The Effect of Compliant Inflow Cannulae on the Hemocompatibility of Rotary Blood Pump Circuits in an In Vitro Model

Abstract

Rotary blood pumps (RBPs) are used for mechanical circulatory support in heart failure patients but exhibit a reduced response to preload changes, which can lead to ventricular suction events. A passive control system, in the form of a compliant inflow cannula (IC), has been developed to mitigate suction, although this device may cause significant hemolysis. This study compared the incidence of mechanically induced hemolysis of two compliant IC designs (strutted and nonstrutted) with a rigid IC (control) in a blood circulation loop over 90 min. The nonstrutted compliant IC introduced high frequency and high amplitude oscillations in RBP inlet pressure and RBP IC resistance. These oscillations were correlated with a significant increase in plasma-free hemoglobin (pfHb) and hemolysis: pfHb increased to 2.005 ± 0.665 g/L, while normalized index of hemolysis (NIH) and modified index of hemolysis (MIH) increased to 0.04945 ± 0.01276 g/100 L and 4.0505 ± 0.6589 after 90 min (P < 0.05). In contrast, the strutted compliant IC performed similar to the clinically utilized rigid IC and did not increase pfHb (0.300 ± 0.090 and 0.320 ± 0.171 g/L, respectively) and rate of hemolysis (NIH 0.00435 ± 0.00155 and 0.00543 ± 0.00371 g/100 L; MIH 0.3896 ± 0.1749 and 0.4261 ± 0.2792, respectively) within the RBP circuit. These data indicated that strutted, compliant ICs meet the hemocompatibility of clinically used rigid ICs while also offering a potential solution to prevent ventricular suction events.