EFFECTS OF ANESTHESIA ON ACUTE ISCHEMIC ARRHYTHMIAS AND EPICARDIAL ELECTROGRAMS IN THE PIG-HEART INSITU

Study objective - The aim of the study was to assess the influence of general anaesthesia on electrocardiographic and arrhythmogenic responses to left anterior descending coronary artery occlusion.Design - Pigs weighing 18-20 kg were anaesthetised with α chloralose 100 mg·kg-1 (n=9) or thiopentone 30 mg·kg-1 (n=9) and the arrhythmogenic effects of coronary artery occlusion were examined by sequential electrocardiographic measurements every 5 min and arrhythmia analysis every minute over a 60 min period.Results - α Chloralose predisposed to lower ST segment elevation (analysis of variance for repeated measurements p<0.002), less marked epicardial conduction delay (p<0.01) with slower progression to monophasic potentials, and in contrast, to a greater number of episodes of ventricular premature beats (p<0.005), ventricular tachycardia (51 υ 32 episodes), and ventricular fibrillation (6 υ 2 pigs) than barbiturate anaesthesia.Conclusions - α Chloralose and barbiturates exerted opposite electrocardiographic and arrhythmogenic effects in a porcine model of acute myocardial ischaemia. Due to its proarrhythmic effect chloralose should probably be used in studies dealing with spontaneous and induced ischaemic arrhythmias.