Atheroma of the aortic arch: an important and poorly recognised factor in the aetiology of stroke

Long-Chain Acyl Carnitines Aggravate Polystyrene Nanoplastics-Induced Atherosclerosis by Upregulating MARCO

Exposure to micro- and nanoplastics (MNPs) is common because of their omnipresence in environment. Recent studies have revealed that MNPs may cause atherosclerosis, but the underlying mechanism remains unclear. To address this bottleneck, ApoE^-/- mice are exposed to 2.5-250 mg kg^-1 polystyrene nanoplastics (PS-NPs, 50 nm) by oral gavage with a high-fat diet for 19 weeks. It is found that PS-NPs in blood and aorta of mouse exacerbate the artery stiffness and promote atherosclerotic plaque formation. PS-NPs activate phagocytosis of M1-macrophage in the aorta, manifesting as upregulation of macrophage receptor with collagenous structure (MARCO). Moreover, PS-NPs disrupt lipid metabolism and increase long-chain acyl carnitines (LCACs). LCAC accumulation is attributed to the PS-NP-inhibited hepatic carnitine palmitoyltransferase 2. PS-NPs, as well as LCACs alone, aggravate lipid accumulation via upregulating MARCO in the oxidized low-density lipoprotein-activated foam cells. Finally, synergistic effects of PS-NPs and LCACs on increasing total cholesterol in foam cells are found. Overall, this study indicates that LCACs aggravate PS-NP-induced atherosclerosis by upregulating MARCO. This study offers new insight into the mechanisms underlying MNP-induced cardiovascular toxicity, and highlights the combined effects of MNPs with endogenous metabolites on the cardiovascular system, which warrant further study.

Vessel Wall Imaging in Cryptogenic Stroke

Cryptogenic strokes are symptomatic cerebral ischemic infarcts without a clear etiology identified following standard diagnostic evaluation and currently account for 10% to 40% of stroke cases. Continued research is needed to identify and bridge gaps in knowledge of this stroke grouping. Vessel wall imaging has increasingly shown its utility in the diagnosis and characterization of various vasculopathies. Initial promising evidence suggests rational use of vessel wall imaging in stroke workup may unravel pathologies that otherwise would have been occult and further improve our understanding of underlying disease processes that can translate into improved patient outcomes and secondary stroke prevention.

Current perspectives on the clinical management of cryptogenic stroke

INTRODUCTION

Cryptogenic stroke is a heterogeneous entity defined as an ischemic stroke for which no probable cause is identified despite thorough diagnostic evaluation. Since about a quarter of all ischemic strokes are classified as cryptogenic, it is a commonly encountered problem for providers as secondary stroke prevention is guided by stroke etiology.

AREAS COVERED

In this review, the authors provide an overview of stroke subtype classification schemes and diagnostic evaluation in cryptogenic stroke. They then detail putative cryptogenic stroke mechanisms, their therapeutic implications, and ongoing research. This review synthesizes the available evidence on PubMed up to December 2022.

EXPERT OPINION

Cryptogenic stroke is an evolving concept that changes with ongoing research. Investigations are focused on improving our diagnostic capabilities and solidifying useful constructs within cryptogenic stroke that could become therapeutically targetable subgroups within an otherwise nonspecific entity. Advances in technology may help move specific proposed cryptogenic stroke mechanisms from undetermined to known source of ischemic stroke.

Spontaneous Echo Contrast in the Left Atrium and Aortic-Arch Atheroma, Detected by Transesophageal Echocardiography, Was Negatively Correlated with Cognitive Function

BACKGROUND

The relationship between transesophageal echocardiography findings and cognitive function.

OBJECTIVE

This study aimed to establish an association between transesophageal echocardiography findings and cognitive function in stroke survivors.

METHODS

A single-center study was conducted between April 1, 2017 and March 31, 2022. All subjects that were included had a past history of ischemic stroke and were admitted after >21 days from onset. The participants underwent cognitive function tests including a Mini-Mental State Examination, Revised Hasegawa Dementia Scale, Frontal Assessment Battery, and transesophageal echocardiography.

RESULTS

The results of 126 participants were analyzed. The cognitive function of participants with a spontaneous echo contrast (+) in the left atrium including appendage or of those with an aorta-arch plaque with a maximum thickness ≥4 mm significantly worse while neither the patent foramen ovale nor the branch extending plaque influenced cognitive function (The median cognitive scores of the spontaneous echo contrast (-) versus (+) were 26 versus 22, p < 0.01**, 26 versus 21, p < 0.001***, and 14 versus 11, p < 0.01**. Those of the aortic-arch plaque max thickness (<4 mm) versus (≥4 mm) were 26 versus 25, p < 0.05*, 27 versus 24, p < 0.05*, and 15 versus 13, p < 0.05*).

CONCLUSION

Our findings show that spontaneous echo contrast in the left atrium and aortic-arch atheroma detected by transesophageal echocardiography, were negatively associated with cognitive function.

Comprehensive review of hybrid aortic arch repair with focus on zone 0 TEVAR and our institutional experience

Even with increasing operator experience and a better understanding of the disease and the operation, intervention for aortic arch pathologies continues to struggle with relatively higher mortality, reintervention, and neurologic complications. The hybrid aortic arch repair was introduced to simplify the procedure and improve the outcome. With recent industry-driven advances, hybrid repairs are not only offered to poor surgical candidates but have become mainstream. This review discusses the evolution of hybrid repair, terminology pertinent to this technique, and results. In addition, we aim to provide a pervasive review of hybrid aortic arch repairs with reference to relevant literature for a detailed understanding. We have also discussed our institutional experience with hybrid repairs.

A Cerebrovascular Incident Secondary to Extensive Aortic Arch Atheroma

Plaques can form across different parts of the aorta, from the aortic arch to the thoracic and abdominal aorta. Aortic arch atheroma, however, is highly associated with cerebrovascular insults due to their dislodgement. Although no concise management protocol has been defined for dealing with such presentations, antiplatelet agents and anticoagulants are most frequently used. In this case, we present a 78-year-old male with a known case of diabetes mellitus type 2, hypertension, and dyslipidemia who presented to the emergency department with acute onset of slurred speech. A CT angiography was performed that revealed extensive plaque formations across the aortic arch with a 90% occlusion of the distal left common carotid artery and carotid bifurcation along with 99% stenosis of the internal carotid artery. The patient underwent aspiration thrombectomy and was started on dual antiplatelets but passed away after developing decompensated heart failure.

