Reliable long-term non-pulsatile circulatory support without anticoagulation

Objective: The Terumo implantable left ventricular assist system (T-ILVAS) consists of a titanium centrifugal pump with a unique magnetically suspende d impeller producing continuous (non-pulsatile) flow up to 101/min. The int erior surface is heparin-coated and there is no purge system. We implanted the device into six sheep to ascertain in-vivo haemodynamic function, mecha nical reliability and biocompatibility. Methods: The T-ILVAS was implanted via left thoracotomy without cardiopulmonary bypass. The inflow cannula was placed in the left ventricular apex and a Dacron outflow graft anastomosed to the descending aorta. All animals recovered well. No anticoagulation (h eparin or warfarin) was given after the surgery. Suspension position, motor current, impeller speed and pump flow were continuously monitored and stor ed by on-line computer. Serial blood samples were collected to determine ha ematological and biochemical indices of renal function, liver function and haemolysis. All animals were electively euthanized between 3 and 7 months p ostoperatively. The explanted pumps were examined for mechanical reliabilit y and thrombus formation. Major organs were examined macroscopically and hi stologically for thromboembolism. Results: All animals appeared completely normal for up to 210 days. At speeds between 1500 and 2000 rev./min the dev ice pumped up to 81/min capturing all mitral flow. There were no major comp lications (pump failure, thromboembolism, haemorrhage, or driveline infecti on). Indices of haemolysis, liver and renal function remained within normal limits. All pumps were mechanically sound and free from thrombus. One embo lus was found in a sectioned kidney. Conclusion: The T-ILVAS successfully s upported the systemic circulation without anticoagulation for up to 210 day s. Mechanical reliability and biocompatibility were demonstrated. Organ fun ction remained within normal limits during continuous non-pulsatile flow. ( C) 2001 Elsevier Science B.V. All rights reserved.