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心肌梗死再灌注早期磁共振心肌应变的初步研究

Tracking Early Reperfused Myocardial Infarction using Cardiac MR

    摘要
  • 摘要:
      目的  应用磁共振成像(MRI)心肌应变技术研究心肌梗死患者经皮冠状动脉介入治疗(PCI)后及心肌梗死再灌注模型大鼠不同节段的心肌应变特点。
      方法  10例心肌梗死患者在PCI术后早期(2~10 d)进行MRI检查，完成序列扫描后，经患者肘正中静脉注入磁共振对比剂〔按0.1 mmol/kg体质量注入钆喷酸葡胺(Gd-DTPA)〕，10 min后采集对比剂延迟增强图像(LGE)，测量心内膜心肌应变运动参数，包括径向应变(RS)、周向应变(CS)峰值，在每一层心肌选取完全心肌梗死、部分心肌梗死及无梗死3个节段进行统计学分析。10只SD大鼠行冠状动脉左前降支结扎60 min后松开制备心肌梗死再灌注模型，在再灌注48 h及7 d采集MRI数据，分别勾画并计算：收缩末期及舒张末期心肌梗死面积所占整体心肌比例、舒张末期容积(EDV)、射血分数(EF)。心肌应变分析方法与患者类似。
      结果  心肌梗死患者的RS和CS在完全心肌梗死节段及部分心肌梗死节段均小于无梗死心肌节段(P均 < 0.01)，但完全心肌梗死节段与部分心肌梗死节段间差异无统计学意义(P>0.05)。大鼠再灌注48 h与7 d的EF及EDV差异无统计学意义(P>0.05)；完全心肌梗死节段及部分心肌梗死节段的RS、CS均小于无梗死心肌节段(P均 < 0.01)，完全心肌梗死节段与部分心肌梗死节段间差异无统计学意义(P>0.05)。再灌注48 h心肌整体应变(RS和CS)与7 d相比变化不大(P>0.05)，但48 h完全心肌梗死节段、部分心肌梗死节段及无梗死心肌节段心肌应变峰值小于7 d(P < 0.05)。
      结论  心肌梗死再灌注早期完全梗死节段及部分梗死节段心肌应变峰值没有差异。再灌注损伤会导致心肌梗死再灌注早期心肌运动能力降低，但随着再灌注时间延长，心肌运动能力逐渐恢复。

     

    Abstract:
      Objective  To determine segmental myocardial changes in cardiovascular magnetic resonance feature-tracking (CMR-FT) in the early phase of reperfused myocardial infarction in patients and rats.
      Methods  Ten patients receiving percutaneous coronary interventions (2-10 d) and 10 rats with 60 min induced myocardial ischemia followed by reperfusions (48 h and 7 d) were investigated by MRI. The steady state free precession cine and late gadolinium enhancement (LGE) sequences were measured to evaluate the standard short axis of the whole heart after an injection of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA, Magnevist, Bayer Health Care Pharmaceuticals) at a dose of 0.1 mmol/kg. The infarction sizes (all areas were expressed as a percentage of the whole myocardial tissues of left ventricle (LV), end-diastolic volume (EDV) and ejection fractions (EF) were calculated. The MRI cine images were analyzed using the myocardial feature tracking software CVI, estimating the peak value of radial strains (RS) and circumferential strains (CS) of the 16 AHA segments excluding apex cordis. The complete myocardial infarction (CMI) segments, partial myocardial infarction (PMI) segments and non-myocardial infarction (NMI) segments were identified and compared.
      Results  Patients: The radial strain and circumferential strain of the CMI and PMI segments were smaller than the NMI segment (both P < 0.01). However, there was no significant difference between the CMI and the PMI segment (P>0.05). Rats: No significance differences were found in EF and EDV between the two time period 48 h and 7 d (both P>0.05). The radial strain and circumferential strain of the CMI and PMI segments were smaller than the NMI segment (all P < 0.01). But there was no significance difference between the CMI segment and the PMI segment (P>0.05). No significant changes in the global radial strain and the circumferential strain were found over time (both P>0.05). But the segmental radial strain and circumferential strain became larger over time (all P < 0.05).
      Conclusion  The systolic ability of myocardium decreases as a result of reperfusion injury in the early phase of reperfused myocardial infarction. But it can gradually recover over time with reperfusion.

     

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