Automated analysis of a cardiac signal based on dynamical characteristics of the cardiac signal
First Claim
1. A machine-implemented method comprising:
- obtaining a sensed cardiac signal of an organism, the sensed cardiac signal comprising a time series x(t);
applying a Hilbert (H) transform to the time series x(t) to obtain H(x(t)), wherein x(t) and H(x(t)) together forming a partial state space trajectory;
determining a speed of trajectory, for the sensed cardiac signal, from the partial state space trajectory; and
identifying physiological information concerning the organism based on a combination of first and second signal elements, the first signal element comprising a phase property or an amplitude property of the speed of trajectory, and the second signal element comprising an amplitude property of the partial state space trajectory.
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Abstract
Systems and techniques relating to locating cardiac wave forms in a cardiac signal, and to detecting a physiological condition, such as ventricular fibrillation. In general, in one aspect, a machine-implemented method includes obtaining a sensed cardiac signal of an organism, the sensed cardiac signal comprising a time series x(t); applying a Hilbert (H) transform to the time series x(t) to obtain H(x(t)), wherein x(t) and H(x(t)) together forming a partial state space trajectory; determining a speed of trajectory, for the sensed cardiac signal, from the partial state space trajectory; and identifying physiological information concerning the organism based on a combination of first and second signal elements, the first signal element including a phase property or an amplitude property of the speed of trajectory, and the second signal element including an amplitude property of the partial state space trajectory.
160 Citations
31 Claims
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1. A machine-implemented method comprising:
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obtaining a sensed cardiac signal of an organism, the sensed cardiac signal comprising a time series x(t);
applying a Hilbert (H) transform to the time series x(t) to obtain H(x(t)), wherein x(t) and H(x(t)) together forming a partial state space trajectory;
determining a speed of trajectory, for the sensed cardiac signal, from the partial state space trajectory; and
identifying physiological information concerning the organism based on a combination of first and second signal elements, the first signal element comprising a phase property or an amplitude property of the speed of trajectory, and the second signal element comprising an amplitude property of the partial state space trajectory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A machine-readable medium encoding a computer program product operable to cause data processing apparatus to perform operations comprising:
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obtaining a sensed cardiac signal of an organism, the sensed cardiac signal comprising a time series x(t);
applying a Hilbert (H) transform to the time series x(t) to obtain H(x(t)), wherein x(t) and H(x(t)) together forming a partial state space trajectory;
estimating a speed of trajectory, v(i), for the sensed cardiac signal, in discrete time t≡
i, i=[0 . . . n], using finite differences in the partial state space trajectory, wherein the estimated speed of trajectory v(i) includes a first component corresponding to x(t) and a second component corresponding to H(x(t));
determining from v(i), by division, a phase property of the estimated speed of trajectory v(i) in accordance with a trigonometric function of phase; and
identifying physiological information concerning the organism based on the phase property. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A cardiac monitoring apparatus comprising:
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an input element;
a processor; and
a machine-readable medium encoding instructions operable to cause the processor to perform operations comprising;
obtaining, from the input element, a sensed cardiac signal of an organism;
applying a Hilbert transform to the sensed cardiac signal to form a partial state space trajectory;
determining a speed of trajectory, for the sensed cardiac signal, from the partial state space trajectory;
combining an amplitude property of the partial state space trajectory with an amplitude property of the speed of trajectory to form a calculated signal; and
identifying physiological information concerning the organism based on the calculated signal. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification