Clinical implications of ultrasonic tissue characterization for atherosclerotic carotid intima-media

Current imaging modalities, such as ultrasonic tissue characterization, have enabled accurate determination of the composition of atherosclerotic plaque of excised aortic tissue. The aim of this study is to compare integrated backscatter (IBS) echo signals of the intima-media complex of human carotid arteries between young and elderly subjects, and to evaluate the ability of ultrasonic tissue characterization. We compared the difference in ultrasonic parameters between the carotid arteries of young healthy subjects (n = 27, 25 +/- 1 y.o.) and elderly subjects (n = 55, 75 +/- 4 y.o.). Intima-media thickness (IMT) and calibrated IBS value (C-IBS: Tissue IBS-vessel lumen IBS value) were measured. The IMT values of young and elderly subjects were 0.54 +/- 0.03 and 1.08 +/- 0.07 mm, respectively (p < 0.01). C-IBS of elderly subjects (11.7 +/- 0.8 dB) was significantly higher than that of young subjects (6.9 +/- 0.7 dB). Significantly wider standard deviation of C-IBS value in each individual was observed in elderly subjects (mean +/- SE of individual standard deviation in C-IBS: 4.2 +/- 0.9 dB) compared with that in young subjects (1.7 +/- 0.3 dB). This might reflect varied composition of atherosclerotic plaques in elderly subjects. IBS analysis would become a promising method to distinguish plaque composition quantitatively and to assess the stability of plaques in clinical setting.     

高分辨磁共振成像评价颈动脉粥样硬化斑块成分

目的探讨高分辨MRI不同序列检查评价缺血性脑血管病患者颈动脉粥样硬化斑块成分的临床意义。方法选择64例缺血性脑血管病患者,其中短暂性脑缺血发作(TIA)患者18例,脑梗死患者46例。采用头颈联合线圈,行高分辨MRI检查,先后选用三维时间飞跃法、T_1WI、T_2WI和质子加权成像4种不同序列,分析斑块成分。结果 64例患者中,有完整厚纤维帽25例(39.1%)、完整薄纤维帽20例(31.2%)、破损纤维帽19例(29.7%),脂质池和坏死核心53例(82.8%),斑块内钙化44例(68.8%),斑块内出血31例(48.4%),斑块内纤维化33例(51.6%),脑梗死患者与TIA患者各类斑块成分所占比例比较,差异均无统计学意义(P>0.05)。结论高分辨MRI不同序列检查对颈动脉斑块的检测有助于分析斑块的成分特征,确定斑决的稳定性。     

应用光学相干断层成像对老年与中青年颈动脉粥样硬化性斑块特征的分析

目的 应用光学相干断层成像(OCT)评价老年与中青年患者颈动脉粥样硬化性斑块特征的区别.方法 回顾性连续纳入2017年6月至2021年2月在东部战区总医院神经内科完成颈动脉OCT检查的颈动脉粥样硬化性狭窄患者86例,分别将年龄<60岁、年龄≥60岁患者分为中青年组(17例,占19.8％)和老年组(69例,占80.2％)...     

Role of intravascular ultrasound imaging in identifying vulnerable plaques

A plaque that has a large lipid core and a thin fibrous cap may undergo rupture. Once it ruptures, it may lead to thrombus formation and subsequent vessel occlusion. To identify unstable plaques before they rupture is essential for clinical management and patient's prognosis. Intravascular ultrasound (IVUS) opens a new window for the assessment of plaque morphology to identify vulnerable plaques and plaque rupture. We examined 144 patients with angina and ischemic ECG changes using IVUS. Ruptured plaques, characterized by a plaque cavity and a tear on the thin fibrous cap, were identified in 31 patients (group A) of which 23/31 (74%) clinically presented as unstable angina. Plaque rupture was confirmed by injecting contrast medium filling the plaque cavity during IVUS examination. Of the patients without plaque rupture (group B, n = 108), only 19 (18%) had unstable angina. No significant differences between the 2 groups were found concerning the vessel and plaque areas (p > 0.05). The percent stenosis in group A (56.2 +/- 16.5%) was significantly lower than in group B (67.9 +/- 13.4%) (p < 0.001). Area of the plaque cavity in group A (4.1 +/- 3.2 mm2) was significantly larger than the echolucent zone in group B (1.32 +/- 0.79 mm2) (p < 0.001). The plaque cavity/plaque ratio in group A (38.5 +/- 17.1%) was larger than the echolucent area/plaque ratio in group B (11.2 +/- 8.9%) (p < 0.001). The thickness of the fibrous cap in group A (0.47 +/- 0.20 mm) was significantly thinner than that (0.96 +/- 0.94 mm) in group B (p < 0.001). CONCLUSIONS: Plaques seem to be prone to rupture when the echolucent area is larger than 1 mm2, the echolucent area/plaque ratio greater than 20% and the fibrous cap thinner than 0.7 mm. IVUS has the capacity of identifying plaque rupture and vulnerable plaques. This may have potential influence on patients management and therapy.     

