Clip occlusion versus coil embolization for the treatment of cerebral aneurysms

Advances in the endovascular treatment of intracranial aneurysms since the advent of detachable coil embolization continue to expand the spectrum of lesions amenable to minimally invasive therapy. The feasibility of treating a given cerebral aneurysm by a given open or endovascular modality does not necessarily make such an approach the optimal choice. Rather, any given cerebral aneurysm and patient should be carefully analyzed on a multitude of parameters which are based on available adjunctive technology, aneurysm morphology and characteristics, endovascular vs. microsurgical accessibility, and long-term angiographic outcome. In addition to patient age, co-morbid conditions, lesion size and attendant risk, one must also consider patient preference with respect to length of hospital stay, recovery duration and required follow-up and radiographic assessments. The relentless improvements in minimally invasive embolization therapies ranging from coiling with adjunctive balloon and stent support to the emerging role of flow-diversion must be balanced against the lower cost and complexity associated with longitudinal clinical and radiographic follow-up requirements of microsurgical clipping. This review will consider the various factors involved in the determination of optimal modality choice based on an assessment of clinical, morphological and anatomical considerations. In this rapidly evolving field, the quest for maximizing protection from aneurysm rupture at the lowest neurological cost dictates that a balance be maintained between technical virtuosity and procedural safety of either microsurgical clipping or endovascular repair to insure that the advantages of the selected modality not be negated by its associated shortcomings.

Stent-assisted coiling of intracranial bifurcation aneurysms leads to immediate and delayed intracranial vascular angle remodeling

BACKGROUND AND PURPOSE

Wide-neck bifurcating aneurysms are increasingly treated with intracranial stent-assisted coiling by using shape-memory alloy microstents. We sought to investigate the short- and long-term effects of intracranial stent implantation on the geometry and angular conformation of the stent-coiled vascular bifurcation.

MATERIALS AND METHODS

Thirty patients underwent stent-mediated coiling for 31 bifurcation aneurysms by using 31 self-expanding Neuroform (n = 14) and Enterprise (n = 17) stents (17 women; mean age, 56 years). The angle (δ) between the stented mother and daughter vessels at the bifurcation was measured by using multiplanar imaging of reconstructed rotational conventional angiography volumes and was compared by using matched-pair statistics. Neuroform and Enterprise longitudinal stent stiffness was measured in vitro at an increasing bending angle θ (θ = 180°-δ).

RESULTS

Stent deployment increased the bifurcation angle δ from 101.5° to 119.8° postprocedurally and to 137.3° (P < .0001) at latest follow-up, resulting in effective straightening; the angular remodeling was greater in distal-versus-proximal arteries (anterior cerebral > MCA > BA > ICA), inversely proportional to mother-vessel diameter and proportional to pretreatment bending angle θ. At follow-up, angle δ continued to significantly expand, with remodeling being greater in the early period (1-6 versus >7 months) and more pronounced with the longitudinally stiffer closed-cell Enterprise compared with the open-cell Neuroform stent.

CONCLUSIONS

Stent placement across bifurcation aneurysms leads to a significant biphasic angular remodeling related to stent type and vessel caliber, altering morphology to mimic sidewall lesions, a phenomenon needing consideration during procedural planning. Future work is needed to uncover the hemodynamic implications of this structural change and any possible effect on aneurysm-recurrence rates.

Parent vessel size and curvature strongly influence risk of incomplete stent apposition in enterprise intracranial aneurysm stent coiling

BACKGROUND AND PURPOSE

Flexible microstents, such as the closed-cell EN, have facilitated adjunctive coiling of intracranial aneurysms. Little data are available on the ability of the stent struts to maintain vessel-wall apposition once deployed in the tortuous cerebral vasculature and the prevalence of ISA. The purpose of this study was to evaluate the relationship between geometric features of the parent vessel at the stent deployment site and prevalence of ISA.

MATERIALS AND METHODS

Postprocedural 3T-MRA was performed in a cohort of 39 patients undergoing EN stent-assisted intracranial aneurysm coiling. 3T-MRA was analyzed for the presence of ISA and supplemented by angiographic C-arm FPCT (DynaCT). Parent vessel diameter, curvature radius, and stent-subtended arc angle were measured at the site of deployment and analyzed for prediction of ISA in the ICA.

