What does the P wave represent in an EKG?

What does the P wave represent in an EKG?

• A. Atrial depolarization and atrial contraction
• B. Ventricular depolarization
• C. Ventricular repolarization
• D. Pacemaker activity of the SA node

Answer: (A)

The P wave in an EKG represents atrial depolarization along with the initiation of atrial contraction. This phase occurs when the electrical impulse generated by the sinoatrial (SA) node spreads through the atria, causing them to depolarize and contract. Atrial depolarization is crucial as it precedes the contraction of the atria, allowing blood to be pushed into the ventricles before they contract.

While the activity of the SA node is related to the P wave, the P wave specifically depicts the result of that activity—atrial depolarization—and not the node's direct electrical activity itself. Understanding this distinction is vital for accurately interpreting EKG readings and recognizing the important roles that different waves and segments play in the cardiac cycle.