Plaque surface and microembolic signals in moderate carotid stenosis

We performed Transcranial Doppler Monitoring to detect microembolic signals (MES) in 47 patients with moderate (30%-69%) carotid stenosis proven by selective angiography. We compared the occurrence of MES with the clinical characteristics of stenosis (symptomatic or asymptomatic) and the angiographic plaque features (nonulcerated, deep ulceration, superficial ulceration, ulceration with flap, or ulceration without flap). For these cases there was no indication for endarterectomy, nevertheless we thought it would be useful to identify risk subgroups that might benefit from surgical treatment. MES were detected in 17.9% of the stenoses with a prevalence (p <. 01) in symptomatic cases (25%) compared to asymptomatic cases (14. 3%). There was a significant correlation of MES with plaque ulceration (p <.01) and particularly with ulceration without flap (p <.01). No difference between deep and superficial ulceration was observed. The availability of prospective data on this topic might be useful to select subgroups of patients with moderate carotid stenosis at risk for embolism.     

Site of carotid plaque ulceration in relation to direction of blood flow: an angiographic and pathological study

BACKGROUND: Rupture of atherosclerotic plaque is the main cause of acute coronary syndromes and carotid territory ischaemic stroke. Haemodynamic stress is important in early plaque formation and may affect the stability of mature plaques. There is some evidence that macrophage infiltration and plaque rupture tend to localise to the proximal (upstream) part of the plaque where shear stress is highest. However, previous studies have been too small to assess this reliably. We studied the site of ulceration in a large number of carotid plaques. METHODS: We studied angiograms of 3007 symptomatic carotid stenoses, and the pathological appearance of 119 carotid plaques (77 asymptomatic), to identify the presence and position of plaque ulceration. RESULTS: Angiographic ulceration, which was present in 421 patients (14%), was more likely to be PROXIMAL than DISTAL to the point of maximum stenosis (OR = 16.6, 95% CI = 11.6-26.9, p < 0.001). This trend increased with severity of stenosis (p = 0.002). Pathological examination of the 119 carotid plaques also showed that ulceration was more likely to occur proximal to the point of maximum stenosis (OR = 6.1, 95% CI = 2.8-13.6, p < 0.001). CONCLUSIONS: Ulceration of carotid plaques, visible on angiography or on pathological examination, is seen most often in the proximal (upstream) part where shear stress is highest.     

Ultrasonogram of carotid artery in endoarterectomy patients]

Ultrasonograms of the carotid artery were compared with the intraoperative finding of atheroma plaque in terms of stenosis, fragility, ulceration and calcification. Soft type, intermediate type and these mixed type plaques were fragile plaques in almost all cases. All hard type plaques were tough plaques. The detection of stenosis and calcification was satisfactory, however that of ulceration was not sufficient. The stenotic lesions frequently existed in bilateral carotid arteries and the intima was easy to become thick even after the endoarterectomy. The ultrasonogram was thought to be the essential study for the carotid artery lesions.     

Asymptomatic bruit, carotid and vertebrobasilar transient ischemic attacks--a clinical and ultrasonic correlation

One hundred patients with asymptomatic carotid bruit or transient ischemic attack (TIA) underwent continuous-wave Doppler (CWD) and real time ultrasound (RTU) testing of their cervical carotid arteries. After ultrasonic studies, 51 patients also underwent bilateral carotid angiography. There was 95% agreement between CWD and angiography for the diagnosis of a significant (greater than 50%) stenosis. The RTU diagnosis of a normal or occluded vessel was correct in 100% of cases. Seven plaques appreciated on RTU may not have been large enough for detection by angiography. In this small series, ulceration confirmed pathologically was more reliably predicted by RTU than by cerebral angiography. Significant ipsilateral carotid plaques occurred more often in patients with amaurosis fugax than in patients with hemispheric TIAs. Ipsilateral plaque ulceration occurred in 50% of symptomatic carotid bruits, but in only 10% of asymptomatic carotid bruits. Plasma concentrations of total cholesterol were significantly higher in TIA patients with carotid stenosis than in controls.     

