Intracranial Atherosclerotic Disease Lesions Research Articles

A Systematic Review and Meta-Analysis of Drug Eluting Stents for Safety and Efficacy in Intracranial Atherosclerotic Disease.

Advancements in arterial stenting technology have challenged prior notions favoring medical management for intracranial atherosclerotic disease (ICAD). Where previous conclusions were drawn from bare metal stent (BMS) technology, recent studies suggest drug-eluting stents (DES) are favorable due to their anti-proliferative effect, which reduces vascular remodeling. We conducted a systematic review and meta-analysis of the literature prior to August 2023 reviewing all reports of ICAD treated with DES. Our target outcomes were incidence of any stroke, transient ischemic attack (TIA), or death within 30 days (postprocedural complications), ischemic stroke in the territory of the qualifying artery beyond 30 days (long-term complications), radiographically detected in-stent restenosis rate (ISR), and symptomatic ISR during follow-up. A subgroup analysis further stratified preprocedural mean stenosis above and below 70% into severe and moderate cohorts, respectively. PubMed, Web of Science, Cochrane and EMBASE query identified 527 candidate articles, from which 14 studies met inclusion criteria for a total of 607 patients and 640 ICAD lesions. Incidence of postprocedural complications was 7.3% (95% CI 3.9-11.7%) with subgroup analysis demonstrating significantly higher incidence in the severely stenotic group [9.0% (95% CI 4.7-14.5%)] than the moderately stenotic group [3.0% (95% CI 0.7-6.8%)]. Long-term complications were 1.2% (95% CI 0.4-2.3%). Radiographic ISR was 3.5% (95% CI 1.4-6.3%) and symptomatic ISR was 0.3% (95% CI 0.0-1.5%). Our systematic review and meta-analysis suggest that DES can effectively reduce the risk of ISR and may be a viable treatment modality to reduce long-term complications in refractory ICAD patients.

Abstract WP142: Investigating the Association of Intracranial Stenosis With Low Wall Shear Stress

Background: Intracranial atherosclerotic disease (ICAD) is associated with high recurrence rates of stroke despite aggressive medical management. Low wall shear stress (WSS) alters endothelial function and changes in WSS within the post-stenotic region of ICAD lesions is a potential driver of stroke recurrence. Methods: Using the SAMMPRIS imaging dataset, we identified medically managed patients with symptomatic middle cerebral artery (MCA) stenosis measured by CTA. WSS was calculated by creating a 3D volumetric mesh from CTA source imaging. Pulsatile flow profile reference standard boundary conditions were applied at pressure outlets to simulate normal hemodynamics. Arterial segments extending from the stenosis to the MCA bifurcation were captured and quantified. Contralateral arterial segments were matched by length and area. The ratio of area with low WSS (<4 dyne/cm 2 ) on both sides was then calculated. Differences in the mean arterial area with low WSS and ratio of area with low WSS were compared using paired Student’s t-test with data presented as mean ± SD. Results: Of 451 cases in SAMMPRIS, the medical management arm had 105 MCA cases of which 47 cases had CTA available and 33 cases were able to be analyzed by computational flow dynamics. Symptomatic ICAD lesions demonstrated significant differences in post stenosis area with low WSS (24.7±43.4 mm 2 vs 2.8±3.4 mm 2 p=0.003) and differences in the low WSS ratio (0.25±0.26 vs0.04±0.05 p<0.001). There was no statistically significant difference in the length and area of the arterial segment post stenosis to the bifurcation and the control length on the contralateral side (11.6±7.4 mm vs 10.6±6.1 mm p=0.566; 80.7±55.0 mm 2 vs 95.4±58.3 mm 2 p=0.298). Conclusion: Area with low WSS after ICAD stenoses is increased in the SAMMPRIS imaging dataset and may be a marker of symptomatic ICAD. Further studies are needed to evaluate the association of post stenotic WSS with symptomatic recurrent stroke.

