斑点追踪显像技术评价心肌缺血再灌注对心肌扭转影响的实验研究

Alternations of left ventricular torsion of myocardial ischemia before and after reperfusion assessed by speckletracking imaging

目的 应用斑点追踪显像技术测定心肌缺血及再灌注后不同时刻的心肌扭转.方法 14只小型猪,随机分为两组：A组结扎前降支1 min,B组结扎前降支15 min.分别测定结扎前、解除结扎前及解除结扎后第1、5、30、60、90 min、1周各时间点常规心脏超声指标以及扭转数据,并进行比较.结果 缺血时A组心尖部及左室心内膜下扭转角度峰值再灌注后第1 min即恢复至基线水平；而B组相同扭转指标再灌注后30min出现一过性改善,相对于解除结扎前分别为（6.5±0.8）.对（3.4±1.2）.和（7.8±1.0）°对（6.1±1.1）.（P均＜0.01）,完全恢复则在再灌注后1周.B组心外膜下扭转角度峰值再灌注后呈逐渐上升趋势.结论 心肌缺血时间不同,再灌注前后心内、外膜下心肌扭转角度改变不尽相同.应用斑点追踪显像技术测定再灌注后心肌扭转恢复情况可以反映心肌缺血程度,从而为评价心肌缺血提供更长时间的观察窗.

Objective To evaluate the alternations of left ventricular （LV） torsion of myocardial ischemia before and after reperfusion using speckle tracking imaging （STI）.Methods Fourteen open-chest pigs underwent randomizedly 1 minute （group A） or 15 minutes （group B） of left anterior descending （LAD） ligation and followed up for 1 week.Torsion of LV in both groups were quantified by STI before LAD occlusion,LAD occlusion immediately,and 1-,5-,30-,60-,90-minute and 1-week after reperfusion.Results One minute after reflow,decreased peak apical rotation and peak LV torsion fully recovered in the inner layer in group A.In contrast,there was a brief resumption in group B during 30min after reflow from （6.5 ± 0.8）° to （3.4 ± 1.2）°（ P 〈0.01 ） and from （7.8 ± 1.0）° to （6.1 ± 1.1 ） ° （ P 〈0.01 ）,respectively.Peak LV subepicardial torsion increased gradually after reperfusion.Conclusions As a result of various durations of ischemia,peak torsion in subendocardium and subepicardium change differently before and after reflow.STI may be suitable for evaluation of the extent of ischemia by noninvasive quantification of torsion in subendocardium and subepicardium.Therefore,duration of assessment of myocardial ischemia can be prolonged.