Repeated ventricular fibrillation after defibrillation in a pacemaker patient

History: A 62-year-old patient was admitted for an operation of a hernia of the right groin in the surgical department. He had a dual chamber pacemake r because of a binodal disease. Pre-operatively the patient was reanimated because of ventricular fibrillation in dilated cardiomyopathy and was defib rillated 12 times, unexpectedly often. Diagnosis: The reason of the repeated ventricular fibrillation was a spike- on-T-phenomenon due to loss of the sensing function of the pacemaker (entra nce bloc). Treatment: Therefore, the pacemaker was explanted, and the ventricular fibr illation came to an end. The patient recovered. Conclusions: The repeated defibrillations with the electrodes over the basi s and the apex of the heart damaged the pacemaker. The following fibrillati on episodes were founded on a spike-in-T-phenomenon. In order to prevent su ch damage of pacemakers, pacemaker patients should be defibrillated and car dioverted in anterior-posterior position of the electrodes.