Stabilization of carotid atheroma assessed by quantitative ultrasound analysis in nonhypercholesterolemic patients with coronary artery disease.

OBJECTIVES: This study examined whether intensive cholesterol-lowering therapy with statins in nonhypercholesterolemic patients is effective in improving echolucency of vulnerable plaques assessed by ultrasound with integrated backscatter (IBS) analysis. BACKGROUND: Atherosclerotic plaque stabilization is a promising clinical strategy to prevent cardiovascular events in patients with coronary artery disease (CAD). There is a correlation between coronary and carotid plaque instability, and echolucent plaques are recognized as vulnerable plaques. METHODS: Consecutive nonhypercholesterolemic patients with CAD were randomly assigned Adult Treatment Panel-III diet therapy (diet group; n = 30) or pravastatin (statin group; n = 30). Echolucent carotid plaques were monitored by measuring intima-media thickness (IMT) and echogenicity by IBS for six months. RESULTS: Total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-sensitivity C-reactive protein were significantly decreased in the statin group (from 197 +/- 15 mg/dl to 170 +/- 18 mg/dl [p < 0.001]; from 131 +/- 14 mg/dl to 99 +/- 14 mg/dl [p < 0.001]; and from 0.11 [0.04 to 0.22] mg/dl to 0.06 [0.04 to 0.11] mg/dl [p < 0.05]; respectively), whereas only total cholesterol was moderately reduced (from 193 +/- 24 mg/dl to 185 +/- 22 mg/dl [p < 0.05]) and LDL-C and triglycerides insignificantly reduced in the diet group. Significant increases of echogenicity of carotid plaques were noted in the statin group but not in the diet group (from -18.5 +/- 4.1 dB to -15.9 +/- 3.7 dB [p < 0.001] and from -18.2 +/- 4.0 dB to -18.9 +/- 3.5 dB [p = 0.13]; respectively) without significant regression of plaque-IMT values in both groups. CONCLUSIONS: Statin therapy is rapidly effective in increasing echogenicity of vulnerable plaques without regression of plaque size in nonhypercholesterolemic patients with CAD. Quantitative assessment of carotid plaque quality by ultrasound with IBS is clinically useful for monitoring atherosclerotic lesions by evaluating vulnerability of atheroma.     

颈动脉粥样硬化斑块成分与性别的相关性研究

目的探讨颈动脉粥样硬化患者斑块成分的性别差异。方法选取进行颈动脉3.0T MR高分辨扫描的颈动脉粥样硬化斑块患者154例,男性95例,女性59例,根据MR扫描结果,对斑块成分和性质进行分析,比较男、女性的斑块成分差异。结果男性斑块内富脂质坏死核(42.1%vs 20.0%,P=0.005)和薄或破裂纤维帽(59.7%vs39.5%,P=0.046)的发生率明显高于女性;女性斑块内钙化的发生率有高于男性的趋势(74.6%vs 65.3%,P=0.225),男性与女性斑块内出血发生率比较,差异无统计学意义(24.2%vs 22.0%,P=0.756)。结论颈动脉粥样硬化斑块患者中,男性不稳定斑块的发生率高于女性,这可能有助于解释脑卒中发病率的性别差异。     

Angle dependence of intravascular ultrasound imaging and its feasibility in tissue characterization of human atherosclerotic tissue

