Case presentation
An 88-year-old man came to the cardiology clinic with dizziness on exertion for two months. He had long standing hypertension and a baseline right bundle branch block (RBBB). Blood pressure was 140/70 mmHg and pulse rate was 40 beats/min at presentation. Systemic examination was unremarkable. Electrocardiogram (ECG) recorded in the clinic showed complete heart block. Subsequently, a dual chamber permanent pacemaker (AttestaTM, Medtronic, Minneapolis, MN, USA) was implanted with the ventricular lead placed at the apex. The device was programmed to the DDDR mode, with a 60 bpm lower rate limit, 130 bpm upper tracking rate, mode switch ON, 140 and 120 ms paced and sensed AV intervals, 0.7 and 2.3 mV atrial and ventricular sensitivities, and atrial and ventricular pacing amplitude/pulse width of 1.0 V/0.4 ms and 1.0 V/0.4 ms, respectively. A 12-lead electrocardiogram recorded after pacemaker implantation is shown in Figure 1. What are the abnormalities in this electrocardiogram? What are the immediate concerns regarding pacemaker functionality?