Structural basis of regional dysfunction in acutely ischemic myocardium
Structural basis of regional dysfunction in acutely ischemic myocardium
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DOI：
10.1016/s0008-6363(00)00089-4
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发表时间：
2000-08-01
影响因子：
10.8
通讯作者：
McCulloch, AD
中科院分区：
文献类型：
--
作者：
Mazhari, R;Omens, JH;McCulloch, AD
目的：邻近缺血区域（功能边界区）的正常灌注融合心肌中收缩功能受损被认为是由跨灌注边界的机械相互作用造成的。我们研究了节段方向和所涉及的血管如何影响功能性边界区的区域应变，以及与收缩性阶跃过渡相关的应力变化是否可以解释功能性边界区。 方法和结果：区域心外膜应变分布是通过开胸麻醉犬中测量的不透射线标记物的位移获得的，并且与局部肌纤维角度和血流相关。纤维应变的功能边界区明显窄于交叉纤维应变的功能边界区，左前降支（LAD）冠状动脉闭塞的功能边界区明显宽于左回旋支（LCx）冠状动脉闭塞（1.23 vs. 0.45 cm）。详细的三维计算模型在灌注和肌丝激活之间具有一对一的关系，并且没有中间收缩性的过渡区，显示出与这些观察结果非常一致，并且边界区的应力显着升高。模型中 LAD 和 LCx 闭塞之间的差异是由于左心室收缩压的差异，而不是灌注边界或肌纤维方向的差异。纤维应变的边界区域比纤维交叉应变的边界区域更窄，因为收缩刚度沿肌纤维方向最大。结论：急性缺血边界的异常区域力学是由于壁应力增加而没有中间收缩力的过渡区引起的。灌注与纤维的耦合比跨纤维应变更紧密，并且 LAD 期间纤维应变的功能边界区域比 LCx 闭塞更宽，这主要是由于较高的局部壁应力而不是解剖变化。 (C) 2000 Elsevier Science B.V. 保留所有权利。
Objective: Impaired systolic function in the normally per fused myocardium adjacent to an ischemic region - the functional border zone - is thought to result from mechanical interactions across the perfusion boundary. We investigated how segment orientation and vessel involved affect regional strains in the functional border zone and whether altered stresses associated with a step transition in contractility can explain the functional border zone, Methods and results: Regional epicardial strain distributions were obtained from measured displacements of radiopaque markers in open-chest anesthetized canines, and related to local myofiber angles and blood flows. The functional border zone for fiber strain was significantly narrower than that for cross-fiber strain and significantly wider for left anterior descending (LAD) than left circumflex (LCx) coronary occlusion (1.23 vs. 0.45 cm). A detailed three-dimensional computational model with a one-to-one relation between perfusion and myofilament activation and no transitional zone of intermediate contractility showed close agreement with these observations and significantly elevated stresses in the border zone. Differences between LAD and LCx occlusions in the model were due to differences in left ventricular systolic pressure and not to differences in perfusion boundary or muscle fiber orientation. The border zone was narrower for fiber strain than cross-fiber strain because systolic stiffness is greatest along the muscle fiber direction. Conclusion: Abnormal regional mechanics in the acute ischemic border arise from increased wall stresses without a transitional zone of intermediate contractility. Perfusion is more tightly coupled to fiber than cross-fiber strain, and a wider functional border zone of fiber strain during LAD than LCx occlusion is primarily due to higher regional wall stresses rather than anatomic variations. (C) 2000 Elsevier Science B.V. All rights reserved.