Effects on electricalrestitution of given esmolol during cardiopulmonary resuscitation in a swine ventricularfibrillation model

Abstract

：Objective To investigatethe effect on electrical restitution of β1-adrenergic receptor antagonist esmolol administered duringcardiopulmonary resuscitation in the porcine ventricular fibrillation model. MethodVentricular fibrillation untreated for four minutes was induced by dynamic steady statepacing protocol in 40 healthy male pigs, in which local unipolar electrograms wererecorded using one 10-electrode catheter that was sutured to the left ventrieularepicarditan. During CPR, animals were randomized into two groups to receive saline asplacebo or esmolol after two standards doses of epinephrine. At postresuscitation 2-hour,six pigs were randomly selected from each group and the second VF induction was performed.Local activation-recovery intervals (ARI) restitutions and the VF inducibility betweencontrol group and esmolol group were compared. Western blotting was performed to determinecardiac ryanodine receptor (RyR2) protein expression, and their phosphorylation status.Results No sig-nificant differences were observed at the restoration of spontaneouscirculation between two groups. Higher postre-suseitation 2-hour survival rate wasobserved in the esmolol group. Esmolol significantly flattened ARI restitution slope,lessened regional difference of ARI restitution, decreased the VF inducibility, andalleviated RyR2 hyper-phosphorylation. Conclusions Esmolol given during CPR significantlyimproved postresuscitation 2-hour survival rate. Its effects on modulating electricalrestitution property and intracellular calcium handling make up the most important reasonswhy β1-blockadesignificantly reduced the onset and maintenance of VF. Key words: Veutricularfibrillation; Action potentials; Restitution property; Cardiac ryanodinereceptor; Beta-adrenergic receptor