Abstract TP202: Safety and Efficacy of Drug-Eluting Stents in Intracranial Atherosclerotic Disease: A Systematic Review and Meta-Analysis

Background: Advancements in arterial stenting technology have challenged prior notions favoring medical management over endovascular intervention for intracranial atherosclerotic disease (ICAD). Where previous conclusions were drawn from bare metal stent (BMS) technology, recent studies suggest drug-eluting stents (DES) are favorable over BMS due to their anti-proliferative effect. Methods: We conducted a systematic review and meta-analysis of the literature prior to August 2023 reviewing reports of ICAD treated with DES. Our target outcomes were incidence of any stroke, transient ischemic attack (TIA), or death within 30 days (post-procedural complications), ischemic stroke in the territory of the qualifying artery beyond 30 days (long-term complications), radiographically detected in-stent restenosis rate (ISR), and symptomatic ISR during follow-up. A subgroup analysis further stratified pre-procedural mean stenosis above and below 70% into severe and moderate cohorts, respectively. Results: PubMed and EMBASE query identified 518 candidate articles, from which 13 studies met inclusion criteria for a total of 475 patients and 508 ICAD lesions. Incidence of post-procedural complications was 8.1% (95% CI 3.1-15.1%) with subgroup analysis demonstrating significantly higher incidence in the severely stenotic group [10.4% (95% CI 5.7%-16.2%)] than the moderately stenotic group [3.0% (95% CI 0.7%- 6.8%)]. Long-term complications were 1.2% (95% CI 0.4%-2.4%). Radiographic ISR was 3.2% (95% CI 1.0%- 6.5%) and symptomatic ISR was 0.0% (95% CI 0.0%-0.5%). Conclusions: Our systematic review and meta-analysis suggest that DES can effectively reduce the risk of ISR and may be a viable treatment modality to reduce long-term complications in refractory ICAD patients.

Abstract TP220: Intracranial Dotter Angioplasty Using Tenzing for Symptomatic Atherosclerotic Stenosis: Initial Experience

Introduction: Traditional endovascular treatment for acutely symptomatic intracranial atherosclerotic disease (ICAD) includes balloon angioplasty and stenting. Catheter mediated angioplasty (or “Dotter” angioplasty) has been previously described for extracranial carotid and peripheral arteries. The Tenzing 7 (Route 92 Medical, San Mateo, CA), a novel shelf-reducing delivery catheter, has an atraumatic tapered distal tip that progressively enlarges to a 0.062 inch (1.6 mm) outer diameter, which may enable catheter-mediated Dotter angioplasty of ICAD, or Tenzing-plasty. We report our initial experience in treating symptomatic ICAD using Tenzing-plasty. Methods: After IRB approval, we performed a retrospective review of patients undergoing endovascular treatment for symptomatic ICAD with Tenzing-plasty as a first approach at our stroke centers from 2021-2023. All patients were treated using the Tenzing 7 delivery catheter in an off-label fashion. The Tenzing was slowly inserted across the ICAD stenosis in each case under roadmap fluoroscopic guidance. Subsequent balloon angioplasty and/or stenting were at operator discretion. We examined clinical, imaging, and procedural data. Results: We identified 14 consecutive patients with symptomatic ICAD stenosis who underwent Tenzing-plasty, either as part of an emergent thrombectomy procedure, or if medical management of ICAD had failed. The median age was 62±11 years and 6 were female (43%). Stenosis location was: 1 ICA, 7 M1, 4 M2, 2 vertebral. The average pre-treatment ICAD stenosis was 95±7%, including 6 patients (43%) with complete occlusion. In 100% of cases, Tenzing-plasty resulted in improvement in arterial caliber after median 1 pass (IQR1-1), with average stenosis improving to 64±15%. Subsequent balloon angioplasty was performed in 3/14 cases (21%). Stenting was performed in 10 cases (using Atlas, Wingspan, Onyx Resolute, Onyx Frontier). There were no instances of arterial perforation or symptomatic intracranial hemorrhage. Conclusions: Intracranial Dotter angioplasty as a first approach using the novel tapered tip Tenzing 7 catheter may be a feasible and safe alternative for improving luminal caliber and flow restoration of symptomatic ICAD lesions. Further study is warranted.

Cerebral Hemodynamics Underlying Artery-to-Artery Embolism in Symptomatic Intracranial Atherosclerotic Disease.

