Method and apparatus for separate-capacitor cardioversion
AssigneeAngeion Corporation
InventorMark W. Kroll
Life of this patent
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Abstract
A implantable cardioverter-defibrillator employs, as a battery-saving design, a capacitance about nine time smaller than a typical defibrillation capacitor to provide an optimal-duration pulse of about 1 millisecond with a waveform based on the system time constants, i.e. the tissue resistance, the value of the capacitor and the heart's cardioversion chronaxie, a characteristic time associated with the stimulation of myocardial tissue. For higher-energy defibrillation, a second small capacitance is added to boost the energy.
Claims30
An improved apparatus for producing cardioversion defibrillation waveforms to be delivered to at least two implantable electrodes in a human patient in response to a sensing of a cardiac dysrhythmia in the patient the apparatus including a first capacitor means having a first capacitance value for storing a first amount of electrical energy, means for charging the first capacitor means to the first amount of electrical energy, and switch means for selectively controlling a discharge of the first capacitor means through the at least two electrodes to produce a defibrillation waveform, the improvement comprising:
- a second capacitor means separate from the first capacitor means and having a second capacitance value for storing a second amount of electrical energy, the second capacitance value and the second amount being of smaller values than the first capacitance value and the first amount of electrical energy;
- means for charging the second capacitor means to the second amount of electrical energy;
- and
- switch means for selectively controlling a discharge of the second capacitor means through the at least two electrodes to produce a cardioversion waveform having at least one pulse having a pulse duration.
An improved method for operating a cardioverter defibrillator system connected to at least two implanted electrodes located in a human patient to treat a cardiac dysrhythmia, the method including the steps of sensing a cardiac dysrhythmia and in response delivering an electrical waveform to the at least two implanted electrodes to treat the cardiac dysrhythmia, the improvement comprising the system-implemented steps of:
- (a) in response to the sensing of a fibrillation dysrhythmia, selectively charging and discharging a first capacitor to produce a defibrillation waveform that is time-truncated at a particular duration for defibrillation, and;
- (b) in response to the sensing of a tachycardia dysrhythmia, selectively charging and discharging a second capacitor separate from the first capacitor to produce a cardioversion waveform that is time-truncated at a lesser duration than the duration of the defibrillation waveform.
Dependencies are inferred from the claim text.