As a medical professional with expertise in cardiology, I can explain the significance of waves on an electrocardiogram (ECG) tracing. An ECG is a graphic representation of the electrical activity of the heart, which can be used to diagnose various heart conditions. The standard ECG tracing consists of several waves, each with a specific meaning: 1. P wave: This wave represents the electrical activity associated with atrial depolarization, which is the process by which the atria (the upper chambers of the heart) contract to push blood into the ventricles (the lower chambers). 2. PR interval: This is the period between the start of the P wave and the start of the QRS complex. It corresponds to the time from atrial depolarization to the beginning of ventricular depolarization. 3. QRS complex: This complex is the most prominent part of the ECG and represents the ventricular depolarization, which is when the ventricles contract to pump blood out of the heart. 4. QT interval: This interval is measured from the start of the QRS complex to the end of the T wave. It represents the total time for both depolarization and repolarization of the ventricles. 5. T wave: The T wave corresponds to the repolarization of the ventricles, which is the process of the ventricles returning to their resting state after depolarization. 6. U wave: Sometimes seen after the T wave, the U wave is less well understood but is thought to represent repolarization of the papillary muscles within the ventricles. Each of these waves and intervals has a normal duration and amplitude, and deviations from these norms can indicate various cardiac conditions, such as arrhythmias, heart attacks, or electrolyte imbalances. read more >>

P wave is the first short upward movement of the ECG tracing. It indicates that the atria are contracting, pumping blood into the ventricles. The QRS complex, normally beginning with a downward deflection, Q; a larger upwards deflection, a peak (R); and then a downwards S wave.read more >>