This study investigated the performance of an intravascular, percutaneously inserted, axial-flow blood pump in a patient-specific model of a Fontan physiology. This pump is designed to augment pressure and thus blood flow in the cavopulmonary circulation. The outer cage of the device serves as a protective and functional design component. The performance of three cage geometries with unique directions of filament twist was evaluated via numerical simulations and direct comparison to a previous cage design. The cage designs performed acceptably to support Fontan patients. The cage design with filaments twisted in the opposite direction to the impeller blades and in the direction of the diffuser blades (against-with) outperformed the other designs by producing a pressure rise in the range of 1-8.5 mmHg for flow rates of 1-4 L/min at 1500-4000 RPM and pulmonary arterial pressures of 16 mmHg. Results from the blood damage index analyses indicate a low probability for damage with maximum damage index levels of less than 1%. Fluid force magnitudes in the axial and radial directions were less than 0.2 N, and the exit vorticity from the pump was minimized by the against-with cage. This study represents ongoing progress in the development of this blood pump.