Electrocardiogram was invented by Americans, so according to the development of modern scientific thinking, the electrical pulse of the heart is amplified by circuit design, and the blood supply of myocardium is indirectly judged by whether the electrical pulse is abnormal or not. The recent purpose is to find out the situation of leads and three leads, so that the ECG axis can be basically judged. As for the formation of each waveform, if it is diagnostic, it is relatively simple.
That depends on what your mother is. If it's an undergraduate exam, it's actually ok to recite it. Speaking of clinic, because our domestic doctors don't pay attention to scientific education, many doctors and even cardiovascular doctors rely on rote memorization to complete clinical diagnosis. Many doctors asked him a principled virtue, but he didn't know it. All he knows is that it should be like that.
If you really want to learn thoroughly, you have to choose Huang Wan's Clinical Electrocardiogram. Now the latest edition should be published in his name by his students. The electrocardiogram explains it in detail. From the cellular level, the potential inside and outside the cell membrane is measured by tiny detection electrodes, the activity of ion channels changes with the change of voltage, the vector change caused by the change of the number of myocardial cells in macro three-dimensional space, what causes depolarization to start from the inner wall, and the negative electrode to start from the outer wall, etc.