RESULTS

3T-MRA uncovered a unique crescent flow pattern (CS) outside the EN struts, which was confirmed by FPCT to indicate ISA resulting from EN crimping. ISA was detected on 3T-MRA in 19/39 patients (49%). Univariate analysis revealed ISA in the ICA to correlate with a large stent-subtended angle, a small curvature radius, and a large diameter but not stent length or jailing versus a sequential technique. Multivariate analysis identified ISA to correlate with vessel-curvature radius (OR, 253; P = .009), stent-subtended angle (OR, 225; P = .005), and parent vessel diameter (OR, 8.49; P = .044).

CONCLUSIONS

In this study, ISA was detectable by 3T-MRA in a significant proportion of patients undergoing EN stent-assisted coiling of ICA aneurysms in a vessel geometry- and stent-deployment location-dependent manner. This characteristic of EN coiling at this potentially tortuous location should be taken into account when selecting an endovascular strategy.

Public-private partnerships in healthcare: criteria for success

Public-private partnerships present opportunities for healthcare providers to meet the dual challenges of shrinking public funding and increasing demand for care. Partnering with private sector organizations can provide new sources of capital, expertise and technology. Successful partnerships require specific skills and strategies. This article describes a pilot study that explored the literature and the experiences of participants in a small sample of interviews to compile a set of criteria for successful public-private healthcare partnerships.

Reporting terminology for brain arteriovenous malformation clinical and radiographic features for use in clinical trials

“If you wish to converse with me,” said Voltaire, “define your terms.” How many a debate would have been deflated into a paragraph if the disputants had dared to define their terms!

Will Durant: The Story of Philosophy

Endovascular treatment of a ruptured dual aperture cavernous aneurysm

The authors describe the diagnosis and endovascular management of a multiaperture, ruptured cavernous internal carotid artery aneurysm causing a carotid cavernous fistula (CCF) using both transarterial and transvenous techniques. Although uncommon, recognition of the imaging characteristics of such a lesion will aide in successful management and improve treatment outcome. To the authors' knowledge, CCF due to a ruptured cavernous aneurysm with multiple shunts has not been previously reported.

Stent angioplasty for cervical carotid artery stenosis in high-risk symptomatic NASCET-ineligible patients

BACKGROUND AND PURPOSE

Although the North American Symptomatic Carotid Endarterectomy Trial (NASCET) has shown carotid endarterectomy (CEA) to be protective compared with medical therapy alone, its stringent eligibility criteria excluded patients with severe medical, angiographic, and neurological risk factors. We sought to determine the safety and efficacy of stent angioplasty in this high-risk subset for whom the perioperative morbidity and mortality of surgery are elevated.

METHODS

Twenty-eight consecutive symptomatic NASCET-ineligible patients (10 female; median age, 72.2 years) underwent microcatheter-based carotid stent angioplasty. Half of the patients had sustained a previous stroke. Classification of surgical risk by Sundt criteria yielded no patients in grade 1, 3 patients in grade 2 (10.7%), 8 in grade 3 (28.6%), and 17 (60.7%) in grade 4. Stratification of stroke risk for medical therapy according to the European Carotid Surgery Trial (ECST) 5-point score showed 8 patients with a score of 3 (28.6%), 12 with 4 (42.8%), and 8 with 5 (28.6%). Follow-up was obtained in all patients at a median of 14 months.

RESULTS

The procedure was technically successful in all cases (100%), with immediate stenosis reduction from a mean of 80.3% to 2.7%. There were no periprocedural deaths, 1 major stroke (3.6%), no minor strokes, and 3 transient ischemic attacks (10.7%). In-hospital complications included 2 nonfatal myocardial infarctions, 1 case of acute renal failure, and 1 groin hematoma requiring transfusion. There were 5 deaths during the follow-up period, all beyond 30 days after the procedure: 3 from cardiac causes, 1 from lung cancer, and 1 following unrelated surgery. The patient with major stroke died at 7.8 months during rehabilitation. No surviving patients had further strokes, and all except 1 (95.5%) remained asymptomatic. Anatomic follow-up in 20 patients showed occlusion in 2 (10%) (1 symptomatic, 1 asymptomatic) and intimal hyperplasia in 3 asymptomatic patients (15%).

CONCLUSIONS

The clinical results and sustained freedom from symptoms and stroke during the short available follow-up period suggest that stent angioplasty may be useful in the treatment of symptomatic cervical carotid stenosis in high-risk patients despite a notable incidence of restenosis.

