COMPARATIVE EFFECTS OF HALOTHANE, ENFLURANE, AND ISOFLURANE ON ATRIOVENTRICULAR CONDUCTIVITY AND SUBSIDIARY PACEMAKER FUNCTION IN DOGS

This study compares effects of equipotent concentrations of halothane, enflurane, and isoflurane on atrioventricular (AV) function in dogs. Enflurane anesthesia was associated with more AV nodal depression, onl y at faster heart rates than either halothane or isoflurane. These rat e-related effects are important in the genesis of supraventricular ree ntrant tachyarrhythmias. Subsidiary pacemaker function exhibited marke d variability between and within animals with no demonstrable differen ce between anesthetic drugs. Enflurane has more depressant effects on AV nodal recovery properties than halothane or isoflurane; however, th ere were no differences demonstrated on slow AV nodal conduction. This suggests that enflurane would be the most effective volatile anesthet ic in converting or slowing supraventricular tachyarrhythmias, while c arrying no more risk of causing advanced heart block.