Velocity fields and turbulent stresses downstream of biological and mechanical aortic valve prostheses implanted in pigs

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Abstract
Since detailed knowledge about velocity fields downstream of heart valve prostheses obtained from in vitro studies has not been followed up by similar detailed studies in vivo a pig model for acute velocity field studies downstream or aortic valve prostheses was established. Two mechanical and two bioprosthetic valves were studied and a dynamic three dimensional visualization of velocity fields one diameter downstream performed under different haemodynamic conditions in a total of 22 pigs. The Ionescu-Shiley pericardial valve had velocity fields very similar to the normal native porcine aortic valve. The Edwards-Carpentier porcine valve caused a jet type flow, and the valve design of the St Jude Medical and Bjork-Shiley Monostrut valves was reflected in the velocity profile. Normalized (mean(SEM)) systolic Reynolds normal stresses in the total cross sectional area were: native porcine 15(1.5) Nm-2; St Jude Medical 24(3.4) Nm-2; Bjork-Shiley Monostrut 25(1.6) Nm-2; Edwards-Carpentier Supra-annular 52(6.6) Nm-2; Ionescu-Shiley Pericardial 19(2.0) Nm-2. Reynolds normal stresses were higher in areas of rapidly changing or constantly high velocity gradients.