High-resolution electrocardiography.

The electrocardiogram (ECG) is arguably the most common noninvasive diagnostic test performed by physicians. The instrumentation for recording the ECG has followed technological trends but the addition of new information has not generally been forthcoming from these advances. Instead, the elucidation of the standard waves P, QRS, T, and U is still the primary focus of electrocardiographic recording and interpretation. High-resolution electrocardiography can be defined as the use of methods to record physiological information not measurable with the standard ECG while still maintaining a noninvasive approach. Often these newer methods require digital signal processing for enhancing very low-level signals, deriving parameters from stored waveforms, or adaptively changing filter characteristics to record the normal wave when contaminated with high levels of noise. This review examines most of these approaches but concentrates on the methods which allow the recording of new information which may have significant diagnostic and, perhaps, prognostic value.