Carotid artery stent placement for atherosclerotic disease: rationale, technique, and current status

Carotid arterial endarterectomy is considered to be the standard for the treatment of atherosclerotic carotid arterial occlusive disease. This has been validated with results of several randomized controlled trials in which its effectiveness has been demonstrated over that of the best nonsurgical therapy. In the past several years, however, carotid angioplasty with stent placement has emerged as a potential alternative to carotid endarterectomy. This article represents a critical examination of the rationale for carotid revascularization; the history of endovascular techniques for the treatment of carotid atherosclerosis, beginning with balloon angioplasty and evolving to the use of stents; and the evidence supporting the effectiveness of the endovascular approach. A brief description of the current technical aspects of carotid artery stent placement is presented. The future status of the endovascular approach will be determined with randomized trials in which carotid artery stent placement is directly compared with endarterectomy, as well as by the potential for further innovation and improvement in endovascular devices, technique, and safety.

Primary stenting for high-grade basilar artery stenosis

We report two patients with symptomatic high-grade stenosis of the basilar artery refractory to appropriate maximal medical therapy in whom endovascular stenting was performed successfully without preliminary balloon angioplasty. Excellent angiographic results were achieved and there were no procedural or periprocedural complications. The patients were asymptomatic and neurologically intact at a mean clinical follow-up of 6.5 months. Primary stenting of basilar artery stenosis may be an alternative to balloon angioplasty for patients with symptomatic lesions refractory to medical therapy or in whom anticoagulation is contraindicated.

Endovascular management of extracranial carotid artery dissection achieved using stent angioplasty

BACKGROUND AND PURPOSE

Dissection of the carotid artery can, in certain cases, lead to significant stenosis, occlusion, or pseudoaneurysm formation, with subsequent hemodynamic and embolic infarcts, despite anticoagulant therapy. We sought to determine the therapeutic value of stent-supported angioplasty retrospectively in this subset of patients who are poor candidates for medical therapy.

METHODS

Five men and five women (age range, 37-83 years; mean age, 51.2 years) with dissection of the internal (n=9) and common (n=1) carotid artery were successfully treated with percutaneous endovascular balloon angioplasty and stent placement. The etiology was spontaneous in five, iatrogenic in three, and traumatic in two. Seven of the treated lesions were left-sided and three were right-sided.

RESULTS

The treatment significantly improved dissection-related stenosis from 74+/-5.5% to 5.5+/-2.8%. Two occlusive dissections were successfully recanalized using microcatheter techniques during the acute phase. Multiple overlapping stents were needed in four patients to eliminate the inflow zone and false lumen and establish an angiographically smooth outline within the true lumen. There was one case of retroperitoneal hemorrhage, but there were no procedural transient ischemic attacks (TIAs), minor or major strokes, or deaths (0%). Clinical outcome at latest follow-up (16.5+/-1.9 months) showed significant improvements compared with pretreatment modified Rankin score (0.7+/-0.3 vs 1.8+/-0.44) and Barthel index (99.5+/-0.5 vs 80.5+/-8.9). One delayed stroke occurred in a treated patient with contralateral carotid occlusion following a hypotensive uterine hemorrhage at 8 months; the remaining nine patients have remained free of TIA or stroke.

CONCLUSION

In select cases of carotid dissection associated with critical hemodynamic insufficiency or thromboembolic events that occur despite medical therapy, endovascular stent placement appears to be a safe and effective method of restoring vessel lumen integrity, with good clinical outcome.

Cerebral hyperperfusion syndrome after percutaneous transluminal stenting of the craniocervical arteries

OBJECTIVE

Cerebral hyperperfusion syndrome is a recognized complication of carotid endarterectomy, with a reported incidence of 0.3 to 1.2%. The incidence of cerebral hyperperfusion after endovascular revascularization procedures of the craniocervical arteries remains unknown. We evaluated the incidence of cerebral hyperperfusion syndrome in our endovascular revascularization series. To our knowledge, there are no previous studies evaluating the incidence of hyperperfusion syndrome after percutaneous transluminal angioplasty/stenting.

METHODS

Between March 1996 and February 2000, 140 patients underwent percutaneous transluminal angioplasty/stenting of the craniocervical arteries at our institution. In all patients, selective bilateral arteriography of the carotid and vertebral arteries was performed to document the sites of craniocervical stenosis and collateral blood flow and the results of the endovascular revascularization procedure. We then reviewed all pertinent medical records, arteriographic films, and sectional imaging studies to determine the incidence of cerebral hyperperfusion in this series.

