Hyperhomocysteinemia and recurrent carotid stenosis

Background

Hyperhomocysteinemia has been identified as a potential risk for atherosclerotic disease in epidemiologic studies. This study investigates the impact of elevated serum homocysteine on restenosis after carotid endarterectomy (CEA).

Methods

In a retrospective study, we compared fasting plasma homocysteine levels of 51 patients who developed restenosis during an eight year period after CEA with 45 patients who did not develop restenosis. Restenosis was defined as at least 50% stenosis and was assessed by applying a routine duplex scan follow up investigation. Patients with restenosis were divided into a group with early restenosis (between 3 and 18 months postoperative, a total of 39 patients) and late restenosis (19 and more months; a total of 12 patients).

Results

The groups were controlled for age, sex, and risk factors such as diabetes, nicotine abuse, weight, hypertension, and hyperlipidemia. Patients with restenosis had a significant lower mean homocysteine level (9.11 μmol/L; range: 3.23 μmol/L to 26.49 μmol/L) compared to patients without restenosis (11.01 μmol/L; range: 5.09 μmol/L to 23.29 μmol/L; p = 0.03). Mean homocysteine level in patients with early restenosis was 8.88 μmol/L (range: 3.23–26.49 μmol/L) and 9.86 μmol/L (range 4.44–19.06 μmol/L) in late restenosis (p = 0.50).

Conclusion

The finding suggests that high plasma homocysteine concentrations do not play a significant role in the development of restenosis following CEA.     

颈动脉支架置入术后患者认知功能的变化及CT灌注成像技术的疗效评估价值研究

目的:探讨颈动脉狭窄患者在行颈动脉支架置入术后认知功能的变化情况,并分析CT灌注成像(CTP)对手术疗效的评估价值。方法:选取2015年10月到2018年3月在济宁医学院附属日照市人民医院接受治疗的颈动脉狭窄患者80例,其中有症状性颈动脉狭窄患者49例作为有症状组,无症状性颈动脉狭窄患者31例作为无症状组。所有患者均接受颈动脉支架置入手术及CTP检查,采用蒙特利尔认知评估量表(MoCA)、简易智能精神状况量表(MMSE)、搭火柴测验(Stick Test)综合评价颈动脉狭窄患者的术前、术后1周、术后3个月、术后6个月认知功能的变化情况,比较有症状组和无症状组患者的CTP相对灌注参数。结果:术后1周,颈动脉狭窄患者的MoCA总分、视空间/执行能力、注意力、延迟回忆以及MMSE总分、Stick Test总分较术前有所降低(P0.05);术后3个月、术后6个月,颈动脉狭窄患者的MoCA总分、视空间/执行能力、注意力、延迟回忆以及MMSE总分、Stick Test总分较术前有所升高(P0.05)。术前,有症状组的相对血流达峰时间、相对平均通过时间长于无症状组,相对脑血流量低于无症状组(P0.05);术后1周,无症状组的相对血流达峰时间较术前有所缩短,且短于有症状组(P0.05);术后1周,有症状组的相对血流达峰时间、相对平均通过时间较术前有所缩短,相对脑血流量较术前有所升高(P0.05);两组术前、术后1周相对脑血容量比较均无统计学差异(P0.05)。结论:颈动脉支架置入术后患者会出现暂时的、可逆的认知功能恶化,但最终认知功能会得到明显的改善。CTP可发现异常的脑灌注情况,同时能够较好地评价颈动脉支架置入术治疗颈动脉狭窄患者的疗效。     

Carotid artery stenting: a single center "real world" experience

Background

Percutaneous carotid artery stenting (CAS) became a widely used procedure in patients with symptomatic and asymptomatic carotid artery stenosis. However its role compared to carotid endarterectomy (CAD) remains questioned. We analysed the safety of carotid artery stenting program of a prospective CAS register program of a tertiary teaching hospital.

Method

Between July 2003 and December 2010, 208 patients underwent CAS procedure. Baseline, procedural and follow-up data were prospectively collected. Primary peri-interventional outcome was defined as 30-day major adverse events (MAE), including death, stroke or myocardial infarction, and mid- to long-term follow-up outcome included ipsilateral stroke, myocardial infarction or death. Secondary outcome was restenosis rate ≥50% per lesion.

