What does the P wave represent in an ECG?

The P wave on an ECG represents atrial depolarization. This phase of the cardiac cycle indicates the electrical activation of the atria, which precedes the contraction of these chambers. When the atria depolarize, it triggers them to contract and push blood into the ventricles. It is crucial to understand this concept since the P wave is the first deflection seen on the ECG, and it plays a significant role in the overall timing of the heart's electrical activity. Recognizing the role of the P wave helps in interpreting heart rhythms and diagnosing various cardiac conditions.