冠心病介入治疗前行实时心肌声学造影评价缺血或存活心肌的实用价值

目的:探讨冠状动脉支架置入术前行实时心肌声学造影(RTMCE)评价存活心肌的临床应用价值。方法:对20例择期行经皮冠状动脉支架置入术的冠心病患者(病例组)和7例冠状动脉造影未见异常患者(对照组)分别于支架置入术前后行RTMCE检查及双嘧达莫负荷后RTMCE检查,分析心肌血流再灌注的时间-密度曲线形态及相应的心肌显像峰值强度(A)、曲线上升平均斜率(β)和局部心肌血流量(A·β),评估用药前后各指标的比值变化。结果:静息状态灌注正常的病变节段,负荷前A、β及A·β与正常心肌无显著差异,负荷后A、β及A·β储备值明显低于正常心肌,缺血心肌支架置入术后心肌灌注明显改善。静息状态灌注异常的病变节段,负荷前A、β及A·β明显低于正常心肌,负荷后A、β及A·β储备值明显低于正常心肌,缺血心肌治疗后心肌灌注较治疗前有改善,但仍明显低于正常心肌。结论:冠心病患者冠状动脉支架置入术前行RTMCE检查有助于筛选合适的病例进行血运重建,避免给患者造成不必要的损伤。     

Myocardial Contrast Echocardiography in Assessment of Stable Coronary Artery Disease at Intermediate Dobutamine-Induced Stress Level

Background: Myocardial contrast stress echocardiography (stress MCE) is a novel method for diagnosing coronary artery disease (CAD). Few studies have compared the diagnosis of ischemia by stress MCE to angiographic CAD. Methods: Dobutamine stress MCE and SonoVue contrast infusion were performed before an elective percutaneous coronary intervention in 37 patients (8 women) aged 45–75 years with symptomatic CAD and at least one significant coronary artery stenosis measured by quantitative coronary angiography (QCA). The total and regional perfusion and wall motion (WM) were scored as normal or abnormal and attributed to the three main epicardial coronary arteries using a 17-segment left ventricular model. Results: An intermediate stress level was obtained in 29 (78%) patients, and 2 (5%) patients obtained peak stress. A perfusion defect was detected in 92% and WM abnormality in 57% of the patients at peak stress (P < 0.01). By perfusion, 70% of stenoses were both detected and correctly anatomically located, compared to 42% by WM (P < 0.01). All 21 patients with multivessel disease and/or proximal left anterior descending (LAD) stenosis measured by QCA were identified by stress-induced perfusion defects, while only 11 of them were identified by WM abnormalities (P < 0.01). Conclusion: Perfusion scoring is superior to WM scoring during stress MCE for diagnosing significant CAD in patients obtaining intermediate stress level, in particular, when multivessel disease or proximal LAD stenosis is present.     

心肌超声造影在冠心病中的应用进展

随着对超声造影剂及成像技术的深入研究,心肌声学造影(MCE)取得了极大的发展.作为一项评价心肌微循环灌注的新技术,通过分析心肌组织水平的血流灌注,可对急性心肌梗死及慢性缺血性心脏病进行综合评估,并可检测再灌注治疗后心肌的存活性及收缩功能恢复情况.MCE已成为临床上安全、准确评价冠心病的诊断技术,且在心脏疾病治疗中具有极大的潜在价值.     

Assessment of Myocardial Viability in Patients With Postischemic Left Ventricular Dysfunction: Role of Myocardial Contrast Echocardiography

