The authors report the case of a patient suffering the consequences of harmful preoperative between a prophylactic cardiac pacemaker system and cutting diathermy, resulting in irreversible ventricular fibrillation. After reviewing the different mechanisms responsible for this accident, they attribute the blame to a phenomenon of capture of electromagnetic currents with the pacemaker catheter playing the role of an aerial. They reconsider the indications for the use of prophylactic pacing and recall the safety precautions which must be respected at the time of simultaneous use of an external pacemaker and cutting diathermy.