Pre-excitation of the right branch of the bundle of His

  • FHN Spracklen
  • AC Witham
  • W Beck

Abstract

A patient with an ECG exhibiting a short P-R interval followed by a QRS resembling complete left bundle-branch block (CLBBB) is presented. The Wolff-Parkinson-White (WPW) syndrome complicated by left bundle-branch block was suspected. The vectorcardiogram (YCG) closely approximated that of CLBBB but the characteristic delta segment of WPW conduction was absent. Subsequently, typical delta vectors appeared, and upon abolition of pre-excitation with procainamide, no LBBB was found. Evidence is assembled that a James bundle-like bypass was responsible for the accelerated atrioventricular (AY) conduction in the first tracings with transmission directly into the right bundle system causing functional LBBB; later, the impulse was re-routed either directly or via Mahaim fibres into septal muscle, creating a typical WPW-QRS loop. Six other possible mechanisms for the short P-R-CLBBB pattern are discussed.

S. Afr. Med. J., 48, 1790 (1974).

Author Biographies

FHN Spracklen
Cardiac Clinic, Department of Medicine, Groote Schnur Hospital, Cape Town
AC Witham
Cardiac Clinic, Department of Medicine, Groote Schnur Hospital, Cape Town
W Beck
Cardiac Clinic, Department of Medicine, Groote Schnur Hospital, Cape Town
Published
2018-04-08
Section
Articles

eISSN: 0256-95749