Certified Rhythm Analysis Technician (CRAT) Practice Exam 2026 – All-in-One Study Guide for Exam Success!

The isoelectric line of an ECG tracing represents a baseline level of electrical activity within the heart, indicating a state of no net electrical activity. This line is crucial because it serves as a reference point against which all other electrical activities of the heart can be measured. When there is depolarization or repolarization of the heart's chambers, the ECG will show deflections either above or below this isoelectric line. Therefore, when the ECG tracing is on the isoelectric line, it signifies that there is no significant electrical activity occurring at that moment, which is essential for understanding cardiac rhythms and identifying potential abnormalities.