Vagus nerve stimulation (VNS) has been shown to be beneficial in multiple studies including heart failure. The goal of this clinical investigation is to gain additional information about how vagus nerve stimulation relates to abnormal heart rhythms. The outcomes of this study will help researchers design new therapies for patients that have complex and life-threatening ventricular arrhythmias.

This study is a non-randomized, prospective study in 6 patients with scar mediated ventricular arrhythmias who are scheduled to undergo a catheter ablation procedure. The study will last up to 30 minutes in the cardiac electrophysiology lab. Cervical VNS is performed percutaneously through the internal jugular vein during the patient's routine ventricular tachycardia (VT) ablation procedure.

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.