Hemodynamics Characteristics of a Four-Way Right-Atrium Bypass Connector With an Optimized Central Diverter

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The most common surgical procedure used to treat right ventricular heart failure is the Fontan procedure, which connects the superior vena cava and the inferior vena cava directly to the left and right pulmonary arteries bypassing the right atrium. Many studies have been performed to improve the Fontan procedure. Research has been done on a four-way connector that can both passively and actively improve flow characteristics of the junction between the Superior Vena Cava (SVC), Inferior Vena Cava (IVC), Left Pulmonary Artery (LPA) and Right Pulmonary Artery (RPA), using an optimized connector and dual propeller system. However, the configuration of these devices do not specify propeller motor placement and has a stagnation point in the center of the connector. This study focuses on creating a housing for the motor in the center of the connector to reduce the stagnation area and further stabilize the propellers. To do this, we created a program in ANSYS that utilizes the design-of-experiment (DOE) function to minimize power-loss and stagnation points in the connector for a given geometry. First, a CFD model is created to simulate the blood flow inside the connector with different housing geometries. The shape and size of the housing are used as parameters for the DOE process. In this study, an enhanced central composite design technique is used to discretize the design space. The objective functions in the DOE are red blood cell residence time and power loss. It was confirmed that the addition of the housing did decrease the size of the stagnation point. In fact, the housing added in stabilizing the flow through the connector by creating a more defined flow path. Because the flowrates from the IVC and SVC are not the same, the best configuration for the housing was found to be asymmetric along the axis of the pulmonary artery. While this is a continuation of previous studies, the creation of an optimized housing for the motors for the propellers makes implementation of the propeller idea more viable in a real life situation. The added stability of the propellers provided by the housing can also decrease the risk of propeller failure due to rotordynamic instability.