Which part of the ECG indicates depolarization of the ventricles?

The QRS interval on an electrocardiogram (ECG) represents the depolarization of the ventricles, which is a crucial phase in the cardiac cycle. During this phase, the heart's electrical impulses spread through the ventricles, leading to their contraction and the subsequent pumping of blood to the lungs and the rest of the body.

The shape and duration of the QRS complex provide significant information regarding the health and function of the heart. A narrow and well-defined QRS indicates normal conduction through the ventricles, while a wide or distorted QRS can suggest issues such as bundle branch block or other types of ventricular conduction delays.

In contrast, the other components of the ECG serve different functions. The P wave indicates atrial depolarization, the T wave reflects ventricular repolarization, and the PR interval identifies the time taken for the electrical impulse to travel from the atria to the ventricles. Each part of the ECG has a specific role, but the QRS interval is uniquely responsible for showing the electrical activity that leads to ventricular contraction.