11 steps to read an ECG Note: There is a correction in the video. P-R interval extends from the beginning of the P wave (the onset of atrial depolarization) until the beginning of the QRS complex (the onset of ventricular depolarization). | Davidson's Principles and Practice of Medicine

ECG interpretation involves systematically analyzing the waveforms and intervals to assess heart rhythm, rate, and overall electrical activity. This includes evaluating the P-wave (atrial depolarization), PR interval, QRS complex (ventricular depolarization), ST segment, T-wave (ventricular repolarization), and QT interval. A normal ECG typically shows a regular heart rate (60-100 bpm), normal P-waves, a PR interval between 120-200 ms, a QRS complex duration less than 120 ms, and a normal QT int