Branch Block Under Voluntary Control

Bundle-branch block can no longer be regarded as a static condition always associated with an organic lesion situated in one of the main bundles of the ventricular conduction system, as suggested by the early experiments of Eppinger and Rothberger (1909, 1910) and by Lewis and Rothschild (1915).A great amount of work, based on histological, electrocardiographic, and himodynamic studies, has revealed some of the immense complexity of the subject.In the course of a survey of 167 patients with bundle-branch block (Bauer, 1964), many examples of transient and intermittent bundle-branch block were discovered.In one patient the conduction defect could be made to appear and disappear by simple manceuvres.Subsequently, during the following 12 months, four further examples of voluntary control of bundle-branch block were discovered: these five patients, whose case histories are summarized in Table I and reported in detail below, are the subject of this report.The concept that bundle-branch block, in some instances, may be under voluntary control and can be induced and abolished at will is of obvious practical as well as theoretical interest.TABLE I SUMMARY OF FIVE PATIENTS WITH LEFT BUNDLE-BRANCH BLOCK UNDER VOLUNTARY CONTROL Case No. Sex and age Diagnosis Conduction Electrocardiogram 'Method of inducing Critical |(yr.)defect showing normal normal conduction heart conduction rate/min.1 M.55 Ischemic heart LBBB Anterior Deep inspiration 71-74 disease myocardial and breath holding infarction Carotid sinus stimulation Pharmacological agents 2 M.39 Ischumic and LBBB Anterior and Deep inspiration and 50-60 hypertensive posterior wall breath holding heart disease ischwemia 3 M.42 Ischaemic heart LBBB Antero-septal Deep inspiration and 60-62 disease infarction breath holding 4 M.48 Hypertensive LBBB Left ventricular Carotid sinus 62-68 heart disease hypertrophy; stimulation and chronic ischemia glomerulonephritis 5 M.52 Ischvmic heart LBBB Normal Deep inspiration and Indeter- disease breath holding minate LBBB = left bundle-branch block.