Cardiac stimulation devices and methods for measuring impedances associated with the left side of the heart
First Claim
1. A cardiac stimulation device comprising:
- a first pair of electrodes configured for placement internally in a patient and in operable association with the patient'"'"'s heart;
a current source operably associated with the first pair of electrodes and configured to produce a current therebetween;
a second pair of electrodes configured for placement internally in a patient and in operable association with the patient'"'"'s heart, at least one of the electrodes of the second pair of electrodes being configured for placement in association with the left side of the patient'"'"'s heart;
a voltage measuring circuit operably associated with the second pair of electrodes and configured to measure a voltage therebetween responsive to the current produced by the current source;
an impedance measuring circuit configured for measuring impedance as a function of the current produced by the current source and the voltage measured by the voltage measuring circuit; and
a stimulation circuit associated with the impedance measuring circuit and configured to stimulate the patient'"'"'s heart as a function of the measured impedance.
1 Assignment
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Accused Products
Abstract
Methods of and systems for measuring at least one physiological parameter for assessing a patient'"'"'s cardiac condition based on left heart impedance measurements are described. Various embodiments establish a current flow through a left side of the heart and measure a voltage between a first location on or in the left side of the heart and a second location within the human body while establishing the current flow. The inventive techniques and systems can be used for, among other things, measuring progression or regression of myocardial failure, dilation, or hypertrophy, pulmonary congestion, myocardial contractility, or ejection fraction. The measured voltage, related to left heart impedance, can be used to monitor patient condition for diagnostic purposes or to adapt pacing or defibrillation therapy. Therapy adaptation can include controlling pacing modes, pacing rates, or interchamber pacing delays, for example.
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Citations
66 Claims
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1. A cardiac stimulation device comprising:
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a first pair of electrodes configured for placement internally in a patient and in operable association with the patient'"'"'s heart;
a current source operably associated with the first pair of electrodes and configured to produce a current therebetween;
a second pair of electrodes configured for placement internally in a patient and in operable association with the patient'"'"'s heart, at least one of the electrodes of the second pair of electrodes being configured for placement in association with the left side of the patient'"'"'s heart;
a voltage measuring circuit operably associated with the second pair of electrodes and configured to measure a voltage therebetween responsive to the current produced by the current source;
an impedance measuring circuit configured for measuring impedance as a function of the current produced by the current source and the voltage measured by the voltage measuring circuit; and
a stimulation circuit associated with the impedance measuring circuit and configured to stimulate the patient'"'"'s heart as a function of the measured impedance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An implantable cardiac impedance measuring device comprising:
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means for providing an electrical current between a first pair of electrodes that are configured for placement internally in a patient and in operable association with the patient'"'"'s heart;
means for measuring a voltage, responsive to the electrical current, between a second pair of electrodes that are configured for placement internally of a patient and in operable association with the patient'"'"'s heart;
means for calculating, from the electrical current and a corresponding measured voltage, an impedance; and
switch means for programmably selecting at least one electrode of the first and second pair of electrodes so that the at least one electrode comprises a left side heart electrode, the switch means enabling an impedance to be calculated that is associated with the patient'"'"'s left side heart. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A cardiac stimulation device comprising:
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one or more computer-readable media;
one or more processors; and
instructions embodied on the one or more computer-readable media which, when executed by the one or more processors, cause the one or more processors to calculate an impedance using at least one left side heart electrode. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A cardiac stimulation device comprising:
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one or more computer-readable media;
one or more processors; and
instructions embodied on the one or more computer-readable media which, when executed by the one or more processors, cause the one or more processors to calculate an impedance using a multi-polar electrode configuration with at least one left side heart electrode. - View Dependent Claims (30, 31, 32)
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33. A method of measuring an impedance using a cardiac stimulation device comprising:
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establishing a current path between a first pair of electrodes configured for use internally of a patient;
measuring a voltage between a second pair of electrodes configured for use internally in a patient, at least one electrode of the second pair comprising a left side heart electrode; and
calculating an impedance based upon the established current and the measured voltage. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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59. A method of assessing a patient'"'"'s cardiac condition comprising:
- establishing a current path between a first pair of electrodes configured for use internally in a patient;
measuring a voltage between a second pair of electrodes configured for use internally of a patient, at least one electrode of the second pair comprising a left side heart electrode;
calculating an impedance based upon the established current and the measured voltage; and
based on the calculated impedance, determining one or more physiological parameters for assessing a patient'"'"'s cardiac condition. - View Dependent Claims (60, 61, 62, 63, 64, 65, 66)
- establishing a current path between a first pair of electrodes configured for use internally in a patient;
Specification