Hemodynamic Investigation of a Stentless Molded Pericardial Aortic Valve

摘要

Aortic valve replacement surgery Is the most efficient solution to aortic valve diseases. Recent technological developments in aortic valve replacements saw the materialization of the truly stentless aortic bioprosthetic valves with full pericardial constructs and the Single Point Attached Commissure implantation (SPAC) technique. The truly stentless pericardial SPAC valve developed by Goetz et al [4] boasts superiority in its ability to closely model human native valves. However, actual flow fields in the vicinity of the valve have never been characterized. The characterization of the flow field of the SPAC valve would give insights to the actual hemodynamic performance of the valve and prove its efficacies comparatively to other commercially available valves. To do this, an experimental setup including a left heart simulator was fabricated and fitted to a circulatory loop allowing for physiological pressures and flow rates. Unlike other valve test rigs, an additional valve frame (aortic root) had to be fabricated to support and hold the truly stentless valve. Using a particle image velocimetry (PIV) system, flow field in the vicinity of the valve was obtained. It was discovered that forward flow occurs in the aortic sinuses during systole while recirculation occurs in the sinuses only during diastole, this is unlike framed valves which have been shown to display constant recirculation in the sinuses. Helical flow in the aorta was observed and is attributed to the S-shape crimping action of the closing valve. Reynolds shear stresses were also calculated to be within acceptable range at pre hemolysis levels. Overall, results obtained point to the efficacy of the SPAC valve developed by Goetz et al [4].