The role of leukocytes in acute ischemic stroke-related thrombosis: a notable but neglected topic

Ischemic stroke is one of the most serious diseases today, and only a minority of patients are provided with effective clinical treatment. Importantly, leukocytes have gradually been discovered to play vital roles in stroke thrombosis, including promoting the activation of thrombin and the adhesion and aggregation of platelets. However, they have not received enough attention in the field of acute ischemic stroke. It is possible that we could not only prevent stroke-related thrombosis by inhibiting leukocyte activation, but also target leukocyte components to dissolve thrombi in the cerebral artery. In this review, we expound the mechanisms by which leukocytes are activated and participate in the formation of stroke thrombus, then describe the histopathology of leukocytes in thrombi of stroke patients and the influence of leukocyte composition on vascular recanalization effects and patient prognosis. Finally, we discuss the relevant antithrombotic strategies targeting leukocytes.

EACVI recommendations on cardiovascular imaging for the detection of embolic sources: endorsed by the Canadian Society of Echocardiography

Cardioaortic embolism to the brain accounts for approximately 15-30% of ischaemic strokes and is often referred to as 'cardioembolic stroke'. One-quarter of patients have more than one cardiac source of embolism and 15% have significant cerebrovascular atherosclerosis. After a careful work-up, up to 30% of ischaemic strokes remain 'cryptogenic', recently redefined as 'embolic strokes of undetermined source'. The diagnosis of cardioembolic stroke remains difficult because a potential cardiac source of embolism does not establish the stroke mechanism. The role of cardiac imaging-transthoracic echocardiography (TTE), transoesophageal echocardiography (TOE), cardiac computed tomography (CT), and magnetic resonance imaging (MRI)-in the diagnosis of potential cardiac sources of embolism, and for therapeutic guidance, is reviewed in these recommendations. Contrast TTE/TOE is highly accurate for detecting left atrial appendage thrombosis in patients with atrial fibrillation, valvular and prosthesis vegetations and thrombosis, aortic arch atheroma, patent foramen ovale, atrial septal defect, and intracardiac tumours. Both CT and MRI are highly accurate for detecting cavity thrombosis, intracardiac tumours, and valvular prosthesis thrombosis. Thus, CT and cardiac magnetic resonance should be considered in addition to TTE and TOE in the detection of a cardiac source of embolism. We propose a diagnostic algorithm where vascular imaging and contrast TTE/TOE are considered the first-line tool in the search for a cardiac source of embolism. CT and MRI are considered as alternative and complementary tools, and their indications are described on a case-by-case approach.

Antithrombotic Therapy for Stroke Patients with Cardiovascular Disease

Prevention of ischemic stroke relies on the use of antithrombotic medications comprising antiplatelet agents and anticoagulation. Stroke risk is particularly high in patients with cardiovascular disease. This review will focus on the role of antithrombotic therapies in the context of different types of cardiovascular disease. We will discuss oral antiplatelet medications and both IV and parental anticoagulants. Different kinds of cardiovascular disease contribute to stroke via distinct pathophysiological mechanisms, and the optimal treatment for each varies accordingly. We will explore the mechanism of stroke and evidence for antithrombotic therapy in the following conditions: atrial fibrillation, prosthetic heart values (mechanical and bioprosthetic), aortic arch atherosclerosis, congestive heart failure (CHF), endocarditis (infective and nonbacterial thrombotic endocarditis), patent foramen ovale (PFO), left ventricular assist devices (LVAD), and extracorporeal membrane oxygenation (ECMO). While robust data exist for antithrombotic use in conditions such as atrial fibrillation, optimal treatment in many situations remains under active investigation.

Use of ADAM-C and CHA2DS2-VASc scores to predict complex aortic atheroma after brain ischemia: A prospective observational study

BACKGROUND AND AIMS

Complex aortic atheroma (CAA) is a common cause of acute brain ischemia (BI), including ischemic stroke (IS) and transient ischemic attack (TIA), and is associated with recurrence. The CHA2DS2-VASc score is a useful tool for predicting stroke in patients with atrial fibrillation (AF), and can also predict cardiovascular events in other populations, including non-AF populations. The ADAM-C score is a new risk score for predicting the diagnostic yield of transesophageal echocardiography (TEE) after BI. We aimed to evaluate the ability of CHA2DS2-VASc and ADAM-C scores to predict CAA after BI.

METHODS

This prospective, multicenter, observational study included 1479 patients aged over 18 years who were hospitalized for BI. CAA was defined as the presence of one or more of the following criteria: thrombus, ulcerated plaque, or plaque thickening ≥ 4 mm.

RESULTS

CAA was diagnosed in 216 patients (14.6%). CHA2DS2-VASc and ADAM-C scores were significantly higher in the CAA group versus the non-CAA group (P < .0001 for both). The CHA2DS2-VASc and ADAM-C scores appear to be good predictors of CAA (AUC 0.699 [0.635, 0.761] and 0.759 [0.702, 0.814], respectively). The sensitivity, specificity, predictive positive value (PPV), and negative predictive value (NPV) of the scores for detecting CAA were 94%, 22%, 17%, and 96%, respectively, for a CHA2DS2-VASc score < 2, and 90%, 46%, 22%, and 96%, respectively, for an ADAM-C score < 3 CONCLUSIONS: CHA2DS2-VASc and ADAM-C scores are able to predict CAA after BI. CHA2DS2-VASc < 2 and ADAM-C < 3 both have an interesting NPV of 96%.

Aortic Sources of Embolism

Aortic arch atheroma is a frequent finding in ischemic stroke patients. Its role as a source of cerebral emboli or a marker of atherosclerosis is unclear. Transesophageal echography is considered the gold standard for its detection, whereas computed tomography angiography is a good alternative; magnetic resonance and positron emission tomography could be proposed to better analyze plaque vulnerability. Despite the interest in this condition, the optimal antithrombotic treatment remains uncertain, while intensive lipid-lowering therapy should be recommended. This review aims to offer guidance on patients with aortic arch atheroma, about its causal role in stroke, diagnosis, and treatment based on current available evidence.