Results

Unilateral carotid artery interventions were performed in 186 patients. In 22 patients CAS was performed bilaterally as stages procedures. The 30-day MAE rate was 1.9% consisting of two contralateral strokes and two ipsilateral stroke. Mean clinically follow-up was 22 months. Mid- to long-term MAE was 8.1% with 6.3% (n = 13) deaths, 1.9% (n = 4) myocardial infarctions and 0.9% (n = 2) ipsilateral stroke. The restenosis rate ≥50% per lesion was 4.3% at a mean follow-up of 22 months. Target lesion revascularization was performed in one patient, because of restenosis at 9 months follow-up after first CAS.

Conclusion

Implementation of a carotid artery stenting program at a tertiary, teaching hospital is a safe method for treatment of carotid artery stenosis. The adverse event rate during mid-to-long-term follow-up suggests an appropriate patient selection.     

全麻下颈动脉内膜剥脱术的麻醉体会

目的:评价颈动脉内膜剥脱术(CEA)麻醉疗效,以及经颅多普勒超声(TCD)、微血管多普勒超声(MVD)应用的价值,以及适合颈动脉内膜剥脱术的适合麻醉方法。方法:回顾性分析苏州大学附属一医院脑卒中中心2012年5月至2013年5月所进行的颈动脉内膜剥脱术治疗的19名颅外颈动脉狭窄患者的资料。患者临床症状均伴有不同程度的脑缺血症状。颈动脉狭窄程度2例中度狭窄,17例重度狭窄。所有手术操作均全麻下在显微镜下操作。1例采用补片成形。18例术中采用TCD及MVD监测下完成,1例未采用超声监测。结果:手术成功率为100%,无死亡率。术前脑缺血症状术后患者均有恢复。未发现过度灌注的并发症。麻醉效果达到预期目的。结论:颈动脉内膜剥脱术在多普勒超声MVD及TCD监测下治疗颅外颈动脉狭窄是一种安全、有效的措施;全身麻醉下行CEA手术安全可靠。     

The appropriate use of carotid endarterectomy

FOR THE FIRST 30 YEARS AFTER CAROTID ENDARTERECTOMY WAS FIRST DEVELOPED, anecdotal evidence was used to identify patients with internal carotid artery disease for whom this procedure would be appropriate. More recently, the appropriateness of carotid endarterectomy for symptomatic patients and asymptomatic subjects has emerged from 7 randomized trials. Risk of stroke and benefit from the procedure are greatest for symptomatic patients with at least 70% stenosis of the internal carotid artery. Within this group, carotid endarterectomy is most beneficial for the following patients: otherwise healthy elderly patients, those with hemispheric transient ischemic attack, those with tandem extracranial and intracranial lesions and those without evidence of collateral vessels. Risk of perioperative stroke and death is higher in the following groups, although they still benefit: patients with widespread leukoaraiosis, those with occlusion of the contralateral internal carotid artery and those with intraluminal thrombus. Patients with 50% to 69% stenosis experience lesser benefit, and some other groups may even be harmed by carotid endarterectomy, including women and patients with transient monocular blindness only. The procedure is indicated for patients presenting with lacunar stroke and for those with a nearly occluded internal carotid artery, but the benefit is muted. Patients with less than 50% stenosis do not benefit. In the largest randomized trial of asymptomatic subjects, the perioperative risk of stroke and death was very low (1.5%), but the results indicated that a prohibitively high number of subjects (83) must be treated to prevent one stroke in 2 years. The subsequent literature reported higher perioperative risks (2.8% to 5.6%). In asymptomatic individuals nearly half of the strokes that occur may be due to heart and small-vessel disease. These limitations counter any potential benefit. Another trial is in progress and may identify subgroups of asymptomatic subjects who would benefit. Meanwhile, most individuals without symptoms fare better with medical care.The prevention of ischemic stroke by surgical means goes back half a century. After initial endorsement of carotid endarterectomy, confusion arose as to the appropriate selection of patients and the allowable risk from the procedure. In the past 2 decades large randomized trials have been used to evaluate the benefit of the procedure for patients with symptomatic and asymptomatic disease of the internal carotid artery. Sufficient time has now passed since the publication of these trials to analyze their impact on practice and to make recommendations about the application of carotid endarterectomy. There is strong evidence of benefit in some symptomatic patients, whereas other patients will not benefit and may even face harm. There is weak statistical and weaker clinical evidence that asymptomatic subjects will survive longer without experiencing stroke if they undergo endarterectomy than if they do not. The evidence supporting carotid angioplasty and stenting remains anecdotal and conflicting.The purpose of the present report is to provide a clinical roadmap to which symptomatic patients and asymptomatic subjects with carotid stenosis are candidates for endarterectomy. The risks and complications of endarterectomy are also reported. The outlook and benefit for symptomatic patients and asymptomatic subjects are so different that the evidence supporting appropriate use of endarterectomy in these 2 groups will be presented separately.     

