Maternally administered esmolol decreases fetal as well as maternal heart rate.

Fetal heart rate was monitored during the administration of esmolol 100 micrograms/kg/min to a 36-year-old, 29-week pregnant woman who was undergoing craniotomy for surgical treatment of six cerebral aneurysms. During stable general anesthesia, sodium nitroprusside was administered to induce moderate hypotension; at the same time, esmolol was infused to control maternal tachycardia. Within minutes after starting the esmolol infusion, maternal heart rate decreased from 100 beats/minute to 65 beats/minute, and fetal heart rate decreased from 160 beats/minute to 130 beats/minute. Upon termination of the infusion 3 hours later, both maternal and fetal heart rate returned to preinfusion values. No adverse effects of esmolol infusion were noted in the mother or fetus.