As a medical professional with expertise in cardiology, I can tell you that the portion of a normal ECG that represents ventricular depolarization is the QRS complex. The QRS complex is a graphic representation of the electrical activity of the ventricles as they depolarize during a heartbeat.

Here's a step-by-step breakdown of the ECG components and their meanings:


1. P wave: Represents atrial depolarization, which is the electrical signal that initiates the contraction of the atria.

2. PR interval: This is the time from the beginning of the P wave to the beginning of the QRS complex, representing the time it takes for the electrical impulse to be conducted from the atria to the ventricles.

3. QRS complex: This is the wave that signifies ventricular depolarization, the process by which the ventricles contract to pump blood out of the heart.

4. ST segment: Reflects the early phase of ventricular repolarization, which is the period when the ventricles are relaxing.

5. T wave: Represents ventricular repolarization, the process by which the ventricles return to their resting state after depolarization.

The QRS complex is typically the most prominent deflection on the ECG and can vary in width and morphology depending on the heart's condition and the lead being observed.

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Atrial and ventricular depolarization and repolarization are represented on the ECG as a series of waves: the P wave followed by the QRS complex and the T wave. The first deflection is the P wave associated with right and left atrial depolarization. Wave of atrial repolarization is invisible because of low amplitude.read more >>