Reporting Standards for Carotid Artery Angioplasty and Stent Placement

Evaluation of the association between the internal carotid artery and vertebral artery tortuosity and acute ischemic stroke using tortuosity index

OBJECTIVE

To determine the association between the tortuosity of the internal carotid artery and vertebral artery and the occurrence of acute ischemic stroke based on a new quantitative method.

METHODS

This retrospective case-control study was conducted on 63 patients diagnosed with acute ischemic stroke in the case group and 52 patients in the control group. All the participants underwent neck Computed Tomography Angiography. The images were retrospectively reviewed and the tortuosity index was measured for internal carotid and vertebral artery. Then, a multivariable binary logistic regression model adjusted for the potential confounders was performed to assess the independent effect of internal carotid/vertebral artery tortuosity on acute ischemic stroke.

RESULTS

Analysis of the logistic regression model revealed a significant effect of the internal carotid artery tortuosity index on anterior territory infarction (odds ratio = 1.04, p = 0.01) as well as a significant effect of the vertebral artery tortuosity index on posterior territory infarction (odds ratio = 1.14, p < 0.001). The optimal cut-off points for the internal carotid and vertebral artery tortuosity were 16.91 and 22.96, respectively.

CONCLUSIONS

This study showed that tortuosity of extracranial portions of the internal carotid and vertebral artery could be an independent imaging predictor of acute ischemic stroke in anterior and posterior circulation territories, respectively.

Histological verification of atherosclerosis due to bends and bifurcations in carotid arteries predicted by hemodynamic model

Background

Tortuosity and bifurcations in carotid arteries alter the blood flow, causing atherosclerosis.

Objectives

The aim of the present study is to analyze the effect of variant vascular anatomy in the cervical region on development of atherosclerosis by microanatomical examination.

Methods

The effect of blood flow at anomalous bends and bifurcations was observed in right carotid arteries of a seventy year old female cadaver. Fifteen histological slides were prepared from the carotid arteries and interpreted to verify predictions of atherosclerosis.

Results

The model predicts atherosclerosis at bends, bifurcations and large aperture arteries. Microanatomical examination revealed presence of atherosclerosis of varying thickness at the bends and bifurcation in the right carotid arteries, as predicted. Atherosclerosis was also detected in the straight part of the wider common carotid artery. No atherosclerosis was observed in the contralateral carotid arteries. The variant carotid vascular anatomy consisting of bends, bifurcations and wider arteries revealed that the shear stress and velocity of blood flow are reduced at these anomalous sites.

Conclusions

Anatomical anomalies such as bends and branching in the carotid arteries alter the irrigation pattern and generate biomechanical forces that cause turbulent flow and reduce shear stress/blood flow velocity. Decreased shear stress and velocity causes development of atherosclerosis. Histological slides established the presence of atherosclerosis at bends and bifurcations and in wider arteries.

Association Between Stroke Severity and 5-Year Mortality in Ischemic Stroke Patients with High-Grade Stenosis of Internal Carotid Artery

BACKGROUND

The clinical presentations and outcomes of patients with high-grade stenosis of internal carotid artery (ICA) are highly variable. We investigate the influence of different stroke severity on outcomes of ischemic stroke patients with high-grade stenosis of ipsilateral ICA.

METHODS

372 acute first-ever ischemic stroke patients with high-grade stenosis (70%-99%) or occlusion of ipsilateral ICA were enrolled and followed up for 5years. Stroke severities of the enrolled patients were grouped according to the Oxfordshire Community Stroke Project classification system as total anterior circulation infarcts (TACI) or non-TACI. Demographic features, vascular risk factors, comorbidities, and outcomes were compared between the 2 groups.

RESULTS

A total of 71 patients (19.1%) were presented with TACI. Of laboratory data, the values of white blood cell count and high-sensitivity C-reactive protein were significantly higher in patients with TACI (P = .008 and P = .003, respectively). Of clinical course, the occurrence of initial impaired conscious, stroke-in-evolution, pneumonia, gastrointestinal bleeding, and urinary tract infection were significantly higher in patients with TACI. The prevalence of dependent functional status was higher in patients with TACI. Multivariate Cox regression revealed that TACI is a significant predictor of 5-year all-cause mortality in first-ever ischemic stroke patients with high-grade stenosis of ipsilateral ICA (HR [hazard ratio] = 3.66, 95% confidence interval = 2.23-6.00, P < .001).