Atherosclerotic carotid disease in asymptomatic individuals

The carotid bifurcation was studied histologically in 53 consecutive autopsies from persons over 65 years of age who were asymptomatic for carotid artery disease and showed no carotid related brain infarcts. The autopsy material is considered to be representative for the population in Oslo. The area stenosis was determined morphometrically in histological sections and the cases were examined for the occurrence of atherosclerotic plaques, calcifications, plaque hemorrhages, ulcerations, and mural thrombi. About one half of the cases had more than 50% stenosis. There was increasing frequency of plaque hemorrhages, ulcerations and mural thrombi with increasing stenosis. When the stenosis exceeded 60%, most cases had small recent and old plaque hemorrhages and one half had ulcerations and mural thrombi. In addition, numerous healed ulcerations and organized thrombi were seen. It is concluded that plaque complications are frequent in cases with stenosis and that most of them apparently heal without giving rise to symptoms. The presence of such lesions in asymptomatic cases must therefore be interpreted with caution.     

Blood Flow Pattern Analysis for Carotid Plaque Evaluation

Background and PurposePrevious studies suggested that turbulent flow is closely related to plaque vulnerability. Two-dimensional (2D) flow analysis is a novel modality that enables real-time blood flow analysis by picturing particle movement in the contrast medium. We evaluated flow patterns in the carotid plaque to investigate the correlation between blood flow and plaque vulnerability.Material and MethodsA total of 36 consecutive patients with cervical carotid artery stenosis were evaluated. The flow pattern of carotid artery stenosis was evaluated using 2D real-time flow analysis in the digital subtraction angiography (DSA). The flow pattern was classified into either turbulent or laminar flow as vectors. Plaque vulnerability was evaluated on MR plaque imaging. Univariate analysis was performed to assess the correlation between the flow pattern and plaque features.ResultsThe turbulent pattern was identified in 28 of 36 plaques (77.8%). Turbulence around plaques was significantly associated with Gadolinium enhancement (P = .0004). The maximum degree of stenosis (P = .0005) and concomitant ulceration (P = .02) were significantly associated with the turbulent pattern. There was no relationship between the turbulent pattern and clinical neurological symptoms.ConclusionsIn the present study, the majority of carotid plaques exhibited a turbulent flow pattern, which was significantly associated with Gadolinium enhancement on MR plaque imaging and morphologic factors. Thus, real-time flow analysis may clarify the pathophysiology of plaque instability and the formation of ulceration.     

A clinico-pathologic study of carotid endarterectomy plaques

Carotid endarterectomy specimens surgically removed in one piece were kept intact, processed pathologically, and serially sectioned at 8 microns. There were 34 cases with multiple hemispheric transient ischemic attacks (TIAs), 23 cases with multiple episodes of transient monocular blindness (TMBs), 33 asymptomatic cases, and 51 cases with prolonged or persisting neurologic deficits. The occurrence of TIAs and TMBs correlated best with severe carotid stenosis (1 mm. or less), less well with the presence of mural thrombus, and not at all with ulceration of plaque and intraplaque hemorrhage. The residual lumen in asymptomatic cases was wider. The persistence of neurologic deficits correlated best with carotid occlusion or near-occlusion (37 of 51). In only 3 cases was there evidence of embolism from ulceration with minor stenosis. There were many variations in the size, form, composition, site, and number of mural thrombi, ulcerations, and hemorrhages; to provide an accurate picture, serial sections are necessary. Large rounded cavities in plaques sometimes were empty, smooth-lined cul-de-sacs rather than eroding ulcerations (16 cases). Mural thrombi are probably not an important source of embolism. Ulceration and hemorrhage into plaque posed little or no threat in the present series. Using the pathologic and clinical data, inferences have been made concerning the relative frequency of embolism and hemodynamic failure in the mechanism of the varied events associated with carotid occlusion. Observations have been made on a few additional points--selective involvement of the lower extremity, prolonged TIAs, the onset of symptoms during sleep, unusual motor disorders, the occurrence of headache, retinal embolism and progression of stenosis.     

