As a domain expert in the field of electrophysiology, I can explain the concept of the isoelectric line in the context of an electrocardiogram (ECG or EKG). The isoelectric line on an ECG represents the baseline of the heart's electrical activity when there is no depolarization or repolarization occurring. In other words, it is the flat line that separates the waves and segments of the ECG. This line is crucial for interpreting the ECG because it provides a reference point from which the amplitudes of the P wave, QRS complex, and T wave can be measured. The isoelectric line should be flat and unchanging unless there is an artifact or interference. When discussing intervals, the term includes the duration of a wave and the isoelectric line that follows it. For example, the QT interval includes the Q wave, the entire ST segment, and the T wave, along with the isoelectric line that follows the T wave. read more >>

The U Wave is thought to represent late repolarization of the Purkinje fibers in the Ventricles and is more often not shown on a rhythm strip. [Top] Intervals and Segments. Interval refers to the length of a wave plus the isoelectric line that follows it.read more >>