Cardiac arrest greater than 2 seconds is not very dangerous, but it may lead to dizziness, blackout and general weakness. In case of sudden cardiac arrest for more than 2 seconds, it is recommended that the patient go to the hospital in time to have the cause clarified. Generally, cardiac arrest greater than 2 seconds is not dangerous, but if the heart stops for more than 3 seconds, fainting with pallor may occur. If the cardiac arrest is more than 15 seconds, convulsions, cyanosis, pale skin, A.S. syndrome, etc. may occur. Severe hypoxic brain damage or death may occur if the arrest lasts more than 5 minutes without effective resuscitation. The cause of cardiac arrest may be related to coronary artery disease, cardiomyopathy, cerebral hemorrhage, hyperkalemia, heart valve disease and other diseases. If necessary, a pacemaker can be implanted or drugs to increase the heart rate can be used. It is recommended that the patient go to the hospital in time to clarify the cause of the disease and treat the cause.