Artery-to-artery embolism (AAE) is a common stroke mechanism in intracranial atherosclerotic disease (ICAD), associated with a considerable risk of recurrent stroke. We aimed to investigate cerebral hemodynamic features associated with AAE in symptomatic ICAD. Patients with anterior-circulation, symptomatic ICAD confirmed in CT angiography (CTA) were recruited. We classified probable stroke mechanisms as isolated parent artery atherosclerosis occluding penetrating artery, AAE, hypoperfusion, and mixed mechanisms, largely based on infarct topography. CTA-based computational fluid dynamics (CFD) models were built to simulate blood flow across culprit ICAD lesions. Translesional pressure ratio (PR = Pressurepost-stenotic/Pressurepre-stenotic) and wall shear stress ratio (WSSR = WSSstenotic-throat/WSSpre-stenotic) were calculated, to reflect the relative, translesional changes of the two hemodynamic metrics. Low PR (PR ≤ median) and high WSSR (WSSR ≥ 4th quartile) respectively indicated large translesional pressure and elevated WSS upon the lesion. Among 99 symptomatic ICAD patients, 44 had AAE as a probable stroke mechanism, 13 with AAE alone and 31 with coexisting hypoperfusion. High WSSR was independently associated with AAE (adjusted OR = 3.90; P = 0.022) in multivariate logistic regression. There was significant WSSR-PR interaction on the presence of AAE (P for interaction = 0.013): high WSSR was more likely to associate with AAE in those with low PR (P = 0.075), but not in those with normal PR (P = 0.959). Excessively elevated WSS in ICAD might increase the risk of AAE. Such association was more prominent in those with large translesional pressure gradient. Hypoperfusion, commonly coexisting with AAE, might be a therapeutic indicator for secondary stroke prevention in symptomatic ICAD with AAE.

VWI-APP: Vessel wall imaging-dedicated automated processing pipeline for intracranial atherosclerotic plaque quantification.

Quantitative plaque assessment based on 3D magnetic resonance (MR) vessel wall imaging (VWI) has been shown to provide valuable numerical markers of the burden and risk of intracranial atherosclerotic disease (ICAD). However, plaque quantification is currently time-consuming and observer-dependent due to the demand for heavy manual effort. A VWI-dedicated automated processing pipeline (VWI-APP) is desirable. To develop and evaluate a VWI-APP for end-to-end quantitative analysis of intracranial atherosclerotic plaque. We retrospectively enrolled 91 subjects with ICAD (80 for pipeline development, 10 for an end-to-end pipeline evaluation, and 1 for demonstrating longitudinal plaque assessment) who had undergone VWI and MR angiography. In an end-to-end evaluation, diameter stenosis (DS), normalized wall index (NWI), remodeling ratio (RR), plaque wall contrast ratio (CR), and total plaque volume (TPV) were quantified at each culprit lesion using the developed VWI-APP and a computer-aided manual approach by a neuroradiologist, respectively. The time consumed in each quantification approach was recorded. Two-sided paired t-tests and intraclass correlation coefficient (ICC) were used to determine the difference and agreement in each plaque metric between VWI-APP and manual quantification approaches. There was no significant difference between VWI-APP and manual quantification in each plaque metric. The ICC was 0.890, 0.813, 0.827, 0.891, and 0.991 for DS, NWI, RR, CR, and TPV, respectively, suggesting good to excellent accuracy of the pipeline method in plaque quantification. Quantitative analysis of each culprit lesion on average took 675.7s using the manual approach but shortened to 238.3s with the aid of VWI-APP. VWI-APP is an accurate and efficient approach to intracranial atherosclerotic plaque quantification. Further clinical assessment of this automated tool is warranted to establish its utility in the risk assessment of ICAD lesions.

Plaque modification and stabilization after drug-coated balloon angioplasty for intracranial atherosclerotic lesions.

