REFLEx Study (ENDOTAK RELIANCE G Evaluation of Handling and Electrical Performance

Inclusion Criteria: * Patients who meet current ICD or CRT-D indications * Patients who are going to be implanted with one of the aforementioned ICD or CRT-D devices * Patients who are going to be implanted with active-fixation, dual-coil, endocardial defibrillation leads with compatible connectors (i.e., ENDOTAK RELIANCE G or study-comparative ICD leads) * Patients who sign and date a Patient Informed Consent form prior to device implant * Patients who remain in the clinical care of the enrolling physician in approved centers * Patients who are at least 18 years old Exclusion Criteria: * Patients who have a preexisting transvenous lead system that is not completely explanted * Patients who are hypersensitive to a single dose of approximately 1.0 mg of dexamethasone acetate * Patients who are expected to receive a heart transplant during the duration of the study * Patients whose estimated life expectancy is less than 12 months due to other medical conditions * Patients who currently have or who are likely to receive a tricuspid valve prosthesis * Patients who are likely to have an open-chest surgery in the next three months * Patients who are currently enrolled in another investigational study that would directly impact the treatment or outcome of the REFLEx study. * Patients who are mentally incompetent and cannot sign a Patient Informed Consent form or comply with the study * Patients who are pregnant