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Immediate Termination of Fibrillation at 50% Probability of Overall Success Correlates with Defibrillation Dose‐Response Curve Width
Author(s) -
TOVAR OSCAR H.,
SNYDER DAVID E.,
JONES JANICE L.
Publication year - 2004
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.2004.02571.x
Subject(s) - defibrillation , medicine , defibrillation threshold , waveform , ventricular fibrillation , shock (circulatory) , cardiology , intensity (physics) , physics , voltage , optics , quantum mechanics
Issues in transthoracic defibrillation, including waveform shape, fixed versus escalating dose protocol, and low‐ versus high‐energy shocks, can be addressed by examining the defibrillation dose‐response curve. We tested the hypothesis that, for commonly used defibrillation waveforms, the steepness of the overall defibrillation dose‐response curve, measured as normalized curve width, correlates with the probability of a successful defibrillation being immediate at the shock intensity producing 50% success. Methods and Results: We used 16 isolated rabbit hearts to determine probability of overall success as a function of shock intensity and probability that a successful defibrillation is immediate rather than progressive (followed by several extrasystoles) at the shock intensity producing 50% overall defibrillation success. Two waveform pairs were tested—a monophasic damped sine versus a biphasic truncated exponential waveform commonly used for transthoracic defibrillation, and a monophasic/biphasic truncated exponential waveform pair similar to those used in internal cardioverter defibrillators. There was a close correlation between probability of a successful defibrillation being immediate at I 50 and normalized curve width for the defibrillation dose‐response curve. Conclusion: Our findings suggest that a high probability of successful defibrillation being immediate at low shock intensities is correlated with a narrow normalized curve width for the defibrillation dose‐response curve.