Comparison between carotid stenting and carotid endarterectomy in early outcome

Carotid artery stenting (CAS) is a widely used method in prevention of stroke for carotid artery stenosis as an alternative to surgical treatment. Initial studies reveal higher morbidity and mortality rates for CAS than acceptable standards for carotid endarterectomy (CEA). The aim of this study was to compare results in a series of CAS with concurrent risk-matched group of CEA patients. The study included two groups of 50 patients with internal carotid artery stenosis. We compared early outcome (30 days after procedure) in risk-matched groups of patients that underwent these procedures. Post procedural complications were equally frequent in both groups. There was no significant difference in perioperative complication rates (P = 0.871). Comparison of these two methods shows that CAS and CEA are competitive methods for treatment of carotid artery stenosis. Particularly in symptomatic patients with high risk for surgery CAS is alternative treatment.     

A prospective cohort study of the long-term effects of CPAP on carotid artery intima-media thickness in Obstructive sleep apnea syndrome

Objective

To examine the long-term effect of CPAP on carotid artery intima-media thickness (IMT) in patients with Obstructive sleep apnea syndrome(OSAS).

Methods

A prospective observational study over 12 months at a teaching hospital on 50 patients newly diagnosed with OSAS who received CPAP or conservative treatment (CT). Carotid IMT was assessed with B-mode Doppler ultrasound from both carotid arteries using images of the far wall of the distal 10 mm of the common carotid arteries at baseline, 6 months and 12 months.

Measurements and results [mean (SE)]

Altogether 28 and 22 patients received CPAP and CT respectively without significant differences in age 48.8(1.8) vs 50.5(2.0)yrs, BMI 28.2(0.7) vs 28.0(1.2)kg/m2, ESS 13.1(0.7) vs 12.7(0.6), AHI 38(3) vs 39(3)/hr, arousal index 29(2) vs 29(2)/hr, minimum SaO₂ 75(2) vs 77(2)% and existing co-morbidities. CPAP usage was 4.6(0.3) and 4.7(0.4)hrs/night over 6 months and 1 year respectively. Carotid artery IMT at baseline, 6 months, and 12 months were 758(30), 721(20), and 705(20)micron for the CPAP group versus 760(30), 770(30), and 778(30)micron respectively for the CT group, p = 0.002.Among those free of cardiovascular disease(n = 24), the carotid artery IMT at baseline, 6 months and 12 months were 722(40), 691(40), and 659(30)micron for the CPAP group (n = 12) with usage 4.5(0.7) and 4.7(0.7) hrs/night over 6 months and 12 months whereas the IMT data for the CT group(n = 12) were 660(20), 685(10), and 690(20)micron respectively, p = 0.006.

Conclusions

Reduction of carotid artery IMT occurred mostly in the first 6 months and was sustained at 12 months in patients with reasonable CPAP compliance.     

