Angioplasty and stenting of intracranial stenosis

A Long-Term Outcome of Symptomatic Middle Cerebral Artery Undergoing Intracranial Angioplasty or Stenting

OBJECTIVE

For symptomatic stenosis in the middle cerebral artery (MCA), intracranial angioplasty and stenting are frequently employed. However, limited data exist regarding their long-term impact. Our study demonstrates the long-term advantages in preventing ischemic events through a 5-year follow-up period.

METHODS

A set of 41 individuals with symptomatic stenosis in the MCA who underwent angioplasty or stenting procedures between October 2004 and April 2018 at various hospitals in Southwest China were prospectively enrolled in the study. The rates of successful revascularization, complications, imaging observations, and clinical outcomes were systematically assessed.

RESULTS

A total of 41 individuals successfully underwent stenting, respectively. After stenting, the extent of stenosis was decreased from 71.8% (56-87.8%) to 24.9% (0-45%). The mean follow-up period is 36.9 ± 13.68 months (range, 11-67 months). There was no deterioration of neurological function or a new ischemic event. A DSA or CT angiography was conducted after the procedure and demonstrated no in-stent restenosis. No patient experienced restenosis below 50% during the mean follow-up period. The morbidity and mortality rates of the case series were 7.3% and 2.4%, respectively.

CONCLUSIONS

In the treatment of symptomatic MCA atherosclerotic stenoses, intracranial angioplasty and stenting are demonstrated to be technically feasible and safe. Its early and long-term efficacy on ischemic event prevention is acceptable, with a reduced level of restenosis, although the representative sample is tiny.

Aneurysm healing following treatment with biodegradable embolization materials: assessment in a rat sidewall aneurysm model

BACKGROUND

Biodegradable materials that dissolve after aneurysm healing are promising techniques in the field of neurointerventional surgery. We investigated the effects of various bioabsorable materials in combination with degradable magnesium alloy stents and evaluated aneurysm healing in a rat aneurysm model.

METHODS

Saccular aneurysms were created by end-to-side anastomosis in the abdominal aorta of Wistar rats. Untreated arterial grafts were immediately transplanted (vital aneurysms) whereas aneurysms with loss of mural cells were chemically decellularized before implantation. All aneurysms were treated with biodegradable magnesium stents. The animals were assigned to vital aneurysms treated with stent alone or decellularized aneurysms treated with stent alone, detachable coil, or long-term or short-term biodegradable thread. Aneurysm healing, rated microscopically and macroscopically at follow-up days 7 and 21, was defined by both neointima formation and absence of aneurysm volume increase over time.

RESULTS

Of 56 animals included, significant increases in aneurysm volume 7 days after surgery were observed in aneurysms with vital and decellularized walls treated with a stent only (P=0.043 each group). Twenty-one days after surgery an increase in aneurysm volume was observed in decellularized aneurysms treated with long- and short-term biodegradable threads (P=0.027 and P=0.028, respectively). Histological changes associated with an increase in aneurysm volume were seen for aneurysm wall inflammation, periadventitial fibrosis, and luminal thrombus.

CONCLUSIONS

An increase in aneurysm volume was associated with an absence of intrasaccular embolization material (early phase) and the breakdown of intrasaccular biodegradable material over time (late phase). Thrombus remnant and aneurysm wall inflammation promote aneurysm volume increase.

Balloons in endovascular neurosurgery: history and current applications

The use of balloons in the field of neurosurgery is currently an essential part of our clinical practice. The field has evolved over the last 40 years since Serbinenko used balloons to test the feasibility of occluding cervical vessels for intracranial pathologies. Since that time, indications have expanded to include sacrificing cervical and intracranial vessels with detachable balloons, supporting the coil mass in wide-necked aneurysms (balloon remodeling technique), and performing intracranial and cervical angioplasty for atherosclerotic disease, as well as an adjunct to treat arteriovenous malformations. With the rapid expansion of endovascular technologies, it appears that the indications and uses for balloons will continue to expand. In this article, we review the history of balloons, the initial applications, the types of balloons available, and the current applications available for endovascular neurosurgeons.

