[Abnormal pacing following defibrillation - exit block after microdislocation of the electrode (author's transl)]

Two days after a 52-year-old patient with coronary heart disease (third degree-av-block and ventricular rhythm, permanent pacemaker treatment) had a pacemaker replacement, bradycardia and pacemaker exit block occurred. After defibrillation with 300 Ws pacemaker for spontaneous ventricular fibrillation, entrance block and new fibrillation were observed. Further defibrillation lead to raising the frequency of the pacemaker and to abnormal stimulation, which in turn triggered irreversibly ventricular fibrillation and the death of the patient. Autopsy showed a micro-dislocation of the electrode and the pacemaker showed a defect of the Zener diode and abnormal stimulation with 4000 Hz ith a pulse width of 240-275 ms and a pulse interval of 1010 ms. We like to point out the importance of the stimulation threshold measurement following pacemaker replacement because of early diagnosis of electrode dislocation that can lead to ventricular fibrillation. We also describe the complication of defibrillation with a pacemaker patient and give advice for prevention of its occurrence.