超声心肌声学造影对存活心肌的评价及临床意义

超声心肌声学造影为一种诊断心肌组织水平灌注的新型超声技术,可从微循环完整性的角度评价存活心肌。存活心肌的识别对冠状动脉粥样硬化性心脏病患者选择积极、合理的治疗方案、评估疗效及预后有重要临床价值。本文就该技术对存活心肌的评价及临床意义作一综述。     

实时心肌声学造影结合多巴酚丁胺负荷试验检测存活心肌的临床研究

目的评价实时小剂量多巴酚丁胺(LD-DSE)(10μg·kg~(-1)·min~(-1))负荷心肌声学造影(RT-MCE)试验检测存活心肌的临床价值。方法 22例经彩超检查存在左心室壁节段运动障碍冠心病患者,进行LD-DSE负荷RT-MCE试验、冠状动脉造影(CAG)及介入治疗(PCI),所有狭窄病变行完全血运重建。按美国超声心动图学会16节段划分法获得各运动异常节段显影,图像用目测半定量法分析。术后1、3、6个月时复查心脏超声,以冠脉血运重建后室壁节段收缩功能改善为判断存活心肌的金标准。结果普通RT-MCE目测半定量法检测存活心肌的灵敏度、特异度及准确度分别是75.7%、84.2%、78.8%;LD-DSE负荷RT-MCE目测半定量法检测存活心肌的灵敏度、特异度和准确度分别是89.3%、89.5%、89.4%;应用LD-DSE负荷RT-MCE目测半定量法对存活心肌检测的灵敏度有所提高(89.3%比75.7%,P<0.05)。结论 RT-MCE目测半定量法检测存活心肌具有较高的临床价值,LD-DSE负荷RT-MCE可提高其检测价值。     

经静脉心肌声学造影评价心肌梗死后存活心肌的价值

目的　探讨经静脉心肌声学造影 (MCE)对心肌梗死后存活心肌的诊断价值。方法　 2 4例心肌梗死患者用二维超声评价室壁运动情况 ,同时经静脉进行MCE ,以 3个月后静态超声心动图左室心肌节段性运动改善为依据评价MCE对心肌梗死后存活心肌的诊断价值。结果　在 2 4例病人的 384个心肌节段中 ,运动异常节段 184个。在运动异常的 184个节段中 ,MCE1分 39段 ,0 5分 5 0段 ,0分 95段。 3个月复查 79个节段有运动改善 ,其中 39段来自MCE1分的心肌 ,4 0段来自MCE0 5分的心肌。MCE对预测心肌梗死后室壁运动改善的敏感性、特异性、阳性预测值、阴性预测值及准确率分别为 :10 0 %、89 7%、84 8%、10 0 %和 94 6 %。结论　MCE能比较准确地预测心肌梗死后心肌的存活性     

心肌声学造影的研究现状

经皮冠状动脉造影、核素心肌显像等技术的出现使我们在心肌缺血和存活诊断方面取得了长足进展 ,但这些手段仍有一定缺陷 ,经皮冠状动脉造影可直接观察冠状动脉的狭窄的部位及严重程度 ,但仅能观察直径 >10 0 μm的血管且为有创检查 ,有一定风险。核素检查费用昂贵且有放射辐射     

心肌声学造影评价无再流现象

无再流（NR）在介入治疗后的发病率为15％－50％。目前心肌声学造影（MCE）已成为评价NR的主要方法,具有无创、简便,分辨率高的特点而深受临床欢迎。本文旨在探讨MCE评价NR的原理、优缺点及研究现状。     

心肌声学造影与冠状动脉流量定量关系的实验研究

将14条犬左旋支冠状动脉(LCX)定量缩窄,于主动脉根部注射声振的76%复方泛影葡胺行心肌声学造影(MCE),探讨MCE分析指标及其与冠状动脉流量的定量关系。结果提示:左室后壁MCE的时间—强度曲线中,峰时、D_(1/2)及T_(1/2)在LCX流量减少30～50%时即延长,当LCX流量减到50%以上时,峰时、峰值、D_(1/2)及T_(1/2)均出现明显改变。     