The distinction between viable and nonviable dysfunctional left ventricular (LV) segments after acute myocardial infarction is very important, because revascularization increases survival only in patients with viable myocardial tissue. Recent studies have highlighted a mismatch between two highly specific investigations for viability assessment: dobutamine echocardiography, which measures inotropic reserve, and myocardial contrast echocardiography (MCE), which measures microvascular perfusion. Viability and functional reserve are not synonymous. Maintenance of microvascular perfusion, independently of functional reserve, attenuates left ventricular remodelling, reduces the risk of major cardiac events, and increases survival. MCE provides similar perfusion information as myocardial blush, but image quality is much higher. Quantitative analysis of digital data provides more accurate diagnostic MCE information than qualitative analysis of video signal intensity. In a recent study relating MCE findings to histologic data, MCE-derived quantitative data were closely correlated with microvascular density and capillary area, and inversely correlated with collagen content. One of the contrast agents routinely used for MCE is SonoVue, a second generation microbubble contrast agent, which is characterized by high response to ultrasound energy, ease of destruction at high energy, and strong harmonic signal at low energy. Recommendations for the assessment of postischemic LV dysfunction: routine use of MCE, followed by dobutamine echocardiography if perfusion is documented. If MCE is negative, revascularization is not indicated; if both tests are positive, revascularization is strongly recommended; if they are discordant, useful information can be obtained by assessing the extent of ²⁰¹T1 viability. (ECHOCARDIOGRAPHY, Volume 20, Supplement 1, 2003)     

Quantitative Myocardial Contrast Supine Bicycle Stress Echocardiography for Detection of Coronary Artery Disease

Background: If compared with two‐dimensional echocardiography (2DE), quantitative myocardial contrast echocardiography (MCE) improves detection of coronary artery disease (CAD) during pharmacological stress, but there is paucity of data regarding quantitative MCE performed during supine bicycle stress. Objectives: To determine the feasibility and accuracy of quantitative MCE and assess its incremental benefit over 2DE for detection of CAD during supine bicycle stress. Methods: Sixty‐one consecutive patients (47 males, 14 females, mean age 57 ± 12 years) with suspected CAD, who were scheduled for coronary angiography, underwent 2DE and MCE supine bicycle stress. The diagnosis of obstructive CAD (≥50% stenosis) was based on inducible wall‐motion and myocardial perfusion abnormalities. For quantitative myocardial perfusion analysis, A, β, and Aβ reserve were derived from myocardial contrast replenishment curves. Results: Quantitative coronary angiography revealed ≥50% stenosis in 41, ≥70% stenosis in 18, single vessel disease in 24, and multivessel disease in 17 patients. If compared with 2DE, quantitative MCE was more sensitive (71% vs. 93%; P < 0.05) and more accurate (74% vs. 89%; P < 0.05) to detect obstructive CAD. The sensitivity of 2DE and quantitative MCE was 61% and 91% (P < 0.05) in 50–69% stenosis, and 63% and 92% (P < 0.05) in single vessel disease. No difference in sensitivity between 2DE and quantitative MCE was found in subjects with ≥70% stenosis (83% vs. 94%, P = NS) and multivessel disease (82% vs. 94%, P = NS). Conclusions: Quantitative MCE enhances sensitivity and accuracy of supine bicycle stress 2DE for detection of obstructive CAD, and this incremental benefit is especially present in less severe disease.     

心肌声学造影在冠心病中的临床应用进展

心肌声学造影是诊断微循环水平心肌灌注的新技术。近年来无创性的心肌声学造影取得了突破性进展,已从实验室走向临床应用,现将心肌声学造影在冠心病方面应用的研究进展做一综述。     

Myocardial Contrast Echocardiography: Clinical Benefit and Practical Issues

Real-time bedside evaluation of myocardial perfusion after intravenous application of micro-bubbles is the ultimate goal for contrast echocardiography. Over the past decade rapid evolution has occurred in the development of contrast agents, ultrasound equipment tailored to their detection, and image interpretation. This article offers a review of the basic concepts of the technique's background, contrast agent design, and imaging technology. The major clinical indications of myocardial contrast echocardiography are evaluation of acute ischemic syndromes, diagnosis of viable myocardium following AMI, and the detection of CAD using stress contrast perfusion imaging. Furthermore, the article addresses the most significant practical problems and suggested solutions to master those problems. As major new achievements are realistic expectations for the first decade of the twenty-first century, we conclude that the coupling of a new generation of contrast agents with innovative echocardiographic instrumentation will ultimately enable the full potential of myocardial contrast echocardiography to be realized which may revolutionize modern echocardiography.     

