Determining intercardiac impedance
First Claim
1. A method comprising:
- propagating a modulated signal across a myocardium;
detecting an outputted modulated signal from the myocardium;
using at least one circuit to reduce the influence of process noise in the outputted modulated signal, wherein the at least one circuit reduces the influence of process noise by at least;
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;
determining an amplitude and phase of the fourth outputted modulated signal, the amplitude and the phase indicating a complex impedance of the myocardium;
monitoring the indication of complex impedance for complex impedance patterns of the myocardium; and
based on changes in complex impedance patterns of the myocardium, providing an indication of cardiac function, wherein the cardiac function is at least one of contractility, capture detection, atrium-ventricle optimization, right ventricular function, left ventricular function, cardiac output, or right to left ventricular synchronization.
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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
29 Claims
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1. A method comprising:
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propagating a modulated signal across a myocardium; detecting an outputted modulated signal from the myocardium; using at least one circuit to reduce the influence of process noise in the outputted modulated signal, wherein the at least one circuit reduces the influence of process noise by at least; 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; determining an amplitude and phase of the fourth outputted modulated signal, the amplitude and the phase indicating a complex impedance of the myocardium; monitoring the indication of complex impedance for complex impedance patterns of the myocardium; and based on changes in complex impedance patterns of the myocardium, providing an indication of cardiac function, wherein the cardiac function is at least one of contractility, capture detection, atrium-ventricle optimization, right ventricular function, left ventricular function, cardiac output, or right to left ventricular synchronization. - View Dependent Claims (2, 3, 4, 5, 6, 7, 21, 22)
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8. A system comprising:
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at least one electrode configured to propagate a modulated signal across a myocardium; at least one sensor configured to detect an outputted modulated signal from the myocardium; at least one circuit configured to reduce the influence of process noise in the outputted modulated signal, wherein the at least one circuit comprises; an amplifier configured to amplify the outputted modulated signal to produce a second outputted modulated signal; a demodulator configured to demodulate the second outputted modulated signal to produce a third outputted modulated signal; and an integrator configured to pass the third outputted modulated signal through to produce a fourth outputted modulated signal; and at least one processor configured to; determine an amplitude and phase of the fourth outputted modulated signal, the amplitude and the phase indicating a complex impedance of the myocardium, monitor the indication of complex impedance for complex impedance patterns of the myocardium, and based on changes in complex impedance patterns of the myocardium, provide an indication of cardiac function, wherein the cardiac function is at least one of contractility, capture detection, atrium-ventricle optimization, right ventricular function, left ventricular function, cardiac output, or right to left ventricular synchronization. - View Dependent Claims (9, 10, 11, 12, 13, 14, 25, 26, 27, 28, 29)
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15. A system 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; at least one circuit means for reducing the influence of process noise 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; and at least one processor means for; determining an amplitude and phase of the fourth outputted modulated signal, the amplitude and phase indicate a complex impedance of the myocardium, monitoring the indication of complex impedance for complex impedance patterns of the myocardium, and based on changes in complex impedance patterns of the myocardium, providing an indication of cardiac function and providing an indication of an ischemic event, wherein the cardiac function is at least one of contractility, capture detection, atrium-ventricle optimization, right ventricular function, left ventricular function, cardiac output, or right to left ventricular synchronization. - View Dependent Claims (16, 17, 18, 19, 20)
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23. A method comprising:
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propagating a modulated signal across a myocardium; detecting an outputted modulated signal from the myocardium; using at least one circuit to reduce the influence of process noise in the outputted modulated signal, wherein the at least one circuit reduces the influence of process noise by at least; 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; determining an amplitude and phase of the fourth outputted modulated signal, the amplitude and the phase indicating a complex impedance of the myocardium; monitoring the indication of complex impedance for complex impedance patterns of the myocardium; and based on changes in complex impedance patterns of the myocardium, providing an indication of an ischemic event and, determining an area of the ischemic event based on a location of propagation of the modulated signal across the myocardium. - View Dependent Claims (24)
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Specification