The distribution and size of ischemic lesions after carotid artery angioplasty and stenting: evidence for microembolization to terminal arteries

Newly developed DWI hyperintensities and changes in cerebral blood flow after carotid stent placement for unilateral symptomatic carotid artery stenosis

This study aimed to evaluate changes in cerebral blood flow and perioperative outcomes in patients with unilateral symptomatic carotid artery stenosis before and after carotid artery stenting (CAS), providing insights to guide surgical decision-making. Ninety-six patients with moderate to severe unilateral symptomatic carotid artery stenosis (>50%) admitted to the Neurology Department of the Second Affiliated Hospital of Zhejiang University from June 2023 to April 2024 were included. All patients underwent CAS and magnetic resonance imaging, including diffusion-weighted imaging (DWI) and 3D quasi-continuous arterial spin-labeled perfusion imaging, within 3 days preoperatively and on the third postoperative day. Patients were categorized into microembolic and non-embolic groups based on the presence of new diffusion-weighted imaging hyperintensities. Newly developed diffusion-weighted imaging hyperintensities were detected in 68 patients (70.8%), with a total of 704 lesions, though only 4 cases exhibited symptoms. Most lesions were localized to the frontal-parietal cortex and subcortical areas on the affected side (60.8%) and were <3 mm in size (92.6%). Postoperatively, cerebral blood flow in the frontal-parietal lobe was significantly higher than in the temporal lobe on both the affected (50.49 ± 8.02 vs 47.94 ± 9.08, t = 2.179, P < .05) and healthy sides (50.16 ± 5.79 vs 48.00 ± 5.98, t = 3.835, P < .05). Additionally, cerebral blood flow in the affected frontal and temporal lobes significantly increased after surgery (P < .05). Preoperative frontal-parietal cerebral blood flow was lower in the microembolic group compared to the non-embolic group (P < .05). Microemboli are common after CAS but are unlikely to result from immediate hemodynamic changes. Instead, they appear to be associated with chronic preoperative hypoperfusion, which impairs cerebral blood flow regulation.

Endovascular Debulking of Human Carotid Plaques by Using an Excimer Laser Combined With Balloon Angioplasty: An ex vivo Study

Purpose: We aimed to evaluate the safety and effectiveness of applying an excimer laser in debulking human carotid atherosclerotic plaques by investigating the distal debris, plaque luminal gain, and micromorphology of the plaque surface.

Methods: Eighteen plaque samples obtained from carotid endarterectomy (CEA) were randomly allocated to the excimer laser ablation (45 mJ/mm², 25 Hz) alone group (group 1), balloon angioplasty (8 atm) alone group (group 2), and excimer laser ablation combined with balloon angioplasty group (group 3). Hematoxylin–eosin staining and Movat's pentachrome staining were performed on the collected particles to quantify the size and composition of the debris. The superficial micromorphological structure of the plaque lumen surface after device treatments was observed using a scanning electron microscope. Micro-CT, tissue sections, and pathological stainings were applied to the treated plaques. The plaque lumen and artery lumen were three-dimensionally reconstructed using clinical computed tomography angiography and the micro-CT images. Lumen enlargement was set as the main measurement of effectiveness.

Results: Group 3 produced the highest luminal gain (5.40 ± 4.51 mm²), while the other two groups had gains of 4.05 ± 3.20 and 3.77 ± 2.55 mm². Both devices caused disruptions to the plaque lumen surface. Laser ablation exposed the fibers under the endothelium and balloon angioplasty cracked the surface. The mean amounts were 3,611 ± 1,475.4 for group 1, 2,828 ± 1,266.7 for group 2, and 4,400 ± 2,567.9 for group 3. More than 90% of the distal debris was smaller than 10 μm. Group 2 produced the most debris with Feret (maximum caliper diameter) ≥ 40 μm; group 1 had the least. There was little difference in the contents of collagen and reticular fiber in the debris in each group, but a big difference was observed in the contents of fibrin and mucin.

Conclusion: Excimer laser ablation could significantly increase the luminal gain of carotid plaque with high stenosis. Excimer laser combined with balloon angioplasty achieved the highest lumen enlargement. Our result also suggests that the embolic protection strategy needs to be renewed for the application of a plaque debulking device in the future.

