Electrophysiological Effects of Lidocaine in Acute Myocardial Infarction with Bifascicular Block or Complete A-V Block

Abstract

Electrophysiological effects of lidocaine were studied in 27 patients with acute myocardial infarction complicated by bifascicular block (group I: 20), and complete A-V block (group II: 7). Lidocaine was administered intravenously in bolus doses of 100 mg each at intervals of 10 min. In group I, there was no significant change in the heart rate (Before (B) = 84.85 ± 24.19, After (A) = 87.25 ± 20.26 beats/min) intra-atrial (PA) conduction time (B = 25 ± 6.18, A = 27.22 ± 6.69 ms), A-V nodal (AH) conduction (B = 111.5 ± 56.12, A= 111.5 ± 56.5 ms) or His bundle to ventricular (HV) activation time (B = 59.5 ± 19.32, A = 61.25 ± 18.62 ms) after lidocaine administration. In group II, 2 patients reverted to sinus rhythm, one with 1:1 conduction and the other with type II Wenckebach’s block, while being prepared for the study, but both had complete A-V block within 1 h of the His bundle electrogram recordings. Of the remaining 5 patients, 4 had supra and 1 infra His A-V block. After lidocaine, 2 patients developed asystole. In the remaining 4 patients, there was no change in the escape rate or various conduction intervals.