The so-called electrocardiogram is, as the name implies, a diagram that records the electrical activity of the heart. The heart has to pump the nutritious blood, which is fully absorbed by the gastrointestinal tract and oxygen by the lungs, to the whole body to ensure the supply of nutrients and oxygen to the tissues of the body. The electrodes on the chest and extremities of the body can be used to trace the electrical activity of the heart, and the recorded graph is called an electrocardiogram. It has been 111 years since the ECG was used in clinical practice, and Ein Tolwyn won the first clinically relevant Nobel Prize in medicine for applying the ECG to clinical practice 90 years ago (1924). The ECG mainly reflects the heart’s power generation, the number of electrical impulses (normally 60~100 times per minute), electrical conduction, and is the best for diagnosing arrhythmias; on the other hand, it can also reflect the size of the heart chambers, the presence of ischemia and necrosis, and electrolyte disorders through changes in the ECG waveform, but of course, it is mainly speculative. Just like “the sky is cloudy and the moon is full”, when you are having a heart attack, the ECG can be recorded to be abnormal, but sometimes the duration can be very short, so it is difficult for the doctor to catch the ECG in such a timely and coincidental manner, and when it is recorded, it is likely that your heart has already returned to normal, and the ECG will show false negatives. In other words, a normal ECG will be recorded. Doctors often compare the ECG when you are ill with the ECG when you are not ill, so that it is easier to detect abnormalities, or compare the ECG when you have symptoms with the ECG when the symptoms disappear after medication or rest, so that the dynamic evolution of the ECG has the most clinical diagnostic value. Since a normal ECG cannot fully describe the health of the heart, how should we know whether our heart is healthy or not? For patients who have normal ECG but feel chest pain, chest tightness, palpitations and other uncomfortable symptoms, the doctor will recommend to do an ambulatory ECG, bring an ECG recording box and trace the ECG day and night, which is equivalent to the police “squatting” for 24 hours to catch the crime (a heart attack caught in flagrante delicto). During this period, whenever you have an attack, the dynamic ECG will be recorded. Of course, you should also keep a careful log of what time and what minute you were in discomfort and what you were doing at that time, and your doctor will analyze what happened in conjunction with the ECG at that time. Sometimes your doctor will also recommend an “exercise ECG,” which is a flat-panel exercise test, to induce potential heart health problems (including ischemia and arrhythmias) through exercise. Of course, there is much more to the heart examination than that, sometimes coronary CT or coronary angiogram, which can directly observe the shape of blood vessels, and echocardiogram, which reflects the structure and function of the heart, are also used. Therefore, it should be emphasized that a normal routine ECG does not mean that you do not have heart disease, especially for patients with chest tightness, chest pain, palpitations and other uncomfortable symptoms, it is necessary to go to the cardiology clinic for a detailed examination as soon as possible to find out whether there are abnormalities in the heart. Abnormal ECG is not the same as having a disease As mentioned in the previous article, a normal ECG is not the same as not having a disease, and I’m going to write a sister article, which is “abnormal ECG is not the same as having a disease”. These two points of view belong to the two extremes of patients who come to see the disease. Some patients are obviously sick, and the disease is not light, but he just do not pay attention to it, do not follow the medical advice, and even lead to a big disaster. And some other people, you tell him obviously not sick, but he is suspicious, around the clinic, and outpatient, and hospitalization, and do all kinds of tests, but still not willing, the momentum is not to find out the big disease vow not to be a person. Of course, in the latter process of diagnosis and treatment, some family members, and even doctors also play a dishonorable role, on the one hand, they are limited by knowledge of the problem is not deep enough, on the other hand, is ignorant of psychology, inducing and even aggravating the patient’s hypochondria. The day before yesterday, a 60-year-old female patient, accompanied by her husband and son, made a special trip from the far south of the colorful clouds to Beijing to see a doctor. From her dramatic description, she basically guessed that there should be no major problems, and indeed, the results of several inpatient and outpatient examinations, including cardiac ultrasound, ambulatory electrocardiogram, various laboratory tests, and even coronary angiograms, had no abnormal findings. The cause was an electrocardiogram during a physical examination, and the doctor told her that it was abnormal, with altered T waves, and that it belonged to myocardial ischemia and coronary heart disease. So she was too frightened to sleep that day. As she went to the hospital more and more times, the explanations of different doctors were very different, and the patient’s doubts naturally became bigger and bigger, and the symptoms became more and more obvious accordingly. I carefully analyzed her first ECG at the time of physical examination, which was asymptomatic and done purely for the purpose of physical examination, and did show low and inverted T waves in the inferior wall leads and some of the anterior chest leads. It is recommended that follow-up and regular review when unwell is sufficient. Even if she usually has symptoms of chest pain and tightness, at most she will be asked to do an exercise plate test, and if negative to completely dispel her concerns, and if positive (most likely false positive), a coronary CT screening will be sufficient. In clinical practice, there are many patients who are innocently put on the coronary heart disease cap due to certain changes in the ECG, and some experts even slightly exaggerate that “80% need to remove the cap”, which is somewhat justified. Of course, there is no doubt that ECG is still an important tool for the diagnosis of coronary heart disease. However, for the diagnosis of myocardial ischemia, the dynamic evolution of ECG must be observed, for example, these changes appear on ECG during the onset of chest pain, and the symptoms are relieved after resting or taking nitroglycerin, and these changes no longer appear on ECG, such dynamic changes are necessary to diagnose myocardial ischemia. It is precisely the exercise induced myocardial ischemia that is diagnosed by comparing the dynamic changes of ECG before and after the attack by the flat exercise test. In medicine, there is also myocardial ischemia without symptoms, called asymptomatic myocardial ischemia, which is often reflected in continuous ECG monitoring and requires a specialized physician to diagnose, also focusing on dynamic ECG changes. Therefore, it is not reliable to diagnose myocardial ischemia simply by simple changes in an ECG, and it cannot be arbitrarily labeled as coronary heart disease. However, on the other hand, if a doctor finds specific ECG changes that suggest that you belong to certain diseases, he or she should never disbelieve them. For example, there is a Wellens syndrome in medicine, where the patient will still have ST-segment and T-wave changes on the ECG after the chest pain has subsided, suggesting that the proximal anterior descending branch of the coronary artery is likely to have severe stenosis, which can be quite dangerous if you insist on not listening to your doctor. Both doctors and patients have to keep learning, and if you encounter a specialist problem that is not very clear, it is recommended that you be referred to a specialist for further consultation and treatment.