The ECG shows the heart’s electrical activity as line tracings on paper. It’s the recording of electrical activity of the heart. ECG is an instrument which is used to record the electrical current generated in the heart. By means of this instrument, the electrical current generated in the heart is conducted to remote by connecting any two parts of the body with this instrument. The connections are called as leads they are.
A normal ECG contains waves, intervals, segments and one complex, as defined below. Wave: A positive or negative deflection from the baseline that indicates a specific electrical event. The waves on an ECG include the P wave, Q wave, R wave, S wave, T wave and U wave. Interval: The time between two specific ECG events. The intervals commonly measured on an ECG include the PR interval, QRS interval (also called QRS duration), QT interval and RR interval. Segment: The length between two specific points on an ECG that are supposed to be at the baseline amplitude (not negative or positive). The segments on an ECG include the PR segment, ST segment, and TP segment. Complex: The combination of multiple waves grouped together. The only main complex on an ECG is the QRS complex. The P wave indicates atrial depolarization. The QRS complex consists of a Q wave, R wave, and S wave and represents ventricular depolarization. The T wave comes after the QRS complex and indicates ventricular repolarization.