We have all seen it on TV on shows like "ER", someone has a "heart attack", which is an incorrect, laymans term. When you V-FIB, you have an irregular heartbeat, ventricular fribillation, that leads to no blood pumping, which leads to brain death starting in 4 minutes....If "flatline", arystole, defribillation will not work. The technque to reverse this irregular heatbeat to restore normal circulation is defribillation..the application of electric shock to jolt the heart back into sinus-rythm, a correct heartbeat. Kinda like "rebooting a computer", starting over.