Donald B. Reid

Carotid Plaque Echolucency Increases the Risk of Stroke in Carotid Stenting The Imaging in Carotid Angioplasty and Risk of Stroke (ICAROS) Study

Background—Carotid artery stenting (CAS) has recently emerged as a potential alternative to carotid endarterectomy. Cerebral embolization is the most devastating complication of CAS, and the echogenicity of carotid plaque has been indicated as one of the risk factors involved. This is the first study to analyze the role of a computer-assisted highly reproducible index of echogenicity, namely the gray-scale median (GSM), on the risk of stroke during CAS. Methods and Results—The Imaging in Carotid Angioplasty and Risk of Stroke (ICAROS) registry included 418 cases of CAS collected from 11 international centers. An echographic evaluation of carotid plaque with GSM measurement was made preprocedurally. The onset of neurological deficits during the procedure and the postprocedural period was recorded. The overall rate of neurological complications was 3.6%: minor strokes, 2.2%, and major stroke, 1.4%. There were 11 of 155 strokes (7.1%) in patients with GSM ≤25 and 4 of 263 (1.5%) in patients with GSM >25 (P=0.005). Patients with severe stenosis (≥85%) had a higher rate of stroke (P=0.03). The effectiveness of brain protection devices was confirmed in those with GSM >25 (P=0.01) but not in those with GSM ≤25. Multivariate analysis revealed that GSM (OR, 7.11; P=0.002) and rate of stenosis (OR, 5.76; P=0.010) are independent predictors of stroke. Conclusions—Carotid plaque echolucency, as measured by GSM ≤25, increases the risk of stroke in CAS. The inclusion of echolucency measured as GSM in the planning of any endovascular procedure of carotid lesions allows stratification of patients at different risks of complications in CAS.

Percutaneous Techniques for Endoluminal Carotid Interventions

Purpose: To describe the evolving techniques for stent implantation in the proximal and cervical carotid arteries. Methods and Results: Percutaneous access to proximal and cervical carotid lesions is either via direct puncture of the common carotid artery or through the more familiar retrograde common femoral (RCF) artery approach. Both techniques and their variations are described in detail, along with their benefits, disadvantages, and possible complications. Dual lesions at the arch and higher up the neck can be treated either from the RCF route or, if the cervical lesion requires endarterectomy, with open exposure at the bifurcation and stenting of the proximal lesion. Conclusions: While the RCF route is more familiar to the majority of interventionists and provides adequate access in most situations, traversing the arch and negotiating acute angles at the ostia of the great vessels may render this method infeasible. The direct puncture technique is a useful alternative; however, it requires more expertise to prevent potentially disastrous access-site complications. One further caveat must be stated: regardless of the access approach selected, the opportunity for serious, debilitating—and lethal—complications is always present in cerebrovascular interventions. At this earliest phase in our experience with carotid stenting, cautious investigative methodologies must prevail.

Virtual histology intravascular ultrasound assessment of carotid artery disease: the Carotid Artery Plaque Virtual Histology Evaluation (CAPITAL) study.

Purpose: To determine the diagnostic accuracy of virtual histology intravascular ultrasound imaging (VH IVUS) of carotid plaque and to assess the feasibility of VH IVUS to identify plaque with embolic potential in patients undergoing carotid artery stenting (CAS). Methods: Thirty patients (17 men; mean age 74±7 years) were entered nonrandomly into a single-center, prospective, 2-arm study following FDA and Institutional Review Board approval. In one arm, 15 patients underwent VH IVUS examination of carotid plaque with a cerebral protection device immediately followed by carotid endarterectomy (CEA). A comparison of “virtual” with true histology was then performed, classifying plaque type by VH IVUS and histopathology in a blinded study. In the second arm, 15 patients undergoing CAS had a preliminary VH IVUS scan performed with cerebral protection. Debris collected from the filter following stenting was examined histologically and compared with the VH IVUS data. Results: The diagnostic accuracy of VH IVUS to agree with true histology in different carotid plaque types was 99.4% in thin-cap fibroatheroma, 96.1% for calcified thin-cap fibroatheroma, 85.9% in fibroatheroma, 85.5% for fibrocalcific, 83.4% in pathological intimal thickening, and 72.4% for calcified fibroatheroma. Filter debris was captured in 2 patients prior to CEA and in 4 patients undergoing CAS for restenosis; VH IVUS classification of plaque composition was consistent with the histological evaluation of filter fragments. Calcified nodules projecting into the carotid artery lumen were associated with a higher incidence of previous neurological symptoms (66.7% versus 33.3%, p<0.05), while patients on aspirin has significantly less necrotic lipid core plaque detected by VH IVUS than patients not taking aspirin (6.4%±4.7% versus 9.7%±2.8%, p<0.05). Conclusion: This study showed a strong correlation between VH IVUS plaque characterization and the true histological examination of the plaque following endarterectomy, particularly in “vulnerable” plaque types. The feasibility study to examine VH IVUS data and the filter debris histology in CAS patients supports a larger prospective study.

Virtual histology intravascular ultrasound in carotid interventions.

Purpose: To report early clinical experience with virtual histology intravascular ultrasound (VH IVUS) in carotid endoluminal repair. Technique: A 2.9-F, 20-MHz catheter that utilizes computer software to demonstrate the histological components of arteriosclerotic plaque was evaluated during carotid angioplasty and stenting. VH IVUS images were created following a pullback through the carotid stenosis and produced a color-coded map of the different histological constituents of the disease (dark green: fibrous, yellow/green: fibrofatty, white: calcified, and red: necrotic lipid core plaque). Conclusion: VH IVUS produces a color-coded map of the different histological components of artery plaque. It has the potential to predict how the plaque is likely to behave at the moment of endoluminal treatment.

Intravascular ultrasound assessment in carotid interventions.

Purpose: To demonstrate the clinical value of intravascular ultrasound (IVUS) imaging in monitoring stent deployment in the cervical carotid arteries. Methods and Results: Two-dimensional (2D) and three-dimensional (3D) IVUS imaging has been used routinely in more than 100 patients following carotid stenting and the completion angiogram to detect evidence of inaccurate stent deployment. Axial 2D views were used to measure diameters and cross-sectional areas and provide the basis for 3D reconstruction. These composited images produced single-frame views of entire vascular segments, with definition of vessel wall morphology, stent placement, and angioplasty-induced defects. This information was used in the decision to apply further treatment to the area in order to maximize luminal diameter and/or correct defects. Conclusions: IVUS imaging is an important component of carotid artery stent procedures. It more accurately visualizes stent placement and vessel wall morphology than arteriography, information critical to the intraprocedural assessment process.

The ICAROS Registry of carotid artery stenting

ICAROS (Imaging in Carotid Angioplasties and Risk Of Stroke) is a multicenter international registry of carotid artery stenting designed to determine the criteria for identifying patients at higher or lower risk of periprocedural stroke and restenosis at 1 year. The aim of the registry is to improve patient selection and consequently reduce the risk of cerebral embolization during carotid stenting. The registry is open to all interventionists performing carotid stenting, and the participants are free to apply their own endovascular techniques and devices, including cerebral protection mechanisms. All cerebral ischemic events following the procedure will be reported. Follow-up surveillance to 1 year will include periodic duplex scanning and neurological examinations. Echographic plaque images will be standardized for comparison, processed for echodensity, and analyzed by computer at the Registry Center. Correlation will be investigated between the echographic index (gray-scale median) and the risk of embolism and outcome of carotid stenting.

The ICAROS registry of carotid artery stenting. Imaging in Carotid Angioplasties and Risk of Stroke.

ICAROS (Imaging in Carotid Angioplasties and Risk Of Stroke) is a multicenter international registry of carotid artery stenting designed to determine the criteria for identifying patients at higher or lower risk of periprocedural stroke and restenosis at 1 year. The aim of the registry is to improve patient selection and consequently reduce the risk of cerebral embolization during carotid stenting. The registry is open to all interventionists performing carotid stenting, and the participants are free to apply their own endovascular techniques and devices, including cerebral protection mechanisms. All cerebral ischemic events following the procedure will be reported. Follow-up surveillance to 1 year will include periodic duplex scanning and neurological examinations. Echographic plaque images will be standardized for comparison, processed for echodensity, and analyzed by computer at the Registry Center. Correlation will be investigated between the echographic index (gray-scale median) and the risk of embolism and outcome of carotid stenting.

Endovascular Significance of the External Carotid Artery in the Treatment of Cerebrovascular Insufficiency

Purpose: To present illustrative cases that demonstrate the feasibility and clinical benefits of endovascular treatment of external carotid artery (ECA) stenoses in patients with occluded internal carotid arteries (ICA). Case Reports: Three patients with symptoms of cerebrovascular insufficiency and a stenosis of the ECA in the presence of occluded ICAs and diseased vertebral arteries were treated successfully by percutaneous stent or stent-graft implantation with and without cerebral protection. Conclusions: The ECAs play an important role in providing collateral blood supply to the brain through the many connections between branches of the ECA and cranial branches of the ICA and vertebral arteries. If these important pathways of collateral cerebral blood flow become diseased, ischemic symptoms become apparent. We recommend an endovascular procedure as a potential alternative to surgical endarterectomy of the ECA in patients with severe extracranial arterial disease.

Imaging in Endovascular Therapy: Our Future

The endovascular therapist now has many modern imaging techniques available to plan and execute treatment, whereas in the past vascular surgeons relied mostly on clinical examination and arteriography. Advances in computer technology have enabled fast acquisition and processing of the large amounts of digital data essential to capture the dynamic information from fast-flowing blood at high resolution. Functional imaging has begun to play a role in predicting stability of progressive vascular disease and the need for and risks of intervention. Computing power now affords the interventionist the ability to handle imaging data in powerful 3-dimensional programs and electronically “in-lay” a variety of devices to plan complex endovascular procedures from the familiar platform of a laptop. In four major clinical areas, carotid intervention, peripheral intervention, endoluminal grafting, and cardiac imaging, we review the latest advances and changes with an eye toward how we should best be using imaging in our patients undergoing endovascular treatment…now and into the future.

Commentary: Significance of the internal jugular vein in the treatment of cerebrovascular insufficiency.

The significance of the safety report on endovascular treatment for chronic cerebrospinal venous insufficiency (CCSVI) in patients with multiple sclerosis (MS) by Petrov et al. should not be underestimated. This is the largest series reported in the world to date of patients undergoing venoplasty for CCSVI, a treatment that does not currently have the universal support of the medical community. Nowadays, healthcare systems are reluctant to introduce any new treatment without a strong consensus of acceptance corroborated by good clinical data, so the lack of clinically significant complications in almost 500 procedures certainly supports wider acceptance of this new endovascular therapy. This is, therefore, an important publication. The authors’ observations do not mean, however, that the concept of CCSVI will immediately gain widespread support, and more peer-reviewed clinical publications and trials will be required because certain important issues remain to be clarified. For example, there is uncertainty even among experienced ultrasonographers about how to obtain the diagnosis of CCSVI. This urgently requires published consensus guidelines on how to perform the ultrasound examination and agreed criteria about how to make the diagnosis. It is likely that this diagnostic uncertainty is responsible for different incidences of CCSVI in MS patients and healthy populations at various centers; yet, most studies find a strong association between CCSVI and MS. Another problem muddying the water is that not all patients notice any clinical improvement in their neurological function following endovascular treatment. On the other hand, some patients have an immediate and dramatic clinical recovery. It is not yet possible to predict which patients are likely to respond or why. Multiple sclerosis is a disease with disseminated brain and spinal cord lesions, a wide variety of different neurological symptoms, and a fluctuating clinical course. Given these significant difficulties, one study has thus far demonstrated clinical benefit from this new endovascular therapy. Petrov et al. have found that venoplasty is well tolerated by patients with relatively few complications. However, the procedure does carry some potential risks that need to be considered. Cardiac arrhythmia can occur when a wire or catheter loops and enters the right atrium of the heart. Careful control and awareness of the wire position prevents this problem. The other main risk to the patient is life-threatening hemorrhage because of vein wall rupture. This event could occur either following balloon dilation or because of overinstrumentation. Fortunately, no case of lifethreatening hemorrhage requiring urgent surgical intervention has been reported in ,12,000 cases treated worldwide. Venoplasty for CCSVI has some limitations that need to be addressed. Restenosis can occur several months following balloon