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Can the heart be chronically paced with electrodes on the pericardial surface?
R B Shepard1, A E Epstein, G N Kay
1Department of Surgery, University of Alabama, Birmingham 35294.
Pacing and Clinical Electrophysiology : PACE
|November 1, 1992
Summary
Transpericardial electrodes for implantable defibrillator (ICD) sensing show stable pacing thresholds and satisfactory QRS amplitudes over time. This method offers a less invasive approach, preserving the heart for potential future procedures.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Implantable defibrillators (ICDs) require reliable sensing leads for effective function.
- Transpericardial electrodes offer a potential alternative to traditional endocardial leads.
- Assessing the long-term performance of transpericardial leads is crucial for clinical adoption.
Purpose of the Study:
- To evaluate acute and chronic transpericardial bipolar pacing thresholds and impedance.
- To assess the suitability of transpericardial electrodes for implantable defibrillator (ICD) QRS rate-sensing.
- To compare acute and chronic measurements of pacing parameters and QRS amplitudes.
Main Methods:
- Transpericardial bipolar pacing thresholds and impedance were measured acutely (day 0) and chronically (median 31.7 months) in patients undergoing ICD operations.
- Leads were used solely for QRS rate-sensing between acute and chronic measurements.
- Statistical analysis compared acute and chronic measurements of pacing thresholds, current, impedance, and QRS amplitude.
Main Results:
- Transpericardial pacing thresholds remained stable, with no significant increase over time (acute: 4.5 V, chronic: 3.8 V).
- Pacing impedances were high, and current thresholds were low, both acutely and chronically.
- Acute bipolar QRS amplitude was 12.3 mV, increasing to 13.5 mV chronically, indicating satisfactory sensing.
- Bipolar impedance showed a statistically significant increase (P = 0.054) from acute to chronic measurements.
Conclusions:
- Transpericardial pacing thresholds do not increase over time, supporting long-term viability.
- The transpericardial approach provides high impedance and low current thresholds, with satisfactory QRS amplitudes for ICD sensing.
- This implantation technique avoids scarring the heart, potentially simplifying future cardiac procedures like transplantation and enhancing safety in patients with prior cardiac surgery.