Interactions Between Implanted Pacemaker and Automated External Defibrillator in a Patient With Out-of-Hospital Ventricular Fibrillation

Automated external defibrillator (AED) has been available for out-of-hospital ventricular fibrillation (VF). The algorithm of AED concerning VF was excellent in sensitivity and specificity. However, little information is available on the possible interactions between AED and implanted cardiac pacemaker. We report failure of AED due to impulse of pacemaker. A 68-year-old woman was operated with mitral valvulotomy and replacement, and implantation of pacemaker (VVI) because of bradycardia. Testing of the pacemaker function showed normal resistance of the ventricular lead. She lost consciousness in a bus suddenly, bystander cardio-pulmonary resuscitation was done and an ambulance was called soon. When paramedics arrived at the scene, electrocardiogram showed combination with coarse VF (high amplitude) and impulse of pacemaker. AED did not work at the scene at all. After transfer to our hospital, she received advanced cardiac life support including defibrillation and drugs, and finally restoration of spontaneous circulation was obtained and the patient was carried to intensive care unit. Unfortunately, she later died because of hypoxic brain. We can conclude that a clear understanding of the possible interactions between AED and pacemaker is necessary for further refining the diagnostic algorithms of AED.