Phrenic nerve capture caused by atrial electrode dislodgement: A case report

Figure 1 Changes in the electrocardiogram before and after pacemaker implantation. A: Upon admission, the patient’s electrocardiogram (ECG) showed third-degree atrioventricular block; B: At the end of pacemaker implantation, the ECG showed a pacemaker operating mode of ventricular pacing with atrial sensing and ventricular triggering, indicating normal atrial sensing and ventricular pacing functions; C: On the third postoperative day, when diaphragmatic flutter occurred, the ECG showed a dual-chamber pacing, dual-chamber sensing, dual-response mode. Atrial sensing and pacing were impaired, whereas ventricular sensing and pacing remained normal. The QRS complexes of the 2^nd-5^th ventricular paced beats in the limb leads were all triggered by previously sensed intrinsic atrial waves. An inappropriate atrial pulse was delivered before the QRS complex of the 6^th ventricular paced beat, suggesting abnormal sensing. No atrial wave followed the pulse, suggesting abnormal pacing.