Near fatal bradycardia during cesarean section under spinal anesthesia: "High spinal" may not be only risk factor.

Abstract

Sir, Bradycardia during cesarean section under spinal anesthesia is not uncommon and usually associated with a high sympathetic block. We are reporting a case of severe near fatal bradycardia in 31-year-old parturient undergoing cesarean section under spinal anesthesia without a “high spinal” block. A 31-year-old parturient, weighing 67 kg and height 164 cm, third gravida at 38 completed week pregnancy, was posted for an elective cesarean section for a history of previous two cesarean section and breech presentation in this pregnancy. She did not have any comorbid illness and all the preoperative investigations were within the normal limit. Preoperative blood pressure was 134/86 mm Hg and pulse rate was 86 beats per minute (bpm). In the operating room spinal anesthesia was administered in left lateral posture in L3-L4 intervertebral space by a 25G Qunicke's spinal needle. 10 mg 0.5% hyperbaric bupivacaine and 15 mcg fentanyl was used for spinal anesthesia. 500 ml of Ringer's Lactate was infused during spinal anesthesia. After 5 min of spinal anesthesia, when a T8 height of sensory block was achieved, surgery was started. No significant drop in the blood pressure was note after spinal anesthesia. Ten minutes later, a healthy male baby was delivered uneventfully. Soon after baby delivery, when the obstetrician was massaging the uterus and giving traction to the umbilical cord to take out the placenta, we noticed a sudden severe bradycardia, heart rate dropped to 29 bpm from 68 bpm and the patient complained of nausea. Immediately, we asked the surgeon to stop manipulation and 0.6 mg atropine was given intravenously. She also received 100% oxygen through anesthesia circuit. Sooner, heart rate came to 85 bpm and the patient was fully awake. We checked the height of sensory block again then, and found to be T6. Obstetrician then delivered the placenta; again drop of heart rate from 90 to 65 bpm was noted during this procedure. However, again it came up to 90 bpm without any intervention. Rest of the surgery was uneventful and no episode of bradycardia or hypotension was noted throughout the surgery. Reported incidence of bradycardia during cesarean section under spinal anesthesia is 2.5%.[1] It is classically associated with a “high spinal block”;[2] a sensory block height more than T4 has been described as a risk factor.[1] Cardiac arrest has been reported during cesarean section under spinal anesthesia at the time of placental expulsion.[3] Manipulations of the abdominal viscera, peritoneum or traction of the visceral ligaments during abdominal surgeries can cause a severe bradycardia and hypotension.[4] Bradycardia during surgery under spinal anesthesia is due to a reflex cardiovascular depression mostly due to a decrease in the venous return, known as Bezold-Jarisch reflex or neurocardiogenic syncope.[5] Prompt intervention is the key to the success of management of bradycardia and maternal mortality can be prevented. We treated bradycardia by intravenous atropine as per current advanced cardiovascular life support protocol and it was successful.[6] To best of our knowledge, bradycardia from uterine massage at the time of cesarean section has not been reported until now. Anesthesiologists caring pregnant women must remember that severe bradycardia may occur even without a “high spinal” and timely intervention is the only key to maternal safety.