A Study to Evaluate the Effect of Vagus Nerve Stimulation in Patients Undergoing VT Ablation

Inclusion Criteria: * Presence of structural heart disease as defined as EF ≤ 50% or presence of ventricular scar as detected by imaging modalities or electroanatomic mapping, hypertrophic cardiomyopathy, cardiac sarcoidosis, or arrhythmogenic right ventricular cardiomyopathy. * Age \> 18 years old * Underlying sinus rhythm with heart rate \> 50 bpm. * Provision of signed/dated informed consent and stated willingness to comply with all study procedures Exclusion Criteria: * Active ongoing cardiac ischemia as assessed by: ECG, cardiac enzymes, symptoms, coronary angiography with evidence of significant epicardial coronary stenosis (\>70%), or stress testing. (Note: positive troponin assay due to Internal Cardiac Defibrillator (ICD) shocks is not an exclusion criterion). * Status post orthotopic heart transplantation * Women who are pregnant (as evidenced by pregnancy test if pre-menopausal). * Unable or unwilling to comply with protocol requirements. * Known channelopathy such as long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic VT. * Known peripheral neuropathy or history of autonomic dysfunction due to non-cardiac causes. * New York Heart Association Class IV heart failure or use of current vasopressor medications * Incessant VT * Persistent atrial fibrillation * Frequent premature atrial or ventricular contractions * Inability to give informed consent.