Transthoracic Ventricular Defibrillation with Square-wave Stimuli: One-Half Cycle, One Cycle, and Multicycle Waveforms

Schuder, John C.; Stoeckle, Harry; Dolan, Alfred M.

doi:10.1161/01.res.15.3.258

Cited by 61 publications

(3 citation statements)

References 12 publications

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“…In any case, rectangular stimulation may not extend to sinusoidal waveforms, since rectangular pulses contain a considerable amount of their energy at frequencies higher than their fundamental frequency. Schuder et al 14 reported a clear defibrillation maximum at 128 Hz, but his defibrillation apparatus distorted the waveforms for his next higher point at 256 Hz. For sinusoidal, epicardial stimulation, Witzel et al 15 reported a defibrillation threshold minimum at 60 Hz for sinusoidal waveforms for epicardial, saline-soaked electrodes.…”

Section: Discussionmentioning

confidence: 99%

The Defibrillation Efficacy of High Frequency Alternating Current Sinusoidal Waveforms in Guinea Pigs

Roberts

Guan

Malkin

2003

Pacing Clinical Electrophis

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There have been few basic studies of alternating current (AC) defibrillation, despite growing interest in the ability of AC to terminate or alter ongoing fibrillation. Based on fibrillation threshold testing, it has been suggested that cardiac tissue is most sensitive to long duration, low strength AC stimulation at around 50 Hz. This has not been directly tested for defibrillation. Two subcutaneous electrodes were placed 40 mm apart on opposing aspects of the guinea pig thorax. Seven seconds were allowed to elapse between fibrillation initiation and defibrillation. The tested waveforms were at 50, 100, 200, 500, and 1000 Hz with 2, 4, 8, 16, and 32-cycles. The efficacy of every waveform was measured using a single stimulus in a large population of animals. Forty-one guinea pigs were used in the fixed energy group. Thirty-three guinea pigs were used in the fixed amplitude group with additional 1-cycle waveforms tested. The 200-Hz and the 2-cycle waveforms were significantly more efficacious than those at other frequencies (P < 0.02) and other durations (P < 0.001). The 50-Hz waveforms were the least successful. Amplitude, not duration or energy, was the determinate of efficacy for 2-cycle (the most efficacious) waveforms. Unlike low strength stimulation, defibrillation strength stimuli are most effective with high frequency (200 Hz) pulses (2 cycles).

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Section: Discussionmentioning

confidence: 99%

The Defibrillation Efficacy of High Frequency Alternating Current Sinusoidal Waveforms in Guinea Pigs

Roberts

Guan

Malkin

2003

Pacing Clinical Electrophis

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“…Subject to certain assumptions, the question was answered on theoretical grounds in a paper presented at the 1975 Purdue Cardiac Conference. '*'^ in a 1979 article in Circulation,^" and, with particular emphasis upon implanted systems, in a 1991 article.^' We concluded that if the linear dimensions of the electrodes are scaled hy and the instantaneous current hy (1) (2) then tbe time varying current density vector at corresponding points within the animals will he everywhere identical [primed symbols refer to larger animals/systems; unprimed refer to smaller; d = linear dimensions, m = mass or weight, and I = instantaneous current).…”

Section: Scalingmentioning

confidence: 98%

The Role of an Engineering Oriented Medical Research Group in Developing Improved Methods and Devices for Achieving Ventricular Defibrillation: The University of Missouri Experience

Schuder

1993

Pacing Clinical Electrophis

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Physical scientists and engineers have played important roles in helping to expand our understanding of the factors that influence the defibrillation process and in developing improved methods and devices for achieving cardiac ventricular defibrillation. The long-term experience of one engineering oriented group, based in a clinical department of a medical school, is summarized. Emphasized are the features of a series of research defibrillators that facilitated the generation of an extensive experimental database from studies in dogs and calves, the development of the first automatic implantable defibrillator to be successfully used in dogs, and studies that furnished the rationale for the widespread use of the uniphasic truncated exponential waveform and for the increasing interest in a variety of biphasic and multiphasic waveforms. Also considered are studies concerning the scaling of the defibrillatory shock with subject size and the role of compound units, defibrillation threshold, and contour graphs in the presentation and interpretation of data.

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“…Early devices used a pulse of a single polarity, derived by charging a capacitor, then discharging it through the electrode system (60,74). Research in animals (70), based on previous results in transthoracic defibrillation (72) and isolated cell cultures (41), showed that bidirectional or biphasic pulses ( Figure 2) are safer and more efficacious than the monophasic pulses, defibrillating with lower energies and with potentially less tissue damage. A prospective, randomized trial of biphasic vs monophasic waveforms in humans found that the stored energy defibrillation threshold for monophasic shocks was 8.5 ‫ע‬ 6.1 J and for biphasic shocks was 6.3 ‫ע‬ 5.2 J, lower by 26% (9).…”

Section: Waveformsmentioning

confidence: 99%

Automatic Implantable Cardioverter-defibrillators

Smith

Ideker²

1999

Annu. Rev. Biomed. Eng.

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Ventricular fibrillation, a loss of synchronous electrical activity in the heart which leads to hemodynamic collapse, is a leading cause of death. Because of the devastating personal and societal effects of this phenomenon, the automatic cardioverter-defibrillator has been developed for automatic detection and termination of the arrhythmia and is in widespread clinical use. Advances in circuits, leads, waveforms, and signal processing along with increased knowledge of the mechanisms of fibrillation have led to continuing improvements in this device, extending its use to many patients. A device has also been developed for the automatic or semiautomatic treatment of atrial fibrillation, an arrhythmia less life-threatening than ventricular fibrillation, but still a serious health problem. Continued improvement of these devices and the development of qualitatively new approaches hold great promise for exciting therapeutic advances in this area.

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Transthoracic Ventricular Defibrillation with Square-wave Stimuli: One-Half Cycle, One Cycle, and Multicycle Waveforms

Cited by 61 publications

References 12 publications

The Defibrillation Efficacy of High Frequency Alternating Current Sinusoidal Waveforms in Guinea Pigs

The Defibrillation Efficacy of High Frequency Alternating Current Sinusoidal Waveforms in Guinea Pigs

The Role of an Engineering Oriented Medical Research Group in Developing Improved Methods and Devices for Achieving Ventricular Defibrillation: The University of Missouri Experience

Automatic Implantable Cardioverter-defibrillators

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