心脏磁共振及实验室检查联合评估心肌缺血

A joint assessment in myocardial ischemia by cardiac magnetic resonance and biomarkers

目的探讨心脏磁共振(cardiac magnetic resonance imaging,CMR)及实验室检查指标在评估心肌缺血中的临床价值。材料与方法 7只巴马小型猪成功构建心肌缺血模型,分别于术前、术后2 h、12 h、24 h、48 h、72 h、1周、2周、3周、4周检测心肌酶谱、肌钙蛋白、肌红蛋白等实验室检查指标,并于上述各时段行CMR检查,最终行病理检查。结果巴马猪术后2 h肌钙蛋白及肌红蛋白即明显升高,分别为[(0.005±0.002)、(0.338±0.768) ng/ml,P<0.05],72 h内诸心肌损伤标志物变化显著(均P<0.05),提示心肌损伤,1周后趋于平稳;CMR示缺血早期T2WI黑血序列显示心肌水肿,即危险心肌,电影(cine)序列出现局部室壁运动异常,首过灌注术后2 h即出现灌注减低或缺损,术后24 h部分心肌节段出现延迟强化,透壁程度随着缺血时间的延长,不断增加,最终经病理证实心肌坏死、纤维化。4周CMR所测心功能指标较术前显著降低(左室射血分数%:分别为62.71±8.33、45.97±6.37,P<0.05)。结论心肌酶谱及肌钙蛋白、肌红蛋白对心肌损伤有提示意义,CMR可确切地显示心肌缺血微观组织学变化,联合评估可为急性冠脉综合症提供详细的诊断信息并指导治疗。

Objective:The purpose of this study is to investigate the clinical value of cardiac magnetic resonance(CMR)and biomarkers in evaluating myocardial ischemia.Materials and Methods:Seven pigs of myocardial ischemia modol were successfully established,CMR and biomarkers checks were performed pre-surgery and post-surgery at 2 h,12 h,24 h,48 h,72 h,1 w,2 w,3 w,4 w,respectively.And pathologic histology was given at last.Results:Bama-pigs'cardiac troponin I and myoglobin levels significantly increased in 2 h compared with the baseline results[(0.005±0.002)ng/ml vs.(0.338±0.768)ng/ml,(110.3±53.7)ng/ml vs.(1012±1300)ng/ml,P<0.05,respectively],all the markers for the extent of the myocardial injury increased in 72 h after modeling(all P<0.05),which indicated myocardial injury,and gradually to be stable after 1 week post-surgery.At the early stage of ischemia,T2 weighted imaging(T2WI)CMR showed the myocardial edema,which was also called area at risk.Cine showed the abnormal wall motion.Firstpass perfusion imaging showed the hypoperfusion or perfusion defect at 2 h,delayed enhancement CMR showed the high signal at 24 h,and transmural extent increased with the prolongation of ischemic time,which were confirmed by pathological findings of necrotic myocardium and myocardial fibrosis at last.Cardiac function measured by CMR dropped significantly 4 w after modeling(left ventricular ejection fraction%:62.71±8.33 vs.45.97±6.37,P<0.05).Conclusions:Myocardial enzyme spectrum,cardiac troponin I and myoglobin can indicate the myocardial injury,CMR can exactly reveal micro-histological changes of myocardial ischemia,joint assessment is of great significance in providing detailed prognosis information and guiding treatment options.