The purpose is to further evaluate the operation, safety, and feasibility of a subcutaneous implantable defibrillator (S-ICD) system in patients who require an implantable cardioverter defibrillator (ICD)for treating ventricular tachyarrhythmias. The S-ICD electrode and pulse generator emulator will be briefly implanted and tested during the standard implantation procedure of an ICD, but then the S-ICD system will be removed entirely.