A pilot study on midazolam sedation for murine echocardiography: A potential alternative to isoflurane anesthesia and awake imaging

Isoflurane anesthesia is often used to facilitate murine echocardiography, but can suppress cardiac function. Awake imaging avoids pharmacological interference, but can induce sympathetic activation. In this Midazolam sedation. Parameters were compared using repeated-measures ANOVA. Midazolam enabled imaging without overt stress behavior. Compared to midazolam, heart rate was similar under isoflurane and higher while awake (p ≤ 0.01). End-systolic volume was larger under isoflurane and smaller while awake; stroke volumes remained similar across conditions. Global longitudinal and circumferential strain were less negative under isoflurane (p = 0.03) but similar during awake imaging, while radial strain was higher during awake imaging. Peak longitudinal strain rate was less negative under isoflurane (p ≤ 0.01) and more negative while awake (p = 0.05). Early diastolic strain rate was similar under isoflurane and lower while awake (p = 0.02). In conclusion, cardiac function was most depressed under isoflurane and most enhanced during awake imaging, likely stress-driven. Murine echocardiography under midazolam sedation was feasible, yielding better function than isoflurane anesthesia, closer to awake imaging but without overt handling stress. These findings require further validation across disease models, sexes, and strains.