Altered Left Ventricular Geometry Changes the Border Zone Temporal Distribution of Stress in an Experimental Model of Left Ventricular Aneurysm: A Finite Element Model Study
Altered Left Ventricular Geometry Changes the Border Zone Temporal Distribution of Stress in an Experimental Model of Left Ventricular Aneurysm: A Finite Element Model Study
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DOI：
10.1161/01.cir.0000032898.55215.0d
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发表时间：
2002-09
期刊：
影响因子：
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通讯作者：
P. Moustakidis;H. Maniar;B. Cupps;T. Absi;Jie Zheng;J. Guccione;T. Sundt;M. Pasque
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文献类型：
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作者：
P. Moustakidis;H. Maniar;B. Cupps;T. Absi;Jie Zheng;J. Guccione;T. Sundt;M. Pasque
左室壁瘤（LVA）是心肌梗死的重要并发症，可导致左室功能障碍。然而，异常功能的确切机制尚未阐明。在这项研究中，我们测试的假设，在左心室几何形状的变化，导致增加壁应力和变化的时间分布的应力在LVA边界区（BZ）在收缩期。方法在成年Dorsett绵羊（n=8）上建立室壁前尖梗死模型，并使其成熟为LVAs 10周。随后使用MRI对动物进行成像，同时记录脑室内压力。根据心脏收缩末期、等容收缩期、峰值收缩期和收缩末期的MRI图像构建心脏模型。分析了两个短轴切片，1个基底切片和1个顶端切片。心尖切片包括动脉瘤的间隔和前部以及相应的BZ和正常心肌。采用有限元分析计算局部壁应力，并与正常对照羊（n=7）相应区域的应力进行比较。结果左室舒张末期、等容期、收缩期峰值和收缩末期，左室舒张末期BZ的应力均显著增加（均P <0.001）。此外，应力的时间分布显着改变，最大应力发生在峰值而不是等容收缩期。结论左室流出道心脏几何形状的改变增加了室壁应力，改变了室壁应力在BZ区的时间分布。这一发现与相应的区域血流量，耗氧量和机械收缩性能的相关性可能有助于阐明所观察到的全球LV功能障碍的机制。
BackgroundLeft ventricular aneurysm (LVA) is a significant complication of myocardial infarction that may lead to global left ventricular (LV) dysfunction. However, the exact mechanism underlying the abnormal function has not been elucidated. In this study we tested the hypothesis that changes in LV geometry cause both an increase in wall stress and a change in the temporal distribution of stress in the LVA border zone (BZ) during systole. MethodsTransmural anteroapical infarcts were created in adult Dorsett sheep (n=8) and were allowed to mature into LVAs for 10 weeks. Animals were imaged subsequently using MRI with simultaneous recording of intraventricular pressures. Cardiac models were constructed from the MRI images at end-diastole, isovolumic systole, peak-systole and end-systole. Two short-axis slices, 1 basal and 1 apical were analyzed. The apical slice included the septal and anterior component of the aneurysm as well as the corresponding BZs and normal myocardium. Regional wall stresses were calculated using finite element analysis and compared with stresses in corresponding regions from normal control sheep (n=7). ResultsIn the LVA group, stress was significantly increased in the BZ at the end-diastolic, isovolumic, peak-systolic, and end-systolic instants (P <0.001 for all). In addition the temporal distribution of stress was significantly altered with maximum stress occurring at peak instead of isovolumic systole. ConclusionsGeometric changes in the LVA hearts increased wall stress and altered its temporal distribution in the BZ region. Correlation of this finding with the corresponding regional blood flow, oxygen consumption, and mechanical systolic performance may help elucidate the mechanism underlying the observed global LV dysfunction.