BACKGROUND: Intravascular ultrasound (IVUS) images vary in intensity because of the angle of the transducer relative to the plaque. The purpose of this study was to determine the angle dependence of ultrasound backscatter when the IVUS transducer is aligned coaxially in atherosclerotic arteries and to examine its feasibility in tissue characterization of human atherosclerotic tissue. METHODS AND RESULTS: Thirty-nine noncalcified regions of interest (ROI, 0.4 to 0. 6 mm in diameter) within cross sections of formalin-fixed human iliac arterial plaque were imaged with a 3.9F, 25-MHz IVUS catheter in saline at room temperature. The catheter was moved coaxially from 8 to 16 positions and spanned 50 to 122 degrees relative to the ROI and the lumen center. Echo intensity for each ROI was defined as the videointensity relative to a standard reflector. The angle dependence of echo intensity was defined as the slope of the regression line between the angle of incidence and echo intensity. Each ROI was histologically classified into 4 groups: fibro-acellular (fibrous cap, n=7), fibro-cellular (n=9), fibro-fatty (n=13), or fatty tissue (n=10). The echo intensity of the majority (72%) of plaque components in IVUS images are significantly affected by the angle of incidence of the transducer. The angle dependence of fibro-acellular samples was significantly greater than that of the other 3 groups (4.69 +/- 3.29 x 10(-3) x echo intensity/degree vs 1.06 +/- 1.10 in fibro-cellular area, 2.09 +/- 1.75 in fibro-fatty area, and 2.16 +/- 1.92 in fatty area, P <. 05). CONCLUSIONS: The angle dependence of ultrasound reflections from the fibrous cap of atherosclerotic plaque is another method of tissue characterization in addition to spatial distribution and echo intensity. This technique may be useful in determining the thickness of the fibrous cap, which may be an important predictor of plaque rupture.     

Atherosclerotic plaques composed of a large core of foam cells covered with thin fibrous caps in twice-injured carotid arterial specimens obtained from high cholesterol diet-fed rabbits.

We attempted to find atherosclerotic plaques including a large lipid core and thin fibrous cap in twice-injured arterial specimens obtained from high cholesterol diet (HCD) fed rabbits. Rabbits fed a HCD were subjected to carotid artery injury using a balloon catheter. After 2 or 4 weeks of cholesterol feeding, a second mild injury was induced in the same region as the first injury. The rabbits were given a standard diet for 2 weeks after the second injury. Typical atherosclerotic plaques with a fibrous cap formed by smooth muscle cells and extracellular matrix overlying a core formed by macrophage foam cells were observed in the lesion. Gelatin proteolytic activities were found in homogenates containing either media or intima from the injured artery, and activated matrix metalloproteinase-2 (MMP2) was detected. With prolongation of the HCD feeding period (interval between injuries) from 2 weeks to 4 weeks, typical plaque was observed more frequently. Furthermore, the neointimal area and the macrophage foam cells area increased, as did gelatin-proteolytic activity. Since the typical atherosclerotic plaques observed in the present study have some histopathological and pathogenic characteristics in common with unstable atherosclerotic plaque, we expect that the typical atherosclerotic plaque found in the present study will be useful for basic studies of plaque stabilization and prevention of acute coronary syndromes.     

Assessment of carotid plaque vulnerability using structural and geometrical determinants

BACKGROUND: Because many acute cerebral ischemic events are caused by rupture of vulnerable carotid atheroma and subsequent thrombosis, the present study used both idealized and patient-specific carotid atheromatous plaque models to evaluate the effect of structural determinants on stress distributions within plaque. METHODS AND RESULTS: Using a finite element method, structural analysis was performed using models derived from in vivo high-resolution magnetic resonance imaging (MRI) of carotid atheroma in 40 non-consecutive patients (20 symptomatic, 20 asymptomatic). Plaque components were modeled as hyper-elastic materials. The effects of varying fibrous cap thickness, lipid core size and lumen curvature on plaque stress distributions were examined. Lumen curvature and fibrous cap thickness were found to be major determinants of plaque stress. The size of the lipid core did not alter plaque stress significantly when the fibrous cap was relatively thick. The correlation between plaque stress and lumen curvature was significant for both symptomatic (p=0.01; correlation coefficient: 0.689) and asymptomatic patients (p=0.01; correlation coefficient: 0.862). Lumen curvature in plaques of symptomatic patients was significantly larger than those of asymptomatic patients (1.50+/-1.0 mm(-1) vs 1.25+/-0.75 mm(-1); p=0.01). CONCLUSION: Specific plaque morphology (large lumen curvature and thin fibrous cap) is closely related to plaque vulnerability. Structural analysis using high-resolution MRI of carotid atheroma may help in detecting vulnerable atheromatous plaque and aid the risk stratification of patients with carotid disease.     