Microembolic signals and carotid plaque morphology: a study of 71 patients with moderate or high grade carotid stenosis

OBJECTIVES: To determine whether particular carotid plaque features on ultrasound are more likely to produce microembolic signals (MES). PATIENTS AND METHODS: We have reviewed 71 patients with moderate or high grade carotid stenosis established by ultrasound (30-99%). Plaque appearance was classified according to five subtypes. Transcranial monitoring of the middle cerebral arteries was performed on each patient. RESULTS: MES were more frequently encountered in patients with anechogenic/hypoechogenic plaques compared with isoechogenic/hyperechogenic lesions (P < 0.01). MES+ patients presented also more frequently an irregular surface of the plaque and more severe stenosis, however, the differences did not reach significance. There was no relationship between the presence of MES and a history of stroke or transient ischaemic attack (TIA). When considering the different above mentioned variables (logistic regression), only plaque morphology appeared to be a risk factor for the presence of MES. CONCLUSION: MES+ patients presented a significantly increased frequency of anechogenic/hypoechogenic plaques. As MES may be a marker of increased risk of stroke, the clinical significance of this particular association should be further investigated.     

Computed tomographic evaluation of cervical carotid plaque complications

Twenty five patients with manifestations of cerebrovascular ischemic disease were evaluated with high resolution computed tomography of the neck, following intravenous infusion of a contrast agent. Computed tomography images of extracranial carotid arteries revealed atherosclerotic plaque formations and their complications: stenosis, occlusion, ulceration, calcification and mural lucent defects. Histologic analysis of 15 endarterectomy specimens obtained from symptomatic patients who had computed tomography images of discrete lucent defects in carotid plaques demonstrated subintimal hemorrhage of varying age in 13, focal necrosis in 1 and excessive subintimal thickening in 1. It is concluded that lucent images observed in computed tomography of extracranial carotid arteries represent vascular wall lesions within carotid plaques suggestive of subintimal hemorrhage, focal necrosis and/or excessive subintimal thickening. Computed tomography of the extracranial carotid arteries is a relatively non-invasive method that permits the diagnosis of plaque hemorrhages in symptomatic and asymptomatic carotid arteries.     

Duplex scanner versus conventional arteriography for carotid artery disease evaluation

In order to evaluate extracranial circulation, Duplex scanning and conventional angiography were performed. The group of 41 patients (mean age 53.8 +/- 11.8, 71% male) were examined. Results were analyzed for extracranial disease presence such as presence of vessel stenosis (mild, moderate, severe), occlusion and presence of plaques. Data from Duplex scanning and carotid arteriography were correlated within the patients in the term of sensitivity and specificity of the methods used. The sensitivity of Duplex scanning for disease presence was 93% and specificity was 83%. For the presence of stenosis, sensitivity was 79% and specificity was 62%. For mild and moderate stenosis (less than 50% of lumen narrowing) sensitivity was 63%, whereas for severe, high-grade stenosis (greater than 50%) and occlusion the sensitivity was 100%. For the plaque presence the sensitivity was 52% and specificity was 73%. A good accordance of plaque findings with both methods was found only in 24% of patients. By Duplex scanner the plaques were discovered in 92% of patients while by arteriography they were found only in 32%. Duplex scanning and conventional arteriography are both accurate methods for determination of the reduction in diameter of carotid arteries (especially in stenosis greater than 50%), whereas Duplex scanning is more accurate for plaque detection and plaque characterisation.     

Greater burden of white matter lesions and silent infarcts ipsilateral to carotid stenosis

ObjectivesCarotid stenosis may cause silent cerebrovascular disease (CVD) through atheroembolism and hypoperfusion. If so, revascularization may slow progression of silent CVD. We aimed to compare the presence and severity of silent CVD to the degree of carotid bifurcation stenosis by cerebral hemisphere.Materials and methodsPatients age ≥40 years with carotid stenosis >50% by carotid ultrasound who underwent MRI brain from 2011-2015 at Mayo Clinic were included. Severity of carotid stenosis was classified by carotid duplex ultrasound as 50-69% (moderate), 70-99% (severe), or occluded. White matter lesion (WML) volume was quantified using an automated deep-learning algorithm applied to axial T2 FLAIR images. Differences in WML volume and prevalent silent infarcts were compared across hemispheres and severity of carotid stenosis.ResultsOf the 183 patients, mean age was 71±10 years, and 39.3% were female. Moderate stenosis was present in 35.5%, severe stenosis in 46.5% and occlusion in 18.0%. Patients with carotid stenosis had greater WML volume ipsilateral to the side of carotid stenosis than the contralateral side (mean difference, 0.42±0.21cc, p=0.046). Higher degrees of stenosis were associated with greater hemispheric difference in WML volume (moderate vs. severe; 0.16±0.27cc vs 0.74±0.31cc, p=0.009). Prevalence of silent infarct was 23.5% and was greater on the side of carotid stenosis than the contralateral side (hemispheric difference 8.8%±3.2%, p=0.006). Higher degrees of stenosis were associated with higher burden of silent infarcts (moderate vs severe, 10.8% vs 31.8%; p=0.002).ConclusionsWML and silent infarcts were greater on the side of severe carotid stenosis.     

