Numerical modeling of continuous-flow left ventricular assist device performance

Responses of five rotary blood pumps, namely HeartAssist 5, HeartMate II, HeartWare, Sputnik 1, and Sputnik 2, were extensively assessed in six test cases using a mathematical model of the cardiovascular system. Data for the rotary pumps were derived from pressure-flow curves reported in the literature. The test cases were chosen to attempt to cover most common clinical conditions, such as partial or full support or transitions between different levels of ventricular support. The investigated parameters are collected in a table and presented in figures, such as pressure-volume loops, H-Q curves, pump flow, and aortic pressure waveforms. HeartAssist, Sputnik 1, and Sputnik 2 pumps provide comparable level of aortic pressure, pump flow pulsatility PI(Q_P), and aortic pressure pulsatility PI(AoP) due to the similarity of pressure-flow characteristic curves of these pumps. HeartMate II provides a minimal backflow among other investigated rotary blood pumps due to the maximum pressure head at zero flow. HeartWare provides minimal pulsation of flow, which is confirmed by a flow range from -2 to 7 L/min in case 1. At the same time, the greatest degree of unloading was demonstrated by the HeartWare due to the flatness of the pressure-flow curve shape. The conclusions were made based on the obtained results, including the influence of pressure-flow curve shape on the pump performance and occurrences of adverse events, such as backflow or suction. For example, the increase of the pressure head at zero flow decreases the likelihood of backflow through the pump, and with it, increasing the flow under minimal pressure head increases the likelihood of suction.