Echolucent carotid plaques predict in-stent restenosis after bare metal stenting in native coronary arteries

Echolucent carotid plaque is considered to predict coronary events. This study examined whether echolucent carotid plaque may predict in-stent restenosis (ISR) in coronary arteries. This study included 202 patients who had elective and successful percutaneous coronary intervention (PCI) with bare metal stents in de novo lesions of native coronary arteries for symptomatic coronary artery disease (CAD). Carotid plaque echolucency was assessed by ultrasound with integrated backscatter (IBS) analysis (intima-media IBS value minus adventitia IBS) 1 day before PCI. All patients underwent planned coronary angiography (CAG) at 6 months after PCI, or CAG before 6 months due to acute coronary syndromes. ISR (defined as >50% diameter stenosis) was found in 65 (32%) patients. The calibrated IBS values of carotid plaques were inversely correlated with late luminal loss of the stented lesions. Using multivariate logistic regression analysis, the presence of echolucent carotid plaques (相似文献   

Atherothrombosis: plaque instability and thrombogenesis

Hemostasis involves a carefully regulated balance between circulating and endothelium-derived prothrombotic and antithrombotic factors. The unstable or vulnerable plaque facilitates thrombosis, clinically manifest as an acute coronary syndrome (ACS), by creating an environment that favors thrombus formation over prevention of lysis. Endothelial cell dysfunction is integral to both the development of the atherosclerotic lesion as well as its destabilization. The transformation of a stable plaque to an unstable one involves complex interactions among T lymphocytes, macrophages, endothelial cells, and smooth muscle cells. Degradation of the fibrous cap of the atherosclerotic lesion as well as the overexpression of prothrombotic and underexpression of antithrombotic factors by cells within the plaque precede thrombus formation. Accordingly, pharmacological interventions for the treatment of ACS are directed against the initiation and propagation of thrombosis, as well as toward improvement of endothelial function.     

家兔颈总动脉不稳定斑块模型的建立

目的 建立家兔颈总动脉斑块模型。方法 选取60只雄性纯种的新西兰大白兔,随机分为3组,即球囊损伤+高脂组、高脂喂养组及普通饲料喂养组,每组20只。喂养12周后,分别给予中国斑点蝰蛇毒和组胺药物触发,诱发斑块破裂及血栓形成。结果 球囊损伤+高脂组存活17只白兔中,有38处病变狭窄程度超过50％,并且脂质核心较大、纤维帽的厚度小于65 μm,故判定以上38处病变为易损斑块。高脂喂养组中的19只白兔仅8处可判定为易损斑块;普通饲料喂养组中未见易损斑块。结论 高脂饮食饲养后,进行颈总动脉球囊拉伤制作兔易损斑块模型是切实可行的方法。     

Intravascular Palpography for High-Risk Vulnerable Plaque Assessment

BACKGROUND: The composition of an atherosclerotic plaque is considered more important than the degree of stenosis. An unstable lesion may rupture and cause an acute thrombotic reaction. Most of these lesions contain a large lipid pool covered by an inflamed thin fibrous cap. The stress in the cap increases with decreasing cap thickness and increasing macrophage infiltration. Intravascular ultrasound (IVUS) palpography might be an ideal technique to assess the mechanical properties of high-risk plaques. TECHNIQUE: Palpography assesses the local mechanical properties of tissue using its deformation caused by the intraluminal pressure. IN VITRO VALIDATION: The technique was validated in vitro using diseased human coronary and femoral arteries. Especially between fibrous and fatty tissue, a highly significant difference in strain (p = 0.0012) was found. Additionally, the predictive value to identify the vulnerable plaque was investigated. A high-strain region at the lumen-vessel wall boundary has an 88% sensitivity and 89% specificity for identifying such plaques. IN VIVO VALIDATION: In vivo, the technique was validated in an atherosclerotic Yucatan minipig animal model. This study also revealed higher strain values in fatty than fibrous plaques (p < 0.001). The presence of a high-strain region at the lumenplaque interface has a high predictive value to identify macrophages. PATIENT STUDIES: Patient studies revealed high-strain values (1-2%) in thin-cap fibrous atheroma. Calcified material showed low strain values (0-0.2%). With the development of three-dimensional (3-D) palpography, identification of highstrain spots over the full length of a coronary artery becomes available. CONCLUSION: Intravascular palpography is a unique tool to assess lesion composition and vulnerability. The development of 3-D palpography provides a technique that may develop into a clinical tool to identify the high-risk plaque.     

