A.S. syndrome is a syndrome of cerebral ischemia due to cardiac causes. For cerebral ischemia, loss of consciousness with convulsive seizures may occur. In cardiac disease, it may result in pump failure or in fatal malignant arrhythmias, with symptoms associated with cerebral hypoxia due to insufficient blood supply to the brain as a result of a dramatic decrease in cardiac output. It often occurs in severe bradycardia, ventricular tachycardia, ventricular fibrillation, etc. The sudden drop in cardiac output can lead to fainting and convulsions due to insufficient blood supply to the brain. Clinically, A.S. syndrome is common in bradyarrhythmias, such as sick sinus node syndrome, as well as ventricular tachycardia and ventricular fibrillation caused by coronary artery disease and myocardial infarction.