Guccione J M, Costa K D, McCulloch A D
Department of Mechanical Engineering, Washington University, St Louis, MO 63130-4899, USA.
J Biomech. 1995 Oct;28(10):1167-77. doi: 10.1016/0021-9290(94)00174-3.
A three-dimensional finite element model was used to explore whether or not transmural distributions of end-diastolic and end-systolic fiber stress are uniform from the apex to the base of the canine left ventricular wall. An elastance model for active fiber stress was incorporated in an axisymmetric model that accurately represented the geometry and fiber angle distribution of the anterior free wall. The nonlinear constitutive equation for the resting myocardium was transversely isotropic with respect to the local fiber axis. Transmural distributions of end-diastolic fiber stress became increasingly nonuniform from midventricle toward the apex or the base. At a typical diastolic left ventricular pressure (1 kPa), the differences between largest and smallest fiber stresses were only 0.5 kPa near midventricle, compared with 4.6 kPa at the apex, and 3.3 kPa at the base. Transmural fiber stress differences at end-systole (14 kPa) were relatively small in regions from the base to the midventricle (13-22 kPa), but were larger between midventricle and the apex (30-43 kPa). All six three-dimensional end-diastolic strain components were within or very close to one standard deviation of published measurements through the midanterior left ventricular free wall of the passive canine heart [Omens et al., Am. J. Physiol. 261, H918-H928 (1991)]. End-systolic in-plane normal and shear strains also agreed closely with published experimental measurements in the beating dog heart [Waldman et al., Circ. Res. 63, 550-562 (1988)]. The results indicate that, unlike in the midventricle region that has been studied most fully, there may be significant regional nonhomogeneity of fiber stress in the normal left ventricle associated with regional variations in shape and fiber angle.
采用三维有限元模型来探究舒张末期和收缩末期纤维应力在犬左心室壁从心尖到心底的透壁分布是否均匀。将主动纤维应力的弹性模型纳入一个轴对称模型，该模型能准确呈现前游离壁的几何形状和纤维角度分布。静息心肌的非线性本构方程相对于局部纤维轴是横观各向同性的。舒张末期纤维应力的透壁分布从中心室向心尖或心底变得越来越不均匀。在典型的舒张期左心室压力（1千帕）下，中心室附近最大和最小纤维应力之间的差异仅为0.5千帕，而在心尖处为4.6千帕，在心底处为3.3千帕。收缩末期（14千帕）的透壁纤维应力差异在从心底到中心室的区域相对较小（13 - 22千帕），但在中心室和心尖之间较大（30 - 43千帕）。所有六个三维舒张末期应变分量都在已发表的通过被动犬心左心室前壁中部测量值的一个标准差范围内或非常接近该范围[奥门斯等人，《美国生理学杂志》261卷，H918 - H928页（1991年）]。收缩末期面内法向应变和剪应变也与在跳动的犬心的已发表实验测量值非常吻合[沃尔德曼等人，《循环研究》63卷，550 - 562页（1988年）]。结果表明，与研究最充分的中心室区域不同，正常左心室中纤维应力可能存在显著的区域非均匀性，这与形状和纤维角度的区域变化有关。
