The pulsatile flow fields downstream of the three aortic bileaflet mechanical valves: St. Jude Medical (SJM), CarboMedics (CM), Edwards Tekna (modified Duromedics, DM) have been investigated in vitro. An experimental circulatory mock loop has been used to simulate the left heart under the conditions of geometric and dynamic similarities. These tested valves have been mounted on the base of a glass‐made model aorta with symmetrical sinus. The blood analog fluid has a viscosity of 3.9 cP and has matching refractive index with the model aorta. Experimental parameters have been set at the rate of 70 heartbeats and 5 liters of flow per minute. A two‐component laser Doppler anemometer has been used to measure the distributions of pulsatile velocities at five different axial locations inside the sinus of the aorta. Results show that although all the three valves are aortic bileaflet valves, they have different flow patterns, due to their different opening angles, shapes of leaflets and movements of hinges. Among these three valves, SJM has been found to have the smallest turbulent stress, CM has slightly higher whereas DM has the greatest stress. The levels of stress that these three valves generate are greater than the threshold for blood damage and thrombosis hence, resulting in the clinical complications.
關聯:
Journal of the Chinese Institute of Engineers=中國工程學刊 19(3), pp.333-344