RESULTS

Seven patients (5.0%) developed clinical or radiological manifestations of cerebral hyperperfusion. In the target group, percutaneous transluminal stenting achieved a 90 to 100% reduction in stenotic lesions (mean stenosis, 91%) of the carotid (n = 5) and vertebral (n = 2) arteries. All seven patients remained neurologically stable immediately after treatment. There was delayed development of clinical and radiographic findings, suggestive of cerebral hyperperfusion. Six patients showed evidence of ipsilateral hemispheric edema, including two patients who developed intracranial hemorrhage (one parenchymal, one parenchymal and subarachnoid) documented by computed tomographic brain scans. Symptoms resolved within 72 hours in the four patients without hemorrhage. The two patients with hemorrhage recovered during a more protracted period (range, 3 wk to 6 mo). There were no long-term sequelae or deaths during a cumulative follow-up of 84 months (mean follow-up, 12 mo).

CONCLUSION

Hyperperfusion syndrome is an uncommon but potentially serious complication of extracranial and intracranial angioplasty and stenting procedures. The clinical manifestations are similar to hyperperfusion syndrome after carotid endarterectomy; however, the prevalence may be greater in the high-risk cohort commonly referred for endovascular treatment. Our findings suggest that patients undergoing endovascular stenting procedures should be closely monitored for evidence of hyperperfusion, with careful monitoring of blood pressure, heart rate, and anticoagulation. Further research is needed to confirm that cerebral hyperperfusion is the pathogenesis of this condition.

Endovascular treatment of cerebral artery aneurysms during pregnancy: report of three cases

Historically, surgical management of cerebral aneurysms during pregnancy has been controversial. Debate originally focused on early versus late intervention, before or after delivery of the fetus. More recently, treatment has centered on rapid intervention. We describe the endovascular treatment of cerebral artery aneurysms with Guglielmi detachable coils in three pregnant women.

Stent-supported coil embolization: the treatment of fusiform and wide-neck aneurysms and pseudoaneurysms

OBJECTIVE

We describe a consecutive series of patients treated with endovascular stent-supported coil embolization for symptomatic or enlarging wide-neck and fusiform aneurysms and pseudoaneurysms of the carotid and vertebrobasilar arteries.

METHODS

Seven stent-supported coil embolization procedures were performed for seven aneurysms in seven consecutive patients. There were five pseudoaneurysms, one dissecting aneurysm, and one berry aneurysm. Four aneurysms were located in the carotid artery, and three were located in the vertebrobasilar system. Three aneurysms were intracranial. Four patients were symptomatic, and three had angiographic evidence of increasing aneurysm size.

RESULTS

Technical success was achieved in six (86%) of seven patients. Entanglement of a coil with the stent struts necessitated partial coil delivery into the parent artery in one patient, but there were no neurological or other adverse sequelae. The 30-day rate of periprocedural stroke or mortality was 0%. At a mean clinical follow-up of 14.5 months, neurological status was at baseline or better in all patients. To date, all treated patients remain clinically asymptomatic with oral administration of aspirin only.

CONCLUSION

Stent-supported coil embolization represents an emerging therapeutic alternative to surgery for the treatment of symptomatic or enlarging wide-neck and fusiform aneurysms and pseudoaneurysms of the cervical and vertebrobasilar arteries, which are not amenable to conventional unsupported coil embolization. Experience with greater numbers of patients and long-term follow-up are required to further validate this technique.

Balloon-assist technique for endovascular coil embolization of geometrically difficult intracranial aneurysms

OBJECTIVE

The balloon-assist or neck-remodeling technique is an adjunctive method devised for the endovascular coil embolization of aneurysms characterized by a wide neck or unfavorable geometric features. Since its initial description, there have been few data to corroborate its utility, efficacy, and safety in aneurysm embolization.

METHODS

Twenty patients (19 female patients and 1 male patient) with 22 aneurysms (19 unruptured aneurysms and 3 ruptured aneurysms) underwent balloon-assisted coil embolization. The balloon-assist technique was performed in the same treatment session after conventional coil embolization had failed in 55% of cases (12 of 22 cases) and was the primary treatment in 45% of cases. The majority of aneurysms were located in the supraclinoid carotid artery (13 paraophthalmic and 3 superior hypophyseal aneurysms). The mean angiographic measurements included a fundus of 8.7 +/- 3.7 mm, a neck of 5.3 +/- 2.2 mm, and a comparatively unfavorable fundus/neck ratio of 1.33 +/- 0.23.

