This study is designed to evaluate the energy requirements of two different Nonvascular ICD (NV-ICD) electrode configurations for achieving successful defibrillation of ventricular arrhythmias.

Inclusion Criteria:

1. Patient that is scheduled to undergo surgery requiring midline sternotomy or implantation of a commercially-available TV-ICD or S-ICD system per local guidelines
2. Patient must be at least 18 years of age
3. Subject must provide written informed consent prior to any clinical investigation-related procedure.

Exclusion Criteria:

1. Pacemaker dependency
2. Chronically implanted cardiac implantable electronic device or other device which delivers an electrical current
3. Currently taking amiodarone or a Class IC antiarrhythmic drug
4. Hypertrophic cardiomyopathy
5. Anticipated high risk of stroke
6. Anticipated high surgical risk or risk of infection
7. Severe aortic stenosis
8. Severe proximal three vessel coronary disease (over 70% in each vessel)
9. Greater than 50% left main stem disease
10. Prior surgery or anatomical abnormality that significantly increases implant risk per physician's discretion
11. Medical conditions that preclude defibrillation testing
12. Chronic renal insufficiency including patients on dialysis
13. Subject is currently participating in another clinical investigation.
14. Pregnant or nursing subjects and those who plan pregnancy during the clinical investigation follow-up period.
15. Presence of other anatomic or comorbid conditions, or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the subject's ability to participate in the clinical investigation or to comply with the 1-month phone follow-up requirements of the clinical investigation results.