The Antiarrhythmic Properties of Lidocaine and Procaine Amide

Abstract

The effects of lidocaine (Xylocaine) and procaine amide on arterial pressure, myocardial contractile force, and ventricular excitability were studied in 12 patients undergoing cardiac operations. Both compounds resulted in an increase in the stimulation threshold of the ventricle during diastole and neither caused a significant change in the duration of the absolute refractory period. Lidocaine, in doses of 1.0 to 2.0 mg./Kg., produced no significant circulatory depression but every patient given procaine amide (2.0 or 4.0 mg./Kg.) evidenced a fall in arterial pressure and a decrease in the contractile force of the right ventricle. These physiologic observations and clinical experiences with the use of lidocaine indicate that it is an effective antiarrhythmic agent and that it is preferable to procaine amide in the management of ventricular arrhythmias that occur during and following cardiac operations.