Tenascin-C is associated with coronary plaque instability in patients with acute coronary syndromes.

BACKGROUND: Tenascin-C (TNC) is an extracellular matrix glycoprotein that increases after inflammation and injury. In cultured cells TNC has been reported to markedly induce the expression of matrix metalloproteinase-9, which stimulates collagen degradation in the fibrous cap of human atherosclerotic plaque. METHODS AND RESULTS: Immunohistochemical techniques were used to analyze the expression of TNC protein in 51 coronary atherectomy specimens obtained from patients with stable angina pectoris (SAP, n=23) or acute coronary syndromes (ACS) (n=28; unstable angina pectoris, n=20, acute myocardial infarction, n=8). Immunostaining for alpha-smooth muscle actin, CD68, CD45, and CD31 was also performed in serial sections to identify the cell types that express TNC protein. The %TNC + area (percentage of the area of immunostaining for TNC protein in the total surface area of the plaque) was larger in coronary samples with the plaque characteristics of thrombus, angiogenesis, intraplaque hemorrhage, and macrophage (CD68(+)), and lymphocyte (CD45 (+)) clusters than in coronary samples without them (52+/-3.4 vs 39+/-4.8, p<0.05; 57+/-3.7 vs 36+/-3.7, p<0.01; 51+/-3.6 vs 39+/-4.8, p<0.05; 53+/-3.4 vs 33+/-4.5, p<0.01; 56+/-4.1 vs 37+/-3.6, p<0.01, respectively). The presence of other components, such as dense fibrous tissue, neointimal hyperplasia, atheromatous gruel and calcification, was not significantly correlated with the %TNC + area. The %TNC + area was larger in coronary samples from patients with ACS than in samples from patients with SAP (56+/-3.2% vs 34+/-4.3%, p<0.01). CONCLUSIONS: The results suggest that TNC may have specific functions in coronary plaque formation and may be involved in the pathogenesis of coronary lesions in ACS.     

Characterization of signal properties in atherosclerotic plaque components by intravascular MRI

Magnetic resonance imaging (MRI) is capable of distinguishing between atherosclerotic plaque components solely on the basis of biochemical differences. However, to date, the majority of plaque characterization has been performed by using high-field strength units or special coils, which are not clinically applicable. Thus, the purpose of the present study was to evaluate MRI properties in histologically verified plaque components in excised human carotid endarterectomy specimens with the use of a 5F catheter-based imaging coil, standard acquisition software, and a clinical scanner operating at 0.5 T. Human carotid endarterectomy specimens from 17 patients were imaged at 37 degrees C by use of an opposed solenoid intravascular radiofrequency coil integrated into a 5F double-lumen catheter interfaced to a 0.5-T General Electric interventional scanner. Cross-sectional intravascular MRI (156x250 microm in-plane resolution) that used different imaging parameters permitted the calculation of absolute T1and T2, the magnetization transfer contrast ratio, the magnitude of regional signal loss associated with an inversion recovery sequence (inversion ratio), and regional signal loss in gradient echo (gradient echo-to-spin echo ratio) in plaque components. Histological staining included hematoxylin and eosin, Masson's trichrome, Kossa, oil red O, and Gomori's iron stain. X-ray micrographs were also used to identify regions of calcium. Seven plaque components were evaluated: fibrous cap, smooth muscle cells, organizing thrombus, fresh thrombus, lipid, edema, and calcium. The magnetization transfer contrast ratio was significantly less in the fibrous cap (0.62+/-13) than in all other components (P<0.05) The inversion ratio was greater in lipid (0.91+/-0.09) than all other components (P<0.05). Calcium was best distinguished by using the gradient echo-to-spin echo ratio, which was lower in calcium (0.36+/-0.2) than in all plaque components, except for the organizing thrombus (P<0.04). Absolute T1 (range 300+/-140 ms for lipid to 630+/-321 ms for calcium) and T2 (range 40+/-12 ms for fresh thrombus to 59+/-21 ms for smooth muscle cells) were not significantly different between groups. In vitro intravascular MRI with catheter-based coils and standard software permits sufficient spatial resolution to visualize major plaque components. Pulse sequences that take advantage of differences in biochemical structure of individual plaque components show quantitative differences in signal properties between fibrous cap, lipid, and calcium. Therefore, catheter-based imaging coils may have the potential to identify and characterize those intraplaque components associated with plaque stability by use of existing whole-body scanners.     