[Treatment of high grade intracranial stenoses]

Intracranial stenosis is the cause of 10 % of strokes. Besides medicinal treatment, intracranial bypass surgery, percutaneous transluminal angioplasty and stenting are available treatment approaches. According to the 2005 published WASID trial antiplatelets should be preferred to oral anticoagulation in secondary preventive therapy of ischemic stroke; however patients with high grade intracranial stenosis still have a poor prognosis. Intracranial bypass surgery, which was taken into account as a treatment option even in 1985, showed a generally worse outcome in relation to medicinal therapy. Intracranial angioplasty and stenting, representing improvements in endovascular treatment, were proven to be effective and feasible treatment approaches for patients with symptomatic high grade intracranial stenosis. Within the scope of the SAMMPRIS trial published in 2011, which propagated an advantage of aggressive medicinal treatment versus endovascular therapy, a retrospective study was performed at the department of neuroradiology of the Homburg University of Saarland.

Intracranial atheromatous disease treatment with the Wingspan stent system: evaluation of clinical, procedural outcome and restenosis rate in a single-center series of 21 consecutive patients with acute and mid-term results

BACKGROUND

Intracranial atherosclerosis may be the underlying pathology in up to 15% of ischemic strokes, but may account for about 40% of strokes in some populations. After an ischemic event determined by intracranial atherosclerosis, patients have a 12% annual risk of stroke recurrence, mostly during the first year.

OBJECTIVE

To evaluate procedural safety, clinical outcome and restenosis rate of Wingspan stent placement.

METHODS

Twenty-one caucasoid patients were enrolled. Target patients were affected by high-grade, symptomatic, intracranial atherosclerotic lesions, were on antithrombotic therapy and at high stroke risk. All patients were treated with the Wingspan stent system.

RESULTS

Technical success resulted 100%, with all target lesions being reduced to <50%. No stroke or death were observed at 30. The mean percent of stenosis was reduced from a middle value of 84% to a middle value of 17% after stent placement. Medium follow-up was 19.5months (range 6-36months). No stroke or death occurred in any patient. None of the patients presented a <50% stent patency rate at follow-up.

CONCLUSIONS

The short-term results and follow up analysis provide evidence demonstrating the safety of the Wingspan system when used in high-risk patient population. Due to concerns regarding long-term stent patency and ischemic events occurrence emerged from clinical trials such as the SAMMPRIS, intracranial angioplasty and stent with the Wingspan system should be considered only for high risk patients in which it may be considered the only viable therapeutic option.

Stent design lowers angiographic but not clinical adverse events in stenting of symptomatic intracranial stenosis - results of a single center study with 100 consecutive patients

BACKGROUND AND AIMS

Comparing safety and technical success of balloon-expandable stents and self-expanding stents for intracranial angioplasty and stenting in medically refractory intracranial atherosclerotic disease in a single center series.

METHODS

Fifty-four self-expanding stents and 46 balloon-expandable stents were implanted in 100 consecutive patients (mean age 64 years, 74% male) from April 2000 to September 2009. All patients had symptomatic intracranial stenosis (anterior circulation, n = 40; posterior circulation, n = 60), presenting with recurrent transient ischemic attack or stroke under antithrombotic treatment. Mean degree of stenosis before treatment was 83 ± 13%. We assessed safety, defined as any stroke or death during the procedure and at 30 days follow-up, and technical success, defined as accurate delivery of the stent at the site of the target lesion.

RESULTS

Safety - periprocedural stroke or hemorrhage occurred in 11 patients treated with balloon-expandable stent, and in 14 of the patients treated with a self-expanding stent. One patient with a balloon-expandable stent died because of acute vessel rupture during treatment. One balloon-expandable stent and one self-expanding stent patient developed a severe reperfusion hemorrhage that resulted in death. Overall, the combined stroke and death rate at 30-day follow-up was 25·0% (23·9% for balloon-expandable stent group and 25·9% for the self-expanding stent group, P = 0·84). Technical success - intracranial angioplasty and stenting was technically successful in 96·3% of the self-expanding stent and 89·1% of the balloon-expandable stent patients (P = 0·31). Vascular complications were significantly less frequent in patients treated with a self-expanding stent (11·1%) than with a balloon-expandable stent (36·9%, P = 0·002).

CONCLUSION

Despite a high technical success, the rate of clinical adverse events at 30 days after intracranial angioplasty and stenting is high independently of the stent design. Thus, further development of intracranial stent systems and careful patient selection are mandatory.

Wingspan stenting with modified predilation for symptomatic middle cerebral artery stenosis

OBJECTIVES

Our purpose was to assess the feasibility, safety, and effectiveness of a modified predilation for middle cerebral artery (MCA) stenosis.