CONCLUSIONS

TACI is associated with increased risk of 5-year mortality in ischemic stroke patients with high-grade stenosis of ipsilateral ICA. Intensive medical treatment for stroke prevention in patients with severe carotid artery stenosis is warranted.

Effect of Cervical Siphon of External and Internal Carotid Arteries

Variant courses, configuration, and branching pattern of the external and internal carotid arteries, especially when curved in S-shape, are important for hemodynamic changes and clinical implications. Therefore, the aim of the study is to report abnormal cervical siphons observed in external and internal carotid arteries to explore clinical significance by review of literature and hemodynamic changes theoretically.The right common carotid artery bifurcated into external and internal carotid arteries at the level of the upper border of thyroid cartilage in a 70-year-old female cadaver. After bifurcation, the external carotid artery underwent severe tortuosity coursing through 5 bends at points A, B, C, D, and E from its origin to termination and 2 bends at A' and B' in internal carotid artery in the cervical region. The angles between inflow and out flow of the blood at the bends were measured and the change in velocity at each bend was computed for both arteries. Hemodynamic changes were calculated, compared and relevant clinical complications were theoretically correlated.The angles of 20°, 30°, 51°, 52°, 60°, and 28°, 48° were formed by 5 bends of external and 2 bends of internal carotid arteries, respectively. The curved courses of these arteries caused reduction in velocity/stasis, turbulence, and low shear stress. Such kinks might cause stroke, ischemia and mistaken for tumors and abscess in imagery leading to or otherwise producing iatrogenic repercussions. This study will be useful for anatomists, clinicians, and radiologists.

Secondary Prevention of Ischemic Cerebrovascular Disease. What Is the Evidence?

Patients who had a transient ischemic attack or stroke are at increased risk of experiencing recurrent cerebrovascular events. For this reason, secondary prevention of ischemic cerebrovascular disease is essential. Several modifiable, lifestyle-associated risk factors have been implicated, such as physical activity, smoking, and alcohol consumption. Established and emerging vascular risk factors are associated with an increased risk of stroke. Pharmacologic treatment, including the use of antiplatelet, antihypertensive, and lipid-lowering agents, has also been shown to reduce the risk of secondary cerebrovascular events. Surgical intervention, either open or endovascular, may be the preferred therapeutic option in well-defined subsets of patients. It is important to establish specific measures for the early detection and prevention of recurrent cerebrovascular disease. Therefore, further research and greater awareness in this field are needed.

Clinical implications of internal carotid artery tortuosity, kinking and coiling: a systematic review

Anatomical variations of the internal carotid artery are diverse. Abnormalities in their geometry and paths are commonly identified by ultrasonography and angiography. The surgical correction of symptomatic CAs is better in preventing stroke compared with best medical therapy, as well as it completely eliminates the symptoms in patients with nonhemispheric symptoms. The ICA anomalies may be dangerous and represent a risk factor for massive bleeding. Suture ligatures can penetrate and occlude torn vessels, scalpels or biting instruments can lacerate vessels, and indirectly conducted electric cauterization can burn the soft of bony tissues

Endovascular remodeling of tortuous cervical segments of the internal carotid artery that hinder the management of complex intracranial aneurysms

Introduction: Severe tortuosity of the cervical segment of the internal carotid artery (ICA) may hamper the navigation of intravascular devices for the management of complex intracranial aneurysms and even conventional techniques of ICA access can fail. In a group of selected cases, we analyzed the efficacy and safety of carotid stenting to straighten the Severe tortuosity for direct navigation of the devices. Methods: A case series of 16 patients harboring 18 intracranial aneurysms with a difficult endovascular approach because of a cervical ICA with Severe tortuosity were prospectively recruited at our institution from January 2005 to December 2007. When traditional means of correction could not surmount this obstacle, an overlap stenting with a distal-to-proximal technique was used to overcome the Severe tortuosity. The efficacy of the procedure was defined as the ability to reach and be able to treat the target lesion with a smooth navigation of the endovascular devices. Safety was documented by procedure-related complications. Results: The straightening of the vessel by the stent helped to overcome pitfalls, making possible an obstacle-free navigation of the endovascular devices to the target lesion in all cases. In 5 cases with severe or double kinking, a distal transfer of the curve beyond the stent was observed, without impact on the efficacy of the procedure. One case of periprocedural related technical complication occurred with a permanent stroke. During the follow-up period (22.7 ± 8.4 months) no case of stent-related stroke or severe hyperplasia was observed. Conclusions: Carotid stenting is an available option when a cervical ICA with Severe tortuosity hampers a smooth catheterization of the intracranial circulation, in carefully selected cases. It allows a relatively safe and free navigation and/or deployment of additional endovascular devices needed for the treatment of complex intracranial aneurysms.