The Value of the Serum Neurofilament Protein Heavy Chain as a Biomarker for Peri-operative Brain Injury After Carotid Endarterectomy

This prospective study examined the value of serum neurofilament protein levels for detecting peri-operative brain damage following carotid endarterectomy. An ELISA was used for quantification of neurofilament protein heavy chain (NfH^SMI35) levels from patients undergoing endarterectomy for symptomatic (n = 17) and asymptomatic high-grade internal carotid artery stenosis (n = 30). All patients underwent diffusion-weighted brain imaging before and after the procedure. NfH^SMI35 levels were significantly higher in patients with a symptomatic carotid artery stenosis (0.131 ng/ml) if compared to asymptomatic patients (0.055 ng/ml, P = 0.01). However, serum NfH^SMI35 levels were not related to signs of brain ischemia on routine brain imaging techniques. Our pilot data suggests that raised NfH^SMI35 serum levels in patients with symptomatic carotid artery disease may be a sensitive biomarker for diffuse ischemic damage to the CNS. We conclude that NfH^SMI35 failed to qualify as a biomarker for peri-operative brain injury in CEA and factors that may have compromised the validation of this biomarker are discussed and need to be taken into account for the design of further studies.     

Stent implantation at the site of the myocardial bridge after myocardial infarction. Long-term results

Although myocardial bridge is asymptomatic in most patients, it can lead to myocardial ischemia, myocardial infarction, cardiac arrhythmias, and sudden death. The authors report the case of a symptomatic myocardial bridge treated by classical stenting of the mid left anterior descending artery. The outcome was good. A control coronary angiography performed 36 months later showed no significant restenosis. No recurrence of angina during five years follow-up was observed.     

Development of atherosclerotic lesions in cholesterol-loaded rabbits.

To examine both of the target vessels and the optimal time of their endothelial denudation to study vascular restenosis after balloon injury in cholesterol-loaded rabbits, we made 36 atherosclerotic rabbits by feeding a hypercholesterol diet, and histologically examined the onset time and the development of atherosclerosis. Atheromatous changes were observed first after the 5th week in the thoracic aorta from the start of the diet, and then extended to the abdominal aorta, coronary artery with time. The atherosclerotic lesions in the thoracic aorta and the proximal portion of the coronary artery showed high-grade concentric intimal thickening with luminal stenosis. The abdominal aortic lesion mildly progressed. In the renal, carotid and femoral arteries, in contrast, slight atheroscleromatous changes developed during the diet period. These results suggest that the thoracic and abdominal aortas and the coronary artery would be suitable as target vessels to study vascular restenosis after balloon injury, and the endothelial denudation of these vessels should be performed between the 8th and 15th week in this diet protocol for an accurate analysis.     

Prevalence and outcome of symptomatic carotid lesions in young adults. National Research Council Study Group.

OBJECTIVE--To estimate the prevalence and outcome of symptomatic internal carotid artery lesions in young adults. DESIGN--Multicentre hospital based observational study with five year follow up. SETTING--Seven neurological departments in northern and central Italy. SUBJECTS--240 patients (115 men) aged 15-44 with a recent transient ischaemic attack or stroke in the carotid territory. MAIN OUTCOME MEASURES--(a) Prevalence of symptomatic internal carotid artery stenosis or occlusion detected by continuous wave Doppler ultrasonography at entry; (b) incidence rates of cerebral, cardiac, and non-vascular death; non-fatal stroke; and non-fatal myocardial infarction. RESULTS--Carotid stenoses of 50-99% and occlusions were found in 38 patients (15.8%). Both conditions were significantly more frequent in patients aged over 35 and in those with hypertension, diabetes mellitus, and stroke at entry. The standardised mortality ratio at five years was 10.5 (95% confidence interval 5.0 to 19.3). Survival of patients with stenoses of 0-49% and occlusions was significantly better than that of patients with stenoses of 50-99%. Carotid stenosis of 50-99% was an independent predictor of death (hazard ratio 7.9; 95% confidence interval 2.2 to 29) and non-fatal stroke (hazard ratio 7.4; 1.5 to 37.4). CONCLUSIONS--The prevalence of carotid stenosis or occlusion in young adults after a cerebrovascular event is low. Though patients with high grade symptomatic carotid stenosis are at risk of non-fetal and fetal events, patients with internal artery occlusion apparently have a benign prognosis.     