BACKGROUND

Wingspan stenting of MCA remains a technical challenge, and rates of residual stenosis and restenosis must be lowered.

METHODS

A series of 48 patients with symptomatic MCA stenosis greater than 50% and refractory to medical therapy underwent Wingspan stenting with different balloon/artery ratios before (group 1, Boston guidelines predilation) or after (group 2, modified predilation) July of 2008. Technical success, periprocedural complications, recurrent symptoms, and restenosis were assessed retrospectively, and risk factors for restenosis were analyzed using logistic regression.

RESULTS

Successful stenting occurred in 48 of 49 (98%) lesions. Primary endpoints within 30 days included one (2.12%) minor stroke and two (4.26%) transient ischemic attacks. Stenoses were reduced from 77.11% ± 10.09% to 27.50% ± 6.91% in group 1 versus from 72.56% ± 10.46% to 8.20% ± 5.41% in group 2. A total of 43 patients were followed up for 12.92 ± 5.08 months, and recurrent stroke or transient ischemic attack occurred in two (4.65%) patients. Vessels were followed with transcranial Doppler (43 vessels), angiography (23 vessels), or computed tomographic angiography (one vessel). The restenosis rate was 8 of 18 (44%) in group 1 and 3 of 25 (12%) in group 2. Restenosis was associated with residual stenosis and diabetes.

CONCLUSIONS

Wingspan stenting for symptomatic MCA stenosis can be performed with high success and low complication rates, and modified predilation with the Gateway balloon can reduce the rates of residual stenosis and restenosis.

Intracranial atherosclerotic disease

Intracranial atherosclerotic disease (ICAD) is the most common proximate mechanism of ischemic stroke worldwide. Approximately half of those affected are Asians. For diagnosis of ICAD, intra-arterial angiography is the gold standard to identify extent of stenosis. However, noninvasive techniques including transcranial ultrasound and MRA are now emerging as reliable modalities to exclude moderate to severe (50%-99%) stenosis. Little is known about measures for primary prevention of the disease. In terms of secondary prevention of stroke due to intracranial atherosclerotic stenosis, aspirin continues to be the preferred antiplatelet agent although clopidogrel along with aspirin has shown promise in the acute phase. Among Asians, cilostazol has shown a favorable effect on symptomatic stenosis and is of benefit in terms of fewer bleeds. Moreover, aggressive risk factor management alone and in combination with dual antiplatelets been shown to be most effective in this group of patients. Interventional trials on intracranial atherosclerotic stenosis have so far only been carried out among Caucasians and have not yielded consistent results. Since the Asian population is known to be preferentially effected, focused trials need to be performed to establish treatment modalities that are most effective in this population.

Stenting for the treatment of high-grade intracranial stenoses

To date, evidence to recommend endovascular treatment in patients with intracranial stenoses is lacking. Recently, the introduction of self-expanding stents (Wingspan Stent System) aroused considerable expectations in their employ for stroke prevention. We report a single-center experience of percutaneous transluminal angioplasty and stenting in a series of consecutive patients with intracranial stenoses and compare the safety and performance of balloon-mounted stents versus self-expanding stent systems (Wingspan). Thirty-four patients with 39 severe (>70%) intracranial stenoses were treated during a 6-year period. An independent stroke neurologist collected data about intra and periprocedural complications and short-term outcome. We considered as endpoint measures (1) any 30-day stroke or death (2) any major 30-day complication and (3) procedure technical success. Technical success was achieved in all patients. No vessel dissection or ruptures were observed. The 30-day stroke/death rate was 17.9%. Five ischemic strokes in the territory of treated vessels and two intracranial hemorrhages occurred respectively within 24 h and 5 days after endovascular treatment. Three (17.6%) patients of Wingspan treated group and four (18.2%) of the patients treated with different stent systems had unfavorable outcome. Our study confirms that endovascular treatment can be performed with a high technical success rate, even though the safety of these devices has still to be demonstrated.

Biomedical applications of thermally activated shape memory polymers

Shape memory polymers (SMPs) are smart materials that can remember a primary shape and can return to this primary shape from a deformed secondary shape when given an appropriate stimulus. This property allows them to be delivered in a compact form via minimally invasive surgeries in humans, and deployed to achieve complex final shapes. Here we review the various biomedical applications of SMPs and the challenges they face with respect to actuation and biocompatibility. While shape memory behavior has been demonstrated with heat, light and chemical environment, here we focus our discussion on thermally stimulated SMPs.

