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The Promise of Electrocardiography in the 21st Century

The original concept behind this conference was based on the belief that an analysis of the electrical activity of the heart with multiple electrocardiographic techniques could contribute a great deal to the diagnosis of its various physiologic, pathologic, and anatomic abnormalities. Obviously, this had already been wonderfully accomplished by the originators of various isolated electrocardiographic (ECG) techniques. Nonetheless our firm belief was that much more clinically usable information would be available if two conditions were met. First, many of the various electrocardiographic techniques that have been discussed at this conference, such as signal averaging, power spectrum analysis, body surface mapping, and quantitative electrocardiography, would have to be applied to a large clinical population. Second, a data base consisting of a combination of invasive and noninvasive diagnostic tests would have to be developed to correlate these electrocardiographic changes with certain normal and abnormal states so that one could understand the significance of these various ECG-derived waveforms in living patients rather than relying on postmortem materials for correlations that, naturally, have limited applicability. The creation of these two conditions would necessitate the creation of new technologies and organizations. These would consist of new ways of obtaining and recording electrocardiographic data, new ways of analyzing these data, and new ways of presenting them to the clinician. This paper will review the application of various electrocardiographic techniques to the diagnosis of morphologic and physiologic changes in the heart, how they have been correlated with pathologic entities, present a view of a hypothetical electrocardiographic system of the future, and suggest an organi~ational mechanism by which electrocardiographic interpretation may be furthered. The electrocardiograph is capable of supplying much more information than has been extracted by it in the past. Information about infarction, hypertrophy, conduction disturbances, and arrhythmias has been available since the late 1940s and early 1950s. But now we have the capacity to use the electrocardiograph more fully and quite differently from ever before. The physiology of the entire organism, the quantitative and qualitative assessment of the activity of the autonomic nervous system, and indirect assessment of ventricular function are all potentially analyzable through detailed study of the power spectrum analysis of the heartbeat variation, analysis of the circadian variability of the heart rate, and a detailed analysis of the ambient heart rate surrounding cardiac arrhythmias.'-' The status of the heart with regard to its potential for arrhythmogenesis can be defined by application of techniques of signal averaging.' In the future this technique may be useful in predicting the response, both positive and negative, to various therapeutic interventions and conceivably might be used to assess the probability of atrial arrhythmias as well as ventricular events. Fourier analysis of the various