Stroke Prevention After Cryptogenic Stroke

PURPOSE OF REVIEW

Cryptogenic stroke represents a heterogenous but clinically important collection of stroke etiologies for which our understanding continues to grow. Here, we review our current knowledge and most recent recommendations on secondary prevention for common causes of cryptogenic stroke including paroxysmal atrial fibrillation, atrial cardiopathy, patent foramen ovale, and substenotic atherosclerotic disease as well as the under-recognized mechanisms of occult malignancy, heart failure, and, most recently, infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

RECENT FINDINGS

The results from recent observational studies and randomized clinical trials have provided greater insight into the causal relationship and attributable risk of these suspected etiologies and have identified potential strategies to reduce the rates of recurrence. However, further clinical trials are needed to confirm the benefits of specific stroke prevention strategies, including the patient populations most likely to benefit from anticoagulation. There is ongoing research aimed at both reducing the proportion of ischemic strokes classified as cryptogenic and resolving much of the clinical equipoise that still exists. The results of these studies have the potential to provide us with a better understanding of these occult mechanisms and allow for more targeted interventions.

The effect of TEE on treatment change in patients with acute ischemic stroke

Background and purpose

Ischemic stroke is a widespread disease carrying high morbidity and mortality. Transesophageal echocardiography (TEE) is considered an important tool in the work-up of patients with acute ischemic stroke (AIS) and transient ischemic attack (TIA) patients; its utility is limited by a semi-invasive nature. The purpose of this study was to evaluate the probability of treatment change due to TEE findings (yield) in the work-up of AIS and TIA patients.

Methods

Retrospective data on patients with AIS or TIA who underwent TEE examination between 2000–2013 were collected from the institutional registry.

Results

The average age of 1284 patients who were included in the study was 57±10.4, 66% of patients were male. The most frequent TEE findings included aortic plaques in 54% and patent foramen ovale (PFO) in 15%. TEE findings led to treatment change in 135 (10.5%) patients; anticoagulant treatment was initiated in 110 of them (81%). Most common etiology for switch to anticoagulation was aortic plaques (71 patients); PFO was second most common reason (26 patients). Significant TEE findings (thrombus, endocarditis, tumor) were found in 1.9% of patients, they were more common in young patients (<55; 56% of the patients).

Conclusions

The beginning of anticoagulation treatment in patients with thick and complicated plaques was found frequently in our study. Significant TEE findings, were infrequent, constituted an absolute indication for treatment change and were more common in younger patients.

Complex Aortic Arch Atherosclerosis in Acute Ischemic Stroke Patients with Non-Valvular Atrial Fibrillation

Aim: Aortic arch atherosclerosis, particularly complex aortic arch plaques (CAPs), is an important source of cerebral emboli. CAPs and atrial fibrillation (AF) often co-exist; however, the prevalence and risk of CAPs in acute ischemic stroke patients with AF is unclear.

Methods: In patients with acute ischemic stroke with non-valvular AF admitted to Jichi Medical University Hospital during April 2016 to September 2019, we retrospectively evaluated the presence of CAPs on transesophageal echocardiography (TEE).

Results: CAPs were observed in 41 (38.7 %) of 106 patients with non-valvular AF. Older age, diabetes mellitus, chronic kidney disease, low high-density lipoprotein cholesterol (HDL-C) levels, higher levels of glycohemoglobin A1c (HbA1c), higher CHADS ₂ and CHA ₂ DS ₂ -VASc scores, and intracranial or carotid artery stenosis were more frequently observed in CAPs-positive than in CAPs-negative patients. In multivariable analyses, older age (odds ratio [OR]: 1.2 per year increase; 95% confidence interval [CI]: 1.07–1.24; P ＜0.0001), diabetes mellitus (OR: 4.7; 95%CI: 1.27-17.35; P ＜0.05), and low HDL-C (OR: 0.95 per 1 mg/dl increase; 95%CI: 0.92-0.99; P ＜0.01) were independent risk factors for CAPs. The prevalence of CAPs was age-dependent, and there was a significantly higher risk in patients aged either 75–84 years or ＞84 years than in those aged ＜65 (OR: 7.6; 95%CI: 1.50-38.62, and OR: 32.1; 95%CI: 5.14-200.11, respectively).

Conclusions: Even in patients with ischemic stroke with non-valvular AF, concomitant CAPs should be considered in older individuals and those who have diabetes or low HDL-C.

Successful concomitant open surgical repair of aortic arch pseudoaneurysm and percutaneous myocardial revascularization in a high risk patient: A case report

INTRODUCTION

We present a case of open surgical repair of an aortic arch pseudoaneurysm (AAP) without the use of hypothermic circulatory arrest in a patient with low ejection fraction and associated coronary artery disease (CAD) and discuss some issues regarding the management of this case.

PRESENTATION OF THE CASE

A 69-year-old male with multiple pathologies and history of angina pectoris was transferred to our center from a local hospital with an initial diagnosis of non-ST-segment elevation myocardial infarction. Coronary angiography revealed stenotic lesions affecting all three coronary arteries. Multislice 3D contrast-enhanced computed tomography (CT-scan) revealed a 36 × 27 mm AAP. Endovascular stent-grafting was deemed to be unsuitable due to hostile landing zone. Therefore, the heart team decided for simultaneou treatment of the AAP and percutaneous therapy of CAD. The AAP was excised, and repair was performed with a Dacron patch on beating heart. After the surgical procedure, PCI with drug-eluting stents (DES) was performed on the right coronary artery (RCA) and the left circumflex artery (LCx) in the operating room. The patient's postprocedural course was uneventful and after thirteen days, he was discharged in good shape. 3D CT-scan performed after three month showed no residual AAP.

DISCUSSION

We established this approach as being the most suitable for our case based on favorable circumstances such as: stable CAD, beating heart procedure with low impact on myocardial ischemia, the impossibility of successful placement of an endovascular stent-graft, the presence of a pseudoaneurysm neck with minimum calcification.

CONCLUSION

We consider the best approach for individual cases is tailoring the treatment plan and the procedure to the patient's specific anatomy and pathology.