实时心肌超声造影与磁共振心肌灌注延迟增强检测存活心肌的比较

目的评价实时心肌超声造影(RT-MCE)与磁共振心肌灌注延迟增强(DE-MRI)检测存活心肌的临床价值。方法入选2012年7月至2013年12月徐州矿务集团总医院(徐州医学院第二附属医院)心内科收治入院的冠状动脉粥样硬化性心脏病(冠心病)患者27例,男性16例,女性11例,平均年龄62.5岁。所有患者行RT-MCE、DE-MRI、冠状动脉造影(CAG)及冠状动脉介入治疗(PCI)。对患者的RT-MCE图像分析采用目测半定量法,判定存活心肌;对心肌灌注延迟增强情况进行分级,根据分级结果对心肌存活情况进行判定。术后1、3、6月时复查心脏超声,以冠状动脉血运重建后室壁节段收缩功能改善为判断存活心肌的金标准。结果 RT-MCE目测半定量法检测存活心肌的灵敏性、特异性及准确度分别是70.9%、85.7%、76.3%;DE-MRI法检测存活心肌的灵敏性、特异性及准确度分别是72.7%、76.2%、74.0%,RT-MCE目测半定量法检测存活心肌较DE-MRI法具有较高的特异度(76.2%vs.85.7%,P0.05)。两种检测方法的相关性良好。结论 RT-MCE目测半定量法与DE-MRI法检测存活心肌具有较高的临床价值,RT-MCE目测半定量法具有更高的特异性。     

小剂量多巴酚丁胺超声心动图联合心肌声学造影对心肌梗死后存活心肌的诊断价值

目的前瞻性评价小剂量多巴酚丁胺超声心动图(LDDE)联合心肌声学造影(MCE)对心肌梗死后存活心肌的诊断价值。方法对24例心肌梗死者进行静态MCE、LDDE及3个月后静态超声心动图随访分析。MCE和室壁运动均用16段划分法进行目测半定量计分。心肌造影计分(MCS)回声均匀性增强为1分,回声低淡不均匀为0.5分,缺损为0分。室壁运动计分(WMS)用常规计分法。结果随访时,运动改善的心肌节段中MCS1分占49.4%、0.5分占50.6%,对LDDE均有反应;运动无改善的节段MCS0.5分占9.5%,0分占90.5%,对LDDE有反应者占13.3%,无反应占86.7%。预测存活心肌的敏感性、特异性及准确率分别为LDDE86%、86.7%、86.4%;MCE100%、89.7%、94.6%;LDDE联合MCE86.1%、100%、94.0%。结论心肌微血管结构与功能的完善是心肌存活的基本条件。MCE灌注正常和低灌注,且对多巴酚丁胺有反应的心肌有收缩力储备;而对多巴酚丁胺无反应的低灌注或无灌注心肌则多不能恢复收缩功能。LDDE联合MCE能提高检测存活心肌的特异性及准确率。     

实时三维斑点追踪成像结合实时心肌声学造影预测心肌梗死后患者心肌存活性的临床研究

摘要 目的 探讨实时三维斑点追踪成像技术（RT-3D-STI）结合实时心肌声学造影（RT-MCE）技术评价心肌梗死后患者心肌存活性的临床应用价值。方法 选取 25 例根据心电图、心肌酶学及冠脉造影确诊,且成功进行冠状动脉血运重建术的心肌梗死患者。所有患者于术前 1 周内行 RT-MCE 检查,对心肌灌注结果进行半定量评价;分别于术前及术后 6 个月行二维超声分析左室各节段心肌进行室壁运动,根据术后室壁运动是否改善将室壁运动异常的心肌节段分为两组：存活心肌组和非存活心肌组;同时行 RT-3D-STI 技术测得左室心肌整体及各节段三维峰值长轴应变 (3D-LPS) 、环向应变 (3D-CPS) 、面积应变 (3D-APS) 及径向应变 (3D-RPS) 参数指标。结果 血运重建术前,存活心肌组 3D-PLS、3D-PAS、3D-PCS、3D-PRS 明显高于无存活心肌组（P <0.05）;单参数 ROC 曲线分析结果显示,静息状态下,以术前 3D-PAS ≤ -16.5% 作为截断值判断心肌梗死后存活心肌的 AUC 为 0.944,敏感性为 91.3%,特异性为 93.8%,明显高于其它应变值;多参数联合分析结果显示,三维应变参数联合判断心肌梗死后存活心肌的 AUC 为 0.969,灵敏度及特异度分别为 95.7%、 90.6%。血运重建术前,RT-MCE 评价存活心肌的敏感度及特异度分别为 93.1％、 68.8％,一致性分析得出 Kappa 值为0.645。结论 在静息状态下, RT-3D-STI 技术预测心肌梗死后心肌的存活性地价值高于 RT-MCE 技术,其中三维应变参数以 3D-PAS ≤ -16.5% 作为截断值判断心肌梗死后心肌存活性的价值最高,且两种技术联合应用能更好地评价心肌存活性。     

