Method for optimal pulse defibrillation using an implantable defibrillator
First Claim
1. A method for operating a device connected to at least two implanted electrodes located in a human patient to treat a myocardial dysrhythmia, the method comprising the device-implemented steps of:
- (a) sensing a myocardial dysrhythmia in the human patient; and
(b) in response to the myocardial dysrhythmia, delivering from electrical energy stored in a capacitor system in the device to the implanted electrodes a truncated defibrillation waveform comprising at least one electrical pulse and having a predetermined optimum pulse duration set automatically by the device based on an optimization of an effective current of the electrical pulse for a preselected amount of electrical energy stored in the capacitor system.
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Abstract
The model that is developed in the present invention is based upon the pioneering neurophysiological models of Lapicque and Weiss. The present model determines mathematically the optimum pulse duration, dp, for a truncated capacitor-discharge waveform employed for defibrillation. The model comprehends the system time constant, RC, where R is tissue resistance and C is the value of the capacitor being discharged, and also the chronaxie time, dc, defined by Lapicque, which is a characteristic time associated with the heart. The present model and analysis find the optimum pulse duration to be dp =(0.58)(RC+dc). Taking the best estimate of the chronaxie value from the literature to be 2.7 ms, permits one to rewrite the optimum pulse duration as dp =(0.58)RC+1.6 ms. The present invention makes use of the mathematical definition of optimum pulse duration by storing in the control circuitry of the defibrillation system the actual measured value of the particular capacitor incorporated in the system. The optimized-pulse prescription of this invention can be applied to a monophasic waveform, or to either or both of the phases of a biphasic waveform.
53 Citations
12 Claims
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1. A method for operating a device connected to at least two implanted electrodes located in a human patient to treat a myocardial dysrhythmia, the method comprising the device-implemented steps of:
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(a) sensing a myocardial dysrhythmia in the human patient; and (b) in response to the myocardial dysrhythmia, delivering from electrical energy stored in a capacitor system in the device to the implanted electrodes a truncated defibrillation waveform comprising at least one electrical pulse and having a predetermined optimum pulse duration set automatically by the device based on an optimization of an effective current of the electrical pulse for a preselected amount of electrical energy stored in the capacitor system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification