多巴酚丁胺负荷超声结合心肌超声造影同步检测兔顿抑心肌

Combination of dobutamine stress and myocardial contrast echocardiography for simultaneous detection of postischemic myocardium in anesthetized rabbits

目的探讨多巴酚丁胺负荷超声结合心肌超声造影同步检测兔顿抑心肌的可行性及其应用价值。方法45只家兔按阻断冠状动脉左室支和再灌注时间不同分为三组，Ⅰ组阻断15min再灌注30min，Ⅱ组阻断30min再灌注60min，Ⅳ组阻断45min再灌注120min。分别在基础状态、阻断、再灌注和多巴酚丁胺负荷（5、10、15、20μg·kg^-1·min^-1）各阶段团注心肌造影剂。测量危险心肌的收缩期室壁增厚率（WT）和标化的造影剂密度（CI），最后行1％氯化三苯基四氮唑染色确定梗死面积。结果①阻断时，危险心肌的WT降到零点或呈负值，标化CI明显低于对应区域；②再灌注和多巴酚丁胺5μg·kg^-1·min^-1后，各组危险心肌的WT和标化CI仍减低；③多巴酚丁胺10和15μg·kg^-1·min^-1时，Ⅰ组和Ⅱ组的WT和标化CI恢复至基础状态，但Ⅲ组仍保持较低水平；④多巴酚丁胺20μg·kg^-1·min^-1时，Ⅲ组仍存在灌注-收缩不匹配，即标化CI已恢复接近基础状态，但WT仍较低。结论多巴酚丁胺负荷超声结合心肌超声造影是识别顿抑和梗死心肌安全可行的方法。

Objective To evaluate the feasibility and value of determining stunned or infarcted myocardium by dobutamine stress and myocardial contrast echocardiography in anesthetized rabbits. Methods Forty-five rabbits were divided into three experimental groups according to the duration of occlusion and reperfusion. Myocardial contrast agent was used by bolus at baseline,occlusion, reperfusion and dobutamine infusion （5,10,15 and 20 μg·kg^-1·min^-1）. Percentage wall thickening（WT） and calibrated contrast intensity （CI） of each risk segment at each stage were measured. The infarcted area was identified as the results of 1% triphenyl-tetrazolium chloride. Results ①WT in the areas at risk decreased to zero or even showed negative value at occlusion and the calibrated CI values were significantly lower than those in the control region;②After reperfusion and 5 μg·kg^-1·min^-1 dobutamine administration,WT and calibrated CI in all rabbits remained depressed;③During 10 μg ·kg^-1·min^-1 and 15μg· kg^-1· min^-1 dobutamine infusion,WT and calibrated CI in groups Ⅰand Ⅱ recovered to baseline, however, those in group m remained low; ④At 20 μg·kg^-1 min^-1 dobutamine, it still exist perfusion-contraction mismatch in group m, that was calibrated CI recovered and WT still remained decreased. Conclusions Combination of dobutamine stress and myocardial contrast echocardiography appears to be feasible technique for differentiating stunned myocardium from infarcted myocardium.