应变率成像定量评价犬急性缺血再灌注局部心肌收缩功能的实验研究

目的探讨应变率成像(SRI)定量评价急性缺血再灌注左心室局部收缩功能变化的可行性,探求评价局部心肌功能的合理化指标。方法14只健康杂种犬,麻醉后开胸,于第一对角支起点以下套扎冠状动脉左前降支(LAD),结扎后30min,再灌注120min,建立缺血再灌注模型。分别于LAD结扎前,结扎后30min,再灌注后30min,60min,120min采集连续3个心动周期的组织速度图,用SRI软件分析左室各节段纵轴方向上收缩期应变率曲线的变化,Simpson's双平面法测量左室射血分数(LVEF),舒张末(EDV)及收缩末容积(ESV)。心肌缺血程度通过心肌特染病理切片确定。结果14只犬中12只成功建立缺血再灌注模型。结扎后30min,左室前壁缺血节段收缩期应变率明显降低(P<0.05),并出现收缩后压缩(PSC),再灌注30min后缺血节段收缩期应变率进一步降低,再灌注60min及120min后有所恢复,但仍未达到结扎前水平,LVEF,EDV,ESV于冠脉结扎前后差异无显著意义(P>0.05)。结论应变率能敏感定量评价局部心肌收缩功能的异常,可作为评价局部心肌缺血再灌注的定量指标。

Quantitative assessment of regional left ventricular contractile function in dogs during acute ischemia reperfusion using strain rate imaging

Objective To investigate the feasibility of quantitative evaluation for regional left ventricular contractile function during acute ischemia reperfusion (AIR) using strain rate imaging (SRI) echocardiography. Methods Fourteen anaesthesia opened-chest dogs were scanned before, at 30 min after left anterior descending coronary artery (LAD) ligation, subsequently reperfused for 30 min, 60 min, 120 min. 3 complete cardiac cycles were stored in cine-loop format of tissue velocity imagine. Off-line left ventricular regional strain rate along long axis using digital workstation were obtained and analyzed the features of strain rate. Left ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV) were obtained by Simpson biplane method. Results AIR models of 12 dogs were successfully established from 14 dogs. The peak strain rate (SR_peak) in ischemia segment was decreased obviously (P<0.05), and postsystolic compression (PSC) was found in ischemia segment. SR_peak was decreased seriously during reperfusion 30 min. SR_peak increased slightly after reperfusion 60 min and 120 min, but still decreased than before ligation. There was no significant difference between before and after LAD ligation at LVEF, EDV, ESV (P>0.05). Conclusion Regional wall motion abnormalities can be evaluated quantitatively and synchronously with high sensitivity by strain rate which has potential value in early diagnosis of regional myocardial ischemia and reperfusion.