Vagal Nerve Stimulation Device-Induced Second-Degree Heart Block and Sinus Pauses

A 41-year-old male with a history of preterm birth, intellectual disability, and refractory epilepsy on multiple anti-seizure medications with an active vagus nerve stimulation device (VNS) presented for progressive lethargy and a global decline in health. The symptoms began two years after placement of a second VNS, as the first was removed years earlier due to infection complications. At the time of the lethargy and global decline presentation, the VNS was set at an output of 3.25 mA. On admission to the hospital, telemetry showed frequent sinus pauses lasting 2 to 8.5 seconds. An electrocardiogram (EKG) showed a second-degree Mobitz type II atrioventricular block. A transthoracic echocardiogram showed an ejection fraction of 65% without valvular abnormalities. A sleep study showed mild sleep apnea. The electroencephalogram (EEG) did not show epileptiform activity correlated to these events. Previous workup included a transthoracic echocardiogram and a 30-day cardiac monitor, which had shown normal sinus rhythm. Complete resolution of sinus pauses occurred after the VNS device was turned off. Cardiac arrhythmias associated with VNS are exceedingly rare and can occur years after implantation. High clinical suspicion is required in patients with VNS devices who develop new-onset lethargy and/or atonic episodes without other causes. This case aligns with previously reported cases and provides more evidence of these rare but potentially life-threatening events.