Impact of anesthesia on valvular function in normal rats during echocardiography.

Anesthetic agents have different effects on hemodynamic and cardiac functional parameters. The influence of these changes on valvular function has not been studied in small animals. For this purpose, 48 male Wistar rats were divided into three equal groups. An echocardiogram was performed under inhaled isoflurane 2% gas (group I) or under intraperitoneal pentobarbital 50 mg/kg (group II) or ketamine/xylazine (group III) 40/8 mg/kg. Aortic regurgitation was only found in group III (80%, p < 0.0001 vs. groups I and II). Pulmonary and mitral regurgitation (PR, MR) were observed in all groups but were more frequent in group III (PR 67%, MR 100%) compared with group I (PR 13%, p = 0.003; MR 44%, p = 0.001 vs. group III) and group II (PR 19%, p = 0.011; MR 25%, p < 0.0001 vs. group III). Moreover, valvular regurgitations in group III (except tricuspid regurgitation) were more severe compared with groups I and II. The findings in group III were the result of increased blood pressure and afterload, left ventricular (LV) dilation and decreased function. Also in group III, the regurgitations diminished over time as the blood pressure decreased and LV function recovered. Isoflurane and pentobarbital had less pronounced effects on valvular function (5 and 10 min after induction, respectively) compared with ketamine/xylazine and, therefore, might be the anesthetics of choice for valvular evaluation in male Wistar rats. In conclusion, anesthesia causes hemodynamic changes that may result in functional valvular regurgitations in normal rats.