Effects of stent design and atherosclerotic plaque composition on arterial wall biomechanics

PURPOSE

To examine the solid mechanical effects of varying stent design and atherosclerotic plaque stiffness on the biomechanical environment induced in a diseased artery wall model.

METHODS

Computational modeling techniques were employed to investigate the final radius of the lumen and artery wall stresses after stent implantation. Two stent designs were studied (one stiff and one less stiff). The stenotic artery was modeled as an axisymmetrical diseased vessel with a 20% stenosis by diameter. The material properties of the diseased tissue in the artery models varied. Atherosclerotic plaques half as stiff (0.5x), of equal stiffness (1.0x), or twice as stiff (2.0x) as the artery wall were investigated.

RESULTS

Final lumen radius was dependent on stent design, and the stiffer stent deformed the artery to an approximately 10% greater radius than the more compliant design. Alternatively, circumferential stress levels were dependent on both stent design and plaque material properties. Overall, the stiffer stent subjected the artery wall to much higher stress values than the more compliant design, with differences in peak values of 0.50, 0.31, and 0.09 MPa for the 2.0x, 1.0x, and 0.5x stiff plaques, respectively.

CONCLUSION

Evidence suggests that a judicious choice of stent design can minimize stress while maintaining a patent lumen in stenotic arteries. If confronted with a rigid, calcified plaque, stent design is more important, as design differences can impose dramatically different stress fields, while still providing arterial patency. Alternatively, stent design is not as much of an issue when treating a soft, lipid-laden plaque, as stress fields do not vary significantly among stent designs.

Reporting standards for endovascular repair of saccular intracranial cerebral aneurysms

BACKGROUND AND PURPOSE

The goal of this article is to provide consensus recommendations for reporting standards, terminology, and written definitions when reporting on the radiological evaluation and endovascular treatment of intracranial, cerebral aneurysms. These criteria can be used to design clinical trials, to provide uniformity of definitions for appropriate selection and stratification of patients, and to allow analysis and meta-analysis of reported data.

METHODS

This article was written under the auspices of the Joint Writing Group of the Technology Assessment Committee, Society of NeuroInterventional Surgery, Society of Interventional Radiology; Joint Section on Cerebrovascular Neurosurgery of the American Association of Neurological Surgeons and Congress of Neurological Surgeons; and Section of Stroke and Interventional Neurology of the American Academy of Neurology. A computerized search of the National Library of Medicine database of literature (PubMed) from January 1991 to December 2007 was conducted with the goal to identify published endovascular cerebrovascular interventional data about the assessment and endovascular treatment of cerebral aneurysms useful as benchmarks for quality assessment. We sought to identify those risk adjustment variables that affect the likelihood of success and complications. This article offers the rationale for different clinical and technical considerations that may be important during the design of clinical trials for endovascular treatment of cerebral aneurysms. Included in this guidance article are suggestions for uniform reporting standards for such trials. These definitions and standards are primarily intended for research purposes; however, they should also be helpful in clinical practice and applicable to all publications.

CONCLUSIONS

The evaluation and treatment of brain aneurysms often involve multiple medical specialties. Recent reviews by the American Heart Association have surveyed the medical literature to develop guidelines for the clinical management of ruptured and unruptured cerebral aneurysms. Despite efforts to synthesize existing knowledge on cerebral aneurysm evaluation and treatment, significant inconsistencies remain in nomenclature and definition for research and reporting purposes. These operational definitions were selected by consensus of a multidisciplinary writing group to provide consistency for reporting on imaging in clinical trials and observational studies involving cerebral aneurysms. These definitions should help different groups to publish results that are directly comparable.

