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The interdependence between electrogram, total electrode impedance and pacemaker input impedance necessary to obtain
Pacing and Clinical Electrophysiology : PACE
|July 1, 1979
Summary
This study on permanent pacemaker treatment found that electrogram maximum derivatives decreased significantly from acute to chronic phases, while amplitudes remained stable. Electrode size impacted tissue impedance but not signal derivatives, with smaller electrodes showing higher impedance and lower capacitance.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Permanent pacemaker implantation involves monitoring electrogram parameters.
- Electrogram characteristics can change over time, influencing pacemaker function.
- Electrode size and impedance are critical factors in pacemaker lead performance.
Purpose of the Study:
- To investigate changes in electrogram maximum derivatives (DMAX, SMAX) and amplitudes (AMAX, UMAX) from acute to chronic phases in patients with permanent pacemakers.
- To evaluate the impact of electrode surface area on tissue impedance (RT) and interface impedance (RF, CH).
- To correlate electrogram parameters with clinical conditions like bundle branch block, coronary heart disease, myocardial infarction, and cardiomyopathy.
Main Methods:
- Analysis of electrogram maximum derivatives and amplitudes in 71 patients during acute (implantation) and chronic (replacement) pacemaker phases.
- Measurement of tissue impedance (RT) and interface impedance (Faraday resistance RF, Helmholtz capacity CH) in a subset of patients.
- Comparison of electrogram parameters between different patient groups and electrode sizes (8 mm2 vs. 12 mm2).
Main Results:
- DMAX and SMAX significantly decreased from acute to chronic phases (p < 0.02, p < 0.01), while AMAX and UMAX remained unchanged.
- No significant difference in electrogram parameters was observed in patients with bundle branch block.
- Patients with coronary heart disease had significantly higher AMAX (p < 0.01).
- Smaller electrodes (8 mm2) exhibited significantly higher tissue impedance (RT) (p > 0.005) and lower Helmholtz capacity (CH) (p < 0.05) compared to larger electrodes (12 mm2).
Conclusions:
- Electrogram maximum derivatives decline over time post-pacemaker implantation, necessitating monitoring.
- Electrode surface area influences impedance characteristics, with smaller electrodes posing a higher risk of sensing failure due to lower capacitance.
- Electrogram parameters may vary with underlying cardiac conditions, impacting pacemaker sensing efficacy.