Waveform feature value averaging system and methods for the detection of cardiac events
First Claim
1. A device for assessing the condition of a mammalian heart, comprising:
- a lead comprising two sensors,a processor coupled to the lead, the processor configured to;
(i) obtain a first signal from the lead, and compute a first waveform corresponding to the first signal, the first waveform being characterized by a plurality of QRS complexes and T waves;
(ii) compute a plurality of first fiducial points associated with corresponding QRS complexes;
(iii) compute a plurality of second fiducial points associated with corresponding T waves;
(iv) compute a plurality of values of a T wave timing measure based on the differences in time between corresponding members of the first and second pluralities of fiducial points;
(v) derive an average of the T wave timing measure based on the plurality of values of the T wave timing measure;
(vi) apply a test to detect a pathological heart condition, wherein the test is based on the average of the T wave timing measure.
1 Assignment
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Accused Products
Abstract
Disclosed is a system for detecting pathophysiological cardiac conditions. The system comprises a diagnostic device that contains electronic circuitry that can detect a cardiac event such as an acute ischemia. The cardiac diagnostic device receives electrical signals from subcutaneous or body surface sensors. The cardiac diagnostic device includes a processor that computes QRS onset and offset points and fiducial points associated with T and U waves. The processor than baseline corrects the original signal/waveform by fitting a polynomial function to QRS offset points, and subtracting this function from the original waveform. Based on the baseline adjusted signal and/or the above mentioned fiducial points, the processor then computes averages of various waveform feature values, including a QRS measure sensitive to QRS curvature, T wave timing measures, ST segment deviation (difference between signal amplitudes at QRS offset and onset and/or minimum amplitude between QRS offset and peak T wave); and T/U wave amplitudes. These averages are computed by exponential averaging. From the exponential averages, the processor computes an average of the change in the averages over time. Based on the averages and the change in the averages, the processor applies an ischemia test to determine a likelihood of ischemia.
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Citations
20 Claims
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1. A device for assessing the condition of a mammalian heart, comprising:
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a lead comprising two sensors, a processor coupled to the lead, the processor configured to; (i) obtain a first signal from the lead, and compute a first waveform corresponding to the first signal, the first waveform being characterized by a plurality of QRS complexes and T waves; (ii) compute a plurality of first fiducial points associated with corresponding QRS complexes; (iii) compute a plurality of second fiducial points associated with corresponding T waves; (iv) compute a plurality of values of a T wave timing measure based on the differences in time between corresponding members of the first and second pluralities of fiducial points; (v) derive an average of the T wave timing measure based on the plurality of values of the T wave timing measure; (vi) apply a test to detect a pathological heart condition, wherein the test is based on the average of the T wave timing measure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for assessing the condition of a mammalian heart, comprising:
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a lead comprising two sensors, a processor coupled to the lead, the processor configured to; (i) obtain a first signal from the lead, and compute a first waveform corresponding to the first signal, the first waveform being characterized by a plurality of QRS complexes; (ii) compute a plurality of values of a first waveform feature indicative of the curvature of at least some portion of a corresponding one of the plurality of QRS complexes; (iii) derive an average of the first waveform feature based on the plurality of values of the first waveform feature; (iv) apply a test to detect a pathological heart condition, wherein the test is based on the average of the first waveform feature value.
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10. A device for assessing the condition of a mammalian heart, comprising:
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a lead comprising two sensors, a processor coupled to the lead, the processor configured to; (i) obtain a signal from the lead, and compute a waveform corresponding to the signal, the waveform being characterized by a plurality of QRS complexes; (ii) compute a plurality of values of the waveform feature from the waveform representing the values of the waveform feature over time; (iii) compute, based on the plurality of values of the waveform feature, a measure of the average change in the waveform feature over time, thereby deriving an average change metric; (iv) apply a test to detect a pathological heart condition, wherein the test is based on the average change metric. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A device for assessing the condition of a mammalian heart, comprising:
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a lead comprising two sensors, a processor coupled to the lead, the processor configured to; (i) obtain a signal from the lead, and compute a waveform corresponding to the signal, the waveform being characterized by a plurality of QRS complexes; (ii) compute a plurality of values of the waveform feature from the waveform representing the values of the waveform feature over time; (iii) apply a first filter the plurality of values of the waveform feature, thereby deriving a filtered waveform; (iv) compute, based on the filtered waveform, a measure of the change in the waveform feature over time, thereby deriving a change metric; (iv) apply a test to detect a pathological heart condition, wherein the test is based on the change metric. - View Dependent Claims (17, 18, 19, 20)
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Specification