In Vitro Modelling for Bulging Sinus Effects of an Expanded Polytetrafluoroethylene Valved Conduit Based on High-Speed 3D Leaflet Evaluation

The study aimed to develop a pulmonary circulatory system capable of high-speed 3D reconstruction of valve leaflets to elucidate the local hemodynamic characteristics in the valved conduits with bulging sinuses. Then a simultaneous measurement system for leaflet structure and pressure and flow characteristics was designed to obtain valve leaflet dynamic behaviour with different conduit structures. An image preprocessing method was established to obtain the three leaflets behaviour simultaneously for one sequence with two leaflets images from each pair of three high-speed cameras. Firstly, the multi-digital image correlation analyses were performed, and then the valve leaflet structure was measured under the static condition with fixed opening angles in the water-filled visualization chamber and the pulsatile flow tests simulating paediatric pulmonary flow conditions in the different types of conduit structures; with or without bulging sinuses. The results showed the maximum 3D reconstruction error to be around 0.06 mm. In the steady flow test, the evaluation of opening angles under the different flow rates conditions was achieved. In the pulsatile flow test, each leaflet's opening and closing behaviours were successfully reconstructed simultaneously at the high-frequency recording rate of 960fps. Therefore, the system developed in this study confirms the design evaluation method of an ePTFE valved conduit behaviour with leaflet structures interacting with local fluid dynamics in the vicinity of valves.