静脉注射间充质干细胞对兔颈动脉易损斑块的影响

目的探讨静脉注射骨髓间充质干细胞(MSC)对动脉粥样硬化易损斑块(VP)稳定性的影响。方法选择雄性新西兰大白兔30只,随机分为MSC组,VP组,稳定斑块(SP)组,每组10只。分别于细胞移植后3d、1周、2周采集兔血清,ELISA法检测血清高敏C反应蛋白(hs-CRP)、TNF-α、白细胞介素6(IL-6),白细胞介素10(IL-10)水平。10周末处死所有动物,取右侧颈总动脉分别行HE染色观察镜下病变,并测量纤维帽/脂核横截面厚度的比值。结果 SP组粥样硬化斑块形态结构完整,纤维帽较厚,斑块内炎性细胞较少,未见斑块破裂。VP组斑块中心可见大量脂核,表面覆盖较薄纤维帽,肩部可见残存泡沫细胞和大量炎性细胞浸润,部分斑块可见破裂和(或)血栓形成。MSC组形态介于之间。MSC组和SP组纤维帽/脂核比值明显高于VP组(P<0.01)。与VP组比较,MSC组各时间点hs-CRP、TNF-α和IL-6水平明显降低,IL-10水平明显升高(P<0.05,P<0.01);与SP组比较,MSC组和VP组各时间点hs-CRP、TNF-α、IL-6和IL-10水平明显升高(P<0.05,P<0.01)。结论 MSC可降低斑块不稳定性,其机制可能与降低机体炎性因子水平、增加抑炎因子及减轻炎性反应有关。     

Clinical utility of carotid ultrasonography: Application for the management of patients with diabetes

Carotid ultrasonography is a non‐invasive, simple and inexpensive modality to assess the severity of atherosclerosis. This article reviews related articles, summarizes the rationale for the application of carotid ultrasonography in clinical practice, and addresses the features and the limitations of carotid ultrasonography in cardiovascular risk prediction. Numerous large studies have confirmed that various carotid ultrasound measures, such as carotid intima‐media thickness, the presence or absence of carotid plaque, plaque number and plaque area, can be independent predictors of cardiovascular diseases in individuals with and without diabetes mellitus. Furthermore, many studies showed that the use of carotid intima‐media thickness (especially maximum intima‐media thickness, including plaque thickness) and/or carotid plaque in addition to traditional risk factors significantly improved the prediction of the occurrence of cardiovascular diseases, while controversy remains. Several studies showed that the progression of carotid intima‐media thickness also can be a surrogate end‐point of cardiovascular events. However, the accumulated evidence has not been sufficient. Further study with sufficient power should be carried out. As plaque disruption, which plays a crucial role in the pathogenesis of cardiovascular events, is dependent on the content of lipid in the atheroma and the thickness of the fibrous cap, tissue characterization of a plaque might be useful for determining its fragility. Interestingly, recent studies have shown that ultrasonic tissue characterization of carotid lesions could improve the prediction ability of future cardiovascular diseases. Thus, carotid ultrasonography is a useful modality for better clinical practice of atherosclerosis in patients with diabetes.     

