Significance of His and Left Bundle Recordings from the Left Heart in Man

Abstract

Eight patients were studied by simultaneous intracardiac recordings of the specialized conduction system from left and right heart. Five patients had normal A-V conduction, one had left axis deviation (LAD), and two had bundle-branch block. Bundle of His (BH) and right bundle (RB) recordings from the right heart were obtained and validated as previously described. In addition a bipolar electrode catheter was introduced into the root of the aorta and left ventricle via the right brachial artery. BH and left bundle (LB) electrograms were recorded at the level of the aortic cusps and just below the aortic valve, respectively. BH recordings from both sides could be temporally superimposed and were similar in onset and duration. In patients with normal A-V conduction the duration of these deflections was BH 15 to 20, LB 15, and RB 10 msec. The conduction time from the proximal LB to ventricular (V) activation (LB-V) ranged from 20 to 25 msec. The LB-V and RB-V conduction times from comparable points were similar and support the previous observations that interventricular septal activation occurs almost simultaneously on both sides. In the patient with right bundle-branch block (RBBB) and LAD with a slightly prolonged H-V time (50 msec), the delay was localized distal to the main LB (LB-V = 30 msec). During ectopic "ventricular," probably left bundle rhythm, retrograde activation of the BH was demonstrated. Aberration (RBBB) of the supraventricular impulse resulting from invasion of the RB by the preceding interpolated premature "ventricular" beat is suggested.