The Added Clinical Value of Second Generation Ultrasound Contrast Agents

Intravenous contrast echocardiography using second generation contrast agents improves wall motion analysis in difficult-to-image patients and increases diagnostic accuracy of stress echocardiography. New and still experimental technology enables simultaneous evaluation of myocardial perfusion and wall motion. First clinical and experimental studies demonstrate an acceptable diagnostic accuracy of intravenous contrast echocardiography in detecting stress-induced ischemia and in differentiating viable from irreversibly damaged myocardium. Current data encourage the use of intravenous contrast echocardiography to evaluate microvascular integrity in patients with unstable angina and in acute infarction following coronary revascularization. However, attenuation artefacts may limit interpretation of findings in basal myocardial segments. Standardization of the method on the basis of more solid data derived from large clinical trials is needed before introducing intravenous myocardial contrast echocardiography into clinical practice. (ECHOCARDIOGRAPHY, Volume 20, Supplement 1, 2003)     

Optimal Use of Contrast Echo in Daily Practice: What Do We Need?

With new low power imaging and contrast application technology, it seems possible for the first time to develop a protocol that combines acquisition of both function and perfusion data using a simple modality. For this purpose a European network has been created and this group is currently developing a protocol using a commercially available ultrasound scanner and the infusion of the echocontrast agent SonoVue^® (Bracco). This study describes the technical developments that will promote a comprehensive clinical contrast protocol for assessment of patients with ischemic heart disease. (ECHOCARDIOGRAPHY, Volume 20, Supplement 1, 2003)     

Prognostic Value of Real Time Myocardial Contrast Echocardiography after Percutaneous Coronary Intervention

Real time myocardial contrast echocardiography (RTMCE) is a cost‐effective and simple method to quantify coronary flow reserve (CFR). We aimed to determine the value of RTMCE to predict cardiac events after percutaneous coronary intervention (PCI). We have studied myocardial blood volume (A), velocity (β), flow indexes (MBF, A × β), and vasodilator reserve (stress‐to‐rest ratios) in 36 patients with acute coronary syndrome (ACS) who underwent PCI. CFR (MBF at stress/MBF at rest) was calculated for each patient. Perfusion scores were used for visual interpretation by MCE and correlation with TIMI flow grade. In qualitative RTMCE assessment, post‐PCI visual perfusion scores were higher than pre‐PCI (Z = ?7.26, P < 0.01). Among 271 arteries with TIMI flow grade 3 post‐PCI, 72 (36%) did not reach visual perfusion score 1. The β‐ and A × β‐reserve of the abnormal segments supplied by obstructed arteries increased after PCI comparing to pre‐PCI values (P < 0.01). Patients with adverse cardiac events had significantly lower β‐ and lower A × β‐reserve than patients without adverse cardiac events. In the former group, the CFR was ≥ 1.5 both pre‐ and post‐PCI. CFR estimation by RTMCE can quantify myocardial perfusion in patients with ACS who underwent PCI. The parameters β‐reserve and CFR combined might predict cardiac events on the follow‐up.     

Myocardial Viability Detected by Myocardial Contrast Echocardiography—Prognostic Value in Patients after Myocardial Infarction

Objective: This study aimed to assess the role of myocardial contrast echocardiography (MCE) as a predictor of cardiac events and death in patients with acute myocardial infarction (AMI). Methods: Eighty‐six patients underwent primary percutaneous coronary angioplasty for AMI. Segmental perfusion was estimated by MCE in real time at mean 5 days after PCI using low MI (0.3) after 0.3–0.5 ml bolus injection of intravenous Optison. MCE was scored semiquantitatively as: (1) normal perfusion (homogenous contrast effect), (2) partial perfusion (patchy myocardial contrast enhancement), (3) lack of perfusion (no visible contrast effect). A contrast score index (CSI) was calculated as the sum of MCE scores in each segment divided by the total number of segments. The patients were followed up for cardiac events and death. Results: A CSI of >1.68 was taken to be a predictor of cardiac events and death. Death occurred only in patients with CSI >1.68. Patients with CSI >1.68 had a significantly (P = 0.03) higher incidence of cardiac death or cardiac events (75%) compared to those with CSI <1.68 (27%). The absence of residual perfusion within the infarct zone was an independent predictor of death and cardiac events (P = 0.02). Conclusions: The absence of residual myocardial viability in the infarct zone supplied by an infarct‐related artery is a powerful predictor of cardiac events in patients after AMI. (Echocardiography 2010;27:430‐434)     

