The principle of electrical defibrillation is a method of restoring sinus rhythm by depolarizing the cardiac muscle cells, i.e., by bringing all the previously beating heart activity to a standstill, thus allowing the sinus node, which is the most autonomic part of the heart, to pulsate again, by means of a high voltage, strong current direct current. Sinus rhythm is the normal heart rhythm, so when some non-sinus rhythm occurs, such as ventricular fibrillation, ventricular flutter, or pulseless ventricular tachycardia, electrical defibrillation is performed. Asynchronous defibrillation is the immediate release of electricity at the push of a button, allowing all heart cells to be depolarized and all electrical activity to be quiescent, allowing the sinus node to resume pacing. Synchronous electric defibrillation is used when the patient is suffering from supraventricular tachycardia, atrial fibrillation, etc., because the rapid heartbeat is uncomfortable and difficult to correct with medication. By detecting the patient’s own heartbeat, the machine discharges when two RR waves are detected, quickly terminating the patient’s arrhythmia and turning it into sinus rhythm.