As a cardiac electrophysiologist, I can explain the nuances of the T wave in an ECG reading. The T wave represents the repolarization of the ventricles, which follows the depolarization phase marked by the QRS complex. When the ventricles depolarize, it's a coordinated process that starts from the ventricular endocardium (inner layer) and moves towards the epicardium (outer layer). However, during repolarization, the process is reversed; the epicardium repolarizes first, followed by the endocardium. The positive T wave in most leads is a result of the net current flow during this repolarization phase. The direction of the current flow is opposite to that of depolarization. When the epicardium repolarizes before the endocardium, it creates a current that flows from the outside to the inside of the heart. This inward current, from the perspective of the electrodes on the body surface, appears as a positive deflection on the ECG, hence the T wave is typically positive. Now, let's translate that into Chinese: 作为一名心脏电生理学家，我可以解释心电图中T波的细微差别。T波代表了心室的复极化，它跟随QRS波群所标记的去极化阶段。当心室去极化时，这是一个从心室内膜（内层）向心外膜（外层）协调进行的过程。然而，在复极化期间，这个过程是相反的；心外膜先复极化，然后是心内膜。 在大多数导联中，正向T波是复极化阶段净电流流动的结果。电流流动的方向与去极化相反。当心外膜在心内膜之前复极化时，它产生了一个电流，从心脏的外部流向内部。从身体表面的电极角度来看，这种向内的电流在心电图上表现为正向偏转，因此T波通常是正向的。 read more >>

In most leads, the T wave is positive. This is due to the repolarization of the membrane. During ventricle contraction (QRS wave), the heart depolarizes. Repolarization of the ventricle happens in the opposite direction of depolarization and is negative current.read more >>