Sonographic characterisation of radiation-induced carotid artery stenosis

BACKGROUND AND PURPOSE: To study the distribution, extent and sonographic characterisation of radiation-induced carotid artery stenosis in nasopharyngeal carcinoma (NPC) patients. METHODS: The distribution of plaques, the extent of stenosis, and the sonographic characterisation of the plaque at maximum stenosis were recorded in 71 NPC patients. The results were compared with the ultrasound results of a control group of 142 patients presenting with symptoms of cerebrovascular disease or carotid bruit. RESULTS: NPC patients had a higher incidence of carotid stenosis (77 vs. 50.7%). The common carotid arteries were most commonly affected by radiation-induced stenosis (93/142 vs. 37/284 in the control group), whereas the carotid bulb was the most commonly affected (56/284) site in the control group. Significantly more NPC patients had moderate-to-severe stenosis (21/71 vs. 27/142). Analysis of the sonographic appearance of radiation-induced and atherosclerotic plaques showed more diffuse involvement in the post-radiation group. Non-calcified plaques and intraplaque hypoechoic foci were also more frequent in the post-radiation group. CONCLUSIONS: Radiation-induced carotid stenosis is more diffuse in distribution, is associated with more severe luminal stenosis and has different sonographic plaque characterisation compared with carotid stenosis without radiation exposure.     

超声观察颈动脉粥样硬化斑块纤维帽完整性的临床价值简

目的回顾分析单侧前循环急性脑卒中患者颈动脉超声检查结果,探讨粥样硬化斑块纤维帽完整性对斑块稳定性的影响。方法通过彩色多普勒超声长轴和短轴观察并记录颈动脉管壁、粥样硬化斑块及纤维帽完整性,以及单侧颈动脉低、中等和强回声斑块数目,判断狭窄动脉血流动力学变化。结果86例患者共检出粥样硬化斑块215个,共77例患者发现纤维帽不完整,72例存在低回声斑块,仅5例检出中等回声斑块（x^2=37．703,P=0．000）。其中患侧纤维帽不完整者46例、健侧31例（x^2=5．291,P=0．021）;患侧检出低回声斑块者56例、健侧44例（x^2=0．168,P=0．682）。共计发现颈动脉狭窄15例,均为低回声斑块所致,分别发生于颈内动脉起始部（10例）、颈动脉分叉部（4例）、颈外动脉（1例）,以颈动脉分叉部（8．16％,4／49）与颈内动脉起始部（27．03％,10／37）之间差异具有统计学意义（x^2=3．900,P=0．048）。结论动脉粥样硬化斑块纤维帽完整性与脑卒中关系密切。纤维帽不完整的粥样硬化斑块以低回声斑块为主,通过超声波评价斑块回声及其表面纤维帽完整性,可以判断斑块稳定性,而观察斑块纤维帽完整性较单纯评价斑块回声特点更具临床价值。     

The symptomatic carotid plaque

BACKGROUND: The natural histories of equally severe symptomatic and asymptomatic carotid stenoses are very different, which suggests dichotomy in plaque behavior. The vascular biology of the symptomatic carotid plaque is presented in this review. SUMMARY OF REVIEW: Histology studies comparing asymptomatic and symptomatic plaques were identified from MEDLINE. Reports in which stenosis severity was not stated or not similar for symptomatic and asymptomatic patients were excluded. In vitro studies and reports from the coronary circulation were reviewed with regard to the vascular biology of the plaque. Histology studies comparing carotid plaques removed from symptomatic and asymptomatic patients reveal characteristic features of unstable plaques: surface ulceration and plaque rupture (48% of symptomatic compared with 31% of asymptomatic, P<0.001), thinning of the fibrous cap, and infiltration of the cap by greater numbers of macrophages and T cells. In vitro studies suggest that macrophages and T cells release cytokines and proteinase, which stimulate breakdown of cap collagen and smooth muscle cell apoptosis and thereby promote plaque rupture. CONCLUSIONS: Infiltration of inflammatory cells to the surface of carotid plaques may be a critical step in promoting plaque rupture and resultant embolization or carotid occlusion. Further understanding of cell recruitment and behavior in carotid atherosclerosis may allow better detection of unstable plaques and therapeutic methods of plaque stabilization.     