A drug-coated balloon (DCB) has potential applications in the treatment of intracranial atherosclerotic disease (ICAD). We aimed to evaluate changes of vessel wall features of ICAD lesions after DCB treatment by using vessel wall MRI (VWMRI). We retrospectively included patients with symptomatic ICAD who underwent DCB angioplasty alone. The incidences of stenosis of the lumen area, vessel wall thickening, hyperintense plaques, and prominent wall enhancement were compared between the baseline and follow-up VWMRI. There were 29 ICAD lesions from 29 patients, of which 22 were stenosis and 7 were occlusion. The median interval between DCB treatment and follow-up VWMRI was 4.1 [3.3, 6.7] months. After DCB treatment, follow-up VWMRI showed a significant decrease in the stenosis degree of the lumen area (83% [71%, 96%] vs 15% [3%, 41%], p < 0.001). Thirty-eight percent (11/29) of the patients observed normal appearance of the target vessel wall on follow-up VWMRI. In the stenosis group, the prevalence of hyperintense plaques decreased from 66.7% (14/21) at baseline to 23.8% (5/21) at follow-up, and prominent wall enhancement decreased from 66.7% (14/21) at baseline to 19.0%(4/21) at follow-up. The incidence of hyperintense plaques (p = 0.028) and vessel wall thickening (p = 0.018) tended to decrease with follow-up time. Although not significant (p = 0.106), a similar trend was observed between the incidence of prominent wall enhancement and follow-up time. Vascular healing with plaque modification and stabilization occurred following DCB treatment of ICAD lesions. • A drug-coated balloon (DCB) has potential applications in the treatment of intracranial atherosclerotic disease (ICAD). • Vascular healing with plaque modification and stabilization occurred following DCB treatment of ICAD lesions.

Abstract P572: Cerebral Hemodynamics Underlying Artery-To-Artery Embolism in Symptomatic Intracranial Atherosclerotic Disease

Background: Artery-to-artery embolism (AAE) is a common stroke mechanism in patients with symptomatic intracranial atherosclerotic disease (ICAD), which might be associated with a higher risk of recurrent stroke than other stroke mechanisms. We aimed to investigate cerebral hemodynamic features associated with AAE in symptomatic ICAD patients. Methods: Patients with acute, anterior-circulation ischemic stroke attributed to ICAD (50-99% stenosis) confirmed in CT angiography (CTA) were recruited from two teaching hospitals. We classified probable stroke mechanisms as isolated parent artery atherosclerosis occluding penetrating artery (PAO), AAE, hypoperfusion, and mixed mechanisms, based on infarct topography in MRI and ICAD lesion features. CTA-based computational fluid dynamics (CFD) models were built to simulate blood flow across culprit ICAD lesions. Translesional pressure ratio (PR=Pressure post-stenotic /Pressure pre-stenotic ) and translesional wall shear stress ratio (WSSR=WSS stenotic-throat /WSS pre-stenotic ) were calculated, to reflect the relative change of the two hemodynamic metrics across an ICAD lesion. PR ≤ median was defined as low PR, indicating a larger pressure gradient across the lesion; and WSSR ≥ 4 th quartile as high WSSR, indicating elevated WSS upon the lesion. We associated PR and WSSR with presence of AAE as a probable stroke mechanism. Results: Among 99 symptomatic ICAD patients, 44 had AAE as a probable stroke mechanism, 13 with AAE alone and 31 with coexisting hypoperfusion; the remaining patients respectively had isolated PAO (n=18) and isolated hypoperfusion (n=37) as the probable stroke mechanisms. High WSSR was independently associated with AAE (adjusted OR 4.21; 95% CI 1.33-13.26; p=0.014). The significant, positive relationship between high WSSR and higher risk of AAE remained in those with a low PR (adjusted OR 4.01; 95% CI 1.03-15.46; p=0.044), but not in those with a normal PR (p=0.621). Conclusions: High WSS upon ICAD lesions may increase plaque vulnerability and lead to distal embolism, while sustained antegrade flow across the ICAD lesion (normal PR) may help clear the emboli. In secondary prevention of symptomatic ICAD with AAE, impaired cerebral perfusion may be a therapeutic target.