Recovery of Hypoxic Regions in a Rat Model of Microembolism

OBJECTIVES

Endovascular treatment (EVT) has become the standard of care for acute ischemic stroke. Despite successful recanalization, a limited subset of patients benefits from the new treatment. Human MRI studies have shown that during removal of the thrombus, a shower of microclots is released from the initial thrombus, possibly causing new ischemic lesions. The aim of the current study is to quantify tissue damage following microembolism.

MATERIALS AND METHODS

In a rat model, microembolism was generated by injection of a mixture of polystyrene fluorescent microspheres (15, 25 and 50 µm in diameter). The animals were killed at three time-points: day 1, 3 or 7. AMIRA and IMARIS software was used for 3D reconstruction of brain structure and damage, respectively.

CONCLUSIONS

Microembolism induces ischemia, hypoxia and infarction. Infarcted areas persist, but hypoxic regions recover over time suggesting that repair processes in the brain rescue the regions at risk.

New-onset lesions on MRI-DWI and cerebral blood flow changes on 3D-pCASL after carotid artery stenting

This study aimed to investigate the relationship between the new-onset hyperintense lesions on diffusion-weighted images (DWI) and the changes of cerebral blood flow (CBF) before and after carotid artery stenting (CAS) in patients with symptomatic unilateral carotid artery stenosis. Twenty-four patients with symptomatic unilateral carotid stenosis (50-99%) were enrolled. Routine head magnetic resonance imaging and three-dimensional pseudo-continuous arterial spin labeling were taken 7 days before the surgery and for four consecutive days post CAS. While the incidence of new DWI lesions were high (17/24, 70.8%) and 176 lesions were observed among the 17 cases, there was only one subject showing the symptoms. The majority of the lesions were located at the cortex/subcortex of the ipsilateral frontal and parietal lobes (60.8%) with 92.6% of the lesions size being less than 3 mm. The CBFs in this area were significantly higher than that of the temporal lobe on the first 3 days post stenting (p < 0.05). No periprocedural CBF differences were observed between the two groups, however, the micro-embolism group presented decreased relative CBF in frontal and parietal lobes prior to stenting compared with the non-embolism group. The systolic blood pressure in the micro-embolism group at discharge was significantly lower than that at admission. The high incidence rate of micro-embolism in patients receiving CAS may not be the result of direct changes of hemodynamics in the brain but rather the loss of CBF regulation due to long-term hypoperfusion prior to the stenting.

Cognitive Function and Atrial Fibrillation: From the Strength of Relationship to the Dark Side of Prevention. Is There a Contribution from Sinus Rhythm Restoration and Maintenance?

Atrial fibrillation (AF) is the most common chronic cardiac arrhythmia with an increasing prevalence over time mainly because of population aging. It is well established that the presence of AF increases the risk of stroke, heart failure, sudden death, and cardiovascular morbidity. In the last two decades several reports have shown an association between AF and cognitive function, ranging from impairment to dementia. Ischemic stroke linked to AF is a well-known risk factor and predictor of cognitive decline. In this clinical scenario, the risk of stroke might be reduced by oral anticoagulation. However, recent data suggest that AF may be a predictor of cognitive impairment and dementia also in the absence of stroke. Cerebral hypoperfusion, reduced brain volume, microbleeds, white matter hyperintensity, neuroinflammation, and genetic factors have been considered as potential mechanisms involved in the pathogenesis of AF-related cognitive dysfunction. However, a cause-effect relationship remains still controversial. Consequently, no therapeutic strategies are available to prevent AF-related cognitive decline in stroke-free patients. This review will analyze the potential mechanisms leading to cognitive dysfunction in AF patients and examine the available data on the impact of a sinus rhythm restoration and maintenance strategy in reducing the risk of cognitive decline.

Silent brain infarcts on diffusion-weighted imaging after carotid revascularisation: A surrogate outcome measure for procedural stroke? A systematic review and meta-analysis

Aim

To investigate whether lesions on diffusion-weighted imaging (DWI+) after carotid artery stenting (CAS) or endarterectomy (CEA) might provide a surrogate outcome measure for procedural stroke.

