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Title: Design and dynamic analysis of a self-pumping Fontan system using bistable mechanisms

Abstract: The Fontan procedure is a surgical remedy for single ventricle heart defect (Mixing of good and bad blood) in children 8 to 13 years of age, approximately. This study develops a parametric model that allows the prediction of the dynamic, sequential responses in a series of bistable mechanisms that will promote the desired pulsatile blood flow in the Fontan conduit. The work includes determining the stiffness and quasi-geometric parameters that can lead a future team to development of a prototype self-pumping Fontan . The mechanism will use the ‘Piston-Like’ motion of the atrioventricular valve (AVV) within the heart to pump the Fontan conduit. Bistable mechanisms are chosen because their snap-through behavior can lead to lower power consumption. A three-strap model, with spring, mass and damper is analyzed. Static analysis using Mathematica and dynamic analysis using MATLAB simulated time-dependent behavior and un/damped effects on the system. With addition of damping effect, viscoelastic properties of the systems were included. A set of parameters were determined that satisfied mathematical criteria required to promote pulsatile flow in systole (heart contraction). However, negative forces observed in the damped three strap model observed in diastole (heart relaxation) after snap-through suggest the need further optimization and refinement of the system. Overall, the study verifies the snap-through behavior of forces in association with bistable mechanism for both static and dynamic case for a three-strap model.