Intracardiac impedance and its applications
First Claim
1. A medical device comprising:
- a controller circuit configured to;
receive a sensed cardiac cycle and an intracardiac impedance signal;
determine at least two of;
a cardiac-cycle-to-cardiac-cycle change in a value of a baseline intracardiac impedance value calculated, for a particular cardiac cycle, to represent the baseline intracardiac impedance for that particular cardiac cycle;
a cardiac-cycle-to-cardiac-cycle change in a value of maximum intracardiac impedance value calculated, for a particular cardiac cycle, to represent the maximum intracardiac impedance value for that particular cardiac cycle;
ora cardiac-cycle-to-cardiac-cyclea change in a slope value of an intracardiac impedance waveform signal, for a particular cardiac cycle, the slope value measured at a time corresponding to one-half of a time interval over which a maximum intracardiac impedance change occurs during the particular cardiac cycle; and
generate an indication that the measured at least two of the cardiac-cycle-to-cardiac-cycle changes represent heart failure (HF) decompensation when the changes occur absent detection of an intervening event during the measuring of the intracardiac impedance parameters.
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Abstract
A system to measure intracardiac impedance includes implantable electrodes and a medical device. The electrodes sense electrical signals of a heart of a subject. The medical device includes a cardiac signal sensing circuit coupled to the implantable electrodes, an impedance measurement circuit coupled to the same or different implantable electrodes, and a controller circuit coupled to the cardiac signal sensing circuit and the impedance measurement circuit. The cardiac signal sensing circuit provides a sensed cardiac signal. The impedance measurement circuit senses intracardiac impedance between the electrodes to obtain an intracardiac impedance signal. The controller circuit determines cardiac cycles of the subject using the sensed cardiac signal, and detects tachyarrhythmia using cardiac-cycle to cardiac-cycle changes in a plurality of intracardiac impedance parameters obtained from the intracardiac impedance signal.
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Citations
20 Claims
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1. A medical device comprising:
a controller circuit configured to; receive a sensed cardiac cycle and an intracardiac impedance signal; determine at least two of; a cardiac-cycle-to-cardiac-cycle change in a value of a baseline intracardiac impedance value calculated, for a particular cardiac cycle, to represent the baseline intracardiac impedance for that particular cardiac cycle; a cardiac-cycle-to-cardiac-cycle change in a value of maximum intracardiac impedance value calculated, for a particular cardiac cycle, to represent the maximum intracardiac impedance value for that particular cardiac cycle;
ora cardiac-cycle-to-cardiac-cyclea change in a slope value of an intracardiac impedance waveform signal, for a particular cardiac cycle, the slope value measured at a time corresponding to one-half of a time interval over which a maximum intracardiac impedance change occurs during the particular cardiac cycle; and generate an indication that the measured at least two of the cardiac-cycle-to-cardiac-cycle changes represent heart failure (HF) decompensation when the changes occur absent detection of an intervening event during the measuring of the intracardiac impedance parameters. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of operating a medical device, comprising:
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determining, using a controller circuit configured to receive a sensed cardiac cycle and an intracardiac impedance signal, at least two of; a cardiac-cycle-to-cardiac-cycle change in a value of a baseline intracardiac impedance value calculated, for a particular cardiac cycle, to represent the baseline intracardiac impedance for that particular cardiac cycle; a cardiac-cycle-to-cardiac-cycle change in a value of maximum intracardiac impedance value calculated, for a particular cardiac cycle, to represent the maximum intracardiac impedance value for that particular cardiac cycle; and a cardiac-cycle-to-cardiac-cycle change in a slope value of an intracardiac impedance waveform signal, for a particular cardiac cycle, the slope value measured at a time corresponding to one-half of a time interval over which a maximum intracardiac impedance change occurs during the particular cardiac cycle; and generating, using the controller circuit, an indication that the measured at least two of the cardiac-cycle-to-cardiac-cycle changes represent heart failure (HF) decompensation when the changes occur absent detection of an intervening event during the measuring of the intracardiac impedance parameters. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A system, comprising:
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a controller circuit configured to; receive a sensed cardiac cycle information and an intracardiac impedance signal; determine a cardiac-cycle-to-cardiac-cycle intracardiac impedance change using the received sensed cardiac cycle information and the intracardiac impedance signal; generate an indication of heart failure (HF) decompensation using the determined cardiac-cycle-to-cardiac-cycle intracardiac impedance change and the received cardiac cycle information. - View Dependent Claims (19, 20)
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Specification