Materials and Methods

Systematic MedLine® database search with selection of all studies published up to the end of 2016 in which DWI scans were obtained before and within seven days after CAS or CEA. The correlation between the underlying log odds of stroke and of DWI+ across all treatment groups (i.e. CAS or CEA groups) from included studies was estimated using a bivariate random effects logistic regression model. Relative risks of DWI+ and stroke in studies comparing CAS vs. CEA were estimated using fixed-effect Mantel-Haenszel models.

Results

We included data of 4871 CAS and 2099 CEA procedures (85 studies). Across all treatment groups (CAS and CEA), the log odds for DWI+ was significantly associated with the log odds for clinically manifest stroke (correlation coefficient 0.61 (95% CI 0.27 to 0.87), p = 0.0012). Across all carotid artery stenting groups, the correlation coefficient was 0.19 (p = 0.074). There were too few CEA groups to reliably estimate a correlation coefficient in this subset alone. In 19 studies comparing CAS vs. CEA, the relative risks (95% confidence intervals) of DWI+ and stroke were 3.83 (3.17-4.63, p < 0.00001) and 2.38 (1.44-3.94, p = 0.0007), respectively.

Discussion

This systematic meta-analysis demonstrates a correlation between the occurrence of silent brain infarcts on diffusion-weighted imaging and the risk of clinically manifest stroke in carotid revascularisation procedures.

Conclusion

Our findings strengthen the evidence base for the use of DWI as a surrogate outcome measure for procedural stroke in carotid revascularisation procedures. Further randomised studies comparing treatment effects on DWI lesions and clinical stroke are needed to fully establish surrogacy.

Neurological signs in 23 dogs with suspected rostral cerebellar ischaemic stroke

BACKGROUND

In dogs with ischaemic stroke, a very common site of infarction is the cerebellum. The aim of this study was to characterise neurological signs in relation to infarct topography in dogs with suspected cerebellar ischaemic stroke and to report short-term outcome confined to the hospitalisation period. A retrospective multicentre study of dogs with suspected cerebellar ischaemic stroke examined from 2010-2015 at five veterinary referral hospitals was performed. Findings from clinical, neurological, and paraclinical investigations including magnetic resonance imaging were assessed.

RESULTS

Twenty-three dogs, 13 females and 10 males with a median age of 8 years and 8 months, were included in the study. The Cavalier King Charles Spaniel (n = 9) was a commonly represented breed. All ischaemic strokes were located to the vascular territory of the rostral cerebellar artery including four extensive and 19 limited occlusions. The most prominent neurological deficits were gait abnormalities (ataxia with hypermetria n = 11, ataxia without hypermetria n = 4, non-ambulatory n = 6), head tilt (n = 13), nystagmus (n = 8), decreased menace response (n = 7), postural reaction deficits (n = 7), and proprioceptive deficits (n = 5). Neurological signs appeared irrespective of the infarct being classified as extensive or limited. All dogs survived and were discharged within 1-10 days of hospitalisation.

CONCLUSIONS

Dogs affected by rostral cerebellar ischaemic stroke typically present with a collection of neurological deficits characterised by ataxia, head tilt, and nystagmus irrespective of the specific cerebellar infarct topography. In dogs with peracute to acute onset of these neurological deficits, cerebellar ischaemic stroke should be considered an important differential diagnosis, and neuroimaging investigations are indicated. Although dogs are often severely compromised at presentation, short-term prognosis is excellent and rapid clinical improvement may be observed within the first week following the ischaemic stroke.

Atrial Fibrillation and Stroke: Increasing Stroke Risk with Intervention

This article focuses on the important newly recognized appreciation for the paradoxic increase in stroke and transient ischemic attack as a result of intervention meant to treat atrial fibrillation (AF) with the hope of decreasing stroke risk in the long term. The impact of silent cerebral lesions has recently been identified as a potentially major limitation, and the risks with AF ablation, as well as the present understanding of how risk can be minimized, are explained. This article provides a platform for newer study, changes in the way procedures are done, and possibly vascular-based stroke-reduction strategies.