The normal P waves in the chest leads (leads V1 to V6), will reflect the anterior and then posterior, and the rightward to leftward spread of normal atrial depolarization as first the anterior right atrium and then the posterior left atrium are depolarized. This will cause the P wave to be biphasic in the anterior chest leads (lead V1 and often V2); first positive and then negative and then progressively more positive in the leftward and more posteriorly oriented chest leads (leads V3 to V6)