Assessment of ophthalmic artery collateral pathway in the hemispheric cerebral hemodynamics in patients with severe unilateral carotid stenosis

The role of ophthalmic artery collateral pathway in hemispheric hemodynamics in patients with severe carotid stenosis is controversial. The aim of the present study was to address this question comparing the asymmetry of the velocity in middle and anterior cerebral arteries (MCAs and ACAs) and cerebrovascular reactivity (CVR) in MCA on stenotic side in the patients with unilateral severe stenosis of internal carotid artery (ICA) in patients with and without ophthalmic artery collateral pathway. The cohort of 118 patients with carotid stenosis was prospectively assembled. Fifty patients who had severe unilateral ICA stenosis (71%-99%) by Duplex Ultrasound (DUS) were observed by transcranial Doppler (TCD). Cerebral blood flow velocity in MCA and ACA in both sides, direction of blood flow in ophthalmic artery (OA) and CVR on the side of stenosis were determined. There were 14 patients with retrograde blood flow in OA (Group I). The remaining 36 patients with anterograde flow in OA composed Group II. The degree of interarterial asymmetry of peak and mean velocity (Vpeak and Vmean) in MCA and ACA and CVR in MCA were compared in both groups. The degree of ACA asymmetry by Vpeak was 44.0% +/- 6.9% in Group I and 38.3% +/- 3.9% in Group II (p = 0.49), by Vmean 40.3% +/- 6.7% and 36.6% +/- 3.8% (p = 0.63) respectively. The degree of MCA asymmetry by Vpeak was 24.2% +/- 2.8% in Group I and 19.5% +/- 5.0% in Group II (p = 0.42), by Vmean 23.5% +/- 2.9% and 20.6% +/- 5.1% (p = 0.63) respectively. CVR in Group I was 26.1% +/- 6.1%, in Group II 29.0% +/- 6.7% (p = 0.65). The ophthalmic collateral pathway has no influence on hemispheric cerebral hemodynamics in patients with severe unilateral carotid stenosis.     

电子束CT血管造影、B型超声与DSA诊断颅外颈动脉狭窄的对照研究

目的探讨电子束CT血管造影（EBCTA）和B型超声（BUS）检查诊断颈动脉狭窄闭塞性疾病的准确性.方法对10例（20根）颅外颈动脉进行EBCTA、DSA和BUS对照研究.结果EBCTA与DSA的吻合率达95%,r=0.9935;BUS与DSA的吻合率仅为65%,r=0.8333,P=0.001.针对以70%～99%狭窄度为绝对手术指征,EBCTA的敏感性、特异性、准确性、阳性和阴性预测值均为100%,BUS则分别为33%、94%、85%、50%和89%.结论EBCTA诊断颅外颈动脉疾病有明显的优越性和可行性,且与DSA有互补作用;BUS对斑块溃疡具高度敏感性,但单独使用有漏诊和误诊的可能,需与EBCTA或DSA结合应用.     

