TABLE OF CONTENTS If conduction abnormalities are transient, then an abnormal beat manifests. If conduction problems persist, then the abnormal morphology repeats and an arrhythmia is manifest, or the ECG degenerates into an almost unrecognizable pattern. There are three general approaches to arrhythmia analysis. One method is to perform QRS detection and beat classification, labeling an arrhythmia as a quorum of a series of beats of a particular type. The common alternative approach is to analyze a section of the ECG that spans several beat intervals, calculate a statistic (such as variance or a ratio of power at different frequencies) on which the arrhythmia classification is performed. A third option is to construct a model of the expected dynamics for different rhythms and compare the observed signal (or derived features) to this model. Such model-based approaches can be divided down into ECG-based methods or RR interval statistics-based methods. Linear ECG-modeling techniques [26] are essentially equivalent to spectral analysis. Nonlinear state-space model reconstructions have also been used [27], but with varying results. This may be partly due to the sensitivity of nonlinear metrics to noise. See Chapter 6 for a more detailed description of this technique together with a discussion of the problems associated with applying nonlinear techniques to noisy data.
A run of abnormal beats can be classified as an arrhythmia. Therefore, as long as consistent fiducial points can be located on a series of beats, simple postprocessing of a beat classifier's output together...
