P wave

A P wave is the initial electrical signal generated by the heart's sinoatrial (SA) node, which is the heart’s natural pacemaker. It represents the electrical activity that causes the upper chambers (atria) of the heart to contract and pump blood into the lower chambers (ventricles). On an ECG (electrocardiogram), the P wave appears as a small, upward bump before the main heartbeat spike. It reflects the regular, organized heartbeat process and helps doctors assess how well the heart's electrical system is functioning.