As a domain expert in cardiology, I can explain the significance of the P wave in an ECG reading. The P wave on an electrocardiogram (ECG) is a crucial indicator of the electrical activity of the heart. Specifically, it represents the depolarization of the atria, which is the initial phase of the heart's contraction process. When the atria depolarize, they contract and push blood into the ventricles. The P wave is the first wave that appears on the ECG, and it is followed by the QRS complex and the T wave. The QRS complex indicates the depolarization of the ventricles, and the T wave represents the repolarization of the ventricles. Here is the translation of the above explanation into Chinese: 作为心脏病学领域的专家，我可以解释心电图（ECG）上P波的重要性。具体来说，P波是心脏电活动的关键时刻。它代表了心房的去极化，这是心脏收缩过程的初始阶段。当心房去极化时，它们收缩并将血液推入心室。P波是心电图上出现的第一个波，它后面是QRS波群和T波。QRS波群表示心室的去极化，而T波代表心室的复极化。 read more >>

Atrial and ventricular depolarization and repolarization are represented on the ECG as a series of waves: the P wave followed by the QRS complex and the T wave. The P Wave. The first deflection is the P wave associated with right and left atrial depolarization.read more >>