Abstract WMP44: Differential Middle Cerebral Artery Plaque Characteristics in Patients With Transient Ischemic Attack and Ischemic Stroke: A High-Resolution MR Vessel Wall Imaging Study

Introduction: Intracranial atherosclerotic disease (ICAD) correlates highly with transient ischemic attack (TIA) and acute ischemic stroke (AIS). Magnetic Resonance (MR) vessel wall imaging (VWI) is an emerging non-invasive imaging modality for directly assessing ICAD lesions. Methods: We retrospectively analyzed MR-VWI from 42 TIA patients and 45 AIS patients with ICAD. All patients fulfilled the following criteria: (1) stenosis &gt;30% of a middle cerebral artery (MCA), (2) symptoms contralateral to stenotic MCA, (3) no coexisting stenosis at other major vessels; (4) lack of compelling evidence to other etiologies of stroke/TIA. Vascular lesions were analyzed with MR-VWI with respect to the stenosis degree, vessel wall irregularity, plaque burden (PB), remodeling index (RI), plaque-wall contrast ratio (CR) and plaque enhancement grade (EG). Results: EG (OR 3.88, 95%CI 1.42-10.57, P=0.006) was a risk factor for AIS while PB (OR 0.65, 95%CI 0.27-1.54, P=0.008) was a risk factor for TIA. In patients with 30-70% degree stenosis, CR (OR 5.38, 95%CI 1.39-20.75, P=0.008) was a risk factor for stroke, while PB (OR 0.4, 95%CI 0.1-1.65, P=0.006) remained a risk factor for TIA. Conclusions: In our study, PB appeared as a risk factor for TIA but not for AIS. This suggests that unstable plaque accounting for AIS may have a wide range of PB. We further found that CR and EG are more associated with AIS than TIA. Lesions with high CR and strong enhancement may be more prone to producing the permanent ischemic injury. Further study is needed to elucidate the role of MR-VWI in differential diagnosis and management of TIA and AIS.

Intracranial Vessel Wall Segmentation Using Convolutional Neural Networks.

To develop an automated vessel wall segmentation method using convolutional neural networks to facilitate the quantification on magnetic resonance (MR) vessel wall images of patients with intracranial atherosclerotic disease (ICAD). Vessel wall images of 56 subjects were acquired with our recently developed whole-brain three-dimensional (3-D) MR vessel wall imaging (VWI) technique. An intracranial vessel analysis (IVA) framework was presented to extract, straighten, and resample the interested vessel segment into 2-D slices. A U-net-like fully convolutional networks (FCN) method was proposed for automated vessel wall segmentation by hierarchical extraction of low- and high-order convolutional features. The network was trained and validated on 1160 slices and tested on 545 slices. The proposed segmentation method demonstrated satisfactory agreement with manual segmentations with Dice coefficient of 0.89 for the lumen and 0.77 for the vessel wall. The method was further applied to a clinical study of additional 12 symptomatic and 12 asymptomatic patients with >50% ICAD stenosis at the middle cerebral artery (MCA). Normalized wall index at the focal MCA ICAD lesions was found significantly larger in symptomatic patients compared to asymptomatic patients. We have presented an automated vessel wall segmentation method based on FCN as well as the IVA framework for 3-D intracranial MR VWI. This approach would make large-scale quantitative plaque analysis more realistic and promote the adoption of MR VWI in ICAD management.

Abstract 86: Morphological Evolution of Symptomatic Intracranial Atherosclerotic Plaques: a 10-year Longitudinal Study by 3-Dimensional Rotational Angiography

Introduction: Patients with symptomatic high-grade intracranial atherosclerotic disease (ICAD) are at risk of stroke recurrence even under stringent medical therapy. Understanding how the plaque evolves in these patients may help prevent recurrent stroke. Methods: In a prospective, multicenter referral, longitudinal study, we recruited 40 patients (mean age = 61.1 years) with symptomatic high-grade ICAD (70-99% stenosis) confirmed by 3-dimensional rotational angiography (3DRA) from July 2007 to Feb 2016. All patients had 3DRA at baseline and 1 year. All patients received contemporary optimal medical treatment. We assessed the morphological features of qualifying ICAD lesions in the paired 3DRA images. A plaque was considered progressive if the plaque surface evolved from being smooth to irregular/ulcerated or from irregular to ulcerated, or the affected artery occluded at 1 year. We explored factors associated with plaque progression. Results: The qualifying ICAD lesions were in average 77.7% stenosis at baseline. The point of maximum stenosis was located at the distal end of the plaques in 21 (52.5%) cases, and 38 (95.0%) patients had eccentric plaques at baseline. The mean upstream plaque shoulder angulation was 46.4° at baseline. Eleven (27.5%) ICAD lesions progressed from baseline to 1 year. Longer lesions (p=0.038) with a smaller upstream plaque shoulder angulation (p=0.038) and the maximum stenosis locating at the distal end of the lesion (p=0.056) at baseline were more likely to progress in the plaque morphology over 1 year. Conclusions: Under modern medical treatment, although the majority of symptomatic ICAD lesions might regress over 1 year after an index stroke, lesions of a longer length, a smaller upstream angulation, or with the maximum stenosis located at the distal end were more likely to progress in terms of the plaque morphology.

