Refractory bradycardia during retrograde pyelography and spinal anesthesia

Bradycardia commonly occurs during spinal anesthesia as a result of vagally mediated slowing of sinoatrial (SA) node firing. Peritoneal traction or urinary bladder distension, for example, may serve as a stimulus for SA node inhibition, particularly when thoracic levels of spinal anesthesia interrupt function of the sympathetic limb of the autonomic nervous system. Although atropine dependably reverses such heart rate slowing, we recently encountered, during spinal anesthesia for cystoscopy and retrograde pyelography, bradycardia that was unexpected and refractory to treatment with atropine.