ECG abnormalities are categorized into sinus arrhythmia, atrial arrhythmia, atrioventricular junctional arrhythmia, ventricular arrhythmia, and conduction block according to the site of origin, as well as some ECGs suggestive of specific diseases, such as acute myocardial infarction. 1. Sinus arrhythmia: sinus tachycardia (adult sinus heart rate more than 100 beats/minute), sinus bradycardia (adult sinus heart rate less than 60 beats/minute), sinus arrest, pathological sinus node syndrome (such as non-drug-induced persistent and significant bradycardia, coexistence of sinus block and atrioventricular block, etc.). 2. Atrial arrhythmias: atrial pre-systole (P-wave occurs in advance, different from sinus P-wave), supraventricular tachycardia, atrial flutter, atrial fibrillation (appears as small and irregular baseline fluctuations). 3. Atrioventricular junctional arrhythmias: atrioventricular junctional pre-systole, atrioventricular block (including first-degree, second-degree and third-degree atrioventricular block). 4. Ventricular arrhythmias: ventricular premature beats, ventricular tachycardia, ventricular flutter (electrocardiogram shows sinusoidal waveform with large and regular amplitude), ventricular fibrillation. 5. Acute myocardial infarction: the patient’s electrocardiogram typically shows secondary changes in the ST segment after chest pain, such as elevation or depression of ≥0.1mv. It is recommended that the patient go to the cardiology department in time, under the guidance of the doctor, improve the relevant examination and receive standardized treatment.