Patients treated with the 70cc TAH-t System for DT under the Primary Arm will be adult male and female patients between the ages of 19 and 75 years old with a BSA ≥1.7m2 with life-threatening irreversible biventricular failure who are not eligible for a heart transplant (as determined by the implanting center at the time of implant assessment) and who meet the enrollment criteria defined in the clinical protocol. Patients treated with the 70cc TAH-t System for DT under the Secondary Arm will be adult male and female patients who are at least 19 years old, are not eligible for a heart transplant (as determined by the implanting center at the time of implant assessment), and who meet the less restrictive enrollment criteria defined in the clinical protocol.