Periprocedural MRI perfusion imaging to assess and monitor the hemodynamic impact of intracranial angioplasty and stenting for symptomatic atherosclerotic stenosis

We aimed to assess the clinical value of MRI perfusion imaging in the periprocedural management of intracranial atherosclerosis, analyzing if changes in mean transit time (MTT), cerebral blood volume (CBV) and cerebral blood flow (CBF) correlated with angiographic outcomes. Pre-procedural and post-procedural MRI perfusion was performed on six patients who underwent angioplasty and/or stenting for symptomatic intracranial atherosclerosis. MTT, CBV and CBF were analyzed and graded. In 83% of patients, perfusion imaging correlated with angiographic outcomes. Perfusion parameters improved to normal in two patients. Two showed marked improvement and one showed mild improvement. In one patient, the results of the post-procedural MRI perfusion prompted an angiogram, which confirmed stent occlusion. Semi-quantitative scores of MTT and CBF changed over time (p=0.05, p=0.03) whereas CBV did not change significantly (p>0.05). We conclude that MRI perfusion appears a promising technique for analyzing the impact of intracranial stenosis on cerebral hemodynamics before and after treatment.

Therapeutic modalities in symptomatic intracranial arterial occlusive disease

Intracranial atherosclerotic disease (ICAD) is a frequent cause of stroke that is sometimes underdiagnosed. In this review, we survey the literature concerning ICAD and present the prognostic factors and the therapeutic options pertinent to it by comparing medical, surgical and endovascular approaches.

Thermomechanical properties, collapse pressure, and expansion of shape memory polymer neurovascular stent prototypes

Shape memory polymer stent prototypes were fabricated from thermoplastic polyurethane. Commercial stents are generally made of stainless steel or other alloys. These alloys are too stiff and prevent most stent designs from being able to navigate small and tortuous vessels to reach intracranial lesions. A solid tubular model and a high flexibility laser etched model are presented. The stents were tested for collapse in a pressure chamber. At 37 degrees C, the full collapse pressure was comparable to that of commercially available stents, and higher than the estimated maximum pressure exerted by intracranial arteries. However, there is a potential for onset of collapse, which needs further study. The stents were crimped and expanded, the laser-etched stent showed full recovery with an expansion ratio of 2.7 and a 1% axial shortening.

Intracranial atherosclerotic disease; current options for surgical or medical treatment

Recently, intracranial atherosclerosis has become a major cause of ischemic stroke, appearing more frequently in Koreans than Caucasians. Symptomatic or asymptomatic intracranial atherosclerosis is a disease that could recur readily even during the treatment with anti-platelet agents. When the symptoms develop, ischemic stroke can not be recovered readily. Therefore, aggressive treatments such as endovascular therapy and bypass surgery are required in addition to medical treatment for the intracranial artery stenosis. Recent intracranial stenting and drug eluting stenting have shown as very advanced effective therapeutic modalities. Nevertheless, until now, a randomized controlled study has not been conducted. Regarding bypass surgery, since the failed EC-IC bypass surgery study performed 20 years ago, extensive studies on its efficacy has not been conducted yet, and thus it has to be performed strictly only in hemodynamically compromised patients. Unless breakthrough drugs that suppress the progression of intracranial atherosclerosis and the formation of thrombi, and facilitate the regression of the arterial stenosis, the treatment concept of the recovery of the blood flow of stenotic arterial territory by mechanical recanalization or bypass surgery would be remained for the prevention as well as treatment of ischemic stroke caused by intracranial atherosclerosis.

VAST: Vertebral Artery Stenting Trial. Protocol for a randomised safety and feasibility trial

Background

Twenty to 30 percent of all transient ischaemic attacks and ischaemic strokes involve tissue supplied by the vertebrobasilar circulation. Atherosclerotic stenosis ≥ 50% in the vertebral artery accounts for vertebrobasilar stroke in at least one third of the patients. The risk of recurrent vascular events in patients with vertebral stenosis is uncertain and revascularisation of vertebral stenosis is rarely performed. Observational studies have suggested that the risk of subsequent stroke or death in patients with vertebrobasilar ischaemic events is comparable with that in patients with carotid territory events. Treatment of vertebral stenosis by percutaneous transluminal angioplasty has been introduced as an attractive treatment option. The safety and benefit of stenting of symptomatic vertebral stenosis as compared with best medical therapy alone remains to be elucidated in a randomised clinical trial.

