比较小剂量多巴酚丁胺负荷磁共振评价陈旧性心肌梗死和心肌活性的联系

Relationship between low dose dobutamine stress and late enhancement MRI in evelating myocardial viability in chronic myocardial infarction

目的:比较小剂量多巴酚丁胺负荷磁共振(MRI)和延迟强化MRI评价陈旧性心肌梗死和心肌活性的价值。方法:25例陈旧性心肌梗死患者于血运重建前行静息及小剂量多巴酚丁胺负荷(5～10μg.kg-1.min-1)心脏电影MRI和延迟强化心脏MRI,小剂量多巴酚丁胺负荷MRI存活心肌的定义为:≥2个相邻的静息期无运动及反向运动的节段,负荷后节段心肌收缩≥2 mm;延迟强化透壁程度分为5个等级评分,分别为无强化(0分),0～25%(1分),25%～50%(2分),50%～75%(3分),75%～100%(4分),节段心肌评分≤2为预测心功能可恢复。结果:延迟强化透壁程度≤50%的心肌节段(评分0～2),89%多巴酚丁胺负荷阳性;延迟强化透壁程度≥75%的心肌节段(评分4),21%多巴酚丁胺负荷阳性(P<0.05)。延迟强化透壁程度在50%～75%(评分3)之间时,54%多巴酚丁胺负荷阳性,46%多巴酚丁胺负荷阴性。结论:当延迟强化为心内膜下强化和透壁强化时,与多巴酚丁胺负荷一致性好。当延迟强化透壁程度在50%～75%(评分3)之间时,需要进一步进行多巴酚丁胺负荷以更好地预测心肌活性。

Objective：The relation between contrast-enhanced MRI and low dose dobutamine stress,and exPlore the Possibility of detection myocardial viability combined with morPhological and functional MRI.Methods：Rest and low dose dobutamine（5 μg·kg-1·min-1,10 μg·kg-1·min-1）stress cine-MRI were Performed in 25 Patients with chronic myocardial infarction,and additional contrast-enhanced MRI were Performed to evaluate the transmural extent of infarct tissue.Left ventricular were divided into 16 segments,the criteria of viability in different techniques is： MRI：dobutamine induced systolic wall thickenning was ≥2 mm in akinetic or diskinetic segments at rest;contrast-enhanced MRI： each segment was graded on a 5-Point scale,0=absence of hyPerenhancement;1=hyPerenhancement of 1% to 25% of LV wall thickness;2=hyPerenhancement extending to 26% to 50%;3=hyPerenhancement extending to 51% to 75%;4=hyPerenhancement extending to 76% to 100% of LV wall thickness.Results：Most segments 89% of small subendocardial scar [hrPerenhancement score 0-2] had contractile reserve,whereas contractile reserve was not frequently 21% observed in segments with transmural infarction[hrPerenhancement score 4]（P0.05）.in the segments with an intermediate infarct transmurality[hrPerenhancement score 3],contractile reserve was observed in 54%,but contractile reserve was not observed in 46%.Conclusion：The agreement between contrast-enhancement MRI and low-dose dobutamine MRI is large in the extremes（subendocardial and transmural scar）,however in the intermediate contrast segments,low-dose dobutamine stress MRI may be needed to suPPort additional information to oPtimally evaluated myocardial viability.