What does the P wave represent on an ECG?

The P wave on an electrocardiogram (ECG) represents atrial depolarization. This is the electrical activity that occurs when the atria of the heart contract to push blood into the ventricles. The P wave is the first deflection on the ECG trace, indicating that the sinoatrial (SA) node has initiated the impulse that leads to atrial contraction. Depolarization is the process of electrical activation, which precedes heart muscle contraction.

Understanding the significance of the P wave is crucial for interpreting an ECG. It allows healthcare professionals to assess the atrial activity and can provide insights into conditions such as atrial enlargement or atrial fibrillation if the P waves are absent or abnormal. By correctly identifying the P wave as representing atrial depolarization, clinicians can evaluate the overall rhythm and function of the heart more effectively.