Sevoflurane has no effect on sinoatrial node function or on normal atrioventricular and accessory pathway conduction in Wolff-Parkinson-White syndrome during alfentanil/midazolam anesthesia

Background: The effects of sevoflurane on the electrophysiologic properties of the human heart are unknown. This study evaluated the effects of sevofl urane on the electrophysiologic properties of the normal atrioventricular c onduction system, and on the accessory pathways in patients with Wolff-Park inson-White syndrome, to determine its suitability as an anesthetic agent f or patients undergoing ablative procedures. Methods: Fifteen patients with Wolff-Parkinson-White syndrome undergoing el ective radiofrequency catheter ablation were studied. Anesthesia was induce d with alfentanil (20-50 mu g/kg) and midazolam (0.15 mg/kg), and vecuroniu m (20 mg) and maintained with alfentanil (0.5 to 2 mu g . kg(-1) min(-1)) a nd midazolam (1 or 2 mg every 10-15 min, as required). An electrophysiologi c study measured the effective refractory period of the right atrium, atrio ventricular node, and accessory pathway; the shortest conducted cycle lengt h of the atrioventricular node and accessory pathway during atrial pacing; the effective refractory period of the right ventricle and accessory pathwa y; and the shortest retrograde conducted cycle length of the accessory path way during ventricular pacing. Parameters of sinoatrial al node function in cluded sinus node recovery time, corrected sinus node recovery time, and si noatrial conduction time. Intraatrial conduction time and the atrial-sis in terval were also measured. Characteristics of induced reciprocating tachyca rdia, including cycle length, atrial-ais, His-ventricular, and ventriculoat rial intervals, also were measured. Sevoflurane was administered to achieve an end-tidal concentration of 2% (1 minimum alveolar concentration), and t he study measurements were repeated. Results: Sevoflurane had no effect on the electrophysiologic parameters of conduction in the normal atrioventricular conduction system or accessory pa thway, or during reciprocating tachycardia, However, sevoflurane caused a s tatistically significant reduction in the sinoatrial conduction time and at rial-His interval, but these changes were not clinically important. All acc essory pathways were successfully identified and ablated. Conclusions: Sevoflurane had no effect on the electrophysiologic nature of the normal atrioventricular or accessory pathway and no clinically importan t effect on sinoatrial node activity. It is therefore a suitable anesthetic agent for patients undergoing ablative procedures.