多巴酚丁胺负荷试验对冬眠心肌QT离散度影响的实验研究

Experimental study of the effect of dobutamine stress test on QT dispersion in acute hibernating myocardium

目的观察急性冬眠心肌模型制备前后及多巴酚丁胺负荷期间QT离散度（QTd）的变化情况，探讨其临床意义。方法对13只小型中国家猪采用闭胸介入法制备急性冬眠心肌模型（右冠状动脉为靶血管），利用多巴酚丁胺超声负荷试验（DSE，0～40μg·kg^-1·min^-1）检出冬眠心肌，之后成功复灌，处死动物，对心脏行三硝基四氮唑红（TTC）大体染色及光镜检查。分别于模型制备前后、DSE期间及复灌后观察QTd的变化情况。结果10只动物（76．92％）成功制备成模型，病理检查未示心肌坏死改变。模型制备成功后QTd较正常状态明显增加[（68．75±5．33）ms vs（25．00±1．77）ms，P〈0．05]；复灌后明显降低[（35．62±3．47）ms vs（68．75±5．33）ms，P〈0．05]，但与正常状态无统计学差异（（35．62±3．47）ms vs（25．00±1．77）ms，P〉0．05]。DSE期间QTd呈现先降低后增加的双相反应的变化趋势。模型制备成功后的QTd与DSE检出的急性冬眠心肌节段数呈中等程度的负相关（r=-0．64，P〈0．05）。结论急性冬眠心肌动物模型的QTd明显增加，早期有效复灌可降低QTd。DSE期间急性冬眠心肌模型的QTd呈现双相反应趋势。急性冬眠心肌模型的QTd是反映冬眠心肌数量的指标之一。

Objective To establish the animal model of acute hibernating myocardium （AHM） by close- chest method, so as to observe the changes of QT dispersion （QTd） of AHM and its responses to dobutamine. Methods 13 little domestic Chinese swine were used to form the model of AHM by interventional method （close - chest ）, with right coronary artery （RCA） as the target vessel. Standard dobutamine stress echocardiography （DSE, 0 - 40 μg·kg^-1·min^-1 ） was performed to identify hibemating myocardium. After successful reperfusion, the animals were killed; the heart was stained with TIE to study the histopathologic changes of AHM cells. QTd was monitored throughout the course of the experiment. Results The successful rate of AHM model was 76.92% （10/13）, with no myocardial necrosis detected. QTd increased significantly in AHM model [ （ 68.75 ± 5.33） ms vs （25.00 ± 1.77 ） ms, P 〈 0. 05 ] and decreased obviously after successful reperfusion [ （35.62 ± 3.47 ） ms vs （ 68.75 ± 5.33） ms, P 〈 0. 05 ], approximating that in normal status [ （ 35.62 ± 3.47 ） ms vs （25.00 ± 1.77 ） ms, P 〉 0.05]. In the course of DSE, QTd showed a trend of biphasic response. The QTd of AHM was found to be correlated to the amount of AHM segments negatively （ r = - 0. 64, P 〈 0.05）. Conclusions The QTd of AHM increased significantly in AHM, and decreased obviously after early successful repeffusion. During DSE, QTd will show a trend of biphasic response. QTd may be a valuable index to reflect the extent of hibernating myocardium.