What does the QRS complex represent in an EKG?

The QRS complex in an electrocardiogram (EKG) specifically represents ventricular depolarization. This is the electrical activity that occurs just before the ventricles contract and pump blood out of the heart. When the ventricles depolarize, it indicates that they are preparing to undergo contraction, which is vital for the effective circulation of blood to the lungs and the rest of the body.

During this phase, the electrical impulse that starts in the atria travels through the AV node and into the ventricles, leading to their activation. The QRS complex is typically characterized by a sharp and significant deflection on the EKG trace, as it corresponds to the larger muscle mass of the ventricles in comparison to the atria.

In contrast, other options refer to different processes within the cardiac cycle. Atrial depolarization is represented by the P wave, while ventricular repolarization is shown by the T wave. The resting state of the heart is not represented by a specific wave on the EKG but is instead a baseline reference when the heart is not actively contracting.