Method and apparatus for progressive recruitment of cardiac fibrillation
First Claim
1. An improved implantable defibrillator system for producing a multiple pulse capacitive-discharge countershock to be delivered through at least two electrodes adapted for implantation in a human patient, the implantable defibrillator system being a self-contained human implantable housing containing a waveform-generating capacitor means for storing an electrical charge, means for charging the waveform-generating capacitor means, means for sensing a cardiac dysrhythmia in the human patient, and means for selectively discharging the electrical charge in the waveform-generating capacitor means as a countershock to be delivered through the at least two electrodes in response to the means for sensing the cardiac dysrhythmia, the improvement comprising:
- the means for selectively discharging including;
means for selectively discharging a plurality of recruitment pulses, each recruitment pulse spaced apart by a first time interval and delivering an electrical charge from the waveform-generating capacitor means that is less than a maximum recruitment charge; and
means for selectively discharging a defibrillation pulse spaced apart by a second time interval from the plurality of recruitment pulses and delivering an electrical charge that is greater than the maximum recruitment charge,wherein the maximum recruitment charge is determined by an amount of electrical charge which the charging means can recharge the waveform-generating capacitor means during the second time interval.
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Accused Products
Abstract
A method and apparatus for progressive recruitment of cardiac fibrillation uses an implantable defibrillator to deliver a multiple, discontinuous pulse waveform that is comprised of a series of smaller recruitment pulses delivered prior to delivery of a larger defibrillating pulse. Instead of using multiple identical pulses to accomplish defibrillation, the present invention decreases the overall energy required for effective defibrillation with a single, larger defibrillation pulse by using multiple, smaller recruitment pulses to recruit or capture as many heart cells as possible into a primary one of the many activation wavefronts in a fibrillating heart. By synchronizing the heart cells recruited in this manner, the effectiveness of the single, larger defibrillation pulse is increased, thereby decreasing the maximum stored energy required for defibrillation.
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Citations
33 Claims
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1. An improved implantable defibrillator system for producing a multiple pulse capacitive-discharge countershock to be delivered through at least two electrodes adapted for implantation in a human patient, the implantable defibrillator system being a self-contained human implantable housing containing a waveform-generating capacitor means for storing an electrical charge, means for charging the waveform-generating capacitor means, means for sensing a cardiac dysrhythmia in the human patient, and means for selectively discharging the electrical charge in the waveform-generating capacitor means as a countershock to be delivered through the at least two electrodes in response to the means for sensing the cardiac dysrhythmia, the improvement comprising:
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the means for selectively discharging including; means for selectively discharging a plurality of recruitment pulses, each recruitment pulse spaced apart by a first time interval and delivering an electrical charge from the waveform-generating capacitor means that is less than a maximum recruitment charge; and means for selectively discharging a defibrillation pulse spaced apart by a second time interval from the plurality of recruitment pulses and delivering an electrical charge that is greater than the maximum recruitment charge, wherein the maximum recruitment charge is determined by an amount of electrical charge which the charging means can recharge the waveform-generating capacitor means during the second time interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for operating an implantable defibrillator device electrically connected to at least two electrodes adapted for implantation in a human patient to treat cardiac dysrhythmia by delivering a multiple pulse capacitive-discharge countershock, the method comprising the device-implemented steps of:
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(a) sensing for a cardiac dysrhythmia in a human patient; (b) in response to sensing the cardiac dysrhythmia, charging a capacitive charge storage system within the implantable defibrillator device to a charge value; (c) selectively discharging less than a first portion of the charge value stored in the capacitive charge storage system through the at least two electrodes to produce a plurality of recruitment pulses, each recruitment pulse spaced apart by a first time interval; (d) recharging the capacitive charge storage system to the charge value after each recruitment pulse; and (e) discharging more than the first portion of the charge value stored in the capacitive charge storage system through the at least two electrodes to produce a defibrillation pulse that is spaced apart by a second time interval from the plurality of recruitment pulses. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An implantable defibrillator apparatus electrically connected to at least two electrodes adapted for implantation in a human patient to treat cardiac dysrhythmia by delivering a multiple pulse capacitive-discharge countershock, the implantable defibrillator apparatus comprising:
an implantable housing which contains; sensing means for sensing a cardiac dysrhythmia in the human patient; capacitor means for storing an electrical charge; power source means for charging the capacitor means to a charging voltage; and control means for selectively controlling the power source means and the capacitor means in response to the sensing of the cardiac dysrhythmia to deliver a multiple pulse capacitive-discharge countershock to the at least two electrodes including; means for selectively discharging a plurality of recruitment pulses, each recruitment pulse spaced apart by a first time interval and delivering an electrical charge that is less than a maximum recruitment charge; and means for selectively discharging a defibrillation pulse spaced apart by a second time interval from the plurality of recruitment pulses and delivering an electrical charge that is greater than the maximum recruitment charge. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
Specification