System and method to localize changes in intrathoracic fluid content using measured impedance in an implantable device
First Claim
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1. A method of detecting a thoracic fluid condition in an implantable medical device system, comprising:
- periodically measuring intrathoracic impedance for one of a plurality of intrathoracic measurement vectors using a pair of a plurality of electrodes implanted along the thoracic cavity of a patient, the one of the plurality of intrathoracic measurement vectors selected as representative of a global intrathoracic impedance of the patient, wherein the global intrathoracic impedance is sensitive to an intrathoracic impedance change with low specificity as to a location of the intrathoracic impedance change;
detecting, based on the periodic measurements, the intrathoracic impedance change for the one of the plurality of intrathoracic measurement vectors representative of the global intrathoracic impedance of the patient, wherein the intrathoracic impedance change is a trigger for intrathoracic impedance measurements for the plurality of intrathoracic measurement vectors;
in response to detecting the intrathoracic impedance change, measuring intrathoracic impedance for the plurality of intrathoracic measurement vectors using the plurality of electrodes;
in response to measuring the intrathoracic impedances, computing a conductivity of each of a plurality of intrathoracic impedance mapping locations corresponding to the plurality of intrathoracic measurement vectors, wherein each of a plurality of anatomic regions is associated with a respective one or more of the mapping locations;
detecting a change in conductivity for one or more of the mapping locations based on the computed conductivities of the mapping locations;
detecting the thoracic fluid condition in response to the detected change in conductivity; and
discriminating, by a processor, within which one or more of the plurality of anatomic regions the thoracic fluid condition occurred based upon for which of the mapping locations the change in conductivity was detected.
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Abstract
An implantable medical device and associated methods monitor thoracic fluid status and discriminate thoracic fluid conditions. Intrathoracic impedance is measured along multiple intrathoracic measurement vectors using implanted electrodes. A map of thoracic conductivity is computed using the measured intrathoracic impedances. A thoracic fluid condition is detected in response to the computed map.
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Citations
20 Claims
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1. A method of detecting a thoracic fluid condition in an implantable medical device system, comprising:
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periodically measuring intrathoracic impedance for one of a plurality of intrathoracic measurement vectors using a pair of a plurality of electrodes implanted along the thoracic cavity of a patient, the one of the plurality of intrathoracic measurement vectors selected as representative of a global intrathoracic impedance of the patient, wherein the global intrathoracic impedance is sensitive to an intrathoracic impedance change with low specificity as to a location of the intrathoracic impedance change; detecting, based on the periodic measurements, the intrathoracic impedance change for the one of the plurality of intrathoracic measurement vectors representative of the global intrathoracic impedance of the patient, wherein the intrathoracic impedance change is a trigger for intrathoracic impedance measurements for the plurality of intrathoracic measurement vectors; in response to detecting the intrathoracic impedance change, measuring intrathoracic impedance for the plurality of intrathoracic measurement vectors using the plurality of electrodes; in response to measuring the intrathoracic impedances, computing a conductivity of each of a plurality of intrathoracic impedance mapping locations corresponding to the plurality of intrathoracic measurement vectors, wherein each of a plurality of anatomic regions is associated with a respective one or more of the mapping locations; detecting a change in conductivity for one or more of the mapping locations based on the computed conductivities of the mapping locations; detecting the thoracic fluid condition in response to the detected change in conductivity; and discriminating, by a processor, within which one or more of the plurality of anatomic regions the thoracic fluid condition occurred based upon for which of the mapping locations the change in conductivity was detected. - View Dependent Claims (2, 3, 4, 5, 6, 14, 15, 16, 17, 18, 19, 20)
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7. An implantable medical device, comprising;
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a plurality of electrodes configured to be implanted along the thoracic cavity of a patient; an impedance measuring module configured to periodically measure intrathoracic impedance for one of a plurality of intrathoracic measurement vectors using a pair of the plurality of electrodes implanted along the thoracic cavity of the patient, the one of the plurality of intrathoracic measurement vectors selected as representative of a global intrathoracic impedance of the patient, wherein the global intrathoracic impedance is sensitive to an intrathoracic impedance change with low specificity as to a location of the intrathoracic impedance change; a processor configured to detect, based on the periodic measurements, the intrathoracic impedance change for the one of the plurality of intrathoracic measurement vectors representative of the global intrathoracic impedance of the patient, wherein the intrathoracic impedance change is a trigger for intrathoracic impedance measurements for the plurality of intrathoracic measurement vectors, and wherein the impedance measuring module is configured to, in response to the detection of the intrathoracic impedance change, measure intrathoracic impedance for the plurality of intrathoracic measurement vectors between the plurality of electrodes; and a mapping module configured to, in response to the intrathoracic impedances being measured, compute a conductivity of each of a plurality of intrathoracic impedance mapping locations corresponding to the plurality of intrathoracic impedance measurement vectors, wherein each of a plurality of anatomic regions is associated with a respective one or more of the mapping locations, wherein the processor is configured to detect a change in conductivity for one or more of the mapping locations based on the computed conductivities of the mapping locations, detect a thoracic fluid condition in response to the change in conductivity being detected, and discriminate within which one or more of the plurality of anatomic regions the thoracic fluid condition occurred based upon for which of the mapping locations the change in conductivity was detected. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A system for detecting a thoracic fluid condition in an implantable medical device, comprising:
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means for periodically measuring intrathoracic impedance for one of a plurality of intrathoracic measurement vectors using a pair of a plurality of electrodes implanted along the thoracic cavity of a patient, the one of the plurality of intrathoracic measurement vectors selected as representative of a global intrathoracic impedance of the patient, wherein the global intrathoracic impedance is sensitive to an intrathoracic impedance change with low specificity as to a location of the intrathoracic impedance change; means for detecting, based on the periodic measurements, the intrathoracic impedance change for the one of the plurality of intrathoracic measurement vectors representative of the global intrathoracic impedance of the patient, wherein the intrathoracic impedance change is a trigger for intrathoracic impedance measurements for the plurality of intrathoracic measurement vectors; means for, in response to detecting the intrathoracic impedance change, measuring intrathoracic impedance for the plurality of intrathoracic measurement vectors; means for, in response to measuring the intrathoracic impedances, computing a conductivity of each of a plurality of intrathoracic impedance mapping locations corresponding to the plurality of intrathoracic measurement vectors, wherein each of a plurality of anatomic regions is associated with a respective one or more of the mapping locations; means for detecting a change in conductivity for one or more of the mapping locations based on the computed conductivities of the mapping locations; means for detecting the thoracic fluid condition in response to the detected change in conductivity; and means for discriminating within which one or more of the plurality of anatomic regions the thoracic fluid condition occurred based upon for which of the mapping locations the change in conductivity was detected.
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Specification