Basic laws of blood screw motion in human common carotid arteries

The basic laws of blood screw motion in common carotid arteries in people were determined by means of modern ultrasound techniques for the first time. 92 healthy adults, aged 18-30, were examined. The blood flow in the middle one-third of common carotid arteries was registered by means of Color Doppler Imaging and impulse Doppler with the help of ultrasound Medison 8000EX scanner by linear transducer of 5-9 MHz. The steady registration of blood screw motion in both common carotid arteries in Color Doppler Imaging regimen was observed in 54.3 % of cases. The direction of screw stream rotation in most cases (54%) was multi-directed: in the right common carotid artery it was right, in the left common carotid artery--left (48%), and in 6% of cases it was reverse. For 46% of cases blood rotation in both common carotid arteries was one-directed (26%--right, 20%--left). The velocity parameters of rotation component of blood motion were determined, maximum velocity being 19.68 +/- 5.84 cm/sec, minimum--4.57 +/- 2.89 cm/sec, average--7.48 +/- 2.49 cm/sec, angular--10.7 +/- 2.49 sec(-1). The rated velocity of blood cells motion in screw motion with regard of screw current lines to the vessel vertical axis makes up from 158.67 +/- 32.79 to 224.39 +/- 46.37 cm/sec.     

Thematic review series: patient-oriented research. Imaging atherosclerosis: state of the art

The ability to image obstructive arterial disease brought about a revolution in clinical cardiovascular care; the development of newer technologies that image arterial wall thicknesses, areas, volumes, and composition allows valid imaging of atherosclerosis for the first time. Development of noninvasive imaging of atherosclerosis has further led to a quantum shift in research in the field by enabling the study of asymptomatic populations and thus allowing investigators to focus on preclinical disease without the many biases associated with the study of symptomatic patients. These noninvasive investigations have broad implications for clinical care as well. Coronary angiography, computed tomographic (CT) imaging of coronary calcium, intravascular ultrasound, multidetector CT angiography, B mode ultrasound of the carotid arteries, and MRI of the carotid arteries all have unique strengths and weaknesses for imaging atherosclerosis. Certain of these techniques are extremely useful as outcome variables for clinical trials, and others are uniquely useful as predictors of the risk of cardiovascular disease. All are informative in one way or another with regard to the role of plaque remodeling and composition in disease causation. CT and MRI technology are advancing very rapidly, and research and clinical uses of these imaging modalities promise to further advance our understanding of atherosclerosis and its prevention.     

Long-term assessment of clinical parameters in patients with coronary heart disease after balloon angioplasty and stenting balloon angioplasty

The aim of this study was to assess clinical parameters in patients with coronary heart disease (CHD) in the late period after balloon coronary angioplasty (BCA) and intracoronary stenting (ICS). The study included 104 patients who underwent repeated coronary angiography (CA) 2-10 months after successful coronary angioplasty. Clinical parameters were analyzed in 2 groups comparable at the moment of its performance in terms of major clinical characteristics. Group 1 comprised 51 patients following BCA and group 2 included 53 patients after ICS. Six months after the first procedure, repeated coronary angioplasty was performed in 19 (37.2%) and 6 (9.4%) patients after BCA and ICS, respectively (p < 0.05). Recurrent angina pectoris was observed in 42 patients from group 1 and in 25 ones from group 2, which was 82.3 and 47.2%, respectively (p < 0.05). Control CA revealed restenosis of the dilated artery in 22 (43.1%) of the 51 patients of group 1 and in 12 (22.6%) of the 53 patients of group 2. There were no differences between the groups in late postoperative bicycle ergometric and 24-hour ECG monitoring findings. The findings have led to the conclusion that implantation of a stent into the coronary artery greatly prolongs the antiischemic effect of coronary angioplasty and reduces a need for repeated endovascular intervention, which appears as lower incidence rates of restenosis and recurrent angina as compared to routine balloon angioplasty.     

