Influence of crimping textile polyester vascular prostheses on the fluid flow kinetics

Objectives: to characterise the impact of the crimping of polyester prosthe ses on the fluid flow kinetics. Design: an experimental in vitro study. Materials and methods: we investigated four models of polyester vascular pr ostheses in a continuous laminar flow circuit. The flow velocity was 80 ml/ s for all experiments. We studied two fluids of different viscosity within the circuit. The speed of the particles was measured by a laser Doppler ane mometer 2 to 52 mm from the prosthetic interface. We first established a ca librated flow-velocity profile corresponding to the study of the support in side the circuit without any prosthesis. We measured the velocity profiles for each prosthesis corresponding to four crimp densities obtained by stret ching the grafts. Results: the crimping of PET textile prostheses led to a decrease of flow v elocity especially closer to the prosthetic surface. The decrease of flow v elocity was dependent on the model of prosthesis. This decrease of flow vel ocity is described by the following negative Exponential law: Delta V=a.b(- x) where (a) is the crimp density and (b) the fluid viscosity. Conclusions: flow velocity near a prosthetic surface is influenced by the m orphology of the crimping. The impact of crimping on the flow velocity in a vascular prosthesis can be predicted by computer simulation models. This m ay provide the optimal shape of crimping for each prosthesis.