Athlete’s heart syndrome: it is an adaptive change of the heart that occurs during long-term exercise, and its ST-T changes mostly appear in Ⅱ, Ⅲ, aVF leads and anterior thoracic leads, and may show coronary T wave, which is easy to be misdiagnosed as myocarditis and coronary artery disease. Years of exercise, good cardiac function, exercise or isoproterenol can make ST – T changes to normal to help identify. ② persistent juvenile (infantile) type T wave: manifested as TV1 ~ V4 inversion, deep inhalation or oral potassium salt can make T wave to upright. The incidence is 0.5%~4.2% in normal people, and it is common in people with chest wall collapse. ③ Apical phenomenon: manifested as TV4 (or TV5) inversion, right lateral lying position can make the T wave turn upright. It is mostly seen in young people with long and thin bodies, and may be related to the contact between the heart tip and the chest wall or the pressure interfering with myocardial repolarization. Two and a half point syndrome: in normal people, especially in long and thin people, the frontal QRS – T angle can be seen to increase, the QRS electrical axis points to + 90 °, and the T electrical axis points to – 30 °, like a clock 02:30. The manifestation of Ⅱ, Ⅲ, aVF leads in the main wave of QRS wave upward, the T wave inverted; exercise test or oral administration of potassium salts can make the T wave to return to upright, which is helpful for differentiation. ⑤Cardiovascular neurosis: it is often manifested in Ⅱ, Ⅲ, aVF leads with low T-wave and inverted (may be accompanied by ST-segment downshift), and can be restored to normal by taking cardiac glycosides. It is common in young and middle-aged women with clinical manifestations of autonomic dysfunction. (6) Upright T-wave abnormality: T-wave is inverted in the Ⅱ lead position, and becomes shallow or returns to the upright position when lying down, and can be prevented by taking xin dean, which may be related to sympathetic excitation during standing. (7) Hyperventilation T-wave changes T-wave flattening and inversion may occur in the thoracic leads after excessive whistling (tens of seconds), and can be prevented by administration of cardioplegia. Over-whistling can cause T-wave changes in about 11% of healthy people, and it has been suggested that it may be related to the uncoordinated repolarization of ventricular muscle caused by early sympathetic arousal. ⑧ postprandial T-wave changes: postprandial in Ⅰ, Ⅱ and V1 ~ V4 leads appear T-wave low flat inversion, fasting or meal with potassium salt 3g can eliminate or prevent this T-wave changes, some people think that it may be related to postprandial blood potassium reduction. Although the above T-wave changes have no pathological significance, they are easily misdiagnosed.