Assessment of regional myocardial blood flow with myocardial contrast echocardiography: an experimental study

OBJECTIVES: The aim of this study was to verify the accuracy of using myocardial contrast echocardiography (MCE), to quantify regional myocardial blood flow (MBF), and to evaluate myocardial viability in comparison to that measured by radiolabeled microsphere and pathologic examination. METHODS: Epicardial MCE was obtained in five myocardial ischemic dogs with constant microbubble intravenous infusion. After the video intensity (VI, y) versus pulsing interval plots derived from each myocardial pixel were fitted to an exponential function: y = A(1 - e(-beta t)), the MBF was calculated as the product of A (microvascular cross-sectional area or myocardial blood volume) and beta (mean myocardial microbubble velocity). The MBF was also obtained by radiolabeled microsphere method. RESULTS: The MBF derived by radiolabeled microsphere method in the normal, ischemic, and infarcted region was 1.5 +/- 0.3, 0.7 +/- 0.3, and 0.3 +/- 0.2 ml/min per gram, respectively; P < 0.01. The product of A and beta in those regions was 52.5 +/- 15.1, 24.4 +/- 3.9, and 3.7 +/- 3.8, respectively; P < 0.01. The normalized product of A and beta correlated well with normalized MBF (r = 0.81, P = 0.001). CONCLUSION: Our initial study demonstrated that MCE has an ability to assess MBF in ischemic myocardium in the experimental model. It may provide a potential capability to detect viable myocardium noninvasively after total persistent coronary occlusion in the clinical setting.     

An Experimental Study of Myocardial Viability with MyocardialContrast Echocardiography

Background Myocardial blood flow(MBF) can be quantified with myocardial contrast echocardiography (MCE) during a venous infusion of microbubble. A minimal MBF is required to maintain cell membrane integrity and myocardial viability in ischemic condition. Thus, we hypothesized that MCE could be used to assess myocardial viability by the determination of MBF. Methods and ResultsMCE was performed at 4 hours after ligation of proximal left anterior descending coronary artery in 7 dogs with constant venous infusions of microbubbles. The video intensity versus pulsing interval plots derived from each myocardial pixel were fitted to an exponential function: y=A(1-e-βt), where y is Ⅵ at pulsing interval t, A reflects microvascular cross - sectional area (or myocardial blood volume), and (3 reflects mean myocardial microbubble velocity. The product of A·β　represents MBF. MBF was also obtained by ra-diolabeled microsphere method servered as reference. MBF derived by radiolabeled microsphere - method in the re     

Assessment of myocardial viability using myocardial contrast echocardiography

Myocardial contrast echocardiography (MCE) is a technique that uses microbubbles as a tracer during simultaneous ultrasound of the heart. The microbubbles can be used to provide quantitative information regarding the adequacy of myocardial blood flow (MBF), as well as the spatial extent of microvascular integrity. In acute myocardial infarction, MCE can identify the presence of collateral flow within the risk area, and can therefore predict preservation of myocardial viability and ultimate infarct size even prior to reperfusion. After reperfusion, the extent of microvascular no-reflow can be determined, and has significant implications for recovery of left ventricular function. In chronic ischemic heart disease, MCE has also been shown to successfully differentiate viable from necrotic myocardium. This technique can accurately predict recovery of function after revascularization. More importantly, MCE can be used to identify viable segments that may help to prevent infarct expansion and remodeling, and thus improve patient outcomes.     

Assessment of myocardial viability with myocardial contrast echocardiography

The application of noninvasive imaging techniques to assess myocardial viability has become an important part of routine management of patients with acute myocardial infarction and chronic coronary artery disease. Information regarding the presence and extent of viability may help identify patients likely to benefit from revascularization or therapy directed at attenuating left ventricular remodeling. Myocardial contrast echocardiography (MCE) is capable of defining the presence and extent of viability by providing an accurate assessment of microvascular integrity needed to maintain myocellular viability. It is especially suited for the spatial assessment of perfusion, even when myocardial blood flow is reduced substantially in the presence of severe epicardial stenoses or in a bed dependent on collateral perfusion. The routine use of MCE to evaluate viability in patients with acute and chronic coronary artery disease is now feasible with the advent of new imaging technologies and microbubble agents capable of myocardial opacification from venous injections. The utility of this technique for determining treatment strategies has not been established but is forthcoming.     

