Method for determining the left-ventricular ejection time TLVE of a heart of a subject
First Claim
1. A method of determining the left-ventricular ejection time TLVE of a heart of a subject, comprising:
- deriving a first waveform for determining TLVE including measuring a value selected from the group consisting of thoracic electrical bioimpedance and thoracic electrical bioadmittance over time;
deriving at least a second waveform for determining TLVE by using a method selected from the group consisting of pulse oximetry, Doppler velocimetry, measurement of arterial blood pressure, measurement of peripheral electrical bioimpedance, and measurement of peripheral electrical bioadmittance; and
a) in a first action, independently using said first waveform and said at least a second waveform to determine values of TLVE by applying predetermined criteria to define an opening point and a closure point of the aortic valve in said first waveform and said at least a second waveform, andb) in a second action, averaging the values of TLVE by using predetermined weights for the TLVE values obtained from said first waveform and said at least a second waveform.
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Abstract
In order to reliably determine the left-ventricular ejection time TLVE of a heart of a subject, at least two different measuring methods are employed. This includes in any case the derivation of a first waveform related to thoracic electrical bioimpedance or bioadmittance. A second waveform can be determined by using pulse oximetry, Doppler velocimetry, measurement of arterial blood pressure and measurement of peripheral electrical bioimpedance or bioadmittance. Depending on signal quality, the results obtained by each method are weighted and then averaged. The weighted average for left-ventricular ejection time is used as an input variable for cardiovascular monitoring methods, which determine objective measurements of cardiovascular function and performance. Such measurements include, but are not limited to, left ventricular ejection fraction, stroke volume, cardiac output, systolic time ratio, and indices of ventricular contractility.
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Citations
29 Claims
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1. A method of determining the left-ventricular ejection time TLVE of a heart of a subject, comprising:
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deriving a first waveform for determining TLVE including measuring a value selected from the group consisting of thoracic electrical bioimpedance and thoracic electrical bioadmittance over time; deriving at least a second waveform for determining TLVE by using a method selected from the group consisting of pulse oximetry, Doppler velocimetry, measurement of arterial blood pressure, measurement of peripheral electrical bioimpedance, and measurement of peripheral electrical bioadmittance; and a) in a first action, independently using said first waveform and said at least a second waveform to determine values of TLVE by applying predetermined criteria to define an opening point and a closure point of the aortic valve in said first waveform and said at least a second waveform, and b) in a second action, averaging the values of TLVE by using predetermined weights for the TLVE values obtained from said first waveform and said at least a second waveform. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of determining the left-ventricular ejection time TLVEof a heart of a subject, comprising:
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deriving a first waveform for determining TLVE including measuring a value selected from the group consisting of thoracic electrical bioimpedance and thoracic electrical bioadmittance over time; deriving at least a second waveform for determining TLVE by using a method selected from the group consisting of pulse oximetry, Doppler velocimetry, measurement of arterial blood pressure, measurement of peripheral electrical bioimpedance, and measurement of peripheral electrical bioadmittance; and a) using predetermined criteria to independently define an opening point and a closure point of the aortic valves in said first waveform and said at least a second waveform, b) aligning said waveforms synchronously with time, c) using the opening points defined in said waveforms to derive an averaged opening point by using predetermined criteria, d) using the closure points defined in said waveforms to derive an averaged closure point by using predetermined criteria, and e) determining TLVE by calculating the time interval starting with said averaged opening point and ending at said averaged closure point. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification