The investigators will compare the effects of PSGB(percutaneous stellate ganglion block) in patients with recurrent sustained VT/VF in spite of appropriate medical therapy and cardio-version/ defibrillation after correction of underlying correctable factors with those without PSGB by prospective randomized trail. PSGB will be performed every 3 days by anesthesiology specialist after cardiologist's request, until the stabilization of VT/VF. We will compare the frequency and episode number of VT/VF, procedure related complication, acute and long-term mortality.

Recurrent ventricular tachycardia(VT)/ fibrillation(VF) increases mortality, especially in patients with structural heart disease. It has been reported that cardiac sympathectomy reduces VT/VF episodes in patients with complex VT, long QT syndrome, catecholaminergic polymorphic VT, or myocarditis. However, cardiac sympathectomy operation is hard to conduct in patients with hemodynamically unstable recurrent VT/VF or electrical storm. Therefore, we hypothesized that bed-side percutaneous stellate ganglion block (PSGB) reduces VT/VF episodes and mortality in patients with repetitive VT/VF who are properly managed with optimal medical therapies.

Inclusion Criteria:

• Patients agreement of consent
• AF patient age 20-85
• Patient are diagnosed Refractory Ventricular tachycardia
• Patients who have generated Refractory Ventricular tachycardia despite of defibrillation and drug therapy
• Patients with ICD have generated ICD shock or anti-tachycardia pacing despite of defibrillation and drug therapy

Exclusion Criteria:

• Patients who do not agree with study inclusion
• Patients who do not taken stellate ganglion block due to unstable hemodynamic status
• Patients have experienced major hemorrhagic complication
• Patients of the DNR status
• Patients with malignancy tumor, major neurogenic disease or gastrointestinal disease