CAS和CEA治疗颈内动脉重度狭窄疗效及对脑血流量、血清miR-145、IGF1R的影响

目的:探讨颈动脉支架植入术(CAS)和颈动脉内膜剥脱术(CEA)治疗颈内动脉重度狭窄疗效及对脑血流量、血清miR-145、胰岛素样生长因子1受体(IGF1R)的影响。方法:回顾性分析2018年1月至2019年12月我院收治的100例颈动脉重度狭窄患者的临床资料,按照手术方式不同分为A组和B组,每组50例,A组给予CAS治疗,B组给予CEA治疗。比较两组围术期情况、脑血流量、血清miR-145、IGF1R、简易精神状态检查表(MMSE)量表、蒙特利尔认知评估量表(MoCA)的变化,并比较术后并发症、再狭窄率及死亡率。结果:两组患者手术时间、术中失血量、术后机械通气时间、ICU停留时间、住院时间比较,差异无统计学意义(P>0.05);术后3个月时,两组脑血流量指标相对达峰时间(rTTP)、相对平均通过时间(rMTT)、相对脑血容量(rCBV)、相对脑血流量(rCBE)、血清miR-145、IGF1R、MMSE量表、MoCA量表评分比较差异均无统计学意义(P>0.05);术后30 d内,两组心动过缓、心肌酶谱升高、高灌注综合征、局部血肿、颈动脉急性闭塞比较差异无统计学意义(P>0.05),A组脑卒中、低血压发生率明显高于B组,B组高血压发生率明显高于A组(P<0.05);术后1年时,两组患者死亡率、再狭窄率比较差异无统计学意义(P>0.05)。结论:CAS和CEA治疗颈内动脉重度狭窄患者的疗效相似,均可有效改善脑血流量,调节血清miR-145、IGF1R水平的表达,促进认知功能恢复,但CAS术后脑卒中、低血压发生率更高,CEA术后高血压发生率更高。     

Drug-eluting stents in the treatment of proximal vertebral artery stenosis

The objective of the study was to evaluate the efficacy of endovascular revascularization treatment using drug-eluting stents in patients with atherosclerotic proximal vertebral artery (VA) stenosis. Thirty-two patients (61 ± 10 years old) were implanted with 35 sirolimus and tacrolimus eluting stents (3 patients had them from two sides). 27 patients (84%) had vertebrobasilar symptoms at enrollment. All patients were pretreated with dual antiplatelet therapy. The intervention was technically successful in 89% cases. No stroke, myocardial infarction, or death occurred in perioperative period. On duplex scanning the stents remained completely functional. In the late postoperative period 29 (91%) patients, with 32 implanted stents were followed- up. The mean follow-up was 9.5 months. No stroke occurred in patients during this period. Recurrence of vertebrobasilar insufficiency symptoms was noted in 3 patients. VA renarrowing was detected in 16 (50%) arteries in 15 patients, and 12 (80%) of them were asymptomatic. Restenosis ≥50% (n = 13) and reocclusion (n = 3) were more frequent in those with implantation of tacrolimus eluting stents compared to those with sirolimus eluting stents: 10 (71%) of 14 observations to 6 (33%) of 18 cases (p = 0.1794), respectively. Stent fracture was observed in 2 cases (6%), followed by restenosis. Restenosis rate prevailed in men (p = 0.0173). Thus, stenting of VA extracranial portion is reasonably safe procedure with a good clinical effect. The use of drug-eluting stents looks promising but does not solve the problem of high restenosis rate in the late postoperative period.     

Coronary artery calcium findings in asymptomatic subjects with family history of premature coronary artery disease

ABSTRACT: BACKGROUND: To evaluate the frequency of positive coronary arteries calcium (CAC) scores in a unique population of asymptomatic first degree relatives (FDRs) of patients with angiographically confirmed early onset of coronary artery disease (CAD) and to assess their association with carotid ultrasound findings and other cardiovascular risk factors. Method and Results: We scanned, using 64-slice multi-detector computed tomography, 57 asymptomatic FDRs (47+9 years old; 44% male, 56% female), out of the 111 FDRs previously phenotyped for cardiovascular (CV) risk factors. The controls were 616 individuals (57+10 years old; 76% male, 24% female) with no family history of cardiovascular disease, chest pain or diabetes selected out of the 3500 subjects scanned between 2002 and 2007. FDRs had higher risk of abnormal CAC scores compared to controls; odds ratio (OR) for the 75th percentile was 1.96 (95%CI 1.04 - 3.67, p<0.05). CONCLUSION: The frequency of abnormal CAC scores is two-fold higher in asymptomatic FDRs than in controls. CAC scan provides additional information on CV risk assessment in asymptomatic FDRs, particularly for those in the intermediate risk category. Clinical Trial Registration: NCT00387595.     

