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Pacing impedance variability in tined steroid eluting leads
1Medical Department A, Haukeland University Hospital, Bergen, Norway.
Pacing and Clinical Electrophysiology : PACE
|July 22, 1998
Summary
Pacing impedance (PI) in ambulatory patients showed significant variations up to 450 ohms, influenced by external factors rather than lead stability. These PI changes were similar for unipolar and bipolar configurations.
Area of Science:
- Cardiology
- Biomedical Engineering
- Implantable Electronic Devices
Background:
- Pacing impedance (PI) is a critical parameter for monitoring pacemaker lead function.
- Understanding PI behavior in ambulatory patients is essential for optimizing device performance and patient care.
- Previous studies have focused on acute PI changes, with less data on long-term, dynamic variations in real-world settings.
Purpose of the Study:
- To investigate the behavior and variability of pacing impedance (PI) in ambulatory patients with implanted pacemaker leads.
- To identify factors influencing PI, including patient activity, posture, pacing parameters, and lead characteristics.
- To correlate PI variability with pacing thresholds and other clinical parameters.
Main Methods:
- Ambulatory patients (n=20) with tined steroid-eluting atrial and ventricular leads underwent automated PI measurements.
- Measurements were performed 9-27 months post-implantation using algorithms in Thera pulse generators via telemetry.
- PI was assessed based on voltage drop during pacing impulses, examining variations with breathing, posture, exercise, and over 24 hours.
Main Results:
- Significant PI variations (up to 450 ohms) were observed in leads with proper function.
- PI variability showed a weak negative correlation with pacing thresholds, suggesting positional stability is not the primary driver.
- Unipolar and bipolar PI variations were highly correlated (r=0.93), indicating PI is mainly influenced by the lead tip environment.
Conclusions:
- Pacing impedance is dynamic and exhibits substantial variability in ambulatory patients under various physiological and external conditions.
- The observed PI variations are largely independent of lead configuration (unipolar vs. bipolar) and potentially less dependent on electrode positional stability than previously assumed.
- Environmental factors surrounding the lead tip play a crucial role in modulating pacing impedance over time.