Development of a radial ventricular assist device using numerical predictions and experimental haemolysis

Design and Computational Evaluation of a Pediatric MagLev Rotary Blood Pump

Pediatric heart failure (HF) patients have been a historically underserved population for mechanical circulatory support (MCS) therapy. To address this clinical need, we are developing a low cost, universal magnetically levitated extracorporeal system with interchangeable pump heads for pediatric support. Two impeller and pump designs (pump V1 and V2) for the pediatric pump were developed using dimensional analysis techniques and classic pump theory based on defined performance criteria (generated flow, pressure, and impeller diameter). The designs were virtually constructed using computer-aided design (CAD) software and 3D flow and pressure features were analyzed using computational fluid dynamics (CFD) analysis. Simulated pump designs (V1, V2) were operated at higher rotational speeds (~5,000 revolutions per minute [RPM]) than initially estimated (4,255 RPM) to achieve the desired operational point (3.5 L/min flow at 150 mm Hg). Pump V2 outperformed V1 by generating approximately 30% higher pressures at all simulated rotational speeds and at 5% lower priming volume. Simulated hydrodynamic performance (achieved flow and pressure, hydraulic efficiency) of our pediatric pump design, featuring reduced impeller size and priming volume, compares favorably to current commercially available MCS devices.

Computational Parametric Study of the Axial and Radial Clearances in a Centrifugal Rotary Blood Pump

In centrifugal rotary blood pumps (RBP), clearances are a critical parameter in determining blood trauma. This study investigates the effect of axial clearance (Cax) and radial clearance (Crad) on the hydrodynamic and hemolytic performance of a centrifugal RBP. A centrifugal pump was parameterized so that it could be defined by geometric variables Cax and Crad. Optimal Latin hypercube sampling was used to determine design points based on Cax, Crad, and rotor speed (ω). For each design point, a computational simulation was conducted to determine efficiency (η) and normalized index of hemolysis (NIH). Next, a response surface (RS) was created to estimate these performance parameters based on the design variables. The results show that for a given Cax, when Crad is decreased, η increases until Crad = 0.15 mm, beyond which η deceases. For a given Crad, Cax has a unimodal relationship with η. The NIH has a unimodal relationship with both Cax and Crad. The mechanisms behind these relationships were investigated by various analytical methods. It was found that vortices in the secondary flow paths were a critical factor in determining efficiency and hemolysis. The optimal clearance values discerned in this study are only valid for the specific impeller geometry and operating conditions analyzed.

HYDRODYNAMIC AND HEMOLYSIS ANALYSIS ON DISTANCE AND CLEARANCE BETWEEN IMPELLER AND DIFFUSER OF AXIAL BLOOD PUMP

Low hemolysis and hydraulic performance are important factors for an axial blood pump, which have been transplanted in patients with heart failure (HF). The distance and clearance between impeller and diffuser play a key role in hemolytic properties and hydraulic performances of axial blood pumps that were developed by our group inspired by the design features of HeartMate II. In the present study, we aimed to investigate the appropriate distance and clearance between impellers and diffusers of axial blood pumps, which contains the best low hemolytic property and hydraulic performance using the computational fluid dynamics (CFDs) approach. Specially, the hemolysis of the pump was calculated by using two different empirical power-law hemolytic blood damage models with two sets of parameters. The two hemolytic blood damage models with two sets of parameters were analyzed and compared. Further, the different distances and clearances between impellers and diffusers that affect hemolytic and hydraulic characteristics were also analyzed. The results showed that the pump with distance of 2[Formula: see text]mm and clearance of 0.2[Formula: see text]mm between impeller and diffuser exhibited the best hemolytic property and better hydraulic performance.