Study objectives

The primary aim of the Vertebral Artery Stenting Trial (VAST) is to assess whether stenting for symptomatic vertebral artery stenosis ≥ 50% is feasible and safe. A secondary aim is to assess the rate of new vascular events in the territory of the vertebrobasilar arteries in patients with symptomatic vertebral stenosis ≥ 50% on best medical therapy with or without stenting.

Design

This is a randomised, open clinical trial, comparing best medical treatment with or without vertebral artery stenting in patients with recently symptomatic vertebral artery stenosis ≥ 50%. The trial will include a total of 180 patients with transient ischaemic attack or non-disabling ischaemic stroke attributed to vertebral artery stenosis ≥ 50%. The primary outcome is any stroke, vascular death, or non-fatal myocardial infarction within 30 days after start of treatment. Secondary outcome measures include any stroke or vascular death during follow-up and the degree of (re)stenosis after one year.

Discussion

Improvements both in imaging of the vertebral artery and in endovascular techniques have created new opportunities for the treatment of symptomatic vertebral artery stenosis. This trial will assess the feasibility and safety of stenting for symptomatic vertebral artery stenosis and will provide sufficient data to inform a conclusive randomised trial testing the benefit of this treatment strategy. The VAST is supported by the Netherlands Heart Foundation (2007B045; ISRCTN29597900).

Management of patients with symptomatic intracranial atherosclerosis

Intracranial atherosclerosis is a common cause of stroke, accounting for about 50% of ischaemic stroke in Asia and 8% in North America. Many prospective studies have confirmed that intracranial stenosis is an independent predictor for poor outcomes such as recurrent vascular event and death, despite the use of antiplatelet agents. The annual event rate is about 15% per year. The dismal outcome prompts the study of more aggressive treatment strategies, including warfarin and endovascular intervention. We have reviewed the published literature for the treatment of symptomatic intracranial stenosis. The Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial and Warfarin-Aspirin Recurrent Stroke Study (WARSS) studies failed to show that oral anticoagulation was better than aspirin in IAS. Initial encouraging results were found in the use of dual antiplatelet therapy in arresting the progression of stenosis. The results of the endovascular studies are mixed: there are more encouraging results with recent advances of technology in stent design, but a randomized controlled study is still lacking. Although there is still no established therapy for IAS, the results of ongoing randomized clinical trials to study dual antiplatelet agents and the use of endovascular intervention may soon provide clinicians with more evidence to better manage patients with this condition.

Angiographic CT with intravenous administration of contrast medium is a noninvasive option for follow-up after intracranial stenting

Intracranial angioplasty and stenting (ICAS) is a therapeutic option in symptomatic intracranial atherosclerotic disease. Adequate follow-up examination is necessary to exclude in-stent restenosis. Conventional intraarterial digital subtraction angiography (ia-DSA) is the current gold standard, but it is an invasive technique and carries the risk of neurological complications. Angiographic CT (ACT) is a new technique that provides a volume dataset of the highest spatial resolution and high contrast resolution derived from a rotational acquisition of a c-arm-mounted flat-panel detector. The feasibility of ACT with intravenous administration of contrast medium (iv-ACT) for follow-up after ICAS is demonstrated. In two patients iv-ACT was performed as a follow-up examination 12 months after ICAS. High-resolution volume data from the rotational acquisitions were processed to provide delineation of the stent lumen as well as imaging of the brain parenchyma and vessels. In both patients the patency of the stent lumen was assessed successfully. In addition, all other brain vessels were displayed in a manner similar to their appearance on CT angiograms. The brain parenchyma was also adequately imaged in a manner similar to its appearance on CT images. We demonstrated the feasibility and diagnostic value of iv-ACT for follow-up imaging after ICAS. This new application has the potential to become the imaging method of choice after ICAS since it not only enables visualization of the patency of the stent lumen but also is minimally invasive and provides additional information about all brain arteries and the brain parenchyma.

The NIH registry on use of the Wingspan stent for symptomatic 70-99% intracranial arterial stenosis

BACKGROUND

The Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial showed that patients with symptomatic 70% to 99% intracranial arterial stenosis are at particularly high risk of ipsilateral stroke on medical therapy: 18% at 1 year (95% CI = 3% to 24%). The Wingspan intracranial stent is another therapeutic option but there are limited data on the technical success of stenting and outcome of patients with 70% to 99% stenosis treated with a Wingspan stent.

