Shortness of breath in a patient with complete heart block and permanent pacemaker: A case of effective pacemaker reprogramming

An 82-year-old frail woman with a prior history of hypertension, complete heart block, and dual permanent pacemaker (Sensia DR SEDR01, Medtronic Inc., Minneapolis, MN) presented to pacemaker clinic with symptoms of shortness of breath (SOB), dizziness, and “low pulse rate”. Pacemaker interrogation showed underlying normal sinus rhythm, sinus rate of around 74 beats/ min with atrial sensed events, and ventricular paced rhythm with frequent symptomatic premature ventricular complexes (PVC). Pacemaker parameters were DDD, lower rate limit (LRL) of 60 beats/min, and maximum tracking rate of 120 beats/min, along with paced/sensed AV delay of 300/250 ms. Also noted was high pacing threshold of 3.5 V at 1 ms in the atrial lead with normal sensing parameters. In view of these, the pacemaker mode was reprogrammed to VDD mode and the patient was given betablocker therapy for frequent PVCs. She presented to arrhythmia clinic a few weeks later because of worsening SOB, light-headedness, and transient ischemic attacklike symptoms. Electrocardiography (ECG) performed in the clinic showed ventricular paced rhythmwith retrograde P waves (Fig. 1). What was the underlying arrhythmia mechanism? What treatment options are available? 2. Discussion