What event does the QRS complex represent in EKG?

The QRS complex in an electrocardiogram (EKG) represents ventricular depolarization, which is the electrical event that triggers the ventricles to contract. This complex appears as a series of sharp deflections on the EKG trace and is typically much broader and taller than the preceding P wave, which represents atrial depolarization. Ventricular depolarization is critical because it is responsible for pumping blood into the circulatory system—the right ventricle sends blood to the lungs, while the left ventricle pumps it to the rest of the body.

Understanding that the QRS complex indicates this vital process helps in assessing the heart's rhythm and functionality, as abnormalities in the width or shape of the QRS can indicate conditions such as bundle branch block or other forms of ventricular dysfunction.