Abstract 1. Background Phrenic nerve capture is a well-known complication of pacemaker implantation. In contrast, vagus nerve stimulation resulting in apnea has not been previously described. We report a unique case of pacing-induced apnea, likely due to stimulation of vagal afferents during atrial lead capture. 2. Case Summary A 65-year-old man was admitted following a C3-C4 spinal cord injury resulting in tetraplegia. The patient developed complete third-degree heart block followed by asystolic cardiac arrest, complicated by ventricular tachycardia during cardiopulmonary resuscitation. After return of spontaneous circulation, a temporary single-chamber pacemaker (PM) with a screw-in lead was inserted without complication. Transthoracic echocardiography showed a left ventricular dysfunction. The etiology of the initial syncope remained unexplained (a primary arrythmia could not be ruled out) and a permanent dual-chamber defibrillator was implanted. The right ventricular lead was placed at the apex and the right atrial lead at the right atrial appendage. During intraprocedural atrial lead testing, the patient presented a sudden drop in respiratory rate followed by apnea. This event was reproducibly triggered by atrial capture. Relocation of the atrial lead to the right atrial lateral wall resolved the apnea, which did not recur. 3. Discussion This case describes dual-chamber defibrillator implantation in a patient with cervical spinal cord trauma, who developed sudden apnea associated with atrial capture. This may have inadvertently stimulated the vagus nerve, sending an inhibitory signal to the brain stem, resulting in a sudden respiratory rate drop. Although rare, this phenomenon should be considered when implanting pacing systems in patients with high cervical injuries.
Kaufmann et al. (Tue,) studied this question.
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