As a medical professional with expertise in emergency medicine, I can provide you with an accurate explanation of how defibrillators work in relation to the heart. Defibrillators are crucial devices that deliver an electric shock to the heart. However, they do not "restart" a stopped heart in the literal sense. Instead, they are used to correct life-threatening heart rhythms, such as ventricular fibrillation or ventricular tachycardia, which are rapid and chaotic heart rhythms that prevent the heart from pumping blood effectively. When the heart is truly stopped, meaning it is in a state known as asystole, where there is no electrical activity and the heart is not beating, a defibrillator would not be effective. In cases of asystole, cardiopulmonary resuscitation (CPR) and other advanced life support measures are necessary to try to restore a heartbeat. In summary, defibrillators are not used to restart a completely stopped heart but are essential for treating certain types of abnormal heart rhythms that can lead to sudden cardiac arrest. read more >>

The only effective treatment is to deliver an electrical shock using a device called a defibrillator (to de-fibrillate the heart), which stops the chaotic rhythm of a heart in VF, giving it the chance to restart beating with a normal rhythm.read more >>