ESMOLOL PREVENTS AND SUPPRESSES ARRHYTHMIAS DURING HALOTHANE ANESTHESIA 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-mu-g.kg-1.min-1 (P < 0.001) by the prior administration of esmolol 0.5-mu-g.kg-1 bolus followed by an infusion at the rate of 150-mu-g.kg-1.min-1. Higher esmolol infusion doses of 200-mu-g.kg-1.min-1 further increased ADE to 99.0 +/- 2.92-mu-g.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-mu-g.ml-1 solution of epinephrine. In all dogs ventricular tachycardia was restored to sinus rhythm by a bolus dose of esmolol (1-mu-g.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 epinephrine-related ventricular arrhythmias during anaesthesia in man.