HEARTMATE III

Abstract

PURPOSE: A pump has been designed, built, and run to accommodate a motor with a magnetically levitated rotor for a longterm LVAD (HeartMate III). The goal was to transfer successful hydrodynamic results found in non-biocompatible laboratory prototypes to an implantable, titanium embodiment exhibiting small size, low hemolysis, and low thrombogenicity. METHODS: A simple centrifugal pump housing was constructed in two pieces - an upper housing containing inflow and outflow channels, and a lower housing containing the motor - enclosing an isolated, shrouded, titanium impeller with blades of a number, size, and shape found to be most hydrodynamically efficient near the design point. All stationary, wetted surfaces were textured in order to promote the growth of a stable, adherent pseudoneointima, thereby reducing the complexity of construction and risk of embolus. Attachment of the pump inflow to the left ventricle and of the pump outflow to the aorta was accomplished by adapting established HeartMate I and II techniques. A flexible segment was placed upstream of the pump inflow to improve anatomical fit and decouple the pump from cardiac motion, and to provide a point for clamping and ligation for pump explant. RESULTS: The simple design enabled the relatively fast and inexpensive fabrication and assembly of three pumps. In vitro testing has demonstrated the desired steady-state flow and pressure characteristics (7 Ipm at 135 mmHg achieved at 4800 rpm) and hydrodynamic efficiency (30% at the design point in water). Further, the pumps have met performance requirements in three (40, 27, and 59 days) electively terminated bovine in vivo studies with acceptable hemolysis (4–10 mg/dl plasma free Hb) and no mechanical failures.