Modeling Active Contraction and Relaxation of Left Ventricle Using Different Zero-load Diastole and Systole Geometries for Better Material Parameter Estimation and Stress/Strain Calculations.
Modeling Active Contraction and Relaxation of Left Ventricle Using Different Zero-load Diastole and Systole Geometries for Better Material Parameter Estimation and Stress/Strain Calculations.
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DOI：
10.3970/mcb.2016.013.044
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Tang D
中科院分区：
文献类型：
--
作者：
Fan L;Yao J;Yang C;Xu D;Tang D
基于体内数据对心室主动收缩进行建模极具挑战性，因为心室几何形状复杂，心脏动态运动和主动收缩，其中参考几何形状（零应力几何形状）不断变化。引入了一种新的建模方法，使用不同的收缩期和收缩期零载荷几何形状来处理不断变化的零载荷几何形状，以获得更准确的应力/应变计算。5例有脑梗死患者（脑梗死组）和10例无脑梗死患者（非脑梗死组）采集了超声图像数据。构建了基于回波的计算两层左心室模型，使用一个零负载几何结构（1G）和两个零负载几何结构（2G）。调整Mooney-Rivlin模型中的材料参数值以匹配回波体积数据。计算有效杨氏模量（YM）以便于比较。对于纤维化阶段，纤维方向上的纤维充盈（BF）平均YM值（YMf）比其终末纤维化（艾德）值高738%（645.39 kPa vs. 76.97 kPa，p= 3.38 E-06）。对于收缩期，收缩末期（ES）YMf比其舒张末期射血（BE）值高903%（1025.10 kPa vs. 102.11 kPa，p=6.10E-05）。比较收缩和舒张材料特性，ES YMf比其BF值高59%（1025.10 kPa vs. 645.39 kPa）。p=0.0002）。BE平均应力值比其艾德值高514%（299.69 kPa vs. 48.81 kPa，p= 3.39 E-06），而BE平均应变值比其艾德值高31.5%（0.9417 vs. 0.7162，p=0.004）。同样，ES平均应力值比BF值高562%（19.74 kPa vs. 2.98 kPa，p= 6.22 E-05），ES平均应变值比BF值高264%（0.1985 vs. 0.0546，p= 3.42 E-06）。2G模型优于1G模型的局限性，可以提供更好的材料参数估计和应力/应变计算。
Modeling ventricle active contraction based on in vivo data is extremely challenging because of complex ventricle geometry, dynamic heart motion and active contraction where the reference geometry (zero-stress geometry) changes constantly. A new modeling approach using different diastole and systole zero-load geometries was introduced to handle the changing zero-load geometries for more accurate stress/strain calculations. Echo image data were acquired from 5 patients with infarction (Infarct Group) and 10 without (Non-Infarcted Group). Echo-based computational two-layer left ventricle models using one zero-load geometry (1G) and two zero-load geometries (2G) were constructed. Material parameter values in Mooney-Rivlin models were adjusted to match echo volume data. Effective Young’s moduli (YM) were calculated for easy comparison. For diastole phase, begin-filling (BF) mean YM value in the fiber direction (YMf) was 738% higher than its end-diastole (ED) value (645.39 kPa vs. 76.97 kPa, p=3.38E-06). For systole phase, end-systole (ES) YMf was 903% higher than its begin-ejection (BE) value (1025.10 kPa vs. 102.11 kPa, p=6.10E-05). Comparing systolic and diastolic material properties, ES YMf was 59% higher than its BF value (1025.10 kPa vs. 645.39 kPa. p=0.0002). BE mean stress value was 514% higher than its ED value (299.69 kPa vs. 48.81 kPa, p=3.39E-06), while BE mean strain value was 31.5% higher than its ED value (0.9417 vs. 0.7162, p=0.004). Similarly, ES mean stress value was 562% higher than its BF value (19.74 kPa vs. 2.98 kPa, p=6.22E-05), and ES mean strain value was 264% higher than its BF value (0.1985 vs. 0.0546, p=3.42E-06). 2G models improved over 1G model limitations and may provide better material parameter estimation and stress/strain calculations.