The other day I was watching TV with my daughter and there was footage of a resuscitated patient. On the TV, a critically ill patient suddenly became unconscious, convulsed, and the heart monitor alarmed. The doctor immediately gave the patient an “electric shock” to resuscitate him, and he slowly regained consciousness. My daughter asked me, why do you need to use the machine “electric shock” when resuscitating a patient? Today, I’d like to tell you about it. This resuscitation “machine”, called a defibrillator, is a medical device that is widely used in clinical practice. After the invention of the defibrillator, a significant number of patients with sudden cardiac death have been saved, and some patients with arrhythmias have also had the opportunity to return to a normal heart rhythm. It physically works by storing electricity in a battery, and once it needs to be discharged, the corresponding switch is pressed to charge the defibrillator’s high-voltage capacitor. Once the defibrillation electrodes are in place, the discharge button is pressed and the energy stored in the high-voltage capacitor is released to the patient through a high-voltage relay and electrical impedance to achieve the therapeutic effect. Why does the patient need to be “shocked”? Because critically ill patients often have malignant arrhythmias, such as ventricular tachycardia, ventricular flutter or even ventricular fibrillation. This kind of malignant arrhythmia will appear hemodynamic disorders, the main manifestation is unconsciousness, convulsions, if not timely disposal, in 4 minutes the brain may occur irreversible damage, or even brain death, back to heaven. When this malignant arrhythmia occurs, the first time the patient is “defibrillated”, the high-voltage electrical impulses through the heart will cause all the heart muscle to contract strongly, ending the malignant arrhythmia, followed by the normal pacing point of the heart “sinus node” to issue electrical impulses, the heart rhythm turns to normal. The heart rhythm becomes normal. This is like the heart is a computer. A malignant arrhythmia is a “computer crash” of the heart, and defibrillation is a long press of the power button to restart the computer and get it back to normal operation.