Ultrasonic backscatter of the carotid wall in young and older athletes

OBJECTIVES: The aim of this study was to evaluate the effects of habitual exercise on the age-related changes of carotid wall composition defining its acoustic reflectivity by the quantitative approach of integrated backscatter (IBS) analysis. DESIGN: Cross-sectional study. SETTING: University Hospital. SUBJECTS: Fifty-four competitive long-distance runners (males, age range 22-72 years) and 50 healthy sedentary controls. MAIN OUTCOME MEASURES: All the subjects underwent both 2-D conventional ultrasonography and IBS analysis. IBS values were sampled from a region of interest (ROI) placed within five consecutive regions of the common carotid intima-media, and then corrected (C-IBS) for the IBS value of the adventitia. RESULTS: Athletes showed a lower C-IBS (-27.07 +/- 2.9 dB vs. -24.57 +/- 4 dB, P < 0.0001) and a smaller intima-media thickness (IMT: 0.64 +/- 0.16 mm vs. 0.78 +/- 0.21 mm, P < 0.001) respect to sedentary controls. By selecting the lowest (<30 years of age) and the highest (>60 years of age) tertile of age, we assess the influence of age on IMT and IBS. Sedentary older individuals exhibited an IMT higher respect to young controls and to the both trained subgroups (P < 0.0001). C-IBS was lower in both subgroups of athletes, independently of age, and lower in sedentary young people respect to sedentary older subgroup (P < 0.0001). Endurance chronic exercise blunted the difference of C-IBS observed between young and older sedentary individuals. Moreover, C-IBS was positively related to age (r = 0.77, P < 0.0001) and IMT (r = 0.52, P < 0.0001). CONCLUSIONS: The age-related changes of the arterial wall are attenuated by physical training. These modifications can be quantitatively discriminated by ultrasonic backscatter method.     

光学相干断层扫描比较不稳定性和稳定性心绞痛患者粥样硬化斑块特征

目的 应用光学相干断层成像(OCT)技术比较不稳定性心绞痛(UAP)和稳定性心绞痛(SAP)患者冠状动脉粥样硬化斑块特征.方法 对临床诊断的23例UAP和24例SAP患者,在完成冠状动脉造影并确诊冠心病后进行OCT检查.根据OCT结果 回顾性比较分析UAP和SAP患者冠状动脉粥样硬化斑块特征,包括富含脂质斑块(≥2个象限的脂质斑块)、斑块纤维帽厚度、薄纤维帽粥样斑块(TCFA)、斑块破裂、钙化和血栓等.结果 47例患者中有44例成功进行OCT检查,包括22例UAP和22例SAP患者.UAP患者冠状动脉富含脂质斑块为91%(20/22),多于SAP患者的73%(16/22),但差异无统计学意义(P=0.741).UAP患者冠状动脉脂质斑块表面纤维帽厚度明显小于SAP患者[(69.5±34.7)μm比(141.1±68.5)μm,P=0.000],纤维帽侵蚀比例为59%(13/22),明显多于SAP患者的9%(2/22,P=0.000);TCFA[73%(16/22)比14%(3/22),P=0.000]和斑块破裂[50%(11/22)比9%(2/22),P=0.003]多于SAP患者.UAP患者冠状动脉斑块表而可见血栓形成多于SAP患者,但差异无统计学意义[27%(6/22)比9%(2/22),P=0.761].在斑块钙化方面,UAP与SAP患者之间差异无统计学意义.结论 OCT技术可清晰显示冠状动脉粥样斑块特征.与SAP患者比较,UAP患者冠状动脉粥样硬化斑块表现为纤维帽更薄、更多的纤维帽侵蚀、更多的破裂斑块和TCFA.     

Inflammation and Plaque Vulnerability

Development of a thrombus at the site of an atherosclerotic plaque initiates abrupt arterial occlusion and is the proximate event responsible for the vast majority of acute ischemic syndromes. In nearly 75% of cases thrombus overlies a disrupted or ruptured plaque whereas the remainder of the thrombi overly an intact plaque with superficial endothelial erosion. Over the past several years, it has been recognized that plaque composition rather than plaque size or stenosis severity is important for plaque rupture and subsequent thrombosis. Ruptured plaques, and by inference, plaques prone to rupture, tend to be large in size with associated expansive arterial remodeling, thin fibrous cap with a thick or large necrotic lipid core with immuno-inflammatory cell infiltration in fibrous cap and adventitia and increased plaque neovascularity and intraplaque hemorrhage. The size of the necrotic lipid core and extent and location of plaque inflammation appear to be key factors in determining plaque instability. Inflammation and immune cell activation appears to play a key role in the loss of collagen in the fibrous cap, a prelude to fibrous cap rupture, through release of collagen degrading enzymes. Furthermore, inflammation may also play a key role in the death of collagen synthesizing smooth muscle cells which further contributes to loss of fibrous cap integrity. Inflammation also is likely a key player in the ensuing thrombosis that follows plaque disruption through the elaboration of the pro-coagulant protein, tissue factor. An improved understanding of the pathophysiology of plaque vulnerability and subsequent athero-thrombosis should provide novel insights into improved prevention of athero-thrombotic cardiovascular events.