Beyond the term penetrating aortic ulcer: A morphologic descriptor covering a constellation of entities with different prognoses

Penetrating aortic ulcer (AU) is defined as localized disruption of the intimal layer of the aortic wall, resulting in a crater-like lesion outpouching from the vessel contour. AU is a generic term which encompasses a constellation of entities with different etiologies and prognoses and may be a complication of infective, inflammatory, traumatic, iatrogenic, atherosclerotic processes or intramural hematoma. One of the most challenging scenarios of AU for a differential diagnosis, but also for treatment implications, is when they are associated with acute aortic syndrome. Despite advances in the field of aortic disease, lack of consensus defining these lesions and the significant semantic confusion in the medical literature of the acronym PAU (for penetrating aortic ulcer but also for penetrating atherosclerotic ulcer) have given rise to controversy in guidelines and expert consensus, leading to the same treatment being recommended for entities with different etiology and prognosis. Moreover, in the medical literature, most diagnoses were mainly based on imaging techniques which identified AU regardless of clinical symptoms, surrounding imaging findings or dynamic morphologic changes. In this Review, we provide the latest insight into the differential diagnosis between AU, also called penetrating aortic ulcers, based on clinical context and the newest imaging characteristics to aid treatment decision-making.

Atherosclerotic plaque detected by transesophageal echocardiography is an independent predictor for all-cause mortality

Atherosclerotic lesions in the great arteries are frequent findings in the elderly. Numerous studies have shown their strong predictive value for cardiovascular disease, embolic events, and mortality. We sought to determine the risk of all-cause mortality depending on the localization of plaques in the thoracic aorta evaluated by transesophageal echocardiography (TEE). A total of 2,054 patients (median age 65 years, interquartile range 52–73; 58% men) who underwent a TEE examination between 01/2007 and 03/2015 were retrospectively analyzed. For each patient, the presence of atherosclerotic lesions in the ascending aorta, the aortic arch, and in the descending aorta, as well as cardiovascular risk factors and survival were documented. Median follow-up period was 48 months (interquartile range 38–58). Multivariate Cox regression analysis indicated plaque in the ascending aorta (HR of 1.36, 95% CI 1.01–1.83, P = 0.046), the aortic arch (HR of 1.78, 95% CI 1.29–2.45, P < 0.001), the descending aorta (HR of 2.01, 95% CI 1.54–2.77, P < 0.001), and plaque in any part of the thoracic aorta (HR of 1.84, 95% CI 1.42–2.4, P < 0.001), as independent predictors for all-cause mortality after adjusting for age, sex, arterial hypertension, hyperlipidemia, smoking, and diabetes. In this study, we could demonstrate that more than mild plaque at any site of the thoracic aorta predicts all-cause mortality. Assessment of atherosclerotic lesions in all segments of the thoracic aorta should be part of every routine TEE examination.

Retrograde aortic blood flow as a mechanism of stroke: MR evaluation of the prevalence in a population-based study

OBJECTIVES

Retrograde blood flow from complex atheroma in the descending aorta (DAo) has only recently been described as a potential mechanism of stroke. However, prevalence of this mechanism in the general population and the exact factors influencing stroke risk are unclear.

METHODS

One hundred twenty-six consecutively recruited inhabitants of Freiburg, Germany, between 20 and 80 years of age prospectively underwent 3-T MRI. Aortic plaque location and thickness were determined by 3D T1 MRI (1 mm³). 4D flow MRI (spatial/temporal resolution 2 mm³/20 ms) and dedicated software were used to determine prevalence and extent of flow reversal and potential embolization from DAo plaques. Flow was correlated with baseline characteristics and echocardiographic and MRI parameters (aortic diameter, wall thickness, and pulse wave velocity).

RESULTS

The maximum length of retrograde blood flow connecting the DAo with the left subclavian artery (LSA) increased from 16.1 ± 8.3 mm in 20-29-year-old to 24.7 ± 11.7 mm in 70-80-year-old subjects, correlated with age (r = 0.37; p < 0.001), and was lower in females (p = 0.003). Age was the only independent predictor of increased flow reversal. Complex DAo plaques ≥ 4-mm thickness were found in eight subjects (6.3%) and were connected with the LSA, left common carotid artery, and brachiocephalic trunk in 8 (100%), 1 (12.5%), and 0 (0%) cases, respectively.

CONCLUSIONS

Retrograde blood flow from the DAo was very frequent. However, potential retrograde embolization was rare due to the low incidence of complex DAo plaques. The magnitude of flow reversal and prevalence of complex atheroma increased with age. Thus, older patients with aortic atherosclerosis are especially vulnerable to this stroke mechanism.

KEY POINTS

• 4D flow MRI allows in vivo visualization and quantification of individual and three-dimensional blood flow patterns within the thoracic aorta including retrograde components. • This population-based study showed that blood flow reversal from the proximal descending aorta to the brain-supplying great arteries is very frequent and able to reach all brain territories. The extent of such flow reversal increases with age and with the extent of aortic atherosclerosis. • The combination of blood flow reversal with plaque rupture in the proximal descending aorta constitutes a potential stroke mechanism that should be considered in future trials and in the management of stroke patients in clinical routine.

Cryptogenic stroke - How to make sense of a non-diagnostic entity

Secondary preventive strategies in ischaemic stroke depend on the underlying aetiology. However, approximately one-third of ischaemic strokes remain unexplained, or 'cryptogenic'. There is a wide range of possible underlying causes in cryptogenic stroke, and the best approach to secondary prevention of these may differ. To date, though, the widely accepted and uniform secondary preventive strategy in this group consists of modification of vascular risk factors, and of treatment with a combination of antiplatelet therapy and antihypertensive and lipid-lowering medication. Among the potential causes for cryptogenic stroke are occult atrial fibrillation, patent foramen ovale, atrial cardiopathy, aortic arch atheroma and hypercoagulable states. While it is possible to diagnose these conditions, in individual patients there is often uncertainty over whether they have a directly causative role, are markers of disease, or are innocent bystanders. Similarly, even if the cause is found, the best secondary preventive strategies remain uncertain, which questions the benefit of extensive investigations in a clinical setting. More recently, the concept of "embolic stroke of unknown source (ESUS)" has been introduced, in the hope that anticoagulation may offer better secondary prevention than antiplatelet therapy, but trials so far have been negative. At present, there is little justification for introducing extensive new investigative strategies into the management of patients with cryptogenic stroke. Investigations should be targeted at identifying those high-risk conditions which lead to a change in management. Further investigations need to be tailored individually, according to clinical circumstances. This should include identifying patients for participation in clinical trials, as the significance and best management of many of the potential causes for cryptogenic stroke require further research.