Assessment of myocardial blood flow and volume using myocardial contrast echocardiography

The development of new microbubble agents and ultrasound imaging modalities now allows the assessment of myocardial perfusion with echocardiography. Microbubbles also can be administered intravenously as constant infusions, which allows their concentration in blood to reach steady state. If the relation between microbubble concentration and video intensity is within the linear range, then myocardial video intensity will reflect the concentration of microbubbles in that region, which at steady state is the myocardial blood volume. The ability to destroy microbubbles and measure their replenishment into the ultrasound beam provides an opportunity to evaluate microbubble (or red blood cell) velocity. The product of myocardial blood volume and red blood cell velocity represents myocardial blood flow.     

Assessment of myocardial viability: comparison of echocardiography versus cardiac magnetic resonance imaging in the current era

Detecting viable myocardium, whether hibernating or stunned, is of clinical significance in patients with coronary artery disease and left ventricular dysfunction. Echocardiographic assessments of myocardial thickening and endocardial excursion during dobutamine infusion provide a highly specific marker for myocardial viability, but with relatively less sensitivity. The additional modalities of myocardial contrast echocardiography and tissue Doppler have recently been proposed to provide further, quantitative measures of myocardial viability assessment. Cardiac magnetic resonance (CMR) has become popular for the assessment of myocardial viability as it can assess cardiac function, volumes, myocardial scar, and perfusion with high-spatial resolution. Both 'delayed enhancement' CMR and dobutamine stress CMR have important roles in the assessment of patients with ischaemic cardiomyopathy. This article reviews the recent advances in both echocardiography and CMR for the clinical assessment of myocardial viability. It attempts to provide a pragmatic approach toward the patient-specific assessment of this important clinical problem.     

Combined use of dobutamine echocardiography and myocardial contrast echocardiography in predicting regional dysfunction recovery after coronary revascularization in patients with recent myocardial infarction

BACKGROUND: Myocardial contrast echocardiography and dobutamine echocardiographyhave recently emerged as potentially useful clinical tools todetect reversible myocardial dysfunction. However, the relativeaccuracy of these two techniques in predicting regional wallmotion improvement after coronary interventions is still unclear.The aim of the present study was to compare their diagnosticvalue in predicting functional recovery after coronary revascularizationin patients with recent acute myocardial infarction. METHODS AND RESULTS: Twenty-four patients with acute myocardial infarction underwentmyocardial contrast echocardiography and dobutamine echocardiographywithin 2 weeks of hospital admission. Infarct zone contrastscore and wall motion score indexes were derived in each patient.Infarct-related artery revascularization was performed beforehospital discharge in all selected patients. Resting echocardiographywas repeated 3 months after revascularization, and regionalfunction recovery was analysed. The degree of wall motion scoreimprovement at 3-month follow-up and the percentage of positiveresponses to dobutamine echo were greater (P<0·001and P<0·002, respectively) in patients with a higherbaseline contrast score (0·50). Conversely, no significantchanges were observed either during dobutamine echo or afterrevascularization in the group of patients without residualperfusion within the infarct area. Diagnostic agreement betweenboth techniques in predicting reversible dysfunction was high(81% of segments). The sensitivity and negative predictive valuein predicting functional outcome were 100% (95% confidence interval[CI], 87% to 100%) and 100% (95% CI, 93% to 100%) by contrastecho, and 85% (95% CI, 66% to 96%) and 93% (95% CI, 84% to 98%)by dobutamine echo. The specificity and positive predictivevalue were 90% (95% CI, 80% to 96%) and 81% (95% CI, 64% to93%) by contrast echo, and 88% (95% CI, 78% to 95%) and 76%(95% CI, 58% to 90%) by dobutamine echo. The combination ofmyocardial contrast and dobutamine echocardiography positiveresponses improved specificity and positive predictive valuein detecting functional recovery after revascularization to100% (95% CI, 94% to 100%) and 100% (95% CI, 85% to 100%), respectively.However, the sensitivity and negative predictive value slightlydecreased with the use of both methods (85% [95% CI, 66% to96%)] and (93% [95% CI, 85% to 98%)], respectively. CONCLUSIONS: In patients with recent myocardial infarction, reversible dysfunctionafter coronary revascularization and the response to dobutamineinfusion are strictly dependent on microvascular integrity.However, microvascular perfusion does not always imply functionalrecovery after coronary revascularization. The integration withdob utamine echo results seems particularly helpful to furtherimprove myocardial contrast echo specificity and positive predictivevalues.