Abstracts

Few adverse events on heart rate have been reported with vagus nerve stimulation (VNS) for refractory epilepsy. This effect may be caused by electrical stimulation of the efferent nerve fibers innervating the heart. We describe three cases with intraoperative bradycardia during device testing., From 1999 until 2006 approximately 90 patients with medically refractory epilepsy have been implanted with a VNS system in our centre. We review 3 patients who showed a bradycardia during intraoperative device testing (Lead Test) and their VNS-therapy follow-up outcome., Patient 1, a 32 year old female with complex partial epilepsy, experienced a bradycardia of 43 beats/min during the first Lead Test, and 25 beats/min during a second test. Ten days after the operation the VNS system was activated under ECG-monitoring. No cardiac events occurred. Patient 2, a 52 year old male with partial epilepsy, experienced bradycardia of 40 beats/min. Ten days after implantation no cardiac effects were recorded when VNS therapy started. Patient 3, a 59 year old female with tonic clonic seizures, had a change in heart rate from 63 beats/min to 54 beats/min. No change in cardiac rhythm occurred when VNS therapy started.
All three have had 4-6 years of chronic stimulation without cardiac side effects. The effect on epilepsy varied between 30% - [gt] 50% reduction in seizure frequency. They also had less severe seizures and improved postictal recovery. Patient 1 and 2 have received a new pulse generator when battery was depleted. During the subsequent intraoperative Lead Tests no cardiac changes on ECG occurred., Our results suggest that bradycardia during intraoperative device testing does not have to be a reason for aborting the operation. However, postoperative VNS-therapy onset should be done carefully and under ECG monitoring. Furthermore, long-term VNS in these patients seems safe in respect to heart rate.,