Cerebral embolic protection during endovascular arch replacement

Despite excellent results in high volume centers, open repair of aortic arch pathology is highly invasive, and can result in significant morbidity and mortality in high risk patients. Near-total and hybrid approaches to aortic arch disease states have emerged as an alternative for patients deemed moderate to high risk for conventional repair. Advantages of these approaches include avoidance of extracorporeal circulation and hypothermic circulatory arrest as well as avoidance of cross clamping, all of which are not well tolerated in high risk patients. Anatomically high-risk patients with anastomotic aneurysms from previous arch reconstruction may also benefit from these less invasive approaches. Medical devices designed specifically for the aortic arch are developing at a rapid pace and continue to evolve. Dedicated devices for zone 0-2 aortic arch repair are currently available under special access or being studied in clinical trials. Unfortunately, stroke continues to be the Achilles heel of endovascular approaches to the aortic arch, with cerebral embolism being the culprit in the majority of such cases. This perspective article describes the epidemiology, procedures, and mitigation strategies for current near-total and hybrid approaches to aortic arch pathology, and specifically addresses current means of embolic protection and future direction.

A Novel Evaluation for Predicting Aortic Complicated Lesions Using Calcification on Chest X-ray

BACKGROUND

The aorta is a significant source of cerebral thromboembolisms. Aortic complicated lesions (ACLs) are key findings on transesophageal echocardiography (TEE) for assessing aortic sources of emboli to the brain. TEE is sometimes avoided due to its invasiveness. However, few reports have examined alternative methods for predicting ACLs. We investigated relationships between aortic arch calcification (AAC) on chest X-ray and ACLs.

METHODS

Participants comprised 300 patients with acute ischemic stroke or transient ischemic attack who underwent TEE for the evaluation of the aortic arch and heart. A postero-anterior plain chest X-ray in the recumbent position was evaluated on admission for each patient. AAC was evaluated using 4 grades (0-3) and "AAC thickness" defined as the distance from the inner margin of the most distant AAC to the outer margin of the aortic vessel wall. ACLs were defined by intima-media thickness (IMT) ≥4.0 mm or presence of ulcerated or mobile plaques. Carotid maximum IMT on ultrasonography was also evaluated. Comparison of the diagnostic ability to predict ACL was performed between AAC grades and AAC thickness or AAC thickness and carotid maximum IMT using the Delong method.

RESULTS

ACLs were identified in 71 patients (23.7%), including ACLs with ulcerated plaques in 24 (8.0%) and ACLs with mobile plaques in 9 (3.0%). Plaque thickness was greater in higher AAC grades or higher quartiles of AAC thickness (p for trend <0.001 each). The Cochran-Armitage test showed that both higher AAC grade and higher quartile of AAC thickness were significantly associated with the presence of ACLs, as well as the presence of ulcerated or mobile plaques (p for trend < 0.001 each). Receiver-operating characteristic (ROC) analysis showed optimal cut-off values for AAC thickness of 5.6 mm for ACLs and 6.0 mm for ulcerated or mobile plaques. Multivariate logistic regression revealed a higher grade of AAC (grades 2-3) and AAC thickness (≥6 mm) as significantly associated with ACLs and ulcerated or mobile plaques (p < 0.001 each). ROC curve comparisons showed that AAC thickness offered a better marker of ACLs than AAC grade (p = 0.019), although no significant difference was evident between AAC thickness and carotid maximum IMT (p = 0.567).

CONCLUSIONS

AAC on chest X-ray, evaluated by both AAC grade and AAC thickness to the outer aortic vessel wall, was significantly associated with ACLs on TEE. AAC thickness was suggested as more useful than AAC grade and equivalent to carotid IMT in predicting ACLs.

Endovascular Therapy of Symptomatic Innominate-Subclavian Arterial Occlusive Lesions

The purpose of this study was to determine the safety and efficacy of angioplasty and stenting for symptomatic innominate-subclavian lesions by review of records of symptomatic patients undergoing angioplasty and stenting of high-grade lesions (>80%) of the innominate and subclavian arteries. Follow-up consisted of history (symptoms) and physical examination (pulses and blood pressures) at 1, 3, 6, and then every 12 months plus an annual duplex ultrasound examination. Between 1998 to 2003, 25 patients (27 lesions) were treated. Ages ranged from 48 to 89 years. Symptoms included vertebrobasilar/steal (15), claudication (6), ischemia (4), and coronary artery bypass grafting/left internal mammary artery (2). There were 7 occlusions and 20 high-grade stenoses. Access was attempted via brachial cutdown (19) or percutaneous puncture of the brachial (2) or femoral arteries (10). Twenty-two lesions were stented with either self-expanding (13) or balloon-expandable (9) stents. Technical success was 89%; 3 occluded lesions could not be crossed owing to complete occlusion. The remaining 4 occlusions were all crossed via a retrograde approach. The mean difference in systolic blood pressure between upper limbs decreased from 36 mm Hg (preprocedure) to 10 mm Hg (postprocedure). There were no procedure-related complications. Mean follow-up was 18 months (range 1–62 months). One patient died 4 months after the procedure secondary to complications from pulmonary surgery unrelated to the percutaneous transluminal angioplasty/stent. Of the 4 successfully treated occlusions, 2 were followed up to 3 years with continued patency. Three patients developed recurrent stenoses documented by duplex examination. However, these patients remained asymptomatic and were not treated. Endovascular management of high-grade lesions of the subclavian or innominate arteries is safe and efficacious and may be considered as a first line of therapy. Continued follow-up is needed to assess long-term patency.

Embolic Strokes of Unknown Source and Cryptogenic Stroke: Implications in Clinical Practice

Up to a third of strokes are rendered cryptogenic or of undetermined etiology. This number is specifically higher in younger patients. At times, inadequate diagnostic workups, multiple causes, or an under-recognized etiology contributes to this statistic. Embolic stroke of undetermined source, a new clinical entity particularly refers to patients with embolic stroke for whom the etiology of embolism remains unidentified despite through investigations ruling out established cardiac and vascular sources. In this article, we review current classification and discuss important clinical considerations in these patients; highlighting cardiac arrhythmias and structural abnormalities, patent foramen ovale, paradoxical sources, and potentially under-recognized, vascular, inflammatory, autoimmune, and hematologic sources in relation to clinical practice.

Dual Antiplatelet Therapy of Clopidogrel and Aspirin in Secondary Prevention of Ischemic Stroke: Evidence and Indications

Nowadays the dual antiplatelet therapy (DAPT) becomes more widely used in patients with ischemic stroke. Nevertheless, controversies exist for indications of DAPT. In view of evidence-based medicine analysis, patients with high-risk transient ischemic attack and minor stroke, severe symptomatic intracranial artery stenosis, symptomatic intracranial and extracranial artery stenosis causing artery-to-artery embolism, ischemic stroke attributed to aortic arch plaques, high-risk atrial fibrillation not suitable for oral anticoagulants, intracranial and extracranial stent implantation, and ischemic stroke with acute coronary syndrome may gain great benefit from DAPT of clopidogrel and aspirin. In clinical practice, individualized antiplatelet therapy strategies should be taken by weighing risks of ischemia and hemorrhage.