Timing of stenting of symptomatic carotid stenosis is predictive of 30-day outcome

For patients with symptomatic carotid stenosis, benefit from carotid artery stenting (CAS) highly depends on the 30-day stroke and death rates. Identification of predictors of unfavourable outcome would help guide the patient selection. We analysed the influence of clinical and angiographic factors on the 30-day outcomes of 77 consecutive patients who underwent CAS for > or = 60% symptomatic carotid stenosis within 180 days of transient ischaemic attack or moderate stroke (modified Rankin Scale score < or = 3). The 30-day composite end-point for stroke (7.8%) and death of any cause (1.3%) was 9.1%. Patients with complicated CAS were older than patients with uncomplicated CAS (mean age 75.1 +/- 8.2 vs. 65.9 +/- 9.5 years, P = 0.015) and underwent stenting significantly earlier after the qualifying event: median delay 1.5 weeks (range: 0.2-3.0) vs. 3.2 weeks (range: 0.5-26), P = 0.004. In multivariate logistic regression analyses, age [odds ratio (OR) = 1.148; 95% confidence interval (CI): 1.011-1.304 and P = 0.033] and delay of treatment < 2 weeks (OR = 22.399; 95% CI: 2.245-223.445 and P = 0.008) remained the only variables significantly associated with 30-day outcome. CAS carries a considerable risk in old patients and when performed early (< 2 weeks) after the qualifying event. Future reports should address the timing of CAS.

Symptomatic Intracranial Stenosis: Cerebrovascular Complications from Elective Stent Placement

PURPOSE

To retrospectively evaluate the cerebrovascular complications from elective stent placement for symptomatic intracranial stenosis and to explore preliminarily which factors are associated with complications.

MATERIALS AND METHODS

Institutional ethics committee approval was obtained, with waiver of informed consent. Records were reviewed of 181 consecutive elective stent placement procedures in 169 patients (mean age, 51.8 years; 142 male and 27 female patients) with symptomatic intracranial stenosis of more than 50% diameter reduction. Complications were evaluated. Fisher exact or chi(2) tests were used to assess statistical differences between rates for discrete variables. Stratification analysis was used to assess the significant relationship (P < .05) between a potential risk factor and a complication.

RESULTS

Complications occurred in 20 patients (11.8%) of 169 patients: Ten patients (5.9%) had stroke (four patients had symptomatic intracranial hemorrhages [ICHs], and two of these patients died; six patients had ischemic strokes). Six patients had target-lesion thrombosis for which intrathrombus thrombolysis resulted in early complete patency without sequelae, two had asymptomatic ICHs, one had transient ischemic attack, and one had asymptomatic dissection. Perioperative noncompliance with antiplatelet therapy was found to be significantly associated with target-lesion thrombosis (two of eight patients [noncompliance] vs four of 161 patients [compliance], P = .027). Stratification analysis revealed a significant correlation between the use of double stents for a lesion and ICH (P = .005).

CONCLUSION

Cerebrovascular complications from elective stent placement for intracranial stenosis are diverse. The use of double stents for a lesion is an independent risk factor for ICH. Perioperative noncompliance with antiplatelet therapy is associated with a higher frequency of target-lesion thrombosis.

Stented artery biomechanics and device design optimization

The deployment of a vascular stent aims to increase lumen diameter for the restoration of blood flow, but the accompanied alterations in the mechanical environment possibly affect the long-term patency of these devices. The primary aim of this investigation was to develop an algorithm to optimize stent design, allowing for consideration of competing solid mechanical concerns (wall stress, lumen gain, and cyclic deflection). Finite element modeling (FEM) was used to estimate artery wall stress and systolic/diastolic geometries, from which single parameter outputs were derived expressing stress, lumen gain, and cyclic artery wall deflection. An optimization scheme was developed using Lagrangian interpolation elements that sought to minimize the sum of these outputs, with weighting coefficients. Varying the weighting coefficients results in stent designs that prioritize one output over another. The accuracy of the algorithm was confirmed by evaluating the resulting outputs of the optimized geometries using FEM. The capacity of the optimization algorithm to identify optimal geometries and their resulting mechanical measures was retained over a wide range of weighting coefficients. The variety of stent designs identified provides general guidelines that have potential clinical use (i.e., lesion-specific stenting).

Stent-supported angioplasty versus endarterectomy for carotid artery stenosis: evidence from current randomized trials

BACKGROUND

Carotid artery stenting (CAS) for carotid artery stenoses is evolving as an alternative to carotid endarterectomy (CEA). However, the value of CAS is still a matter of debate. Therefore, we performed a metaanalysis of the randomized controlled clinical trials (RCT) on this issue.

METHODS

RCTs were identified through searching MEDLINE, textbooks and by personal communication.

