Best anesthetics for assessing left ventricular systolic function by echocardiography in mice

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 308; no. 12; pp. H1525 - H1529
• Main Authors: Pachon, Ronald E, Scharf, Bruce A, Vatner, Dorothy E, Vatner, Stephen F
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 15.06.2015
• Subjects: Anesthesia; Anesthetics - pharmacology; Animals; Cardiovascular system; Ethanol - analogs & derivatives; Ethanol - pharmacology; Female; Heart rate; Heart Rate - drug effects; Heart Ventricles - diagnostic imaging; Heart Ventricles - drug effects; Isoflurane - pharmacology; Ketamine - pharmacology; Male; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Muscle Mechanics and Ventricular Function; Physiology; Predictive Value of Tests; Side effects; Stroke Volume - drug effects; Systole; Ultrasonic imaging; Ultrasonography; Ventricular Function, Left - drug effects; Xylazine - pharmacology; conscious state; mice; anesthetics; echocardiography
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00890.2014

Our review of the literature of the major cardiovascular journals for the past three years showed that for all studies using anesthesia for mouse echocardiography, the predominant anesthetic was isoflurane, which was used in 76% of the studies. The goal of this investigation was to determine if isoflurane is indeed the best anesthetic. Accordingly, we compared isoflurane with 2,2,2-tribromoethanol (Avertin), ketamine-xylazine, and ketamine on different days in the same 14 mice, also studied in the conscious state without anesthesia. A randomized crossover study design was employed to compare the effects on left ventricular (LV) systolic function and heart rate of the four different anesthetic agents assessed by transthoracic echocardiography. As expected, each anesthetic depressed LV ejection fraction and heart rate when compared with values in conscious mice. Surprisingly, isoflurane was not the best, but actually second to last in maintaining normal LV function and heart rate. The anesthetic with the least effect on LV function and heart rate was ketamine alone at a dose of 150 mg/kg, followed by Avertin at 290 mg/kg, isoflurane at 3% induction and 1 to 2% maintenance, and lastly ketamine-xylazine at 100 and 10 mg/kg, respectively. In summary, these results indicate that ketamine alone exerts the least depressant effects on LV function and heart rate, with Avertin second, suggesting that these anesthetics should be used when it is not feasible to study the animals in the conscious state as opposed to the most commonly used anesthetic, isoflurane.