Cardiac flow sensor
First Claim
1. A system for determining a measure of arterial blood flow from the heart, comprising:
- a sensor lead having thereon a pair of fast time response temperature sensors positioned a short distance apart on said lead, said lead having output terminals and conducting means for conducting said temperature signals from each of said sensors to respective ones of said output terminals;
processing means for receiving said signals from said output terminals and for processing same to derive sets of digital representations of each of said temperature signals;
correlation means for finding the time delay between said two temperature signals at which said signals optimally correlate; and
computational means for computing from said time delay a measure of blood flow.
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Abstract
Apparatus and method are provided for obtaining a measure of blood flow, and more specifically cardiac output, by analyzing blood temperature variations in the arterial tract. In a first embodiment, a lead carrying two closely spaced temperature sensors is positioned so that the sensors are in the atrial tract and produce temperature signals representative of small cyclical temperature variations of the blood outputted from the heart. The two signals have substantially similar patterns for each cardiac cycle, but the signals are separated by a short time (.increment.T) representative of the distance between the two sensors. The patterns are correlated to find .increment.T, from which cardiac output is calculated. In an alternate embodiment, a single blood temperature sensor is employed along with a sensor for determining cardiac contractions, and a measure of cardiac output is obtained by comparing the time difference between a feature of the blood temperature signal with the time of cardiac contraction.
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Citations
15 Claims
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1. A system for determining a measure of arterial blood flow from the heart, comprising:
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a sensor lead having thereon a pair of fast time response temperature sensors positioned a short distance apart on said lead, said lead having output terminals and conducting means for conducting said temperature signals from each of said sensors to respective ones of said output terminals; processing means for receiving said signals from said output terminals and for processing same to derive sets of digital representations of each of said temperature signals; correlation means for finding the time delay between said two temperature signals at which said signals optimally correlate; and computational means for computing from said time delay a measure of blood flow. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of determining cardiac output of a patient, comprising:
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positioning first and second fast response sensors in the patient'"'"'s arterial tract, said sensors being positioned a short distance from each other along the axis of the atrial tract; obtaining naturally occurring cyclical temperature signals from each of said sensors corresponding to respective cardiac cycles; processing said cyclical signals to obtain therefrom a measure of flow rate; and determining cardiac output from said flow rate measure. - View Dependent Claims (8, 9, 10)
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11. A cardiac flow measurement system, comprising:
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sensor means for providing cyclical signals representative of naturally occurring blood temperature variations of blood in the patient'"'"'s arterial tract; and processing means for processing said signals to obtain a measure of blood flow from the patient'"'"'s heart. - View Dependent Claims (12, 13, 14, 15)
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Specification