A controlled-power arbitrary waveform method of defibrillation

William John Havel, Purdue University

Abstract

Ventricular fibrillation is a condition affecting over 300,000 people annually. With fibrillation, the cardiac muscle does not contract synchronously, causing death if not treated within minutes. The preferred treatment, ventricular defibrillation, is the process of applying a strong electric shock to the ventricles to re-synchronize the cardiac muscle cells. Using an effective shock with a minimal amount of energy is a goal of the defibrillation industry as it allows for smaller and less expensive devices that can be made more accessible to the public. Shock parameters including waveform current, waveform shape and waveform duration have been shown to be important factors in predicting defibrillation efficacy. In fact, for certain waveforms, there exists an optimal duration for which a minimum amount of energy defibrillates. Present defibrillation techniques have the disadvantage of using shocks with parameters that are altered by variations in patient resistance. Thus, it is not possible to deliver a waveform that will be equally optimal for a population. Proposed is a novel technique for generating waveforms independent of variations in patient resistance. Waveform shape, duration and current will be adjustable with the only constraint being the total delivered energy. With the new technique, a waveform with optimal parameters can be found and then delivered using less energy than that required by presently-used techniques. With the controlled-power arbitrary waveform defibrillator, it was possible to defibrillate with 26% less energy than with a traditional truncated-exponential waveform method. When subject resistance was artificially increased by 25%, the controlled-power method required 38% less delivered energy to defibrillate. ^

Degree

Ph.D.

Advisors

Major Professors: Joe D. Bourland, Purdue University, John A. Nyenhuis, Purdue University.

Subject Area

Health Sciences, Rehabilitation and Therapy|Engineering, Biomedical

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