Monitoring hemodynamic status based on intracardiac or vascular impedance
First Claim
1. A method comprising:
- measuring a plurality of impedance values of a path within a patient over time, wherein the path includes at least one blood vessel or cardiac chamber of the patient, and wherein the impedance values vary as a function of blood pressure within the at least one vessel or chamber;
determining a plurality of values of an impedance parameter over time based on the measured impedance values, wherein each of the impedance parameter values is determined based on a respective sub-plurality of the impedance values, determining the plurality of values of the impedance parameter comprisingidentifying an R-wave for a current cardiac cycle,identifying a maximum impedance and a minimum impedance for the current cardiac cycle,determining a first time interval between the R-wave and the minimum impedance,determining a second time interval between the R-wave and the maximum impedance, anddetermining a ratio of the first time interval and the second time interval;
comparing the ratio of the current cardiac cycle to a ratio of a prior cardiac cycle; and
identifying a change in a cardiovascular parameter related to the blood pressure based on the comparison.
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Accused Products
Abstract
This disclosure relates to monitoring intracardiac or vascular impedance to determine a change in hemodynamic status by detecting changes in an impedance parameter over cardiac cycles. An example method includes measuring a plurality of impedance values of a path within a patient over time, wherein the path includes at least one blood vessel or cardiac chamber of the patient, and wherein the impedance values vary as a function of blood pressure within the at least one vessel or chamber, determining a plurality of values of an impedance parameter over time based on the measured impedance values, wherein each of the impedance parameter values is determined based on a respective sub-plurality of the impedance values, comparing at least one of the impedance parameter values to at least one prior impedance parameter value, and identifying a change in a cardiovascular parameter related to the blood pressure based on the comparison.
34 Citations
5 Claims
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1. A method comprising:
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measuring a plurality of impedance values of a path within a patient over time, wherein the path includes at least one blood vessel or cardiac chamber of the patient, and wherein the impedance values vary as a function of blood pressure within the at least one vessel or chamber; determining a plurality of values of an impedance parameter over time based on the measured impedance values, wherein each of the impedance parameter values is determined based on a respective sub-plurality of the impedance values, determining the plurality of values of the impedance parameter comprising identifying an R-wave for a current cardiac cycle, identifying a maximum impedance and a minimum impedance for the current cardiac cycle, determining a first time interval between the R-wave and the minimum impedance, determining a second time interval between the R-wave and the maximum impedance, and determining a ratio of the first time interval and the second time interval; comparing the ratio of the current cardiac cycle to a ratio of a prior cardiac cycle; and identifying a change in a cardiovascular parameter related to the blood pressure based on the comparison. - View Dependent Claims (2, 3, 4)
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5. A non-transitory computer-readable medium comprising instructions for causing a programmable processor to:
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measure a plurality of impedance values of a path within a patient over time, wherein the path includes at least one blood vessel or cardiac chamber of the patient, and wherein the impedance values vary as a function of blood pressure within the at least one vessel or chamber; determine a plurality of values of an impedance parameter over time based on the measured impedance values, wherein each of the impedance parameter values is determined based on a respective sub-plurality of the impedance values, wherein the instructions for causing the programmable processor to determine the plurality of values of the impedance parameter comprise instructions that cause the programmable processor to; identify an R-wave for a current cardiac cycle, identify a minimum impedance and a maximum impedance for the current cardiac cycle, determine a first time interval between the R-wave and the minimum impedance, determine a second time interval between the R-wave and the maximum impedance, and determine a ratio of the first time interval and the second time interval; compare the ratio of the current cardiac cycle to a ratio of a prior cardiac cycle; identify a change in a cardiovascular parameter related to the blood pressure based on the comparison; and execute a programmed response upon identifying a change in the cardiovascular parameter.
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Specification