Individuals with pulseless VT or unstable VT are hemodynamically compromised and require immediate electric cardioversion to shock them out of the VT rhythm. Cardioversion If a person still has a pulse, it is usually possible to terminate the episode using electric cardioversion. This should be synchronized to the heartbeat if the waveform is monomorphic if possible, in order to avoid degeneration of the rhythm to ventricular fibrillation. An initial energy of 100J is recommended. If the waveform is polymorphic, then higher energies and an unsynchronized shock should be provided (also known as defibrillation). Defibrillation A person with pulseless VT is treated the same as ventricular fibrillation with high-energy (360J with a monophasic defibrillator, or 200J with a biphasic defibrillator) unsynchronised cardioversion (defibrillation). They will be unconscious. The shock may be delivered to the outside of the chest using the two pads of an external defibrillator, or internally to the heart by an implantable cardioverter-defibrillator (ICD) if one has previously been inserted. An ICD may also be set to attempt to overdrive pace the ventricle. Pacing the ventricle at a rate faster than the underlying tachycardia can sometimes be effective in terminating the rhythm. If this fails after a short trial, the ICD will usually stop pacing, charge up and deliver a defibrillation grade shock. Medication For those who are stable with a monomorphic waveform the medications procainamide or sotalol may be used and are better than lidocaine. Evidence does not show that amiodarone is better than procainamide. As a low magnesium level in the blood is a common cause of VT, magnesium sulfate can be given for torsades de pointes or if a low blood magnesium level is found/suspected. Long-term anti-arrhythmic therapy may be indicated to prevent recurrence of VT. Beta-blockers and a number of class III anti-arrhythmics are commonly used, such as the beta-blockers carvedilol, metoprolol, and bisoprolol, and the Potassium-Channel-Blockers amiodarone, dronedarone, bretylium, sotalol, ibutilide, and dofetilide. Angiotensin-converting-enzyme (ACE) inhibitors and aldosterone antagonists are also sometimes used in this setting. Invasive treatment An ICD (implantable cardioverter defibrillator ) is more effective than drug therapy for prevention of sudden cardiac death due to VT and VF, but does not prevent these rhythm from happening. Catheter ablation is a potentially definitive treatment option for those with recurrent VT. Remote magnetic navigation is one effective method to do the procedure. In the past, ablation was often not considered until pharmacological options