心肌声学造影评价冬眠心肌灌注改变的实验研究

Assessment of the perfusion changes in hibernating myocardium by myocardial contrast echocardiography:an experimental study

目的 评价慢性冬眠心肌毛细血管水平心肌灌注的改变。方法 在 2 2只犬中造成冠脉左前降支内径 5 0 %的缩窄 ,1个月后在存活犬中进行小剂量多巴酚丁胺超声心动图负荷试验 ,于用药前及负荷时进行心肌声学造影 (MCE) ,测量冬眠节段与正常节段之间MCE峰值强度的比值 (PIr)、时间强度曲线下面积的比值 (AUCr)、峰值减半时间的比值 (HTr)以及平均通过时间的比值 (MTTr) ,并以高频探头测量左前降支狭窄远端的冠脉血流储备。结果 在 10只犬中成功建立了慢性心肌冬眠的动物模型 ,与基础状态相比 ,负荷状态室壁运动改善后 ,PIr和AUCr显著增加 (P <0 .0 5 ) ,HTr和MTTr显著减小 (P <0 .0 5 )。负荷状态 (S)与基础状态 (B)下上述指标的比值S/BPIr和S/BAUCr均与左前降支狭窄远端的冠脉血流储备十分相近。结论 ①基础状态下冬眠节段心肌灌注较正常节段减少约 5 0 % ,负荷状态下心肌灌注虽显著增加但仍低于正常节段 ;②MCE是评价冬眠心肌血流灌注的可靠技术。

Objective To assess the perfusion changes in the coronary capillary vessel of hibernating myocardium(HM).Methods A 50% diameter stenosis in the left anterior descending(LAD) coronary artery was created in 22 dogs and dobutamine stress echocardiography (DSE) was performed one month later in surviving animals.Myocardial contrast echocardiography (MCE) was carried out at rest and during DSE,and the ratios of the peak intensity (PIr),area under the time-intensity curve(AUCr),half-time of the peak intensity (HTr) and the mean transit time(MTTr) in HM segments to those in normal segments were measured.The coronary flow reserve (CFR) distal to the LAD stenosis was recorded using a high frequency transducer.Results The canine model of chronic HM were successfully created in 10 dogs.Compared with rest status,PIr and AUCr were increased while HTr and MTTr were decreased significantly during DSE(P< 0.05 ).The ratios of PIr and AUCr during stress to those at rest were closely related to CFRs measured in the distal LAD.Conclusions Myocardial perfusion in HM segments was about 50% lower than that in normal segments at rest but increased significantly during stress though it remained lower than normal.MCE is a reliable method to assess myocardial perfusion in HM.