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Marked reduction in internal atrial defibrillation thresholds with dual-current pathways and sequential shocks in
R A Cooper1, V J Plumb, A E Epstein
1Department of Medicine, The University of Alabama at Birmingham Medical Center, USA. rac@crml.uab.edu
Circulation
|July 10, 1998
Summary
Sequential shocks using dual-current pathways significantly reduced the atrial defibrillation threshold (ADFT) in patients with atrial fibrillation. This approach offers a more effective method for internal atrial defibrillation compared to standard single-current pathways.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Atrial defibrillation threshold (ADFT) is a critical parameter for effective internal atrial defibrillation.
- Standard single-current pathways may require higher energy levels for successful defibrillation.
Purpose of the Study:
- To evaluate the efficacy of sequential shocks delivered through dual-current pathways in lowering the ADFT.
- To compare the ADFT using dual-current pathways with that of a standard single-current pathway.
Main Methods:
- Investigated 14 patients with chronic atrial fibrillation.
- Utilized a step-up protocol comparing ADFTs for single-current (RA-->DCS) versus dual-current (RA-->DCS followed by CSos-->LSV) pathways.
- Employed sequential biphasic shocks with varying capacitor configurations (150-microF and 600-microF).
Main Results:
- Dual-current pathways (2.0±0.4 J for 150-microF, 2.4±0.5 J for 600-microF) showed significantly lower ADFTs than the single-current pathway (5.1±1.8 J).
- The dual-current pathway with 150-microF capacitance demonstrated a lower energy threshold.
- No induced ventricular arrhythmias were observed with synchronized shocks.
Conclusions:
- Sequential biphasic waveforms delivered over dual-current pathways markedly reduce ADFT (>50% reduction) in humans.
- Dual-current pathways represent a more effective strategy for internal atrial defibrillation.