Blood trauma potential of the HVAD pump in pediatric patients

Abstract Objective Mechanical circulatory support (MCS) has become a standard therapy for adult end-stage heart failure patients. For pediatric patients, technological development lags behind with no currently approved implantable rotary blood pump. As an alternative, the HeartWare HVAD, originally designed for adults, is increasingly used in pediatric patients. The aim of this multicenter study was to assess in-silico , in-vitro and in-vivo the blood trauma potential of this pump in pediatric application. Methods Clinical outcome and indicators for in-vivo blood trauma were investigated retrospectively in 14 pediatric HVAD patients (age 11.3±4.8years). Blood trauma mechanisms of the HVAD were examined in-silico and in-vitro at an adult and pediatric operating point (5L/min and 2.5L/min at 2800rpm and 2200rpm, respectively). The flow was simulated by computational fluid dynamics and analyzed regarding flow structures, shear stresses and washout. Hemolysis was assessed with pumps circulating bovine blood in a temperate flow circuit. Results In the retrospective in-vivo analysis, LDH and D-Dimer values were 1.5 and 3-fold elevated, respectively, compared to adult HVAD patients. Major bleedings were observed in 42.9%, suspected pump thrombosis and neurologic dysfunction in 14.3% of all patients. In the pediatric conditions, simulations predicted elevated mechanical stress profile below 50mPa, more stagnant flow field, with longer washout times within the pump. In-vitro measurements revealed an increased normalized index of hemolysis (NIH = 17.5 mg/100L vs. 8.2 mg/100L, (p=0.0021)). Conclusions The HVAD, operated at lower speeds and flows, induces elevated blood trauma. Further studies are required to assess the clinical implications of these findings.