Atrial repolarization and ventricular depolarization are represented on an ECG by which component?

The QRS complex on an ECG represents ventricular depolarization, which is the process in which the heart's ventricles prepare to contract. It is during this phase that the electrical impulses spread through the ventricles, resulting in their activation and subsequent contraction.

While the QRS complex primarily indicates ventricular activity, it's worth noting that atrial repolarization also occurs during this phase but is typically masked by the larger electrical activity associated with ventricular depolarization. This is why the QRS complex is crucial in interpreting the overall cardiac cycle and determining areas such as heart rate and potential arrhythmias.

Understanding the components of the ECG is essential for recognizing normal and abnormal heart rhythms, which is a key focus in pediatric advanced life support training.