What does the P wave mean?

As a medical professional with expertise in cardiology, I can explain the significance of the P wave in an electrocardiogram (ECG) reading. The P wave represents the electrical activity of the atria during atrial depolarization. It signifies the beginning of a heartbeat and the initiation of atrial contraction. The P wave's morphology can provide valuable information about the heart's atrial function and potential abnormalities. Peaked P waves, which are taller than 0.25 mV, can suggest conditions such as right atrial enlargement or cor pulmonale. However, it's important to note that while these can be indicators, they have a low predictive value, which means they are not definitive on their own. The presence of peaked P waves might suggest the P pulmonale rhythm, which is associated with pulmonary embolism or other pulmonary conditions. Additionally, a P wave with increased amplitude can be indicative of hypokalemia, a condition where there is an abnormally low level of potassium in the blood. It can also suggest right atrial enlargement, which is a condition where the right atrium of the heart is larger than normal. In summary, the P wave is a crucial part of an ECG and can offer insights into the heart's atrial function and potential issues.

Peaked P waves (> 0.25 mV) suggest right atrial enlargement, cor pulmonale, (P pulmonale rhythm), but have a low predictive value (~20%). A P wave with increased amplitude can indicate hypokalemia. It can also indicate right atrial enlargement.