Case #3 - Heart Block in a Pacemaker: Does This Mean Trouble?

by Mark Pollet, MD, Yochai Birnbaum, MD, and Alireza Nazeri, MD

We present a finding in a 61-year-old woman whose St. Jude Medical dual-chamber permanent pacemaker had been implanted to treat symptomatic bradycardia. The pacemaker, programmed in DDD mode, had a lower rate limit of 60 beats/min and an upper limit of 120 beats/min, a paced atrioventricular (AV) delay period of 250 ms, and a sensed AV delay period of 225 ms.

Case #2 - Evaluation of Suspected Device Malfunction on ECG

by Luke Cunningham, MD, Henry D. Huang, MD, and Yochai Birnbaum, MD

A 62-year-old man with nonischemic cardiomyopathy, a history of Boston Scientific biventricular implantable cardioverter-defibrillator placement (in 2011), ventricular tachycardia after radiofrequency ablation (April and November 2014), paroxysmal atrial fibrillation, and severe mitral regurgitation presented with acute exacerbation of heart failure. A resting electrocardiogram (ECG) showed normal sequential atrioventricular (AV) pacing at a heart rate of 63 beats/min. Baseline device settings were DDD with a lower rate of 60 beats/min, an upper rate of 115 beats/min, a minimum sensed AV delay of 135 ms, and a minimum paced AV delay of 180 ms. The patient underwent mitral valve replacement. Three days later, the pacemaker rate was increased to 80 beats/min, and an ECG showed pacing concomitantly within the T wave in beats 5 and 13 of the rhythm strip (Fig. 1).

Case #1 - Pacing on the T Wave: What Is the Cause?

by Amir Gahremanpour, MD, Yochai Birnbaum, MD, Tracy A. Holt, BS, and Mohammad Saeed, MD

We present the case of a 50-year-old man who had a dual-chamber pacemaker that was implanted because of symptomatic bradycardia. The pacemaker was programmed in a DDD mode, with a lower rate of 70 beats/min; upper rate, 120 beats/min; paced atrioventricular (AV) delay, 180 ms; sensed AV delay, 150 ms; and V-blanking period, 200 ms.