Comparison of thiopental and ketamine+xylazine anesthesia in ischemia/reperfusion-induced arrhythmias in rats.

BACKGROUND/AIM To investigate the influence of thiopental (85 mg/kg, intraperitoneally (ip)), and ketamine+xylazine (ketamine 75 mg/kg and xylazine 8 mg/kg, ip) anesthesia on the incidence and duration of ischemia/reperfusion-induced arrhythmias. MATERIALS AND METHODS Myocardial ischemia was induced by a 6-min ligation of the left anterior descending coronary artery, followed by a 6-min reperfusion. Measurements were taken of the incidence and duration of ventricular arrhythmias, the mean arterial blood pressure and heart rate, and the pressure rate-product (as an.index of myocardial oxygen consumption). RESULTS The arrhythmia score and the incidence of ventricular fibrillation and tachycardia were significantly decreased in the ketamine+xylazine-anesthetized rats compared with the thiopental-anesthetized group (arrhythmia score: 2.0 ± 2.1 versus 3.7 ± 1.2, P < 0.05). The heart rate was significantly lower in the ketamine+xylazine group during the entire experiment, whilst the pressure-rate product was also significantly lower in the ketamine+xylazine group at different time points of the ischemia and reperfusion periods. CONCLUSION Ketamine+xylazine anesthesia has a strong antiarrhythmic effect and an apparent depressive action on the heart rate and the myocardial oxygen consumption index. Therefore, ketamine+xylazine anesthesia is not appropriate for the evaluation of possible antiarrhythmic agents. Thiopental anesthesia is preferable to ketamine+xylazine anesthesia in the in vivo ischemia-reperfusion arrhythmia model.