RESULTS

Technical success was achieved in 77% of cases (17 of 22). The rate of aneurysm obliteration at the end of the procedures was 97 +/- 3.8%. Angiographic follow-up data (mean follow-up period, 10.3 mo) obtained for 89% of the treated aneurysms (15 of 17) confirmed stable mean occlusion of 97.8 +/- 3.8%. Technical complications included two cases of asymptomatic distal vessel thromboembolism, which resolved angiographically within 24 hours, and one case of intraprocedural rupture of an arteriovenous malformation-related feeder artery aneurysm, which resulted in no neurological deficits and required no further treatment (transient complication rate, 13.6%; 3 of 22 cases). There were no deaths and no procedure-related 30-day or permanent morbidity.

CONCLUSION

The balloon-assist method of coil embolization is characterized by promising intermediate-term angiographic and clinical outcomes and acceptable morbidity and mortality rates. Although this adjunctive method requires the use of an additional microcatheter and consequently involves a higher level of technical complexity, it extends the range of aneurysms that can be successfully treated with electrolytically detachable coils via an endovascular approach.

Hemorrhagic complications in vein of Galen malformations

The authors report on a series of spontaneous intracranial hemorrhages associated with vein of Galen aneurysmal malformations (VGAMs). Thirty-four children with VGAMs have been treated at this institution since 1986. Eight children (24%) harbored the mural-type malformation, and 26 (76%) had the choroidal-type lesion. Two children (25%) with mural lesions and 1 (4%) with a choroidal lesion suffered hemorrhagic complications. Two presented with acute intracranial hemorrhage. A third child developed acute intracranial hemorrhage due to delayed dural sinus thrombosis after endovascular treatment of his choroidal-type VGAM. The subjects ranged in age from 13 days to 17 months at the time of presentation. Each patient underwent rapid radiological evaluation and treatment with endovascular surgery. Post-procedural arteriography demonstrated complete occlusion of the malformation in each patient. For the 3 patients with hemorrhage, follow-up has taken place over 49-, 107-, and 43-month intervals, respectively. Vein of Galen aneurysmal malformations can present with acute intracranial hemorrhage or develop delayed intracranial hemorrhage but respond to treatment using standard endovascular techniques. The presence of hemorrhage does not de facto portend a poor prognosis.

Endovascular stenting for carotid artery stenosis: preliminary experience using the shape-memory- alloy-recoverable-technology (SMART) stent

We describe our initial clinical experience using the newly available self-expanding, Nitinol, shape-memory-, alloy-recoverable-technology (SMART) stent in treating carotid artery occlusive disease. Five stents were used in four carotid arteries in four consecutive patients with carotid stenosis of at least 70%. Technical success (<20% residual stenosis) was achieved in all cases. No procedural complications specifically related to use of the SMART stent were encountered. All patients remained symptom-free, with no evidence of transient ischemic attacks or new strokes during an average follow-up period of 6 months. Excellent performance of the SMART stent for the endovascular treatment of carotid artery stenosis has been shown based on our early experience. Validation with greater numbers and longer-term follow-up is required. The specific technical characteristics, potential advantages, and disadvantages of this stent are discussed and compared with other currently used carotid artery stents.

Endovascular treatment of noncarotid extracranial cerebrovascular disease

The last two decades have witnessed a growing application of endovascular techniques for the treatment of atherosclerotic disease of the extracranial vertebral arteries, subclavian arteries, and brachiocephalic artery. Beginning with simple balloon angioplasty, these minimally invasive techniques have now progressed to the use of stent-supported angioplasty. Stent-supported angioplasty is currently providing a therapeutic alternative to traditional methods of open surgery for revascularization of these vessels and increasing the therapeutic options available for patients who have failed maximal medical therapy. Additionally, endovascular techniques are also being used successfully to treat a variety of nonatherosclerotic diseases affecting the noncarotid extacranial arteries, such as inflammatory, radiation, and anastomotic-graft strictures; acute intimal dissection; traumatic and spontaneous arteriovenous fistulas; and aneurysms or pseudoaneurysms. Continued innovation and refinement of endovascular devices and techniques will inevitably improve technical success rates, reduce procedure-related complications, and broaden the endovascular therapeutic spectrum for extracranial cerebrovascular disease.

