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Pacing threshold spikes months and years after implant
R B Shepard1, J Kim, E C Colvin
1Division of Cardiothoracic Surgery, University of Alabama, Birmingham 35294-0007.
Pacing and Clinical Electrophysiology : PACE
|November 11, 1991
Summary
Chronic pacing thresholds show significant variation, especially in children. Transient threshold changes can occur years after implantation, sometimes linked to minor illnesses, necessitating further study in pediatric patients.
Area of Science:
- Cardiology
- Biomedical Engineering
- Pediatric Electrophysiology
Background:
- Understanding chronic pacing thresholds is crucial for managing pacemaker-dependent patients, particularly children.
- Variations in pacing thresholds can impact device efficacy and patient safety.
Observation:
- A large dataset of 4,942 threshold measurements from 257 patients (including 46 children) was analyzed.
- Pacing thresholds were measured from implant up to 295 months, with a median of 17 months.
- Endocardial electrodes showed a mean threshold of 1.3 V, while epicardial electrodes had a mean of 2.8 V.
Findings:
- Highest mean thresholds were observed in children aged 6 to 12 years.
- In 59% of leads, maximum pacing threshold occurred more than one month post-implant.
- Gradual threshold increases continued after 3 months in 24% of leads, and 21% exhibited extreme threshold elevations.
- Strikingly, transient multi-volt threshold fluctuations were noted up to 8 years post-implantation in some children, often coinciding with minor illnesses.
Implications:
- These findings highlight the dynamic nature of chronic pacing thresholds, particularly in pediatric populations.
- The study suggests a need for further investigation into pacing threshold variations in highly pacemaker-dependent children requiring epicardial electrodes.
- Recognizing these variations is essential for optimizing pacemaker management and preventing adverse events in children.