Case summaryA 75-year-old woman was referred to our hospital becauseof dizziness and presumed pacemaker dysfunction (Fig. 1).Eight weeks earlier, the patient had underwent implantationof a single chamber pacemaker (Sensia, Medtronic, USA)with a tined, steroid-eluting bipolar right ventricular (RV)lead (4074 CapSure Sense, Medtronic, USA) for chronicatrial fibrillation and symptomatic bradyarrhythmia. Twoweeks post-implantation surgical revision had been neces-sary due to RV lead dislocation. Device interrogation priorto hospital discharge had been inconspicuous with a RVpacing threshold less than 1.0 V at 0.4 ms during unipolarstimulation (Fig. 2), a pacing impedance of 612 Ohms andan R wave amplitude sensing of [22 mV. Chest X-raysuggested a regular lead position in the RV apex.At presentation, the patient reported episodic dizzinessand intermittent sharp left pectoral pain that was presentsince approximately 1 week. Intrinsic heart rate at rest was50–60 bpm and blood pressure 130/85 mmHg. The surfaceElectrocardiogram (ECG) showed unipolar pacing spikeswithout capture (Fig. 1). Device interrogation revealed aRV pacing threshold that had increased to [6Vat1msduring unipolar stimulation, with a pacing impedance of521 Ohms and an R wave amplitude sensing of [22 mV.During bipolar stimulation, a pacing threshold of 2.25 V at1.0 ms was measured, and the device was reprogrammed tobipolar pacing with an output of 4.5 V at 1.0 ms (Fig. 3).On the same day, however, continuos ECG monitoring onthe ward revealed intermittent loss of capture (Fig. 4).Figure 5a shows the chest X-ray that was taken at the timethe patient presented at our clinic. What is the most likelydiagnosis?CommentaryIn patients with presumed pacemaker dysfunction, deviceinterrogation should be performed first. In our case, deviceinterrogation revealed dubious findings. We found excellentsensing parameters, an inconspicuous pacing impedance,unipolar exit block and bipolar capture with an elevatedpacing threshold. In this situation, the comparison of a cur-rent chest X-ray with the image taken earlier after implan-tation may verify lead dislocation. In our case, noconclusionscouldbedrawnfromthepost-implant X-raydueto a low image quality, but in consideration of the patienthistory, the current chest X-ray (Fig. 5a) was found to besuggestive for late lead perforation. This diagnosis wasconfirmed by native multidetector computed tomography(CT)ofthechest(Fig. 6).CTimagingandechocardiographyexcluded significant pericardial effusion. Based on thesefindings, elective lead extraction was performed in theoperating theatre with backup for emergency thoracotomybecause of the elevated procedural risk for haemorrhagicpericardial effusion and tamponade. The lead could beremoved without complications and a new RV lead (samemodel, 4074 CapSure Sense, Medtronic, USA) wasimplanted in the lower RV close to the apex. Postoperativedevice interrogation demonstrated a stable unipolar pacingthreshold of 0.5 V at 0.5 ms.