Study of carotid arterial plaque stress for symptomatic and asymptomatic patients

Stroke is one of the leading causes of death in the world, resulting mostly from the sudden ruptures of atherosclerosis carotid plaques. Until now, the exact plaque rupture mechanism has not been fully understood, and also the plaque rupture risk stratification. The advanced multi-spectral magnetic resonance imaging (MRI) has allowed the plaque components to be visualized in-vivo and reconstructed by computational modeling. In the study, plaque stress analysis using fully coupled fluid structure interaction was applied to 20 patients (12 symptomatic and 8 asymptomatic) reconstructed from in-vivo MRI, followed by a detailed biomechanics analysis, and morphological feature study. The locally extreme stress conditions can be found in the fibrous cap region, 85% at the plaque shoulder based on the present study cases. Local maximum stress values predicted in the plaque region were found to be significantly higher in symptomatic patients than that in asymptomatic patients (200 ± 43 kPa vs. 127 ± 37 kPa, p=0.001). Plaque stress level, defined by excluding 5% highest stress nodes in the fibrous cap region based on the accumulative histogram of stress experienced on the computational nodes in the fibrous cap, was also significantly higher in symptomatic patients than that in asymptomatic patients (154 ± 32 kPa vs. 111 ± 23 kPa, p<0.05). Although there was no significant difference in lipid core size between the two patient groups, symptomatic group normally had a larger lipid core and a significantly thinner fibrous cap based on the reconstructed plaques using 3D interpolation from stacks of 2D contours. Plaques with a higher stenosis were more likely to have extreme stress conditions upstream of plaque throat. The combined analyses of plaque MR image and plaque stress will advance our understanding of plaque rupture, and provide a useful tool on assessing plaque rupture risk.     

Lower wall shear rate of the common carotid artery in treated type 2 diabetes mellitus with metabolic syndrome

Arterial sites with low wall shear stress (WSS) are more prone to the development of atherosclerotic plaques, as was observed in carotid arteries in subjects with atherosclerosis risk factors. Type 2 diabetes mellitus (DM), hypertension, hyperlipidemia and other components of the metabolic syndrome, are associated with high risk for symptomatic cerebrovascular disease. It was shown by others that untreated type 2 DM is associated with lower WSS in common carotid arteries. However, the cardiovascular risk of type 2 DM could be modified by therapy. The aim of our study was to test the hypothesis that treated type 2 DM subjects with metabolic syndrome still have lower WSS in common carotid arteries than healthy controls. We enrolled 26 compensated DM subjects with metabolic syndrome, treated by metformin, statins and ACEI for more than 6 months, and 22 aged-comparable healthy controls. Wall shear rate (WSR) was used as a measure of WSS. A linear 3-11 MHz probe was used to measure blood velocity and internal diameter in the common carotid arteries. We compared observed values of WSR adjusted for age by ANCOVA. Wall shear rate was significantly lower in DM group than in control subjects: peak (systolic) values of wall shear rate were 410+/-130 s(-1) vs. 487+/-111 s(-1) (p<0.005). DM subjects had significantly lower WSR, because of both thinner lumen and slower blood flow velocities. Lower WSR was accompanied by higher IMT (0.73+/-0.12 mm vs. 0.64+/-0.11 mm, p<0.001). Treated subjects with compensated type 2 DM with metabolic syndrome still have atherogenic hemodynamic profile. These findings might help to understand faster progression of atherosclerosis in diabetic subjects with metabolic syndrome despite up-to-date medication.