Optimization of axial-pump pressure sensitivity for a continuous-flow total artificial heart.

BACKGROUND In this study, we describe the potential advantages of a continuous-flow total artificial heart (CFTAH) comprising two small, non-pulsatile pumps with optimized responsiveness to the pressure gradient. METHODS We modified a MicroMed DeBakey axial-flow pump by increasing its inducer-impeller inlet angle, thereby increasing its pressure responsivity. We obtained the in vitro pressure gradient response and compared it with those of the clinically used, unmodified MicroMed DeBakey pump, Jarvik 2000 FlowMaker and HeartMate II. RESULTS The modified pump showed an increased response to changes in the pressure gradient at pump flow rates of between 2 and 4 liters/min. The maximum pressure responsivity of the modified pump was 2.5 liters/min/mm Hg; the corresponding maximum responsivities of the Jarvik 2000, HeartMate II and MicroMed DeBakey ventricular assist devices (VADs) were 0.12, 0.09 and 0.38 liters/min/mm Hg, respectively. CONCLUSIONS Because of the inherent properties of non-pulsatile pumps, the CFTAH may potentially respond to changes in inflow and outflow pressures while maintaining physiologic flow rates sufficient for normal daily activity. In addition, the hemodynamic interplay between the two optimized pumps should allow a physiologic response to normal flow imbalances between the pulmonary and systemic circulations. Improved responsiveness to inflow pressure may further simplify and improve the CFTAH and affect its potential clinical use as a meaningful therapy for terminal heart failure.