T-wave changes in partial leads are mostly considered to be due to myocardial ischemia, but can also be physiologic. T-wave changes in partial leads are mostly a manifestation of myocardial ischemia. When there is stenosis and obstruction in one of the branches of the coronary blood vessels of the heart, some of the cardiac myocytes supplied by this blood vessel will be ischemic and necrotic, and the corresponding T-wave of the partial leads will be altered. For example, inverted or flattened T waves in leads II, III, and aVF of the electrocardiogram are indicative of lower wall myocardial ischemia. If the T wave in ECG I, aVL leads is inverted or flattened, it is a sign of myocardial ischemia in the high lateral wall of the heart. low or inverted T wave in leads V1-V5 suggests extensive anterior wall myocardial ischemia. Inverted or flattened T waves in leads V1-V3 of ECG are changes of myocardial ischemia in the anterior interstitial wall. In addition, physiological reasons such as overwork, mental stress, late night, and after strenuous exercise can cause T-wave changes in some leads of the ECG. If T-wave changes occur in some leads of the ECG, it is necessary to consult a doctor in time, who will combine the history, symptoms, and necessary auxiliary examinations to determine the diagnosis and treat the symptoms.