P wave

Excerpt

The P wave and PR segment is an integral part of an electrocardiogram (ECG). It represents the electrical depolarization of the atria of the heart. It is typically a small positive deflection from the isoelectric baseline that occurs just before the QRS complex. It can sometimes have abnormalities in morphology or timing that can be indicative of significant clinical pathology. An understanding of the normal and abnormal P wave morphology is, therefore, a crucial part of ECG interpretation. This article will review the basics of P wave interpretation, including characteristics of both the normal P wave and its pathologic abnormalities.