RESULTS

Six finished RCTs on this issue could be identified, including 1263 patients, 628 randomized to CAS and 635 to CEA. The 30-day death or stroke rate was 8.0% (50/628) in patients treated with CAS compared to 6.1% (39/635) in CEA patients (OR=1.36, 95% CI: 0.88-2.11; p=0.17; p for heterogeneity=0.009). The rate of cranial nerve palsy was 7.1% in the CEA compared to 0% in the CAS group (p<0.0001). The rate of myocardial infarctions was reduced from 3.1 to 1% (OR=0.32, 95% CI: 0.12- 0.81; p=0.02; p for heterogeneity=0.49). The death or stroke rate during follow-up was 12.1% in patients treated with CAS compared to 12.2% in CEA patients (OR=0.99, 95% CI: 0.70-1.42; p=0.98; p for heterogeneity=0.02).

CONCLUSION

The available RCT data on CAS vs. CEA suggest that both methods seem to be equally effective concerning short- and medium-term results, while CAS is associated with lower minor complications than CEA. However, because of the significant heterogeneity between the study outcomes, the results of the large RCTs underway should be awaited before it can be advised to use CAS in a broader perspective.

Guidelines for Prevention of Stroke in Patients With Ischemic Stroke or Transient Ischemic Attack

The aim of this new statement is to provide comprehensive and timely evidence-based recommendations on the prevention of ischemic stroke among survivors of ischemic stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches for atherosclerotic disease, antithrombotic treatments for cardioembolism, and the use of antiplatelet agents for noncardioembolic stroke. Further recommendations are provided for the prevention of recurrent stroke in a variety of other specific circumstances, including arterial dissections; patent foramen ovale; hyperhomocysteinemia; hypercoagulable states; sickle cell disease; cerebral venous sinus thrombosis; stroke among women, particularly with regard to pregnancy and the use of postmenopausal hormones; the use of anticoagulation after cerebral hemorrhage; and special approaches for the implementation of guidelines and their use in high-risk populations.

Transcervical Approach With Protective Flow Reversal for Carotid Angioplasty and Stenting

PURPOSE

To report our initial experience using a transcervical approach for carotid angioplasty/stenting (CAS) that employs internal carotid artery (ICA) flow reversal for neuroprotection.

METHODS

Seventeen patients (15 men; mean age 65 years, range 49-77) with significant carotid stenosis (mean 88%, 8 symptomatic) were treated with protected transcervical CAS. Eleven patients were considered at high risk for carotid endarterectomy; 8 were also considered high risk for transfemoral access (unfavorable aortic arch anatomy or advanced aortoiliac occlusive disease). Anesthesia was based on patient and anesthesiologist preferences. The approach consisted of a 2-cm cutdown over the common carotid artery and placement of a 9-F sheath. ICA flow was reversed and shunted into the jugular vein during the carotid intervention.

RESULTS

Access and carotid stenting were successful in all cases. Thirteen procedures were performed under general and 4 under local anesthesia. Mean flow reversal time was 34+/-4 minutes (25 minutes in the last 7 cases). The patients tolerated the procedure well and had no neurological events. Four (23%) patients had significant oozing from the operative site; 2 developed small neck hematomas that were treated conservatively. All patients were discharged on the first postoperative day. There were no deaths, changes in neurological status, or restenosis over a mean follow-up of 12 months (range 1-24).

CONCLUSIONS

Our initial experience demonstrates that a transcervical approach is a viable alternative for CAS. The procedure can be performed safely, with good initial clinical outcomes. The approach allows carotid flow reversal and emboli protection without introducing neuroprotection devices. The method appears best suited for patients at high risk for endarterectomy and transfemoral access.

Endovascular Treatment of Extracranial Carotid Artery Stenosis: Update on Carotid Angioplasty and Stenting

The endovascular treatment of carotid artery stenosis has undergone substantial refinement since its introduction, and carotid artery angioplasty and stenting is now widely performed on symptomatic and asymptomatic patients. Well-designed, large randomized prospective trials showed that carotid endarterectomy provided a significant and durable benefit to selected patients with significant carotid narrowing. Many trials are currently under way comparing endovascular stenting and surgery. Two recently published trials suggest endovascular stenting is at least as good as carotid endarterectomy in terms of safety and efficacy. In the future, carotid stenting may become the standard procedure for patients with significant carotid occlusive disease and a high estimated risk of future stroke.