Echocardiographic evaluation of aortic atheromas in patients with aortic stenosis

OBJECTIVES

The association of aortic atheromas in patients with isolated aortic stenosis has recently been acknowledged, probably because the pathogenic mechanisms are similar. Therefore, this study evaluated the extent and severity of thoracic aortic atheromas in patients with different grades of aortic stenosis using transesophageal echocardiography.

METHODS

We retrospectively evaluated transesophageal echocardiographic examinations of 686 consecutive patients with a diagnosis of aortic stenosis. The prevalence and morphologic characteristics of atheromas in 3 segments of the thoracic aorta were assessed. Plaque thickness was measured at each segment, and the thickest plaque was used to establish severity. Atheromas were graded as mild, moderate, or severe according to plaque thickness (<2, 2-4, or >4 mm, respectively). Aortic stenosis was graded as mild, moderate, or severe on the basis of the gradient and anatomic aortic valve area (>1.5, 1.0-1.5, or <1.0 cm(2)).

RESULTS

A total of 382 patients were men, and 304 were women (mean age ± SD, 74 ± 15 years); 86% of the patients had aortic atheromas. The severe stenosis group had a significantly higher rate of atheromas (95% versus 40%; P < .001) than the mild stenosis group, with more complex atheromas (52% versus 22%; P< .001). There was no significant difference in the atheroma grades between the severe and moderate stenosis groups, but moderate cases had more moderate and severe atheromas than mild cases (45% and 15% versus 19% and 3%; P < .01).

CONCLUSIONS

This study showed a correlation in the extent of aortic atheromas across several degrees of aortic stenosis. Patients with moderate and severe stenosis had more extensive atherosclerotic atheromas than those with mild stenosis.

Thoracic aortic calcification is associated with incident stroke in the general population in addition to established risk factors

AIMS

The aorta is a major source of cerebral thromboembolism, but its role in stroke pathogenesis is not well understood due to its poor accessibility for non-invasive imaging. We examined whether thoracic aortic calcification (TAC), a marker of aortic plaque load, is associated with stroke in addition to established risk factors.

METHODS AND RESULTS

A total of 3930 subjects from the population-based Heinz Nixdorf Recall study (45-75 years; 47.1% men) without previous stroke, coronary heart disease, or myocardial infarction were evaluated for incident stroke events over 109.0 ± 23.3 months. Cox proportional hazards regressions were used to examine associations with stroke of TAC in addition to established risk factors (age, sex, systolic blood pressure, LDL, HDL, diabetes, and smoking) and coronary artery calcification (CAC). 101 incident strokes occurred during the follow-up period. Subjects suffering a stroke had significantly higher TAC values at baseline than the remaining subjects (median = 83.1 [Q1;Q3 = 4.7;472.9] vs. 15.7 [0.0;117.1]; P < 0.001). In a multivariable Cox proportional hazards regression, log(TAC + 1) (hazards ratio [HR] = 1.09 [95% confidence interval = 1.00-1.19]; P = 0.044) was associated with stroke in addition to established risk factors. Further analyses revealed that log(DTAC + 1), i.e. calcification of the descending aorta (1.11 [1.02-1.20]; P = 0.016), but not log(ATAC + 1), i.e. calcification of the ascending aorta (1.02 [0.93-1.11]; P = 0.713), was associated with stroke. The HR for log(TAC + 1) decreased to 1.06 (0.97-1.16; P = 0.202), when log(CAC + 1) was also inserted into multivariable analyses.

CONCLUSION

Calcification of the thoracic aorta, more specifically its descending segment, is associated with incident stroke in addition to established risk factors. CAC outperforms aortic calcification as a stroke predictor.

Embolic strokes of undetermined source: the case for a new clinical construct

Cryptogenic (of unknown cause) ischaemic strokes are now thought to comprise about 25% of all ischaemic strokes. Advances in imaging techniques and improved understanding of stroke pathophysiology have prompted a reassessment of cryptogenic stroke. There is persuasive evidence that most cryptogenic strokes are thromboembolic. The thrombus is thought to originate from any of several well established potential embolic sources, including minor-risk or covert cardiac sources, veins via paradoxical embolism, and non-occlusive atherosclerotic plaques in the aortic arch, cervical, or cerebral arteries. Accordingly, we propose that embolic strokes of undetermined source are a therapeutically relevant entity, which are defined as a non-lacunar brain infarct without proximal arterial stenosis or cardioembolic sources, with a clear indication for anticoagulation. Because emboli consist mainly of thrombus, anticoagulants are likely to reduce recurrent brain ischaemia more effectively than are antiplatelet drugs. Randomised trials testing direct-acting oral anticoagulants for secondary prevention of embolic strokes of undetermined source are warranted.

Association Between Arterial Calcifications and Nonlacunar and Lacunar Ischemic Strokes

Background and Purpose—

Nonlacunar cerebral infarcts are presumed to be caused by thromboembolism from the heart or extracranial arteries, whereas lacunar infarcts are thought to be caused by small vessel disease. We investigated to what extent arterial calcifications differ between nonlacunar and lacunar ischemic strokes.

Methods—

We studied 820 consecutive patients with transient ischemic attack or ischemic stroke in the anterior circulation who underwent multidetector computed tomography angiography and had no rare cause of stroke. The presence of likely cardioembolic pathogenesis was determined according to the Trial of Org 10172 in Acute Stroke Treatment criteria. The remaining 708 patients were categorized as nonlacunar or lacunar strokes, either transient ischemic attacks or strokes, based on clinical symptoms corrected by brain imaging results. We measured volume of calcifications in the aortic arch, symptomatic extracranial and intracranial carotid artery using multidetector computed tomography angiography. The difference in calcifications between nonlacunar and lacunar strokes was assessed with a multivariable logistic regression analysis. We adjusted for degree of symptomatic carotid artery stenosis and cardiovascular risk factors.

