As a domain expert in cardiology with a focus on electrophysiology, I can explain the significance of the S wave in an electrocardiogram (ECG). The S wave represents the late phase of ventricular depolarization. In a typical ECG, the S wave follows the R wave, which is the initial positive deflection indicating the beginning of ventricular depolarization. The S wave is the first negative deflection after the R wave and signifies the completion of the depolarization process in the ventricles. It is an important part of the QRS complex, which is the overall pattern seen on the ECG that corresponds to ventricular depolarization. Here's the translation of the above explanation into Chinese: 作为一位专注于心脏电生理学的心脏病学领域专家，我可以解释心电图（ECG）中S波的重要性。 S波代表心室去极化的晚期阶段。在典型的心电图中，S波跟在R波之后，R波是最初的正向偏转，表示心室去极化的开始。S波是R波之后的第一个负向偏转，标志着心室去极化过程的完成。它是QRS波群的重要组成部分，QRS波群是心电图上对应心室去极化的总体模式。 read more >>

The S wave is the first negative deflection after the R wave. It represents the late ventricular depolarisation. Electrocardiogram: The S Wave (arrowed)read more >>