METHODS

Sixteen medical centers enrolled consecutive patients treated with a Wingspan stent in this registry between November 2005 and October 2006. Data on stenting indication, severity of stenosis, technical success (stent placement across the target lesion with <50% residual stenosis), follow-up angiography, and outcome were collected.

RESULTS

A total of 129 patients with symptomatic 70% to 99% intracranial stenosis were enrolled. The technical success rate was 96.7%. The mean pre and post-stent stenoses were 82% and 20%. The frequency of any stroke, intracerebral hemorrhage, or death within 30 days or ipsilateral stroke beyond 30 days was 14.0% at 6 months (95% CI = 8.7% to 22.1%). The frequency of >or=50% restenosis on follow-up angiography was 13/52 (25%).

CONCLUSION

The use of a Wingspan stent in patients with severe intracranial stenosis is relatively safe with high rate of technical success with moderately high rate of restenosis. Comparison of the event rates in high-risk patients in Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) vs this registry do not rule out either that stenting could be associated with a substantial relative risk reduction (e.g., 50%) or has no advantage compared with medical therapy. A randomized trial comparing stenting with medical therapy is needed.

Fabrication and in vitro deployment of a laser-activated shape memory polymer vascular stent

Background

Vascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). Most vascular stents are metallic and are deployed either by balloon expansion or by self-expansion. A shape memory polymer (SMP) stent may enhance flexibility, compliance, and drug elution compared to its current metallic counterparts. The purpose of this study was to describe the fabrication of a laser-activated SMP stent and demonstrate photothermal expansion of the stent in an in vitro artery model.

Methods

A novel SMP stent was fabricated from thermoplastic polyurethane. A solid SMP tube formed by dip coating a stainless steel pin was laser-etched to create the mesh pattern of the finished stent. The stent was crimped over a fiber-optic cylindrical light diffuser coupled to an infrared diode laser. Photothermal actuation of the stent was performed in a water-filled mock artery.

Results

At a physiological flow rate, the stent did not fully expand at the maximum laser power (8.6 W) due to convective cooling. However, under zero flow, simulating the technique of endovascular flow occlusion, complete laser actuation was achieved in the mock artery at a laser power of ~8 W.

Conclusion

We have shown the design and fabrication of an SMP stent and a means of light delivery for photothermal actuation. Though further studies are required to optimize the device and assess thermal tissue damage, photothermal actuation of the SMP stent was demonstrated.

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.

Management of symptomatic intracranial atherosclerotic disease

Recently completed prospective studies have shown that with an incidence of recurrent stroke of approximately 10% per year, significant mortality, and other vascular comorbidities, symptomatic intracranial stenosis is a marker of aggressive vascular disease. Although strict control of atherosclerotic risk factors and antithrombotic therapy preferably with antiplatelet agents should be the mainstay of treatment for every patient with this disease, some patients are likely to remain refractory to medical therapy. These high-risk patients appear to be individuals with recent symptoms and severe (> 70%) stenosis with clinical and imaging evidence of hemodynamic impairment distal to the stenotic artery. Advances in balloon and stent technology have made consideration of these high-risk patients for endovascular management with angioplasty and stenting possible, which should ideally take place as part of randomized clinical trials, because the benefit of these high-risk therapies compared with medical therapy is not yet established. This article reviews available medical treatment options for symptomatic intracranial disease and outlines the current state of endovascular therapy for this disease.

Endovaskuläre Behandlung intrakranieller Stenosen

Intracranial stenoses cause 5-10% of all strokes and are increasingly detected by means of modern imaging methods. The stroke danger of high-grade symptomatic stenoses is relatively high, with an annual risk of approximately 10% under medical treatment. Coumadin increases the risk of hemorrhage, and after risk/benefit considerations, antiplatelets should be preferred for antithrombotic therapy. Despite optimized medical treatment, a small group of patients with recurrent symptoms or symptomatic stenoses without adequate collateral supply probably carry higher spontaneous stroke risk and may be considered for intracranial stenting, which itself is associated with procedural risks of up to 10%. Currently published case series show relatively high complication rates as a major drawback of endovascular treatment, mainly strokes after occlusion of perforating branches extending from the stenotic vessel segment or hemorrhagic complications. According to data from smaller feasibility studies, stroke rates in follow-up after successful stenting seem to be low. The average rate of high-grade restenosis with possible indication for reintervention is 10%. Improvements in endovascular treatment aim at reducing vessel wall trauma during balloon angioplasty by underdilatation or the use of self-expanding stents. Until complication rates are dependably reduced to values of 5-6%, indication for endovascular treatment should be restricted to patients without therapeutic alternatives. According to limited data with large variation between different studies, a prospective multicentric registry is proposed for systematic evaluation and further development of the method.

