Solomon S D, Aikawa Y, Martini M S, Rosario L, Makker G, Gerson D, Greaves S, Lee R T
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass 02115, USA.
J Am Soc Echocardiogr. 1998 Oct;11(10):938-47. doi: 10.1016/s0894-7317(98)70135-x.
The objective of this study was to determine the distribution of regional left ventricular (LV) wall stress after myocardial infarction (MI).
After a large MI, structural changes occur in the heart that ultimately may lead to alterations in LV size and shape, a process generally referred to as ventricular remodeling. Regional variation in myocardial wall stress may be responsible for initiation of physiologic and cellular changes that result in myocardial hypertrophy, dilatation, and remodeling after MI. Simplified geometric analytic methods of estimating global LV wall stress cannot determine regional variation such as that occurring after MI.
To assess regional LV wall stress after MI, we applied the finite element method to patient-specific end-systolic LV models generated from echocardiographic imaging. After validation by comparison with analytic solutions of LV wall stress in idealized ventricles, LV models were constructed from rotated orthogonal apical images from 13 normal volunteers, 16 patients with recent (<4 days) anterior MI, and 7 patients with recent infero-posterior MI. The mean Von Mises stress was calculated for the entire LV and for 5 separate regions of the LV. Von Mises LV wall stress was increased globally in patients with anterior MI (211 +/- 46 kdyne/cm2; P < .002) or infero-posterior MI (175 +/- 23 kdyne/cm2; P = .04) compared with normal patients (144 +/- 57 kdyne/cm2). Global wall stress correlated directly with ejection fraction (P < .0001) and inversely with wall motion index (P < .004) in patients with anterior MI. Wall stress in the apical regions was increased by a factor of 2.3 in patients with anterior MI (P < .0001), whereas other regions did not differ from normal patients. There were no individual regions that were significantly different from normal in patients with infero-posterior MI.
Anterior MI is associated with an increase in apical end-systolic wall stress compared with normal and infero-posterior MI. This may be an important stimulus for LV remodeling after anterior MI.
本研究的目的是确定心肌梗死（MI）后左心室（LV）壁区域应力的分布情况。
大面积心肌梗死后，心脏会发生结构变化，最终可能导致左心室大小和形状改变，这一过程通常称为心室重构。心肌壁应力的区域差异可能是导致心肌梗死后心肌肥大、扩张和重构的生理及细胞变化的起始原因。估算左心室整体壁应力的简化几何分析方法无法确定诸如心肌梗死后出现的区域差异。
为评估心肌梗死后左心室壁区域应力，我们将有限元方法应用于由超声心动图成像生成的患者特异性收缩末期左心室模型。在与理想化心室中左心室壁应力的解析解进行比较验证后，从13名正常志愿者、16名近期（<4天）前壁心肌梗死患者和7名近期下后壁心肌梗死患者的旋转正交心尖图像构建左心室模型。计算整个左心室以及左心室5个不同区域的平均冯·米塞斯应力。与正常患者（144±57达因/平方厘米）相比，前壁心肌梗死患者（211±46达因/平方厘米；P<.002）或下后壁心肌梗死患者（175±23达因/平方厘米；P=.04）的左心室冯·米塞斯壁应力整体增加。在前壁心肌梗死患者中，整体壁应力与射血分数直接相关（P<.0001），与壁运动指数呈负相关（P<.004）。前壁心肌梗死患者心尖区域的壁应力增加了2.3倍（P<.0001），而其他区域与正常患者无差异。下后壁心肌梗死患者中没有任何单个区域与正常情况有显著差异。
与正常情况及下后壁心肌梗死相比，前壁心肌梗死与收缩末期心尖壁应力增加有关。这可能是前壁心肌梗死后左心室重构的一个重要刺激因素。
