Sustained Suppression of Premature Ventricular Contractions by a Three-Month Pacing Adjustment

Figures

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  Figure 1. A three-month pacing elevation produced a sustained PVC decrease that persisted even after return to the original heart rate. Raising the pacemaker lower pacing limit from 50 bpm to 60 bpm (beginning on 5-18-2021) decreased the average number of PVCs per hour (ordinate), recorded as both single PVC's (blue) and PVC runs (red). The initial drop in PVC activity from 31% to 3.6% occurred within seven days. Each point represents PVC activity averaged over two-month intervals (prior to 5-17-21) and then averaged over two-week intervals (after 5-24-21). Resetting the lower limit from 60 to 50 bpm after 9-20-2021 did not significantly increase either single PVCs (green) or PVC runs (yellow) for the next three months. The PVC% in parentheses indicate PVCs (single & multiples) as a percentage of total beats. PVC=premature ventricular contraction, bpm=beats per minute

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  Figure 2. Patient's ECG showing presence of PVCs at the original lower pacing rate limit of 50 bpm. PVC=premature ventricular contraction, HR=heart rate, PMK=pacemaker, bpm=beats per minute

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  Figure 3. Patient's ECG showing absence of PVCs after elevation of the lower pacing rate limit from 50 to 60 bpm. PVC=premature ventricular contraction, HR=heart rate, PMK=pacemaker, bpm=beats per minute

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  Figure 4. Hourly PVCs recorded continuously during a week of normal activity. Patient records of hourly PVCs (ordinate) were recorded with a Zio XT wearable monitor during periods of normal activity and two-hour periods of strenuous tennis (highlighted in yellow). The average single PVCs/hour for this six day period was 81/hour or 2.4% of total beats. The elevated lower pacing limit of 60 bpm was maintained throughout this period. PVC=premature ventricular contraction, bpm=beats per minute

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  Figure 5. Confirmation that increasing the pacing rate increased atrial pacing despite nebivolol reduction of HR. Elevating the lower rate pacemaker setting from 50 bpm (left) to 60 bpm (right) increased both the percent atrial pacing and the peak (paced and sensed) heart rate by 10 bpm, for this patient whose normal sinus rhythm averaged 49±2 bpm with 10 mg nebivolol (q.d.). Pmk=pacemaker, AS=atrial sensing, AP=atrial pacing, VS=ventricular sensing, VP=ventricular pacing, bpm=beats per minute. Bar graphs show an approximate normal distribution around a peak value of mean heart rate.