Abstract TP127: Morphology of Acute Symptomatic Intracranial Atherosclerotic Plaques

Introduction: Intracranial atherosclerotic disease (ICAD) is an important subtype of ischemic stroke worldwide. Understanding the morphologic features of acutely symptomatic plaques may help identify vulnerable lesions and guide treatment. Methods: We prospectively recruited 170 patients (median age = 60.5 years) with acute ischemic stroke attributed to ICAD (≥60% stenosis) confirmed by 3-dimensional rotational angiography (3DRA) from May 2007 to Feb 2017. We evaluated the morphology of the index atherosclerotic plaques in 3DRA. We categorized plaques with irregular or ulcerated surface as complicated plaques. We compared the morphological features of smooth and complicated plaques. Results: The median interval between symptom onset and 3DRA exam was 22 days. The median severity of luminal stenosis was 75%. The median maximum plaque thickness was 1.3mm and lesion length was 8.8mm. The plaque surface was smooth, irregular, or ulcerated in 50 (29.4%), 90 (52.9%), and 27 (15.9%) cases, respectively. The point of maximum stenosis was located in the distal end of the lesions in 88 (51.8%) cases. A majority (85.3%) of the plaques were eccentric. The median angulation between the upstream plaque shoulder and an imagined “normal” vessel wall (assuming there were no plaque) was 33.4°. Overall, complicated plaques led to more severe luminal stenosis (medians 77.0 vs 73.0%; p=0.032); the lesions were longer (medians 10.0 vs 6.9 mm; p&lt;0.001), and the upstream shoulders were steeper (median angles 34.3 vs 28.0°; p=0.048) than smooth plaques. Conclusions: We identified the morphologic pattern of symptomatic high-grade intracranial atherosclerotic plaques during the acute phase that are significantly different between smooth and complicated plaques. The current findings warrant a comparison with silent ICAD lesions for validation.

Abstract WP134: Quantitatively Monitoring Regression or Progression in Intracranial Atherosclerotic Plaques Using 3D Vessel Wall Imaging and Deep-learning-based Vessel Wall Analysis

Introduction: Intracranial atherosclerotic disease (ICAD) is one of the most common causes of ischemic stroke worldwide. Despite aggressive medical management, the rate of recurrent stroke is 13% at 1 year. Intracranial vessel wall imaging (VWI) is a noninvasive, “looking-beyond-the-lumen” imaging method that can directly characterize the geometric and signal features of ICAD lesions. The present work sought to assess the feasibility of quantitatively monitoring regression or progression of ICAD plaques using VWI-based methods. Methods: Eight ischemic stroke patients (1F, 7M; age 27-66 ys) treated with intensive medical therapy underwent initial (4 days - 4 months of onset) and follow-up 3D VWI (6-13 months). Images were randomized and reviewed by two neuroradiologists to determine the culprit lesion in each subject. A custom-designed deep-learning-based intracranial vessel analysis method was used to segment vessel wall boundaries and quantify the following features of the culprit lesion, including peak normalized wall index (NWI), plaque volume, pre-contrast plaque-wall contrast ratio (CR), and post-contrast plaque enhancement ratio (ER). Results: No subjects except for subject #4 had a recurrent stroke during the follow-up period. The four plaque features exhibited different change patterns as shown in Figure . Subject #1 and #4 demonstrated an increase in plaque ER, volume, and peak NWI; subject #7 demonstrated an increase in plaque CR, volume and peak NWI. Other patients had a decrease or no change in these features. Conclusions: In this work, the interrogated plaque features demonstrated regression in most of patients after intensive medical therapy. Elevated values in some of these features appeared positively associated with stroke recurrence. Temporal changes in these features may have a strong indication on culprit lesions’ response to medical therapy. In conclusion, it is feasible to quantitatively monitor plaque-level treatment response.

