Method and apparatus for delivering defibrillation shocks with improved effectiveness
First Claim
1. A method for defibrillating a patient'"'"'s heart with an implantable defibrillator having first and second implanted electrodes spaced apart from each other by at least 4 centimeters, comprising the steps of:
- (a) detecting fibrillation in said patient'"'"'s heart;
(b) monitoring a fibrillation voltage across said first and second implanted electrodes, a waveform of said fibrillation voltage including peaks and troughs;
(c) determining absolute value amplitudes of the peaks and troughs of said fibrillation voltage;
(d) averaging a portion of said absolute value amplitudes to provide an average amplitude;
(e) comparing said average amplitude with the absolute values of the peaks and troughs of said fibrillation voltage to determine if a measure of the absolute values of the peaks and troughs of said fibrillation voltage exceeds said average amplitude determined in step (d) by a predetermined amount; and
(f) delivering a defibrillation shock to said patient'"'"'s heart during a period of ventricular fibrillation when the measure of the absolute values of the peaks and troughs of said fibrillation voltage exceeds said average amplitude determined in step (d) by said predetermined amount.
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Accused Products
Abstract
A method for defibrillating a patient'"'"'s heart with an implantable defibrillator having defibrillation synchronized to the fibrillation waveform is disclosed. The defibrillator is used to detect fibrillation in a patient'"'"'s heart, monitor at least one far-field fibrillation voltage across two spaced-apart electrodes while the high voltage capacitors are charging, then deliver a high energy shock during a period of ventricular fibrillation when the absolute values of the peak and trough voltages exceed a threshold based on a desired percentage greater than a running average of the absolute values of the peaks and troughs of the fibrillation voltages monitored during and after capacitor charging. The shock is then delivered synchronous with the next significant cardiac complex. The defibrillator also includes a safety timer so that if the threshold is not reached within a specified safe time limit, the high energy shock will be delivered without further delay.
36 Citations
15 Claims
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1. A method for defibrillating a patient'"'"'s heart with an implantable defibrillator having first and second implanted electrodes spaced apart from each other by at least 4 centimeters, comprising the steps of:
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(a) detecting fibrillation in said patient'"'"'s heart; (b) monitoring a fibrillation voltage across said first and second implanted electrodes, a waveform of said fibrillation voltage including peaks and troughs; (c) determining absolute value amplitudes of the peaks and troughs of said fibrillation voltage; (d) averaging a portion of said absolute value amplitudes to provide an average amplitude; (e) comparing said average amplitude with the absolute values of the peaks and troughs of said fibrillation voltage to determine if a measure of the absolute values of the peaks and troughs of said fibrillation voltage exceeds said average amplitude determined in step (d) by a predetermined amount; and (f) delivering a defibrillation shock to said patient'"'"'s heart during a period of ventricular fibrillation when the measure of the absolute values of the peaks and troughs of said fibrillation voltage exceeds said average amplitude determined in step (d) by said predetermined amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An implantable defibrillator comprising:
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(a) a pulse generator including a battery, a high voltage capacitor and a charging circuit for charging said capacitor from said battery; (b) bipolar fibrillation sensing means; (c) unipolar sensing means for monitoring a fibrillation voltage and determining a relative measure of the strength of peaks and troughs of said fibrillation voltage measured during a running sequence of windows monitored following fibrillation detection; (d) electrode means for delivering a defibrillation shock from said capacitor, during a period of ventricular fibrillation after said capacitor is charged when a measure of the absolute values of the peaks and troughs of said fibrillation voltage exceeds by a predetermined percentage said relative measure; wherein said unipolar sensing means comprises at least two of the following; (aa) a right ventricular pacing electrode; (bb) a subcutaneous defibrillation electrode; (cc) an electrically active portion of the implantable defibrillator case; (dd) a superior vena cava defibrillation electrode; (ee) a right ventricular defibrillation electrode. - View Dependent Claims (10, 11, 12)
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13. A method for defibrillating a patient'"'"'s heart with an implantable defibrillator having first and second implanted electrodes spaced apart from each other by at least 4 centimeters, comprising the steps of:
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(a) detecting fibrillation in said patient'"'"'s heart; (b) monitoring a fibrillation voltage across said first and second implanted electrodes, a waveform of said fibrillation voltage including peaks and troughs; (c) determining absolute value amplitudes of the peaks and troughs of said fibrillation voltage; (d) calculating a measure of said amplitudes for a sequence of predefined duration portions of said fibrillation voltage; (e) calculating an average of said measures for a predetermined number of said portions; (f) comparing said average measure with at least one of said measures for one of said portions in said sequence subsequent to said predetermined number of said portions to determine if said measure for said subsequent portion exceeds said average measure calculated in step (e) by a predetermined amount; and (g) delivering a defibrillation shock to said patient'"'"'s heart during a period of ventricular fibrillation when said measure for said subsequent portion exceeds said average measure by said predetermined amount. - View Dependent Claims (14, 15)
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Specification