Mathematical modelling is a useful technique to help elucidate the connection between non-transmural ischaemia and ST elevation and depression of the ECG. Generally, models represent non-transmural ischaemia using an ischaemic zone that extends from the endocardium partway to the epicardium. However, recent experimental work has suggested that ischaemia typically arises within the heart wall. This work examines the effect of modelling cardiac ischaemia in the left ventricle using two different models: subendocardial ischaemia and partial thickness ischaemia, representing the first and second scenarios, respectively. We found that it is possible, only in the model of subendocardial ischaemia, to see a single minimum on the epicardial surface above the ischaemic region, and this only occurs for low ischaemic thicknesses. This may help to explain the rarity of ST depression that is located over the ischaemic region. It was also found that, in both models, the epicardial potential distribution is most sensitive to the proximity of the ischaemic region to the epicardium, rather than to the thickness of the ischaemic region. Since proximity does not indicate the thickness of the ischaemic region, this suggests a reason why it may be difficult to determine the degree of ischaemia using the ST segment of the ECG.

中文翻译：

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根据ST段心外膜电位分布的敏感性分析，局部厚度模型和心内膜下缺血模型之间的差异。

数学建模是一种有用的技术，有助于阐明非跨壁缺血与心电图ST升高和降低之间的联系。通常，模型代表使用从心内膜延伸到心外膜的局部缺血区的非透壁缺血。但是，最近的实验工作表明缺血通常发生在心脏壁内。这项工作检查了使用两种不同的模型对左心室心肌缺血建模的效果：心内膜下缺血和局部厚度缺血，分别代表了第一种和第二种情况。我们发现，仅在心内膜下缺血模型中，可能会在缺血区域上方的心外膜表面看到一个最小值，并且仅在缺血厚度较小时才会出现。这可能有助于解释位于缺血区域上方的ST抑郁症的罕见性。还发现，在两个模型中，心外膜电位分布对缺血区域与心外膜的接近程度最敏感，而不是对缺血区域的厚度敏感。由于接近度并不表示缺血区域的厚度，因此这暗示了可能难以使用ECG的ST段确定缺血程度的原因。