Ventricular tachycardia (VT) is a fast heart rhythm arising from the bottom part of the heart. It may arise from the right ventricle or left ventricle. It can be caused either by an irritable spot or by the heartbeat making a continuous circle in the bottom heart chamber. If the bottom part of the heart is weak, then VT is usually life-threatening and an implantable cardiac defibrillator (ICD) is required. If the bottom part of the heart is normal, then VT is not serious and can usually be treated safely either with heart rhythm medications or an ablation.