DETERMINING INTERCARDIAC IMPEDANCE
First Claim
1. A method of determining complex intercardiac impedance comprising:
- propagating a modulated signal across a myocardium;
detecting an outputted modulated signal from the myocardium; and
using at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal, wherein the at least one circuit performs the steps comprising;
amplifying the outputted modulated signal to produce a second outputted modulated signal;
demodulating the second outputted modulated signal to produce a third outputted modulated signal; and
passing the third outputted modulated signal through an integrator to produce a fourth outputted modulated signal,wherein amplitude and phase of the fourth outputted modulated signal indicate the complex impedance of the myocardium,wherein changes in complex impedance patterns of the myocardium provide indication of various cardiac functions and an ischemic event.
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Accused Products
Abstract
A system and method for determining complex intercardiac impedance to detect various cardiac functions are disclosed involving a signal generator means for providing an adjustable direct current signal, a modulator for modulating the adjustable direct current signal to produce a modulated signal, at least one electrode for propagating the modulated signal across a myocardium, at least one sensor for detecting an outputted modulated signal from the myocardium, and at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal. The at least one circuit comprises an amplifier, a demodulator, and an integrator. The amplitude and phase of the final outputted modulated signal indicate the complex impedance of the myocardium. Changes in the complex impedance patterns of the myocardium provide indication of reduced oxygen and blood flow to the myocardium. The apparatus can be employed in implantable devices, including cardiac pacemakers and implantable cardioverter defibrillators.
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Citations
20 Claims
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1. A method of determining complex intercardiac impedance comprising:
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propagating a modulated signal across a myocardium; detecting an outputted modulated signal from the myocardium; and using at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal, wherein the at least one circuit performs the steps comprising; amplifying the outputted modulated signal to produce a second outputted modulated signal; demodulating the second outputted modulated signal to produce a third outputted modulated signal; and passing the third outputted modulated signal through an integrator to produce a fourth outputted modulated signal, wherein amplitude and phase of the fourth outputted modulated signal indicate the complex impedance of the myocardium, wherein changes in complex impedance patterns of the myocardium provide indication of various cardiac functions and an ischemic event. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for determining complex intercardiac impedance comprising:
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at least one electrode for propagating a modulated signal across a myocardium; at least one sensor for detecting an outputted modulated signal from the myocardium; and at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal, wherein the at least one circuit comprises; an amplifier for amplifying the outputted modulated signal to produce a second outputted modulated signal; a demodulator for demodulating the second outputted modulated signal to produce a third outputted modulated signal; and an integrator for passing the third outputted modulated signal through to produce a fourth outputted modulated signal, wherein amplitude and phase of the fourth outputted modulated signal indicate the complex impedance of the myocardium, wherein changes in complex impedance patterns of the myocardium provide indication of various cardiac functions and an ischemic event. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for determining complex intercardiac impedance comprising:
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at least one electrode means for propagating a modulated signal across a myocardium; at least one sensor means for detecting an outputted modulated signal from the myocardium; and at least one circuit means for reducing the influence of process noise (aggressors) in the outputted modulated signal, wherein the at least one circuit means comprises; an amplifier means for amplifying the outputted modulated signal to produce a second outputted modulated signal; a demodulator means for demodulating the second outputted modulated signal to produce a third outputted modulated signal; and an integrator means for passing the third outputted modulated signal through to produce a fourth outputted modulated signal, wherein amplitude and phase of the fourth outputted modulated signal indicate the complex impedance of the myocardium, wherein changes in complex impedance patterns of the myocardium provide indication of various cardiac functions and an ischemic event. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification