The closing behavior of mechanical aortic heart valve prostheses.
Mechanical artificial heart valves rely on reverse flow to close their leaflets. This mechanism creates regurgitation and water hammer effects that may form cavitations, damage blood cells, and cause thromboembolism. This study analyzes closing mechanisms of monoleaflet (Medtronic Hall 27), bileaflet (Carbo-Medics 27; St. Jude Medical 27; Duromedics 29), and trileaflet valves in a circulatory mock loop, including an aortic root with three sinuses. Downstream flow field velocity was measured via digital particle image velocimetry (DPIV). A high speed camera (PIVCAM 10-30 CCD video camera) tracked leaflet movement at 1000 frames/s. All valves open in 40-50 msec, but monoleaflet and bileaflet valves close in much less time (< 35 msec) than the trileaflet valve (>75 msec). During acceleration phase of systole, the monoleaflet forms a major and minor flow, the bileaflet has three jet flows, and the trileaflet produces a single central flow like physiologic valves. In deceleration phase, the aortic sinus vortices hinder monoleaflet and bileaflet valve closure until reverse flows and high negative transvalvular pressure push the leaflets rapidly for a hard closure. Conversely, the vortices help close the trileaflet valve more softly, probably causing less damage, lessening back flow, and providing a washing effect that may prevent thrombosis formation.
Department of Water Resources and Environmental Engineering, Tamkang University, Tamsui, Taipei, Taiwan.
Po-Chien
PC
Lu
Jia-Shing
JS
Liu
Ren-Hong
RH
Huang
Chi-Wen
CW
Lo
Ho-Cheng
HC
Lai
Ned H C
NH
Hwang
D000054:Acceleration; D001021:Aortic Valve; D001330:Electronic Data Processing; D005990:Glycerol; D006350:Heart Valve Prosthesis / Q000592:standards; D006801:Humans; D019563:Mechanics; D010781:Photography; D011474:Prosthesis Design; D012212:Rheology; D012996:Solutions; D013997:Time Factors
D012996:Solutions; D005990:Glycerol