Current Concepts in the Management of Intracranial Atherosclerotic Disease

MEDICALLY REFRACTORY, SYMPTOMATIC intracranial atherosclerotic disease has a poor prognosis. Based on the results of the Warfarin-Aspirin Symptomatic Intracranial Disease study, the risk of ipsilateral stroke at 1.8 years is between 13 and 14% in patients with symptomatic intracranial atherosclerosis. Synergistic advances in intracranial angioplasty and stenting, modern neuroimaging techniques, and periprocedural and postprocedural antithrombotic regimens are creating new models for the diagnosis and successful endovascular treatment of intracranial stenosis. In this article, the most recent clinical developments and concepts for the diagnosis and endovascular treatment of intracranial atherosclerotic disease are discussed.

Safety and Pharmacokinetics of Sirolimus-eluting Stents in the Canine Cerebral Vasculature: 180 Day Assessment

OBJECTIVE

We evaluated local and systemic pharmacokinetics and pharmacodynamics of sirolimus-eluting stents (SES) in canine cerebral vessels.

METHODS

SES (1.5 x 8 mm, 79 microg/479 microg sirolimus) and control stents (1.5 x 8 mm stainless steel with or without polymer) were implanted in canine basilar and ventral spinal arteries. Animals were sacrificed for local pharmacokinetic (36 animals at 1, 3, 8, 30, 90, 180 days) and pharmacodynamic (60 animals at 3, 30, 90, 180 days) assessment.

RESULTS

Postrecovery adverse clinical events were not serious, requiring no unscheduled treatment. Histologically, brain and spinal cord sections revealed scattered microinfarcts and minimal gliosis consistent with postprocedure changes in all four stent-treatment groups. All stented vessels at all time points demonstrated good luminal patency with low injury and inflammation scores and no thrombosis of either stented or branch arteries. Endothelialization was complete in all stent groups by 30 days. Intimal smooth muscle cell scores were reduced in both SES groups at 30, 90, and 180 days. Systemic sirolimus levels peaked between 1 and 7 hours postimplant (maximum concentration, 1.2 +/- 1.47, 79 microg; 4.5 +/- 1.23 ng/ml, 479 microg), then declined rapidly to 1 ng/ml or less by 96 hours. Peak local tissue sirolimus levels were 41.5 ng/mg (79 microg) and 65 ng/mg (479 microg).

CONCLUSION

SES in canine cerebral vessels were associated with good luminal patency to 180 days, with complete endothelialization and no evidence of acute thrombosis. This model has shown that SES deployed within the brain do not cause neurotoxicity during a 180-day time course, even when exaggerated doses are used. The findings support the contention that SES are safe to use and maintain patency in cerebral vessels.

Intracranial aneurysm stenting: follow-up with MR angiography

Intracranial stenting is increasingly being used to treat intracranial aneurysms and stenoses. We wanted to assess the utility of magnetic resonance angiography (MRA) in the follow-up of patients treated with various types of intracranial stents and to assess the utility of performing gadolinium-enhanced MRA. A total of 19 patients having undergone intracranial stenting for aneurysms were imaged by MRI at 1.5T. A total of 20 stents were placed in 19 patients. In addition to conventional T2- and diffusion-weighted MRI, 3D time-of-flight MRA was performed before and after contrast administration. In the case of metallic INX stents (N = 7), there was a signal drop at the level of the vessel. which did not allow to evaluating the parent vessel, whereas this was visible in Nitinol stents (N = 8). Additionally a stent with a wire had a small artifact (N = 3). Contrast administration also improved vessel lumen visualization. In the case of Nitinol stents, MRA can be used to reliably demonstrate the vessel lumen after intracranial stenting. The use of postcontrast 3D time-of-flight imaging helps improve the intraluminal definition.