Myocardial Contrast Echocardiography: Texture Analysis for Identification of Nonperfused versus Perfused Myocardium

This study examined texture analysis for objective identification of nonperfused myocardial segments in myocardial contrast echocardiographic (MCE) images. Short-axis MCE images from six open chest pigs after coronary artery ligation were examined. Six of 26 features (low gray level run emphasis, high gray level run emphasis, sum mean, sum variance, coefficient of variance and diagonal variance) demonstrated a significant texture value difference (P < 0.01) between the nonperfused and perfused segments with minimal statistical distribution overlap between the two groups. This study demonstrates that texture features other than mean gray level can objectively distinguish nonperfused from perfused myocardium in MCE images and may thus augment the diagnostic accuracy of current analysis techniques.     

Contrast Echocardiography: Clinical Utility

This article reviews the advances made by the echocardiography contrast agents from their first appearance in the early 1970s with homemade preparations up to the new generation of transpul-monary contrast agents made of small microbubbles capable of transversing the lung's capillary bed. The great progress in contrast agent development has kept pace with the progress made by echocar-diographic equipment, thus making the study of myocardial perfusion in the clinical settings a near-future reality. This article also discusses the medical need that myocardial contrast echo has the potential to satisfy.     

Bulls-Eye Display and Quantitation of Myocardial Perfusion Defects Using Three-Dimensional Contrast Echocardiography

Three-dimensional (3-D) myocardial contrast echocardiography (MCE) is able to derive parallel cutting planes of the left ventricle (LV). However, assessment of the site and extent of myocardial perfusion abnormalities has to rely on the reader's 3-D mental reconstruction from the tomograms, and a manual approach has to be employed for quantitative analysis. The objective of this study was to explore the display and quantitative capability of a bulls-eye format from contrast 3-D MCE in the assessment of perfusion abnormalities derived from a canine model of acute myocardial infarction (MI). Three-dimensional MCE data were acquired sequentially in a rotational scanning format during triggered harmonic imaging with an intravenous contrast agent. Reconstructed short-axis views of the LV were aligned in a bulls-eye format with the apex as the inner most ring. The total LV was divided into 120 sectors. The number of sectors with lack of contrast enhancement was used to derive the percent of the LV (%LV) with perfusion defect and was compared with the extent of MI calculated from postmortem triphenyl tetrazolium chloride (TTC) staining. The perfusion defect regions shown on bulls-eye images corresponded correctly with the territories of the occluded coronary arteries. Three-dimensional MCE perfusion defect mass (19.2 +/- 6.0 %LV) correlated well with anatomic MI mass (19.3 +/- 5.6 %LV; r = 0.92, SEE = 2.3%, mean differential = 0.1 +/- 2.4%). We conclude that bulls-eye display of contrast 3-D MCE demonstrates the site and extent of perfusion abnormalities in an easily appreciable manner. It also allows fast and accurate assessment of endangered myocardium.     

心肌造影负荷超声心动图研究进展

心肌造影负荷超声心动图将心肌造影与负荷超声相结合,通过检测心肌微循环完整性和心肌血流灌注情况,为临床上冠心病的评价提供了一种简便、可靠、准确的新方法。现就心肌造影负荷超声心动图研究与应用现状作一综述。     

Safety and Feasibility of Real Time Adenosine Myocardial Contrast Echocardiography with Emphasis on Induction of Arrhythmias: A Study in Healthy Volunteers and Patients with Stable Coronary Artery Disease

