If ventricular tachycardia occurs in an Implantable Cardioverter Defibrillator (ICD) wearer, the ICD can combat this with 2 different forms of therapy, provided these are activated (which can be done using a programming device). First, the ICD attempts to override the tachycardia. The fastest pacemaker gets control of the heart. If this is not successful, the defibrillator function is used. Here you can see the limb leads. Initially there is a relatively slow ventricular tachycardia.
This is followed by ATP, which is successful and ends the VT by overstimulation. Then 2 beats with ventricular pacing, followed by a PVC.