Esmolol prevents and suppresses arrhythmias during halothane anaesthesia in dogs

The antiarrhythmic effect of esmolol, a selective beta₁ adrenoreceptor blocker, was evaluated in the presence of epinephrine induced arrhythmias in dogs (n = 6). The arrhythmogenic dose of epinephrine (ADE) during 1.2 MAC halothane in dogs was increased from 3.23 ± 0.25 (mean ± SD) to 30.90 ± 3.56 μg · kg^-1 · min^-1 (P < 0.001) by the prior administration of esmolol 0.5 μg · kg^-1 bolus followed by an infusion at the rate of 150 μg · kg^-1 · min^-1. Higher esmolol infusion doses of 200 μg · kg^-1 · min^-1 further increased ADE to 99.0 ± 2.92 μg · kg^-1 · min^-1 (P < 0.001). After discontinuation of esmolol and during continued halothane anaesthesia, ventricular tachycardia was induced by increasing the infusion rate of the 100 μg · ml^-1 solution of epinephrine. In all dogs ventricular tachycardia was restored to sinus rhythm by a bolus dose of esmolol (1 μg · kg^-1). We conclude that esmolol pretreatment increases the ADE during halothane anaesthesia in dogs. Our data suggest that esmolol may be useful as an antiarrhythmic agent in the management of epinephrinerelated ventricular arrhythmias during anaesthesia in man.