Development status of terumo implantable left ventricular assist system

We have been developing an implantable left ventricular assist system (T-IL VAS) featuring a magnetically suspended centrifugal pump (MSCP) since 1995. In vitro and in vivo studies using a prototype MSCP composed of a polycarb onate housing and impeller (196 ml) have demonstrated long-term durability and excellent blood compatibility for up to 864 days, and excellent stabili ty of the magnetic bearing of the MSCP. These preliminary results strongly suggested that the magnetic bearing of the MSCP is reliable and is a most f easible mechanism for a long-term circulatory assist device. We have recent ly devised a clinical version pump made of titanium (180 ml) with a new pos ition sensor mechanism and a wearable controller with batteries. Cadaver fi t study confirmed that the Type IV pump could be implanted in a small patie nt with a body surface area as small as 1.3. The in vitro performance tests of the Type IV pump demonstrated excellent hydrodynamic performances with an acceptable hemolysis rate. New position sensors for the titanium housing showed more uniform sensor outputs of a magnetic bearing than in the proto type polycarbonate pump. The Type IV pump then was evaluated in vivo in 6 s heep at the Oxford Heart Centre. Four sheep were electively sacrificed at 3 months and were allowed to survive for more than 6 months for long-term ev aluation. In this particular series of experiments, no anticoagulant/antipl atelet regimen was utilized except for a bolus dose of heparin during surge ry. There was a left ventricular mural thrombi around the inflow cannula in 1 sheep. Otherwise. there was no mechanical failure nor sign of thromboemb olism throughout the study.