An Undocumented Effect of Lidocaine Revealed by Computerized Electrocardiography

The influence of an intravenous push of lidocaine 1 mg/kg followed by 2 mg/min infusion on total QRS amplitude and R-to-S duration in leads V₂-V₄ of the electrocardiogram was studied in 11 patients who were hospitalized in the coronary care unit. A computerized system sampled the amplitude and timing of peak R and S waves of 1100 QRS complexes of leads V₂-V₄, starting two minutes before the first push of lidocaine. Curves of amplitude and R-to-S dura tion versus time were obtained in all patients. QRS amplitude in V₂ and V₃ increased significantly in 10 of 11 patients (p < 0.005). The mean voltage in crease for all patients was 0.1±0.07 millivolt. The authors also observed a mild prolongation of R-to-S duration (0.8±1.0 millisecond p < 0.02). This new find ing, obtained by a simple computerized system, may possibly have potential future practical clinical application as a feedback parameter for closed-loop control systems for the administration of lidocaine.