Microembolic signals and intraoperative stroke in carotid endarterectomy

Objectives – Microembolic signals (high-intensity transient signals, HITS) detected by means of transcranial Doppler sonography (TCD) may be relevant for intraoperative strokes in carotid endarterectomy (CEA). Material and methods – An intraoperative HITS detection study was performed on 77 patients (63 men, 14 women, mean age±SD, 64±8 years) with a total of 81 CEAs. Using the Scandinavian Stroke Scale the patients were clinically examined by a neurologist preoperatively and postoperatively within 6 h. A deterioration of the Scandinavian Stroke Scale was considered an intraoperative stroke if persisting longer than 24 h. Cranial computed tomography (CT scan) was performed preoperatively and 3 to 5 days postoperatively. By means of TCD total HITS count and mean blood velocity changes, for shunting, were recorded sufficiently in the middle cerebral artery in 79 CEAs. Results – HITS were significantly more frequent in symptomatic [ n =53; HITS: median, 15 (range 1–159)] than in asymptomatic stenoses [ n =26; HITS: 6.5 (0–41); P < 0.001]. An intraoperative stroke in the hemisphere ipsilateral to the operation occurred in eight of the 81 CEAs. On postoperative CT scans, five of the eight strokes showed new corresponding territorial infarctions. In the three strokes without new CT lesions, the mean blood velocity changes after clamping indicated normal cerebral perfusion. Total HITS count was significantly higher in procedures with intraoperative strokes [ n =8; HITS: 33 (11–159)] than in the uncomplicated [ n =71; HITS: 10 (0–62); P =0.002]. No stroke occurred in 37 CEAs with 10 or less HITS, but eight in 42 CEAs with 11 or more HITS [ P =0.006; relative risk 1.23 (95% confidence interval: 1.06 to 1.43)]. Conclusion – Microembolism seems clinically relevant in carotid endarterectomy. Asymptomatic patients may run a lower risk of intraoperative embolization.     

256层螺旋CT对颈动脉狭窄程度与性别及年龄关系的初步研究

目的采用256 i CT血管造影对颈动脉狭窄定量分析,探讨颈动脉狭窄程度与性别及年龄的关系。方法分析于本院接受256 i CT颈动脉造影检查患者的影像资料573例,男性332例,女性241例,平均年龄57.22±13.02岁。采用多平面重建(MPR)、最大密度图像(MIP)、容积再现(VR)等技术分别测量及统计颈总动脉、颈内动脉动脉粥样硬化斑块部位及狭窄程度。结果颈总动脉轻度狭窄有性别分布差异,男性轻度狭窄者较女性多(P=0.027);颈内动脉轻度狭窄无性别分布差异;颈总动脉及颈内动脉中度及以上狭窄均有性别分布差异(P=0.013,P=0.000),男性中度以上狭窄者较女性多;颈总动脉及颈内动脉动脉狭窄程度与年龄均有相关性(P=0.000),随年龄增加狭窄程度增高。结论 256 i CT颈动脉成像可以客观显示颈动脉狭窄程度及斑块部位,性别与年龄是颈动脉狭窄的重要影响因素。     

颅内外血管狭窄与短暂性脑缺血发作的相关性研究

目的探讨颅内外血管狭窄与短暂性脑缺血发作(TIA)的关系。方法对87例TIA患者应用经颅多普勒(TCD)进行颅内血管检测,应用双功能彩色多普勒检测颅外血管。结果TIA患者病灶侧颈动脉及大脑中动脉中度以上血管狭窄发生率明显高于病灶对侧,差异有统计学意义(P<0.01);病灶侧颈动脉粥样硬化斑块低回声斑块和不均质回声斑块发生率明显高于病灶对侧,差异有统计学意义(P<0.01)。结论颅内外血管狭窄及颈动脉低回声和不均质回声斑块与TIA有关。     

颈动脉粥样硬化斑块与脑梗死的临床相关分析

目的分析颈动脉粥样硬化斑块与脑梗死的关系。方法对临床诊断98例脑梗死(脑梗死组)和同时期的82例非脑梗死患者(对照组)行颈部血管行彩色多普勒超声检查,并对两组颈动脉粥样硬化斑块发生率、大小、性质、好发部位以及颈动脉狭窄程度进行对比分析。结果 1脑梗死组与对照组颈动脉粥样硬化斑块检出率均较高,差异无统计学意义(81.6%vs72.9%,P0.05),但面积大于20mm2斑块的检出率急性脑梗死组显著高于对照组(38.8%vs9.8%,P0.01);2两组颈动脉硬化斑块的分布部位均以颈总动脉分叉处为主,两组间比较,差异无统计学意义(66.6%vs62.7%,P0.05);3两组颈动脉狭窄发生率及程度比较,脑梗死组均高于对照组(χ2=6.98,P0.05)。结论颈动脉粥样硬化斑块形成与脑梗死的有密切相关性,彩色多普勒超声技术对高风险、老年人的脑卒中早期预防及诊治有重要意义。