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  Method and apparatus for determining alternans data of an ecg signalUSPTO Application #: 20060173371Title: Method and apparatus for determining alternans data of an ecg signal Abstract: Method and apparatus for determining alternans data of an ECG signal. The method can include determining at least one value representing at least one morphology feature of each beat of the ECG signal and generating a set of data points based on a total quantity of values and a total quantity of beats. The data points can each include a first value determined using a first mathematical function and a second value determined using a second mathematical function. The method can also include several preprocessing algorithms to improve the signal to noise ratio. The method can also include separating the data points into a first group of points and a second group of points and generating a feature map by plotting the first group of points and the second group of points in order to assess an alternans pattern of variation. The feature map can be analyzed by statistical tests to determine the significance difference between groups and clusters. (end of abstract)
Agent: Andrus, Sceales, Starke & Sawall, LLP - Milwaukee, WI, US Inventor: Joel Q. Xue USPTO Applicaton #: 20060173371 - Class: 600509000 (USPTO) Related Patent Categories: Surgery, Diagnostic Testing, Cardiovascular, Heart, Detecting Heartbeat Electric Signal The Patent Description & Claims data below is from USPTO Patent Application 20060173371. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to cardiology, and more specifically to methods and apparatus for determining alternans data of an electrocardiogram ("ECG") signal. [0002] Alternans are a subtle beat-to-beat change in the repeating pattern of an ECG signal. Several studies have demonstrated a high correlation between an individual's susceptibility to ventricular arrhythmia and sudden cardiac death and the presence of a T-wave alternans ("TWA") pattern of variation in the individual's ECG signal. [0003] While an ECG signal typically has an amplitude measured in millivolts, an alternans pattern of variation with an amplitude on the order of a microvolt may be clinically significant. Accordingly, an alternans pattern of variation is typically too small to be detected by visual inspection of the ECG signal in its typical recorded resolution. Instead, digital signal processing and quantification of the alternans pattern of variation is necessary. Such signal processing and quantification of the alternans pattern of variation is complicated by the presence of noise and time shift of the alternans pattern of variation to the alignment points of each beat, which can be caused by limitation of alignment accuracy and/or physiological variations in the measured ECG signal. Current signal processing techniques utilized to detect TWA patterns of variation in an ECG signal include spectral domain methods and time domain methods. BRIEF DESCRIPTION OF THE INVENTION [0004] In light of the above, a need exists for a technique for detecting TWA patterns of variation in an ECG signal that provides improved performance as a stand-alone technique and as an add-on to other techniques. Accordingly, one or more embodiments of the invention provide methods and apparatus for determining alternans data of an ECG signal. In some embodiments, the method can include determining at least one value representing at least one morphology feature of each beat of the ECG signal and generating a set of data points based on a total quantity of values and a total quantity of beats. The data points can each include a first value determined using a first mathematical function and a second value determined using a second mathematical function. The method can also include separating the data points into a first group of points and a second group of points and generating a feature map by plotting the first group of points and the second group of points in order to assess an alternans pattern of variation. BRIEF DESCRIPTION OF THE DRAWINGS [0005] FIG. 1 is a schematic diagram illustrating a cardiac monitoring system according to the invention. [0006] FIG. 2 illustrates an ECG signal. [0007] FIG. 3 is a flow chart illustrating one embodiment of a method of the invention. [0008] FIG. 4 illustrates a maximum morphology feature. [0009] FIG. 5 illustrates a minimum morphology feature. [0010] FIG. 6 illustrates an area morphology feature. [0011] FIG. 7 illustrates another area morphology feature. [0012] FIG. 8 illustrates a further area morphology feature. [0013] FIG. 9 illustrates still another area morphology feature. [0014] FIG. 10 illustrates a plurality of beats, each beat being divided into a plurality of portions. [0015] FIG. 11 illustrates a window establishing a size of one of the plurality of portions of FIG. 10. [0016] FIG. 12 illustrates a feature matrix. [0017] FIG. 13 illustrates a decomposition of the feature matrix of FIG. 12 as generated by a principal component analysis. [0018] FIG. 14 illustrates a plot of values of data corresponding to values representative of a morphology feature. [0019] FIG. 15 illustrates a determination of difference features using the values plotted in FIG. 14. [0020] FIG. 16 illustrates another determination of difference features using the values plotted in FIG. 14. [0021] FIG. 17 illustrates a further determination of a difference feature using the values plotted in FIG. 14. Continue reading... Full patent description for Method and apparatus for determining alternans data of an ecg signal Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for determining alternans data of an ecg signal patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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