Introduction: Some studies reported an increased incidence of premature ventricular complexes (PVCs) during triggered myocardial contrast echocardiography (MCE) using high-intensity ultrasound destruction. Whether PVCs are also induced by real time MCE using low emission power, is unknown. The aim of the study was to assess the occurrence of arrhythmias during real time adenosine MCE in healthy volunteers and patients with stable coronary artery disease (CAD). Methods: Fifty healthy volunteers and 26 patients with stable CAD underwent real time MCE using Sonovue and power pulse inversion (ATL 5000) at rest and during adenosine stress. The occurrence of premature atrial complexes (PAC) and PVCs was analyzed before and during MCE using ECG-tracings from videotapes. Results: In healthy subjects, the occurrence of PVCs at baseline (0.04 ± 0.23 PVCs/min) was similar at rest (0.04 ± 0.23 PVCs/min, P = NS), and adenosine stress (0.03 ± 0.14, P = NS). In CAD patients, the occurrence of PVCs at baseline was 0.30 ± 0.76 PVC/min, compared to 0.29 ± 0.74 at rest (P = NS), and 0.34 ± 0.74 during adenosine stress (P = NS). The number of subjects demonstrating PVCs did not increase during MCE. The occurrence of PACs during MCE was not increased compared to baseline. Conclusion: Real time MCE using low emission power does not increase the occurrence of premature complexes in healthy volunteers or CAD patients.     

Three-Dimensional Myocardial Perfusion Maps by Contrast Echocardiography

We evaluated the clinical applicability of a system for three-dimensional (3-D) display of a perfusion map following myocardial contrast echocardiography (MCE). The system was used in 12 patients (9 males and 3 females, mean age 52 ± 10 years) undergoing interventional treatment of chronic total coronary occlusion. In each patient three standard apical views were acquired at baseline with sonicated Iopamidol^R injections into the left coronary artery (LCA) and into the right coronary artery (RCA). Following successful recanalization of the occluded artery MCE was repeated. The patients tolerated the procedure well. Acquisition of three standard apical views provided sufficient information for the reconstruction of 3-D perfusion maps containing the 16 standard left ventricular (LV) segments. Side-by-side display of the perfusion maps obtained following LCA and RCA echocontrast injections allowed us to classify the myocardial segments (192) into three groups: (1) those supplied by one major artery (124); (2) those supplied by collaterals from contralateral or both major arteries (58); and (3) segments supplied by none of the major arteries (10). Decreased opacification was observed in 50 segments of group 2. Following successful intervention we were able to visualize the redistribution of blood flow delivered to the LV myocardium by each major coronary artery in 3-D format. We conclude that this 3-D approach, which can easily be performed with currently available ultrasound equipment, allows an estimate of the contribution of each major coronary artery to LV perfusion before and after coronary angioplasty.     

Myocardial Perfusion Abnormalities by Intravenous Administration of the Contrast Agent NC100100 in an Experimental Model of Coronary Artery Thrombosis and Reperfusion

The aim of this study was to evaluate a second-generation echo contrast agent (NC100100) for the study of myocardial perfusion. In eight anesthetized open-chest dogs, this agent was injected intravenously under baseline conditions, during acute coronary thrombosis, and after reperfusion, using both fundamental (FI) and harmonic (HI) imaging, both continuous and intermittent imaging, and both ultrasound (US) and integrated backscatter (IBS) imaging. Contrast injections did not modify the hemodynamic parameters. With all imaging modalities, myocardial contrast enhancement (MCE) was higher with intermittent than with continuous imaging (134 vs 82 gray level/pixel using FI, P = 0.02; 62 vs 32 acoustic units using US HI, P = 0.02; and 52 vs 12 dB using IBS, P = 0.05). MCE equally increased using either US or IBS imaging. The accuracy of MCE in detecting perfusion defects during coronary occlusion and myocardial reperfusion after thrombolysis was very good (sensitivity and specificity = 93% and 95% and 89% and 93%, respectively). The extent of myocardial perfusion defects by echo contrast showed a closer correlation with microspheres using HI (r = 0.82) than FI (r = 0.53). Thus, the intravenous administration of NC100100 during intermittent HI allows myocardial perfusion abnormalities to be accurately detected during acute myocardial infarction.