Marked reduction in internal atrial defibrillation thresholds with dual-current pathways and sequential shocks in humans

This study tested the ability of sequential shocks delivered through dual-current pathways to lower the atrial defibrillation threshold (ADFT) compared with a biphasic shock through a standard single-current pathway. Electrodes were positioned in the right atrial appendage (RA), left subclavian vein...

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Bibliographic Details
Published in:Circulation (New York, N.Y.) N.Y.), 1998-06, Vol.97 (25), p.2527-2535
Main Authors: COOPER, R. A. S, PLUMB, V. J, EPSTEIN, A. E, KAY, G. N, IDEKER, R. E
Format: Article
Language:English
Subjects:
Adult
Aged
Atrial Fibrillation - physiopathology
Atrial Fibrillation - therapy
Biological and medical sciences
Cardiac dysrhythmias
Cardiology. Vascular system
Defibrillators, Implantable
Electric Countershock - adverse effects
Electric Countershock - instrumentation
Electric Countershock - methods
Female
Heart
Humans
Male
Medical sciences
Middle Aged
Treatment Outcome
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Summary:This study tested the ability of sequential shocks delivered through dual-current pathways to lower the atrial defibrillation threshold (ADFT) compared with a biphasic shock through a standard single-current pathway. Electrodes were positioned in the right atrial appendage (RA), left subclavian vein (LSV), proximal coronary sinus (CSos), and distal coronary sinus (DCS) in 14 patients with chronic atrial fibrillation (170+/-185 days). Using a step-up protocol, we compared ADFTs for a single-current pathway (RA-->DCS) that used a single 7.5/2.5-ms biphasic shock from a 150-microF capacitor with those for a dual-current pathway system (RA-->DCS followed by CSos-->LSV) using sequential 7.5/2.5-ms biphasic shocks with capacitor discharge waveforms for 150-microF and 600-microF capacitors. Both dual-current pathway configurations (2.0+/-0.4 J for 150-microF capacitance, 2.4+/-0.5 J for 600-microF capacitance) had a significantly lower ADFT than the single-current pathway (5.1+/-1.8 J). Whereas the dual-current pathway with 150-microF capacitor shocks had a significantly lower energy threshold, there was no statistical difference in terms of leading-edge voltage compared with the dual-current pathway with 600-microF capacitance shocks. There were no ventricular arrhythmias induced with appropriately synchronized shocks. For internal atrial defibrillation in humans, sequential biphasic waveforms delivered over dual-current pathways resulted in a markedly reduced (>50% reduction) ADFT compared with a single shock over a single-current pathway.
ISSN:0009-7322
1524-4539
DOI:10.1161/01.CIR.97.25.2527