What does the QRS complex represent in an ECG?

The QRS complex in an ECG represents ventricular depolarization, which is a critical phase in the cardiac cycle where the ventricles of the heart contract. This electrical activity, indicated by the QRS complex, is essential for pumping blood from the ventricles to the lungs and the rest of the body.

During ventricular depolarization, electrical impulses travel through the ventricles following activation by the AV node. As these impulses move through the cardiac tissue, they trigger the contraction of the ventricular muscle, leading to effective systolic function. The shape and duration of the QRS complex provide important information about the conduction of electrical impulses through the ventricles and can help identify various cardiac abnormalities.

In contrast, other components of the ECG waveform represent different processes; for example, the P wave corresponds to atrial depolarization, while the T wave represents ventricular repolarization. The heart rate, while an important measure in cardiology, is determined by the overall pattern of the ECG and is not specifically represented by any single component like the QRS complex.