Under spinal anaesthesia, intravenous midazolam decreases blood pressure and heart rate (HR)'.

How does midazolam affect heart rate?

Midazolam enhances the dominance of sympathetic activity, which is associated with increased HR and decreased BP. These differences in effects on cardiac autonomic nervous system activity during conscious sedation are important in patients at risk of cardiovascular complications.

Can sedation cause low heart rate?

Effects of sedation or anesthesia on heart rate

Deep sedation caused approximately 5% decrease in heart rate (p = NS). However, general anesthesia caused a highly significant 24% drop in heart rate, compared to mild conscious sedation.