Prevention of Intracranial In-stent Restenoses: Predilatation with a Drug Eluting Balloon, Followed by the Deployment of a Self-Expanding Stent

PurposeStenting in intracranial atherosclerotic disease (ICAD) is increasingly debated, due to issues of procedural safety, technical efficacy, and in-stent recurrent stenoses (ISR). In the present study, feasibility, safety, and efficacy of angioplasty using a drug-eluting balloon (DEB) followed by the implantation of a self-expanding stent (Enterprise) were evaluated for the treatment of ICAD lesions.MethodsFifty-two patients (median age: 71 years; range: 54–86 years; male/female ratio 37:15) underwent stenting of high-grade ICAD lesions between February 2010 and November 2011 in a single center. Angioplasty using a paclitaxel coated SeQuent Please (B. Braun, Germany) or DIOR (Eurocor, Germany) coronary PTCA balloon, followed by the implantation of a self-expanding stent (Enterprise, Codman, USA) was performed in 54 lesions. Angiographic and clinical follow-up was performed at 6 and 12 weeks, 6 and 12 months, and yearly thereafter. Technical success rate, periprocedural complications, occurrence of recurrent ischemic symptoms, and the development of an ISR were analyzed.ResultsAngioplasty using a DEB followed by stent implantation was successfully performed in 44 (81 %) cases. DEB insertion failed in 19 % of the cases and angioplasty was finally performed using a conventional PTCA balloon. The combined procedure related permanent neurologic morbidity and mortality rate (stroke, ICH, and subarachnoid hemorrhage) at 30 days and beyond was 5 %. Angiographic and clinical follow-up were obtained in 33 (61 %) lesions in 32 patients. Recurrent stenosis was seen in one (3 %) lesion.ConclusionAngioplasty and stenting using a DEB is safe and yields encouragingly low ISR rates. Further technical developments to improve lesion accessibility are, nevertheless, mandatory.

PREDICTION OF COMPLEX FLOW PATTERNS IN INTRACRANIAL ATHEROSCLEROTIC DISEASE USING COMPUTATIONAL FLUID DYNAMICS

Although carotid and vertebral intracranial atherosclerotic disease (ICAD) can lead to both hemodynamic insufficiency and thromboembolism, its fluid dynamic properties remain undefined because of its intricate features and complex three-dimensional geometry. We used computational fluid dynamic (CFD) analysis to model the hemodynamics of symptomatic ICAD lesions. Nine ICAD lesions (six carotid, two vertebral, one middle cerebral) underwent high-resolution catheter-based digital rotational angiography. The reconstructed three-dimensional volumes of the target lesions were segmented and used to generate hybrid computational meshes. Dynamic pulsatile CFD analysis was performed using a non-Newtonian shear-dependent model of blood's viscosity. CFD results revealed complex flow patterns within ICAD lesions with midstenotic shear rates of greater than 19,000/s, sufficiently high to induce high-shear platelet activation. Vorticity and helicity within the stenoses were followed by sudden deceleration with formation of vortex cores. Pressure gradients were significant mostly at greater than 75% stenosis with a mean time-averaged drop of 27.2 +/-17.8 mmHg. Unlike the smoothly-varying helicity imparted by the three-dimensional anatomy of the intracranial circulation, poststenotic regions of ICAD lesions showed significant and rapidly fluctuating helicity and vorticity patterns, which may contribute to the propagation of platelets activated by the high shear region within the stenosis throat. Stent angioplasty restored the hemodynamic profile of ICAD lesions to within contralateral controls. Patient-based symptomatic ICAD lesions studied using CFD analysis appear to harbor a hemodynamically pathological environment that favors the activation, aggregation and distal embolization of platelets and is reversed by endovascular stent angioplasty.