|Abstract: ||本研究針對雙葉片主動脈人工心瓣St. Jude Medical(SJM),CarboMedics(CM)和Edwards Tekna(modified Duromedics,DM)進行體外模擬之脈動流場量測。採用流場可視化定性觀察與二分量雷射測速儀(laser Doppler anemometer, LDA)定量量測。結果顯示, SJM、CM和DM均在動脈竇邊壁之側邊孔口流邊緣處形成較大之擾動。雖同為雙葉片人工心瓣,然彼此之葉片分離尾跡呈現不相同流況,此由於幾何形狀差異、開啟角度差異及支位置設計不同。整體而言,SJM之紊流擾動最小,其次CM、DM具有較大的紊流擾動。三種心瓣均達到破壞血球及血小板界限,這與臨床上發現之併發症相符。|
The pulsatile flow fields downstream of the three aortic bileaflet mechanical valves: St. Jude Medical (SJM), CarboMedics (CM), Edwards Tekna (modified Duromedics, DM) were investigated in vitro. Downstream of the valves, flow visualization technique was used to obtain a whole view of the flow pattern qualitatively and a two-component laser Doppler anemometer (LDA) was used to measure the distribution of flow fields quantitatively. 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.