Results—

We found an independent association between volume of aortic arch calcifications and nonlacunar ischemic strokes (adjusted odds ratio [95% confidence interval], 1.11 [1.02–1.21]). No independent associations between extracranial and intracranial carotid artery calcifications and nonlacunar strokes were present.

Conclusions—

The only difference we found between nonlacunar and lacunar strokes was a higher calcification volume in the aortic arch in nonlacunar strokes. Our findings only partially confirm the notion of distinct etiologies and suggest that the potential role of other plaque components, plaque morphology, and aortic arch calcifications in ischemic stroke subtypes awaits further evaluation.

The Norwegian Stroke in the Young Study (NOR-SYS): rationale and design

BACKGROUND

Ischemic stroke in young adults is a major health problem being associated with a higher vascular morbidity and mortality compared to controls, and a stroke recurrence rate of 25% during the first decade. The assumed cause of infarction and the detected risk factors determine the early- and long-term treatment. However, for many patients the cause of stroke remains unknown. Risk factor profile and etiology differ in young and elderly ischemic stroke patients, and atherosclerosis is the determined underlying condition in 10 to 15%. However, subclinical atherosclerosis is probably more prevalent and may go unrecognized.

METHODS/DESIGN

NOR-SYS is a prospective long-term research program. Standardized methods are used for anamnestic, clinical, laboratory, imaging, and ultrasound data collection in ischemic stroke patients aged ≤60 years, their partners and joint adult offspring. The ultrasound protocol includes the assessment of intracranial, carotid and femoral arteries, abdominal aorta, and the estimation of VAT. To date, the study is a single centre study with approximately 400 patients, 250 partners and 350 adult offspring expected to be recruited at our site.

DISCUSSION

NOR-SYS aims to increase our knowledge about heredity and the development of arterial vascular disease in young patients with ischemic stroke and their families. Moreover, optimization of diagnostics, prophylaxis and early intervention are major targets with the intention to reduce stroke recurrence and other clinical arterial events, physical disability, cognitive impairment and death.

Combination aspirin and clopidogrel for secondary prevention of ischemic stroke

OPINION STATEMENT

Though antiplatelet agents are the mainstay of antithrombotic therapy for secondary prevention of noncardioembolic cerebral ischemic events, the efficacy of combination aspirin and clopidogrel has yet to be clarified by clinical trials. Current evidence suggests that there is no role for long-term combination of aspirin/clopidogrel for secondary stroke prevention. Recent preliminary data from the CHANCE (Clopidogrel in High-risk Patients with Acute Non-disabling Cerebrovascular Events) trial suggests that stroke recurrence at 90 days is reduced by a short course (21 days) of combination aspirin/clopidogrel initiated within 24 hours of minor stroke or TIA (Transient Ischemic Attack) compared with aspirin alone [1••] (Table 1). Other ongoing trials, which are also investigating the role of short-term combination antiplatelet therapy initiated immediately after minor stroke and TIA, will determine if these findings will be replicated.

Ischemic lesion burden and characteristics of aortic atheroma

BACKGROUND

To investigate whether ischemic lesion burden including lesion pattern, number, and volume would vary depending on risk stratification of aortic atheroma (AA).

METHODS

Acute stroke patients were enrolled if they had (1) acute ischemic lesions on diffusion-weighted imaging within 5 days of symptom onset, (2) cardioembolic stroke established through extensive workup, and (3) only ascending or arch AA detected by transesophageal echocardiography as an embolic source. AA was classified as complex (protruding ≥4 mm into the aortic lumen or any mobile or ulcerative component) or simple (<4 mm).

RESULTS

Eighty-one patients (male: 65.4% and age: 66.7 ± 11.0 years) were included in the study. Thirty-four patients (41.9%) had complex atheroma. These patients had a greater number of ischemic lesions (median: 2 lesions [range: 1-42] versus one lesion [range: 1-27], P = .017) and a larger infarct size (9.01 cc [range: 3.58-49.14] versus 4.6 cc [range: 2.3-13.28), P = .056) than the simple atheroma group. Multivariable logistic regression analysis showed that ischemic lesion volume was independently associated with complex atheroma (odds ratio: 1.03, 95% confidence interval: 1.002-2.148, P = .035), while multiple lesions were related (odds ratio: 3.03, 95% confidence interval: .88-10.42, P = .079).

CONCLUSIONS

Ischemic lesion burden in patients with AA differed according to AA characteristics, suggesting that the morphological features of AA could reflect an embolic potential of AA.

[Secondary prophylaxis of stroke from a neurological perspective]

Patients who have suffered ischemic stroke or transient ischemic attack (TIA) are at high risk of recurrent stroke, myocardial infarction or vascular death. Early pathophysiological based diagnostics and resulting secondary prevention are critical for reduction of stroke risk. Optimization of lifestyle factors, treatment of hypertension, cholesterol reduction with statins and use of antiplatelet agents in non-cardiogenic or anticoagulation in cardiogenic ischemia as well as internal carotid revascularization, in cases of more than 50% diameter stenosis of the internal carotid artery, are proven strategies for reduction of ischemic stroke risk.

Repeated brain infarction caused by atherosclerosis of the bovine aortic arch successfully treated with arch replacement: case report

A 62-year-old man presented with repeated embolic infarction over the last 3 years. Computed tomography angiography of the aortic arch revealed that the patient had a common trunk for the innominate and left carotid arteries, the so-called bovine aortic arch, with stenosis extending to both the left common carotid artery and innominate artery. Since antiplatelet therapy was not adequate for prevention of recurrent infarction, total replacement of the aortic arch was performed. Since then, no further ischemic events have manifested. Endovascular procedures are not safe enough for atherosclerotic lesions in the aortic arch, especially in a patient with bovine aortic arch, so surgical aortic arch replacement should be considered.

Characterization of the infarct pattern caused by vulnerable aortic arch atheroma: DWI and multidetector row CT study

BACKGROUND

Aortic arch atheroma (AAA) has been accepted as a possible embolic source in patients with ischemic stroke, especially cryptogenic stroke. However, despite its well-known role as a risk factor for stroke, research focused on the mechanism or characteristics of stroke caused by AAA is insufficient. In this study, we aimed to evaluate clinical and radiological characteristics including lesion pattern on DWI in acute stroke patients associated with vulnerable AAA detected by multidetector row computed tomography (MDCT).

