Study:The PediaFlow™ is a miniature, fully-magnetically-levitated, implantable pediatric VAD intended for extended support in neonates and infants that operates over a wide range of flow to accommodate the growing child. Its design is derived from the Streamliner™ maglev VAD, and has evolved through four generations of design from 2004-2014, with support of the NIH/NHLBI Pediatric Circulatory Support and PumpKIN programs. Chronic in-vivo studies of the fourth generation, PF4, demonstrated exceptional hemocompatibility, and was published in 2018. This report describes progress with the clinical, fifth generation, PF5, which is intended for high volume manufacturing and will be carried forward to clinical trials. Methods: The PF5 retains the optimized electromagnetic architecture of its predecessor, including permanent-magnet, passive radial suspension, and Lorentz type, feedback controlled axial suspension. Upgrades were made to (1) improve manufacturability, (2) reduce the diameter of the driveline, (3) provide touchdown protection, (4) improve hydraulic efficiency, (5) increase flow output, (6) improve sensor reliability, (7) provide sensor-less physiological measurements. Results: Optimization of the flow path by computational fluid dynamics (CFD) was able to increase the maximum output from 1.5 LPM (PF4) to 3.5+ LPM (PF5), with commensurate increase of hydraulic efficiency from 27% to 34%. The inflow and outflow diameters were increased slightly from 5 mm to 6 mm while keeping the critical flow path dimensions almost unchanged; however, the overall size of the pump was reduced from 17.6 to 14.9 cc displacement. (See Figure .) The robustness of the sensor was improved by relocating circuitry within the pump, with the added benefit of reducing the driveline diameter from 6 mm to 4 mm. Design-for-manufacture and reduction of part count translated to approximate five-fold reduction in manufacturing cost. Normalized Index of Hemolysis (NIH) remains below 0.01 g/100 dL (0.01 mg/dL), comparable to PF4.
Conclusions:The clinical version of the PediaFlow (PF5) features several improvements over the PF4 that increase its robustness and performance. Ongoing work includes development a miniaturized digital/ clinical-use control unit with embedded physiologic feedback, suction avoidance, pump flow rate output, and diagnostic functions -capitalizing on intrinsic pressure-sensing of the levitation system. Human factors design for infants and young children is an important component of these efforts. We're back, baby! Figure 1. Clinical version of the PediaFlow(PF5) fully magnetically levitated, mixed flow, implantable pediatric VAD and control unit.