Relationship Between Efficacy of Defibrillation Shocks and Frequency Characteristics of Shock Waveforms

Frequency Domain and Defibrillation. Introduction: Using the Fourier transform, it is possible to replace each time domain representation of a defibrillatory shock by a unique frequency domain representation in which the shock waveform is defined in terms of a complex number function of frequency an...

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Bibliographic Details
Published in:Journal of cardiovascular electrophysiology 1998-10, Vol.9 (10), p.1043-1054
Main Authors: SCHUDER, JOHN C., McDANIEL, WAYNE C.
Format: Article
Language:English
Subjects:
Animals
Cattle
defibrillation efficacy
Disease Models, Animal
Dogs
Electric Countershock
Electrophysiology
Fourier Analysis
Fourier transform
frequency domain
Heart Rate
Ventricular Fibrillation - physiopathology
Ventricular Fibrillation - therapy
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Summary:Frequency Domain and Defibrillation. Introduction: Using the Fourier transform, it is possible to replace each time domain representation of a defibrillatory shock by a unique frequency domain representation in which the shock waveform is defined in terms of a complex number function of frequency and typically described as an amplitude in amperes per hertz (or, closely related, joules per hertz) and an associated frequency‐dependent phase angle. Methods and Results: The present article describes the conceptual basis of the Fourier transform, sketches a simplified mathematical framework for deriving frequency domain parameters, considers properties crucial to interpreting defibrillatory‐type shocks when expressed in the frequency domain, and then presents a series of shock waveforms in the frequency domain. Although not definitive, knowledge of the energy distribution with frequency alone, usually presented in joules per hertz, is shown to yield considerable insight into the probable comparable efficacy of uniphasic/biphasic rectangular, untruncated/truncated uniphasic exponential, and various biphasic “single capacitor” waveforms. Conclusion: In general, efficacy in achieving ventricular defibrillation is improved by parameter changes that shift a larger percentage of the delivered energy into a mid‐frequency range (very roughly, 40 to 160 Hz). With further study, the frequency domain approach may prove to be a useful tool in the a priori selection of optimal defibrillatory shock waveforms.
ISSN:1045-3873
1540-8167
DOI:10.1111/j.1540-8167.1998.tb00882.x