METHODS

From September 2008 through May 2011, patients who presented with acute ischemic stroke and underwent MDCT were found in a prospective stroke registry. Patients without evident stroke etiology were included and classified by presence of vulnerable AAA. Vulnerable AAA was defined as (i) at least 6 mm thick adjacent to the aortic wall; (ii) ulcerated plaque, or (iii) soft plaque. Soft plaque was defined as the presence of clearly visualized area of hypoattenuation (<80 Hounsfield units) suggestive of thrombus. The patients without vulnerable AAA were classified as no/simple AAA group. The characteristics of diffusion-weighted MRI (DWI) lesions were analyzed in terms of the number and size of the lesions, and the involved vascular territories.

RESULTS

A total of 63 cryptogenic stroke patients were included in this study. Vulnerable AAA was observed in 15 (23.8%) patients. The patients with vulnerable AAA were older than those with no/simple AAA (p = 0.026). DWI analysis revealed that the vulnerable AAA group had a greater chance of having multiple and small lesions in multiple vascular territories that were mainly located in cortical and border-zone regions than the no/simple AAA group. Multiple logistic regression analysis showed that age (odds ratio 1.17; 95% confidence interval 1.02-1.34) and multiple small lesions in multiple vascular territories (odds ratio 33.18; 95% confidence interval 4.26-258.45) were independently associated with vulnerable AAA.

CONCLUSION

Vulnerable AAA is independently associated with a DWI pattern characterized by multiple small scattered lesions in multiple vascular territories in conjunction with age. It may help determine stroke mechanism quickly and easily, and provide more information about the pathomechanism of vulnerable AAA-related stroke.

Association of the phosphodiesterase 4D (PDE4D) gene and cardioembolic stroke in an Australian cohort

BACKGROUND

Large-scale epidemiological studies support an important role for susceptibility genes in the pathogenesis of ischemic stroke, with phosphodiesterase 4D identified as the first gene predisposing to ischemic stroke. Several single nucleotide polymorphisms within the phosphodiesterase 4D gene have been implicated in the pathogenesis of stroke. Aim Undertake a multivariate analysis of six single nucleotide polymorphisms within the phosphodiesterase 4D gene in a previously defined Australian stroke cohort, to determine whether these single nucleotide polymorphisms have an association with ischemic stroke.

METHODS

This case-control study was performed using an existing genetic database of 180 ischemic stroke patients and 301 community controls, evaluated previously for cerebrovascular risk factors (hypertension, hypercholesterolemia, diabetes, paroxysmal atrial fibrillation, smoking and history of stroke in a first-degree relative). Based on previously reported associations with large vessel disease, ischemic stroke, cardioembolic stroke or a mixture of these, six single nucleotide polymorphisms in the phosphodiesterase 4D gene were selected for study, these being single nucleotide polymorphisms 13, 19, rs152312, 45, 83 and 87, based on previously utilized DeCODE nomenclature. Single nucleotide polymorphisms were genotyped using a sequence-specific polymerase chain reaction method and gel electrophoresis. Logistic regression was undertaken to determine the relevance of each polymorphism to stroke. Further analysis was undertaken to determine the risk of stroke following stratification for stroke sub-type and etiology.

RESULTS

Significant odds ratios were found to be associated with cardioembolic strokes in two single nucleotide polymorphisms: rs152312 and SNP 45 (P < 0 · 05).

CONCLUSIONS

Our findings demonstrated an association between cardioembolic stroke and phosphodiesterase 4D single nucleotide polymorphisms rs152312 and 45. No significant association was found for the other four single nucleotide polymorphisms investigated within the phosphodiesterase 4D gene. We propose that the results from this Australian population support the concept that a large prospective international study is required to investigate the role of phosphodiesterase 4D in the cardiogenic cause of ischemic stroke.

Prevalence of coronary atherosclerosis in patients with cerebral infarction

BACKGROUND AND PURPOSE

there is an overlap between stroke and coronary heart disease, but the exact prevalence of coronary artery disease in patients with nonfatal cerebral infarction is unclear, particularly when there is no known history of coronary heart disease.

METHODS

we consecutively enrolled 405 patients presenting with acute cerebral infarction documented by neuroimaging who underwent carotid and femoral artery, thoracic, and abdominal aorta ultrasound examinations. Of the 342 patients with no known coronary heart disease, 315 underwent coronary angiography a median of 8 days (interquartile range, 6-11) after stroke onset.

RESULTS

coronary plaques on angiography, regardless of stenosis severity, were present in 61.9% of patients (95% confidence interval [CI], 56.5-67.3) and coronary stenoses ≥ 50% were found in 25.7% (95% CI, 20.9-30.5). The overall prevalence of coronary plaque increased with the number of arterial territories (carotid or femoral arteries) involved, with an adjusted odds ratio of coronary artery disease of 1.25 (95% CI, 0.58-2.71) for presence of plaque in 1 territory, and 4.31 (95% CI, 1.92-9.68) for presence of plaque in both territories, compared with no plaque in either territory. The presence of plaque in both femoral and carotid arteries had an age- and sex-adjusted positive predictive value of 84% for presence of coronary plaque and a negative predictive value of 44%.

CONCLUSIONS

there is a high burden of silent coronary artery disease in patients with nonfatal cerebral infarction and no known coronary heart disease, even in the absence of systemic atherosclerosis. The prevalence is even higher in patients with evidence of carotid and/or femoral plaque.

M1-activated macrophages migration, a marker of aortic atheroma progression: a preclinical MRI study in mice

BACKGROUND

M1-activated Macrophages (M1M) play a major role in atherosclerotic lesions of aortic arch, promoting proinflammatory response. In vivo trafficking of M1M in aortic plaques is therefore critical.

METHODS

M1M from bone marrow cell culture were magnetically labeled, using iron nanoparticles, intravenously injected and followed up with 3 day magnetic resonance imaging (MRI) in mice developing macrophage-laden atheroma (ApoE2 knock-in mice). M1M recruitment in aortic arch lesions was assessed both by MRI and histology.

RESULTS

In all ApoE2 knock-in mice injected with labeled cells, high resolution MRI showed localized signal loss regions in the thickened aortic wall, with a maximal effect at day 2 (-34% +/- 7.3% P < 0.001 compared with baseline). This was confirmed with Prussian blue (iron) staining and corresponded to M1M (Major Histo-compatibility Complex II positive). Clear different intraplaque and adventitial dynamic distribution profiles of labeled cells were observed during the 3 days.

CONCLUSION

M1M dynamic MRI is a promising marker to noninvasively assess the macrophage trafficking underlying aortic arch plaque progression.