Flexible impeller blades in an axial flow pump for intravascular cavopulmonary assistance of the fontan physiology

An intravascular axial flow blood pump has suitable hydraulic characteristics for use to augment pressure in the cavopulmonary circulation in Fontan patients. This study presents the experimental hydraulic performance testing of six flexible-bladed and one rigid-bladed pump prototypes for mechanical cavopulmonary assist. Unique in design, six of these prototypes were manufactured using varying grades of polyurethane material to reduce blade hardness. The hydraulic performance of these prototypes were measured and quantitatively compared to a rigid-bladed prototype through a regression analysis. To shield the vessel wall from the rotating impeller blades, two novel protective cage designs were also evaluated for additional energy augmentation. The pumps with no protective cage produced pressure rises of 1-12 mmHg for flow rates of 0.5-4 L/min at rotational speeds of 4000-7000 rpm. The flexible-bladed prototypes generated pressure rises within 12% of the rigid-bladed pump design. The most flexible prototype (F-15) was able to generate pressure rises within 4.1% of the rigid-bladed impeller. The partially twisted and fully twisted protective cage designs also functioned as desired by augmenting energy transfer in range of 5-15 mmHg, respectively. This study dispels the assumption that rigid-impeller blades are absolutely necessary to maintain the pressure generation of rotary blood pumps and demonstrates the potential of uniquely shaped cage filaments to augment the energy transfer of an axial flow blood pump for mechanical cavopulmonary assistance. The successful development of this blood pump will provide clinicians with a therapeutic option for mechanically supporting the failing Fontan physiology in adolescent and adult patients. © 2010 Biomedical Engineering Society.