Which wave is considered the first wave of the cardiac cycle?

The first wave of the cardiac cycle is the P wave. This wave represents atrial depolarization, the process by which the heart's atria contract and pump blood into the ventricles. Occurring just before the atria contract, the P wave is instrumental in the overall timing of the heart's electrical conduction system, indicating the initiation of the cardiac cycle.

Understanding the P wave is crucial, as it reflects the health of the atria and can provide insights into various cardiac conditions if abnormal. When interpreting an electrocardiogram (EKG), recognizing the P wave and its position in relation to the other waves is key to understanding the heart's rhythm and function.