Method and apparatus for vector analysis of ECG arrhythmias
First Claim
1. Apparatus for use in analyzing successive ECG signatures in two-channel vector electrocardiographic signals for sensing the vector angle at the peak of the QRS complex and the vector angle at the peak of the T wave, for determining the difference between the vector angles, and for counting the number of times during a predetermined time interval the angular difference falls within predetermined angular limits, comprising:
- peak-determining means responsive to an applied input signal for sensing the peak of the QRS complex and producing a first sampling signal when it occurs, and for sensing the peak of the T wave and producing a second sampling signal when it occurs;
a rectangular-to-polar coordinate converter responsive to the two-channel electrocardiographic signals to produce a magnitude signal and an angle signal;
sample-and-hold means connected to said peak-determining means, and connected to said rectangular-to-polar coordinate converter, and responsive to said first sampling signal to produce a first sampled angle signal equal to the value of the angle signal at the time of occurrence of the first sampling signal, and responsive to said second sampling signal to produce a second sampled angle signal equal to the value of the angle signal at the time of occurrence of the second sampling signal;
difference means connected to said sample-and-hold means for producing an output difference signal equal to the difference between the first sampled angle signal and the second sampled angle signal; and
,classifying means connected to said difference means for counting the number of difference signals having amplitudes within a predetermined angular range.
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Abstract
ECG signals from two approximately orthogonal leads are combined in a rectangular-to-polar coordinate converter to obtain signals representing the magnitude and angle of the vector. The vector angle existing at the instant the magnitude of the QRS vector reaches its peak is first identified, and a voltage corresponding to the vector angle is sampled and stored for later use. Secondly, the vector angle existing at the instant the magnitude of the T-wave vector reaches its peak later in the cardiac cycle, is identified, and a voltage corresponding to this second vector angle is sampled and stored. The voltages representing the QRS and the T-wave vector angles are then applied to a differential amplifier to obtain a difference voltage representing the angular difference existing between the two maximal vectors. This angular difference possesses certain characteristics which are diagnostically significant. A classifying circuit determines which one of a number of angular ranges the angular difference falls into. A counter is provided for each angular range to accumulate over successive heartbeats the number of differences which have fallen into each of the angular ranges, and the cumulative counts are displayed.
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Citations
22 Claims
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1. Apparatus for use in analyzing successive ECG signatures in two-channel vector electrocardiographic signals for sensing the vector angle at the peak of the QRS complex and the vector angle at the peak of the T wave, for determining the difference between the vector angles, and for counting the number of times during a predetermined time interval the angular difference falls within predetermined angular limits, comprising:
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peak-determining means responsive to an applied input signal for sensing the peak of the QRS complex and producing a first sampling signal when it occurs, and for sensing the peak of the T wave and producing a second sampling signal when it occurs; a rectangular-to-polar coordinate converter responsive to the two-channel electrocardiographic signals to produce a magnitude signal and an angle signal; sample-and-hold means connected to said peak-determining means, and connected to said rectangular-to-polar coordinate converter, and responsive to said first sampling signal to produce a first sampled angle signal equal to the value of the angle signal at the time of occurrence of the first sampling signal, and responsive to said second sampling signal to produce a second sampled angle signal equal to the value of the angle signal at the time of occurrence of the second sampling signal; difference means connected to said sample-and-hold means for producing an output difference signal equal to the difference between the first sampled angle signal and the second sampled angle signal; and
,classifying means connected to said difference means for counting the number of difference signals having amplitudes within a predetermined angular range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for counting the number of times during a predetermined time interval the vector angle at the peak of a chosen type of complex occurring within successive ECG signatures sensed in two-channel vector electrocardiographic signals occurs within predetermined angular limits, comprising:
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peak-determining means responsive to an applied input signal for sensing the peak of each complex of the chosen type and for producing a sampling signal when the peak occurs; a rectangular-to-polar coordinate converter responsive to the two electrocardiographic signals to produce a magnitude signal and an angle signal; sample-and-hold means connected to said peak-determining means, and connected to said rectangular-to-polar coordinate converter, and responsive to the sampling signal to produce as an output a sampled angle signal equal to the value of the angle signal at the time of occurrence of the sampling signal; and
,classifying means connected to said sample-and-hold means for counting the number of sampled angle signals whose amplitudes fall within a predetermined angular range. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for determining the number of times during a predetermined time interval the difference between the vector angles at the peaks of successive QRS and T complexes within successive ECG signatures in two-channel vector electrocardiographic signals occurs within predetermined angular limits, comprising the steps of:
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(a) converting the two-channel vector electrocardiographic signals to polar form including a magnitude signal and an angle signal; (b) producing a sampling signal at the instant when the peak of a complex occurs; (c) sampling the angle signal when the sampling signal is produced; (d) repeating Steps (a)-(c) for the next complex within the signature; (e) subtracting the successive sampled angle signals obtained in Steps (c) and (d) to obtain a difference signal; (f) comparing the difference signal with a series of reference signals to determine which angular range the difference signal falls into; (g) incrementing, by one count, a counter associated with the angular range into which the difference signal falls; and
,(h) repeating Steps (a) through (g) for each successive signature which occurs within the predetermined time interval. - View Dependent Claims (18, 19)
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20. A method for determining the number of times during a predetermined time interval the vector angle at the peak of a chosen type of complex occurring within successive ECG signatures sensed in two-channel vector electrocardiographic signals occurs within predetermined angular limits, comprising the steps of:
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(a) converting the two-channel vector electrocardiographic signals to polar form including a magnitude signal and an angle signal; (b) producing a sampling signal at the instant when the peak of a complex occurs; (c) sampling the angle signal when the sampling signal is produced; (d) comparing the sampled angle signal with a series of reference signals to determine which angular range the sampled angle signal falls into; (e) incrementing, by one count, a counter associated with the angular range into which the sampled angle falls; and
,(f) repeating Steps (a) through (e) for each successive ECG signature which occurs within the predetermined time interval. - View Dependent Claims (21, 22)
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Specification