Akute herzrhythmusstörungen bei schrittmacher- und defibrillatorpatienten

The implantation of an artificial pacemaker (PM) is an established therapy of bradyarrhythmias, whereas implantable cardioverter defibrillators (ICD) are an acceptable approach to treat patients (pts) with life-threatening ventricular tachyarrhythmias. Despite excellent results in pacemaker therapy and the prevention of sudden cardiac death by ICDs, problems anti complications have been reported. Emergency situations can be caused by "true" complications, of the pulse generator and/or the electrode system. In addition, emergencies can occur due to the underlying heart disease. Among "true" complications, infection is the most serious event with an incidence of 2-7%. Infections are associated with increased morbidity and mortality. When an infection is present, usually a complete removal of the entire system is required. Hematoma involving the pulse generator pocket is seen only occasionally (incidence 2-5%). Management of a pocket hematoma can be expectant with local compression; however, when it is unsuccessful, surgical intervention is required. Lead-related complications occur with an incidence of 5-10%: most frequently are dislocations (incidence 3-10%), lead wire fractures (incidence 1-5%) or insulation defects. These complications lead to inappropriate ICD shocks. In all cases of lead-related complications, repair of the electrodes is not recommended and the treatment of choice is replacement of the lead system. Dysfunctions of these devices can produce ineffective pacing or oversensing with a lack of cardiac stimulation or shocks. To analyze the ECG, an exact characterization of the pacemaker spikes and the P- and waves are necessary. Oversensing leads to a lack of artificial pacing whereas undersensing produces a permanent stimulation in competition with the patient's own rhythm. A reentry of ventriculoatrial conduction and atrioventricular pacing produced pacemaker mediated tachycardia (PMT). Inappropriate ICD shocks are mainly caused by atrial fibrillation with an incidence of 20-40%. Slowing of the atrioventricular conduction rate is the adequate therapy in those pts. Frequent appropriate ICD discharges (incidence ≈ 1%) is one of the most important problems in ICD pts and is often caused by poor left ventricular dysfunction in the majority of them. In those pts, aggressive treatment of heart failure is necessary and alternative approaches like antiarrhythmic drug therapy or catheter ablation should be used in only selected cases. In pts with emergency situations after PM/ICD implantation, fast appropriate diagnostic and therapeutic strategies are necessary to avoid further PM/ICD discharges and to avoid risk to the pts.