Design of Axial Blood Pumps for Patients With Dysfunctional Fontan Physiology: Computational Studies and Performance Testing

Abstract

Limited treatment options for patients having dysfunctional single ventricle physiology motivate the necessity for alternative therapeutic options. To address this unmet need, we are developing a collapsible axial flow blood pump. This study investigated the impact of geometric simplicity to facilitate percutaneous placement and maintain optimal performance. Three new pump designs were numerically evaluated. A transient simulation explored the impact of respiration on blood flow conditions over the entire respiratory cycle. Prototype testing of the top performing pump design was completed. The top performing Rec design generated the highest pressure rise range of 2-38 mm Hg for flow rates of 1-4 L/min at 4000-7000 RPM, exceeding the performance of the other two configurations by more than 26%. The blood damage indices for the new pump designs were determined to be below 0.5% and predicted hemolysis levels remained low at less than 7 × 10(-5) g/100 L. Prototype testing of the Rec design confirmed numerical predictions to within an average of approximately 22%. These findings demonstrate that the pumps are reasonably versatile in operational ability, meet pressure-flow requirements to support Fontan patients, and are expected to have low levels of blood trauma.

Pressure–Flow Experimental Performance of New Intravascular Blood Pump Designs for Fontan Patients

“…In this study, we present the results of our effort to develop an optimized impeller design. As a means to facilitate percutaneous insertion and collapsibility using an internal Nitinol wire structure, the impeller geometry of the rectangular impeller design (i.e., Rec model) was improved upon in this work . The geometric simplicity of the Rec design enables the achievement of performance objectives and will enable percutaneous placement in a clinical setting.…”

“…We initially examined five impeller geometries with varying blade twist angles between 100 and 500 degrees using hydraulic testing. These impellers are rigid impeller prototypes which were designed with simplified geometries to provide for optimal pump performance, while allowing the impeller to be collapsible . After positive results were obtained, six additional impellers with twisted blade angles between 100 and 600 degrees of blade twist were developed with optimization of key regions to enhance pump performance.…”

“…Conventional pump design equations were initially used to design the simplified impeller geometries to provide for optimal pump performance. Computational modeling also provided insight into performance predictions and assisted with selection of geometries for experimental evaluation .…”

“…(a) Design consists of a catheter, protective cage of filaments, impeller blade set, and outlet nose cap. (b) Percutaneous placement of the blood pump in the IVC to support a Fontan patient: superior vena cava ( SVC ); inferior vena cava ( IVC ); right pulmonary artery ( RPA ); left pulmonary artery ( LPA ); total cavopulmonary connection ( TCPC ) .…”

Artificial Organs 2015: A Year in Review

“…Dhyaa H. Kafagy et al of the Virginia Commonwealth University, Richmond, VA, USA investigated the impact of geometric simplicity to facilitate percutaneous placement and maintain optimal performance in the design of axial blood pumps for patients with dysfunctional Fontan physiology. The top performing rectangular cross‐section configuration (Rec) generated the highest pressure rise range of 2–38 mm Hg for flow rates of 1–4 L/min at 4000–7000 rpm.…”