二维应变成像结合腺苷负荷超声心动图评价犬存活心肌

目的 探讨二维应变成像结合腺苷负荷超声心动图评价存活心肌的新方法.方法 15只健康杂种犬,结扎其冠状动脉前降支90 min后,恢复血流灌注120 min,建立急性心肌梗死再灌注模型.分别于基础状态下(结扎前)和再灌注后采集心尖三腔、两腔和短轴二尖瓣、乳头肌、心尖水平的图像.随后泵入腺苷并重复采集图像.以氯化三苯基四氮唑溶液(2,3,5-triphenyl tetrazolium chloride,TTC)染色结果测量梗死面积(SN)与该节段总面积(S)的百分比(SN/S),SN/S≤50%即为存活心肌.将前壁、前间壁各节段分为存活心肌和非存活心肌,运用二维应变成像技术定量评价犬不同状态下存活与非存活心肌径向、纵向及圆周的收缩期峰值应变(peak-systolic strain,Speak sys)并进行比较.结果 存活与非存活心肌分别为37和53个节段.(1)基础状态下:存活与非存活心肌的收缩期峰值径向应变(RSpeak sys)、纵向应变(LSpeak sys)及圆周应变(CSpeak sys)比较差异无统计学意义.(2)再灌注120 min后:存活与非存活心肌的RSpeak sys、LSpeak sys及CSpeak sys(绝对值)均低于基础状态,而存活心肌与非存活心肌组间差异无统计学意义.(3)腺肾负荷后:与再灌注120 min后相比,存活心肌的RSpeak sys、LSpeak sys显著升高(P<0.01或P<0.05),且存活心肌的RSpeak sys、LSpeak sys明显高于非存活心肌(P<0.01).(4)腺苷负荷后,RSpeak sys与SN/S呈负相关(r=-0.72,P<0.01),CSpeak sys及LSpeak sys与SN/S呈正相关(r值分别为0.40和0.67,P均<0.01).(5)将腺苷负荷前、后应变数值的变化率(△RSpeak sys和△LSpeak sys)作为研究对象,以△RSpeak sys≥13.5%作为判断心肌存活的最佳截断值,其识别存活心肌的敏感性和特异性分别为83.8%、83.0%;以△LSpeak sys≥11%作为最佳截断值,其敏感性和特异性分别为78.4%、88.7%;联合△RSpeak sys和△LSpeak sys两项指标,其敏感性和特异性分别为91.9%、79.2%.结论 二维应变成像技术结合腺苷负荷超声心动图能比较准确地区分存活心肌与非存活心肌.

Evaluation of viable myocardium by two-dimensional strain imaging combined with adenosine stress echocardiography in dogs underwent experimental ischemia/reperfusion injury

Objective To explore the feasibility of evaluating viable myocardium with twodimensional strain imaging combined with adenosine stress echocardiography. Methods Acute myocardial infarction and reperfusion model was made by ligating anterior descending coronary artery for 90 minutes followed by 120-minute reperfusion in 15 healthy mongrel dogs. Images were acquired at baseline and after reperfusion Adenosine was then infused and image acquisition repeated. Regional peak-systolic strain in radial, circumferential and longitudinal motion on anterior wall and anterior septum were measured. TTC staining served as a "gold standard" to define viable and nonviable myocardium. The ratio of infarct area ( SN ) to total area (S) was calculated and viable myocardium was defined with SN/S ≤ 50%. Results At baseline, RSpeak sys, CSpeak sys and LSpeak syswere similar between viable ( n = 37 ) and nonviable myocardial segments (n = 53 ) and significantly decreased after reperfusion in both viable and nonviable myocardial segments. Compared with values obtained after reperfusion, LSpeak sys and RSpeak sys remained unchanged in nonviable myocardial segments and significantly increased in viable myocardial segments after adenosine (P<0.05). Post adenosine RSpeak sys was negatively correlated with SN/S and CSpeak sys and LSpeak syswere positively correlated with SN/S. With △RSpeak sys(before and after adenosine) ≥ 13.5%, the sensitivity was 83.8% and specificity was 83.0% for distinguishing viable from nonviable myocardial segment. With △LSpeak sys≥11% as cutoff value, the sensitivity was 78.4% and specificity was 88.7% for distinguishing viable from nonviable myocardial segment. Combining △RSpeak sys and △LSpeak sys, the sensitivity and specificity for distinguishing viable from nonviable myocardial segment were 91.9% and 79. 2%,respectively. Conclusions Two-dimensional strain imaging combined with adenosine stress echocardiography could quantitatively identify viable and nonviable myocardium.