What does the QRS wave in an ECG represent?

The QRS wave in an ECG represents ventricular depolarization, which is a critical phase in the cardiac cycle. During this time, the electrical impulses spread through the ventricles, leading to their contraction. This is an essential step that allows the heart to pump blood effectively to the lungs and the rest of the body.

The visual morphology of the QRS complex—comprised of the Q, R, and S waves—reflects the rapid conduction of electrical impulses through the bundle of His and Purkinje fibers, which stimulates ventricle contraction. This event typically occurs after the atrial depolarization phase and is followed by ventricular repolarization, which is represented in the ECG by the T wave. Understanding the significance of the QRS complex is fundamental for interpreting cardiac rhythms and diagnosing various cardiac conditions in the paramedic field.