Apparatus and method for estimating stroke volume of the heart using bio-impedance techniques
First Claim
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1. A method of estimating stroke volume of the heart, comprising:
- acquiring a first set of electrical data of the chest, using electrodes placed on skin around the chest, at a first phase of the cardiac cycle;
estimating a first volume of the heart from the first set of electrical data;
acquiring a second set of electrical data of the chest, using electrodes placed on skin around the chest, at a second phase of the cardiac cycle;
estimating a second volume of the heart from the second set of electrical data; and
using the difference between the first and second volumes of the heart to estimate the stroke volume of the heart;
wherein estimating the first volume of the heart comprises generating a first impedance image of the chest from the first set of electrical data, and estimating the second volume of the heart comprises generating a second impedance image of the chest from the second set of electrical data, and generating the second impedance image of the chest comprises putting constraints on differences between the second impedance image and the first impedance image, but not constraining the volume of the heart to be the same in the first and second impedance images.
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Abstract
A method of estimating stroke volume of the heart is described. In this method, the volume of the heart is estimated from electrical impedance data of the chest, at two different phases of the cardiac cycle. The stroke volume is estimated from the difference between the volumes estimated at the two phases.
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Citations
20 Claims
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1. A method of estimating stroke volume of the heart, comprising:
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acquiring a first set of electrical data of the chest, using electrodes placed on skin around the chest, at a first phase of the cardiac cycle; estimating a first volume of the heart from the first set of electrical data; acquiring a second set of electrical data of the chest, using electrodes placed on skin around the chest, at a second phase of the cardiac cycle; estimating a second volume of the heart from the second set of electrical data; and using the difference between the first and second volumes of the heart to estimate the stroke volume of the heart; wherein estimating the first volume of the heart comprises generating a first impedance image of the chest from the first set of electrical data, and estimating the second volume of the heart comprises generating a second impedance image of the chest from the second set of electrical data, and generating the second impedance image of the chest comprises putting constraints on differences between the second impedance image and the first impedance image, but not constraining the volume of the heart to be the same in the first and second impedance images. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for estimating the stroke volume of the heart, comprising:
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an electrocardiograph; an impedance imaging data acquisition system which acquires impedance data of the chest; a controller which uses data from the electrocardiograph to trigger the data acquisition system to acquire the impedance data at each of a first phase and a second phase of the cardiac cycle; and a data analyzer which reconstructs a first impedance image of the chest at the first phase and a second impedance image of the chest at the second phase, from the data acquired at the first phase and the second phase, and estimates the volume of the heart in each of the impedance images, thereby allowing the stroke volume to be estimated from the difference between the volume of the heart at the first phase and the second phase; wherein the data analyzer reconstructs the second impedance image of the chest by putting constraints on differences between the second impedance image and the first impedance image, but not constraining the volume of the heart to be the same in the first and second impedance images. - View Dependent Claims (18, 19, 20)
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Specification