The effect of conductivity on ST-sSegment epicardial potentials arising from subendocardial ischemia
The effect of conductivity on ST-sSegment epicardial potentials arising from subendocardial ischemia
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DOI：
10.1007/s10439-005-3236-2
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发表时间：
2005-06-01
影响因子：
3.8
通讯作者：
MacLeod, RS
中科院分区：
文献类型：
--
作者：
Hopenfeld, B;Stinstra, JG;MacLeod, RS
我们对双域电导率和心内膜下缺血引起的 ST 段心外膜电位之间关系的某些方面进行量化并提供生物物理学解释。我们使用真实的整个心脏模型对缺血进行了计算机模拟。该模型包括一片心内膜下缺血组织，其透壁厚度可变，动作电位幅度降低。我们还在模拟中改变了心脏的细胞内和细胞外电导率以及心室血液的电导率。在中等或高厚度的透壁缺血处（即，至少 40% 的厚度穿过心壁），在各种电导率值范围内，心外膜上会出现健康组织和缺血组织之间边界相对两侧的心外膜电位的两个最小值的一致模式。净心外膜电位差的大小（心外膜最大值减去心外膜最小值）与沿纤维和跨纤维的细胞内与细胞外电导率比率密切相关。缺血源区域的各向异性对于预测心外膜电位至关重要，而远离缺血区域的心脏的各向异性对心外膜电位的影响不太显着。延伸穿过至少 40% 心壁的心内膜下缺血在心外膜上表现为至少一个位于缺血组织和健康组织之间边界上方的 ST 段压低区域。凹陷的大小是双域电导率值的函数。
We quantify and provide biophysical explanations for some aspects of the relationship between the bidomain conductivities and ST-segment epicardial potentials that result from subendocardial ischemia. We performed computer simulations of ischemia with a realistic whole heart model. The model included a patch of subendocardial ischemic tissue of variable transmural thickness with reduced action potential amplitude. We also varied both intracellular and extracellular conductivities of the heart and the conductivity of ventricular blood in the simulations. At medium or high thicknesses of transmural ischemia (i.e., at least 40% thickness through the heart wall), a consistent pattern of two minima of the epicardial potential over opposite sides of the boundary between healthy and ischemic tissue appeared on the epicardium over a wide range of conductivity values. The magnitude of the net epicardial potential difference, the epicardial maximum minus the epicardial minimum, was strongly correlated to the intracellular to extracellular conductivity ratios both along and across fibers. Anisotropy of the ischemic source region was critical in predicting epicardial potentials, whereas anisotropy of the heart away from the ischemic region had a less significant impact on epicardial potentials. Subendocardial ischemia that extends through at least 40% of the heart wall is manifest on the epicardium by at least one area of ST-segment depression located over a boundary between ischemic and healthy tissue. The magnitude of the depression is a function of the bidomain conductivity values.