1. Design & Optimization of Cavopulmonary Pump Support Pediatric Fontan Patient
School of Engineering, Department of Mechanical & Nuclear Engineering.
By Dhyaa Kafagy and Dr. Amy L. Throckmorton
Abstract:
The treatment for single ventricle physiology involves complex, cardiac surgery, resulting
in bypass of the right side of the heart and facilitating passive blood flow through the
lungs. Patients with single ventricle physiology contend with ongoing morbidity and
progressive decline in ventricular function. Heart transplants for these patients are
challenging to obtain, and there are few, if any, therapeutic options. To address the
growing need for alternative support therapies, we designed 3 unique blood pump
geometries for intravascular mechanical circulatory support. Pressure generation,
estimations of blood damage levels, shear stresses, and fluid streamlines were analyzed
using computational methods. All designs met the target pressure generation of 2-25 for a
range of blood flow rates. The Rec-1 design performed far superior to the other
geometries. Shear stress and blood damage levels indicated a low risk of blood cell
trauma.
Introduction:
Fontan is the third stage surgical treatment for a single ventricle patient. Single ventricle
heart patients have insufficient blood flow toward the left and right lungs. In the normal
heart physiology, the Inferior Vena Cava (IVC) is attached to the bottom portion of the
heart. In the Fontan patient, the surgeons literally divides the IVC where it enters the
heart and then stitches a tube to joint the upper end of the IVC to the lower portion of
the left and right pulmonary arteries, essentially, bypassing the right heart. This operation
allows more blood to reach the lungs passively.
The cavopulmonary pump is designed to augment the blood pressure in the IVC to
provide 5-12 mmHg, and about 2-3 L/min. Our pump is a temporary solution to support
the patient circulation waiting for heart transplant.
Motivation:
· Each year, thousands of children are born with single ventricle case.
· The current medical treatment model is three surgical stages:
· Norwood, Glenn and Fontan.
· The Fontan operation: usually doing well by 80%
· The short-term risk:
· Volume overload to ventricle
· Low saturation of oxygen
· Risk of death
· The long-term risk:
· Early heart failure
· No technology available
· Limited heart donors
Goals:
· Design and develop new blood pump geometries for Fontan patients.
· Create a new impeller design that will lead to a collapsible configuration.
· Conduct computational modeling of these new designs.
· Experimental Design and fabrication.
· Compare the computational performance predictions for all of the new designs
numerically & experimentally.
Methods:
· Three unique impellers have been designed to perform as a pediatric cavopulmonary axial blood
pump.
· They were constructed in a three-dimensional computer-aided design modeling using
Solidworks.
· CFD Meshes were generated using 4-5 million tetrahedral mesh elements.
· CFD simulation was conducted using specific blood physical and thermal properties.
· The pump models rotational speed performed at 4000-7000 rpm, to produce 5-38 mmHg, and
flow rate of 1-4 Liters/min.
Modeling of Three Impellers
Single Ventricle Patient [1]
Conclusions:
· The Model Rec-1 shows the best hydraulic performance among the rest of the models
· Most likely to be built in collapsible form
· Continue with CFD studies
· Blood damage modeling
· Transient simulations – time-varying boundary conditions
· Prototype construction and experimental testing
Future Work:
· Conduct Blood damage evaluation
· Optimization Design of the Model Rec_1, to improve the performance.
· Engineer the collapsible form of the pump and evaluate it experimentally.
Positioning of the pump in the IVC
Resources:
1– Single ventricle Patient: www.youtube.com/watch?v=Wnihgojg-9A
CFD Results & Comparison of the hydraulic performance of three models
Mesh Generation
CFD Simulation of 2B Model
Tel: 804-7404934/804-8826413
Email: Dhyaa.Kafagy@gmail.com
Email: Kafagydh@vcu.edu