Grande-Allen K J, Cochran R P, Reinhall P G, Kunzelman K S
Department of Biomedical Engineering, Cleveland Clinic Foundation, Cleveland, OH, USA.
J Thorac Cardiovasc Surg. 2000 Apr;119(4 Pt 1):753-63. doi: 10.1016/S0022-5223(00)70011-0.
The treatment of choice for aortic valve insufficiency due to root dilatation has become root replacement with aortic valve sparing. However, root replacement with a synthetic graft may result in altered valve stresses. The purpose of this study was to compare the stress/strain patterns in the spared aortic valve in different root replacement procedures by means of finite element modeling.
Our finite element model of the normal human root and valve was modified to simulate and evaluate three surgical techniques: (1) "cylindrical" graft sutured below the valve at the anulus, (2) "tailored" graft sutured just above the valve, and (3) "pseudosinus" graft, tailored and sutured below the valve at the anulus. Simulated diastolic pressures were applied, and stresses and strains were calculated for the valve, root, and graft. Leaflet coaptation was also quantified.
All three root replacement models demonstrated significantly altered leaflet stress patterns as compared with normal patterns. The cylindrical model showed the greatest increases in stress (16%-173%) and strain (10%-98%), followed by the tailored model (stress +10%-157%, strain +9%-36%). The pseudosinus model showed the smallest increase in stress (9%-28%) and strain (2%-31%), and leaflet coaptation was closest to normal.
Valve-sparing techniques that allow the potential for sinus space formation (tailored, pseudosinus) result in simulated leaflet stresses that are closer to normal than the cylindrical technique. Normalized leaflet stresses in the clinical setting may result in improved longevity of the spared valve.
对于因根部扩张导致的主动脉瓣关闭不全，治疗的首选方法已变为保留主动脉瓣的根部置换术。然而，使用合成移植物进行根部置换可能会改变瓣膜应力。本研究的目的是通过有限元建模比较不同根部置换手术中保留的主动脉瓣的应力/应变模式。
我们对正常人体根部和瓣膜的有限元模型进行了修改，以模拟和评估三种手术技术：（1）“圆柱形”移植物在瓣环处瓣膜下方缝合，（2）“定制”移植物在瓣膜上方缝合，（3）“假窦”移植物，定制并在瓣环处瓣膜下方缝合。施加模拟舒张压，并计算瓣膜、根部和移植物的应力和应变。还对瓣叶对合进行了量化。
与正常模式相比，所有三种根部置换模型的瓣叶应力模式均有显著改变。圆柱形模型的应力（16%-173%）和应变（10%-98%）增加最大，其次是定制模型（应力+10%-157%，应变+9%-36%）。假窦模型的应力（9%-28%）和应变（2%-31%）增加最小，瓣叶对合最接近正常。
允许形成窦间隙的保留瓣膜技术（定制、假窦）导致模拟的瓣叶应力比圆柱形技术更接近正常。临床环境中标准化的瓣叶应力可能会提高保留瓣膜的使用寿命。
