Unpinning Termination Therapy for VT/VF

Inclusion Criteria: 1. Life expectancy of 1 year or greater 2. Male or female between 18 and 75 years of age 3. Willing and able to comply with the study protocol, provide a written informed consent 4. Indication for an endocardial VT catheter ablation for sustained, life-threatening monomorphic VT OR an indication for VF and ICD implant (de novo implant, replacement or upgrade) OR CRT-D (de novo implant, upgrade from ICD) with transvenous leads for the risk of or presence of VT and/or VF. 5. Etiology of arrhythmia, or risk of arrhythmia being ischemic dilated cardiomyopathy or non-ischemic idiopathic dilated cardiomyopathy both with LVEF ≤ 35% and meeting local standard of care 6. Medically stable at time of consent to undergo DFT testing performed under general anesthesia or conscious sedation as determined by the investigator Exclusion Criteria: The subject must not meet any of the following exclusion criteria: 1. Medically unstable at time of study and unsafe to undergo DFT testing under general anesthesia or conscious sedation as determined by the investigator 2. Hemodynamic instability as determined by the investigator 3. AF or atrial flutter for ≥ 48 hours or unknown duration, and no anticoagulation for preceding 3 weeks and no preoperative transesophageal echocardiographic confirmation of the absence of RA and LA thrombus 4. AF or atrial flutter for \<48 hours and no Preoperative transesophageal echocardiographic confirmation of the absence of RA and LA thrombus 5. Presence of intracardiac thrombus 6. Inability to pass catheters to heart due to vascular limitations 7. Cardiovascular anatomical defects that would complicate placement of the lead or catheter required by the protocol, including congenital heart disease and cardiac vein anomalies as determined by the investigator 8. Pregnancy confirmed by test within 7 days of procedure 9. Pacemaker dependent 10. The presence of a normally functioning left ventricular lead which is not planned for revision 11. Presence of ventricular assist device, including Intra-aortic balloon pump 12. Subjects requiring the use of I.V. inotropes and/or vasopressors for hemodynamic support in the 14 days prior to the study 13. Prior VT catheter ablation with associated serious complication, such as hemodynamic compromise despite pressor agents, stroke, cardiac perforation, AC fistula, pneumothorax, sepsis 14. Incessant VT/VF or VT/VF storm 15. LVEF \< 20% 16. New York Heart Association (NYHA) Class IV heart failure 17. Planned epicardial VT ablation on the same day as the research study 18. History of hyper-coagulable state that could increase risk of thromboembolic events 19. History of hemodynamic compromise due to valvular heart disease requiring IV inotropes or other circulatory support. 20. Unstable coronary artery disease as determined by the investigator 21. Severe proximal three-vessel or left main coronary artery disease, without revascularization as determined by the investigators 22. History of embolic stroke, Transient Ischemic Attack or other thromboembolic event in the past 6 months 23. History of Hypertrophic Cardiomyopathy, Arrhythmogenic Right Ventricular Dysplasia, Congenital Heart Anomaly, Cardiac Amyloidosis, Genetic Cardiac Channelopathy or Cardiac Sarcoidosis. 24. Cardiovascular surgery or intervention within 1 month prior to enrollment or planned for up to 1 month after enrollment (other than the planned treatment procedure) 25. Morbid obesity: BMI\>39 kg/m2 26. Cognitive or mental health status that would interfere with study participation and proper informed consent 27. Presence of mechanical tricuspid valve 28. Active Endocarditis 29. Ventricular arrhythmia etiology sarcoidosis 30. Valvular ventricular tachycardia 31. Previously implanted lead is under recall by manufacturer or evidence of lead failure as determined by the investigator 32. End Stage Renal Disease on hemodialysis or peritoneal dialysis, or estimated glomerular filtration rate (eGFR) \<15 ml/min 33. Right atrial or right ventricular lead implanted within 12 months prior to screening 34. Any other medical condition which may affect the outcome of this study or safety of the subject as determined by the investigator