What does the R-Wave represent in the EKG?

The R-wave is a crucial component of the electrocardiogram (EKG) and represents the depolarization of the ventricles. During this phase, the electrical impulse generated by the heart spreads through the ventricular myocardium, leading to ventricular contraction. This is the most significant part of the QRS complex on an EKG, which specifically illustrates the rapid depolarization of the ventricles.

Understanding the context of this representation within the cardiac cycle is vital. The atrioventricular (AV) node plays a role in conducting the electrical impulse from the atria to the ventricles, but the R-wave itself indicates that the ventricles are undergoing depolarization that leads to their contraction. This phase is critical for pumping blood out of the heart.

The other choices refer to different parts of the cardiac conduction system or processes. The SA node firing refers to the initiation of the heartbeat and the start of electrical conduction in the heart, while the contraction of the atria is represented by the P wave preceding the QRS complex. Repolarization of the ventricles is shown in the T wave, which occurs after the R-wave and reflects the process of the heart returning to its resting state. Thus, the R-wave specifically reflects the