Implantable cardiac device having an impedance monitoring circuit and method
First Claim
1. In an implantable cardiac stimulation device which applies stimulation pulses having a current and a voltage magnitude across an electrode configuration including first and second electrodes in electrical contact with a heart, circuitry that monitors impedance of the electrode configuration comprising:
- a current sensing circuit that provides a first analog signal representing the magnitude of the current of a stimulation pulse applied to the electrode configuration;
a voltage sensing circuit that provides a second analog signal representing the magnitude of the voltage of the stimulation pulse applied to the electrode configuration; and
an impedance determining circuit having an analog input coupled to one of the current sensing circuit or the voltage sensing circuit for receiving one of the first or second signals, an analog reference input coupled to the other one of the current sensing circuit or the voltage sensing circuit for receiving the other one of the first or second signals, and a digital output for providing a digital signal proportional to the ratio of the first and second signals.
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Accused Products
Abstract
A circuit within an implantable cardiac stimulation device monitors impedance of an electrode configuration including first and second electrodes in electrical contact with a heart. The circuit is within the implantable cardiac stimulation device which applies stimulation pulses having a current and a voltage magnitude across the electrode configuration. The circuit that monitors impedance of an electrode configuration provides an impedance digital output proportional to the ratio of a stimulation pulse voltage and current.
83 Citations
10 Claims
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1. In an implantable cardiac stimulation device which applies stimulation pulses having a current and a voltage magnitude across an electrode configuration including first and second electrodes in electrical contact with a heart, circuitry that monitors impedance of the electrode configuration comprising:
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a current sensing circuit that provides a first analog signal representing the magnitude of the current of a stimulation pulse applied to the electrode configuration;
a voltage sensing circuit that provides a second analog signal representing the magnitude of the voltage of the stimulation pulse applied to the electrode configuration; and
an impedance determining circuit having an analog input coupled to one of the current sensing circuit or the voltage sensing circuit for receiving one of the first or second signals, an analog reference input coupled to the other one of the current sensing circuit or the voltage sensing circuit for receiving the other one of the first or second signals, and a digital output for providing a digital signal proportional to the ratio of the first and second signals. - View Dependent Claims (2, 3, 4, 5)
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6. In an implantable cardiac stimulation device which applies stimulation pulses having a current and a voltage magnitude across an electrode configuration including first and second electrodes in electrical contact with a heart, impedance monitoring means for monitoring impedance of the electrode configuration comprising:
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current sensing means for providing a first analog signal representing the magnitude of the current of a stimulation pulse applied to the electrode configuration;
voltage sensing means for providing a second analog signal representing the magnitude of the voltage of the stimulation pulse applied to the electrode configuration; and
impedance determining means having analog input means coupled to one of the current sensing means or the voltage sensing means for receiving one of the first or second signals, analog reference input means coupled to the other one of the current sensing means or the voltage sensing means for receiving the other one of the first or second signals, and digital output means for providing a digital signal proportional to the ratio of the first and second signals. - View Dependent Claims (7, 8, 9, 10)
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Specification