速度向量成像联合小剂量多巴酚丁胺负荷实验评价兔心肌梗死后存活心肌

目的 评价速度向量成像(VVI)联合小剂量多巴酚丁胺负荷实验检测兔心肌梗死模型存活心肌的价值。方法 结扎新西兰大白兔冠状动脉左心室支,建立心肌梗死兔模型。于术后8周对实验动物行小剂量多巴酚丁胺负荷实验,采用VVI检测局部室壁给药前后应变及应变率的改变;处死实验动物后,取心脏进行氯化三苯四氮唑(TTC)染色观察坏死心肌,以TTC结果为金标准,计算VVI诊断存活心肌的敏感度和特异度。结果 给予小剂量多巴酚丁胺后,非存活心肌节段应变和应变率较给药前均无明显改变(P均>0.05);存活节段收缩期应变和应变率随剂量增加而增加,与给药前比较差异均有统计学意义(P均<0.05),舒张期应变率亦有增加趋势,与给药前比较差异无统计学意义(P>0.05)。VVI联合小剂量多巴酚丁胺负荷实验诊断存活心肌的敏感度和特异度在左心室长轴切面为77.42%(24/31)和82.35%(42/51),在左心室短轴切面为84.31%(43/51)和88.73%(126/142)。结论 VVI联合小剂量多巴酚丁胺负荷实验评价心肌梗死后存活心肌准确、无创,具有潜在临床应用价值。

Velocity vector imaging combined with dobutamine stress echocardiography in assessment of myocardial viability in rabbit model of myocardial infarction

Objective To investigate the value of velocity vector imaging (VVI) combing with low dose dobutamine stress in assessing myocardial viability in rabbit model of myocardial infarction. Methods The myocardial infarction models in New Zealand white rabbits were established by ligating the left ventricular branch of the coronary artery. Low dose dobutamine stress testing was performed 8 weeks after myocardial infarction and VVI was used to measure the changes of strain and strain rate of left ventricular wall after adiministration of dobutamine. The hearts were removed and dyed with triphenyltetrazolium chloride staining (TTC) to observe the infarcted mycardium after executing the aminals. The sensitivity and specificity of VVI combined with dobutamine stress echocardiography in assessing viable myocardial segment were calculated with TTC results as gold standard. Results The strain and strain rate did not change in non-viable segment after infusion of dobutamine (all P>0.05). Systolic strain and strain rate in viable segment significantly increased after dobutamine infusion (all P<0.05), diastolic parameters also increased but without statistical significance (all P>0.05). The sensitivity and specificity of VVI combined with dobutamine stress echocardiography in assessing viable myocardial segment was 77.42% (24/31) and 82.35% (42/51) on long axis section and 84.31% (43/51) and 88.73% (126/142) on short axis section of the left ventricular. Conclusion VVI combining with low dose dobutamine stress can accurately and safely assess the myocardial viability after myocardial infarction, with potential clinical application value.