实时三维超声心动图评价犬多巴酚丁胺负荷试验中左心室容积的变化

Quantitative assessment of left ventricular volume changes during bobutamine stress echocardiography by realtime three-dimensional echocardiography： an experimental study

目的应用实时三维超声心动图（RT-3DE）定量评价犬多巴酚丁胺（Dob）负荷试验（DSE）中左心室容积的变化。方法健康杂种犬32条,随机分为3组：心肌顿抑组8条（冠状动脉结扎15min,再灌注30min）,心肌梗死组16条（冠状动脉结扎180min,再灌注30min）,正常对照组8条。按照心脏负荷5min阶段程序行DSE。应用RT-3DE获取犬静息状态及输注Dob5、10、20、30、40μg·kg^-1·min^-1及终止后5min的RT-3DE容积数据库,根据心尖长轴观8平面法勾画左室舒张末期容积（LVEDV）及收缩末期容积（LVESV）。比较三组实验犬DSE过程中LVEDV及LVESV的变化。结果正常对照组：随Dob剂量的逐级增加,平均LVEDV和LVESV明显减小;心肌顿抑组：平均LVEDV和LVESV在Dob〈20μg·kg^-1·min^-1时呈减小趋势,在Dob≥20μg·kg^-1·min^-1时呈增大趋势;心肌梗死组：平均LVEDV和LVESV在Dob〈20μg·kg^-1·min^-1时也呈减小趋势,但在Dob≥20μg·kg^-1·min^-1时则明显增大。三组实验犬LVEDV及LVESV呈不同的变化趋势。结论应用RT-3DE定量分析DSE过程中左室容积的变化，可以区分心肌顿抑和心肌梗死。RT-3DE有望为临床定量评价心肌顿抑和心肌梗死提供一项有效手段。

Objective To evaluate changes of left ventricular volume of stunned and infarcted myocardium in canine models during dobutamine stress echocardiography （DSE） by real-time three- dimensional echocardiography（RT-3DE）. Methods Thirty-two anaesthetized dogs were divided randomly into three groups as follows：eight dogs were submitted to 15 min of coronary occlusion followed by 30 min of reperfusion（stunned model） ;sixteen dogs underwent 180 min of coronary occlusion followed by 30 min of reperfusion（infarct model） and eight other dogs as control group. DSE were performed in three groups. The duration of each step was 5 minutes. RT-3DE was performed in three groups undergoing DSE. RT-3DE volume data sets were recorded at rest and at each infusion rate of 5 to 40μg·kg^-1·min^-1 and 5 min after infusion. Left ventricular end-diastolic volume（LVEDV） and end-systolic volume（LVESV） were measured according to the apical eight-plane method. Results In the control group,.the dogs demonstrated a marked decrease in mean LVEDV and LVESV throughout DSE. In the stunned model, they exhibited a blunted decrease at relatively smaller doses （〈20 μg·kg^-1·min^-1） and subsequently increased slightly at doses above 20μg·kg^-1·min^-1. In the infracted model, they exhibited a blunted decrease at relatively smaller doses （ 〈 20 μg·kg^-1·min^-1） and subsequently increased significantly at doses above 20μg·kg^-1·min^-1. Conelusions By analyzing changes of left ventricular volume during DSE by RT-3DE, myocardial stunning and infarction can be differentiated.