Pseudomalfunction of a dual chamber pacemaker caused by accelerated junctional rhythm and alternating ventricular safety pacing

A 78-year-old woman presented at the emergency department (ED) with palpitation, cold sweating, and dizziness. A dual chamber pacemaker (PM) (Medtronic Kappa KDR903) had been implanted due to brady-tachycardia syndrome 2 years before and she had a history of hypertension and diabetes. Twelve-lead ECG at the ED showed a regular narrow QRS rhythm with a rate of ∼70 bpm and alternating atrial–ventricular sequential pacing spikes leading to suspicion of PM malfunction ( Figure 1 ). The patient, however, had no abnormalities on a PM check-up 2 weeks prior to the ED visit. After amiodarone therapy for 2 years, the patient became PM-dependent. Histogram from the PM showed …