Background: Most therapy with VAD has been performed for long term usage; therefore implantable VADs have been developed to improve the quality of life and postoperative recovery. To date, only LVAD is available implantable one for clinical situations. Right ventricular failure after LVAD implantation remains a continuing problem. Therefore, this group is investigating the possibility of an implantable RVAD with NED0 PI-710 centrifugal pump. Methods: Eleven long term animal studies were performed in bovine models. In all cases, PI-710 pumps were implanted as hi-ventricular assist. The RVAD was implanted as a right heart bypass between the right ventricular infundibulum and the pulmonary trunk, beneath the diaphragm in the extraperitoneal space. Anticoagulant therapy was performed with heparin in acute phase and wadarin in chronic phase. Performance of RVAD, pulmonary hemodynames, and respiratory function were investigated. Results: Experimental term was 59±26 days (22∼90). RVAD flow, RPM, and consumed power were 4.7±0.5 L/min, 1936 RPM, and 7.6W, respectively. Plasma free Hb was 4.7±1.8 mg/dl. No pulmonary embolism was confirmed. Thrombus formation due to kinking of outflow graft, actuator trouble, inflow sucking, inflow graft stenosis, and outflow graft stenosis were recognized in 1, 1, 1, and 2 cases, respectively. Mean pulmonary artery pressure, pulmonary vascular resistance, PO2, PCO2, and respiratory rate were stable. Conclusions: Results of this study as an implantable RVAD with PI-710 pump were satisfying. However, improvement of actuator, inflow, and outflow is necessary for long term use.