Patient presentation, angiographic features, and treatment of strangulation-induced bilateral dissection of the cervical internal carotid artery. Report of three cases

Domestic violence leading to strangulation by an abusive spouse can cause carotid artery dissection. This phenomenon is rare and has been described in only three previous instances. The authors present their management strategies in three additional cases. Three young women aged 24 to 43 years were victims of manual strangulation committed by their spouses 3 months to 1 year before presentation. Two of the patients suffered delayed cerebral infarctions before presentation and angiography demonstrated focal, mirror-image severe residual stenoses in the high-cervical internal carotid artery (ICA), which were characteristic of a healed chronic dissection; there was no evidence of fibromuscular dysplasia. One of these patients underwent unilateral percutaneous angioplasty with stent placement, and the other underwent bilateral percutaneous angioplasty. Both patients have recovered from their strokes and remain clinically stable at 8 and 20 months posttreatment, respectively. The third patient presented with bilateral ischemic frontal watershed infarctions resulting from an occluded left ICA and a severely narrowed right ICA. Given the extent of the established infarctions, this case was managed with a long-term regimen of anticoagulation medications, and the patient remains neurologically impaired. These cases illustrate the susceptibility of the manually compressed ICA to traumatic injury as a result of domestic violence. They identify bilateral symmetrical ICA dissection as a consistent finding and the real danger of delayed stroke as a consequence of strangulation. Endovascular therapy in which percutaneous angioplasty and/or stent placement are used can be useful in treating residual focal stenoses to improve cerebral perfusion and to lower the risk of embolic or ischemic stroke.

Endovascular treatment of ruptured posterior circulation cerebral aneurysms. Clinical and angiographic outcomes

BACKGROUND AND PURPOSE

We sought to describe the clinical outcome and angiographic results obtained in the endovascular therapy of ruptured posterior circulation cerebral aneurysms using Guglielmi detachable coils (GDC) over a 7-year period.

METHODS

A retrospective analysis was performed of 112 patients evaluated at the University of California at San Francisco Medical Center between June 1991 and August 1998. The Hunt-Hess grade at presentation of treated patients was I in 26 patients (24%), II in 24 (22%), III in 27 (25%), IV in 24 (22%), and V in 8 (7%). Clinical follow-up for the total population was achieved in 104 of 109 patients (96%), with a mean duration of 13.1 months. Angiographic follow-up for the subset excluding parent vessel occlusion cases was obtained in 93% of cases, with a mean duration of 7.2 months.

RESULTS

Technical success, defined as the ability to catheterize and embolize the aneurysm with GDC, was achieved in 109 of 112 of cases (97%). The mean angiographic occlusion rate, or projected area of the aneurysm occluded by the coils, for all 110 successfully treated aneurysms was 94.6%. At latest clinical follow-up, 81 of 109 patients (74%) achieved good recovery with Glasgow Outcome Scale (GOS) score of I, 10 of 109 (9%) were moderately (GOS II) and 5 of 109 (5%) were severely (GOS III) disabled, 1 of 109 (1%) remained in a vegetative state (GOS IV), and 12 of 109 (11%) were dead. Of the subset of 77 patients with Hunt-Hess grades I to III, 68 (88%) achieved a good clinical outcome (GOS I). A statistically significant correlation was demonstrated between Hunt-Hess grade at presentation and final GOS outcome score (chi(2)=41.4, P<0.0005). Procedure-related permanent morbidity was 2.8% (3/109 patients). Repeated hemorrhage was observed in a single patient (0.9%) with a partially treated aneurysm.

CONCLUSIONS

The observed favorable outcome and low morbidity in this group of high-risk patients point to GDC embolization as an effective method for the endovascular management of patients with ruptured posterior circulation aneurysms.

Subclavian arteritis and pseudoaneurysm formation secondary to stent infection

Technically uncomplicated percutaneous angioplasty and stent placement of a left subclavian artery stenosis was performed in a 56-year-old man for treatment of subclavian steal syndrome and vertebrobasilar insufficiency. Six days later the patient was readmitted with Staphylococcus aureus bacteremia and stigmata of septic emboli isolated to the ipsilateral hand. Nine days later he had computed tomography (CT) evidence of a contrast-enhancing phlegmon surrounding the stent. Despite clinical improvement and resolution of bacteremia on intravenous antibiotic therapy, the phlegmon progressed, and at day 21 a pseudoaneurysm was angiographically confirmed. The patient underwent surgical removal of the stented arterial segment and successful autogenous arterial reconstruction. The possible contributory factors leading to stent infection were prolonged right femoral artery access and an infected left arm venous access. Although the role of prophylactic antibiotics remains to be defined, it may be important in cases where the vascular access sheath remains in place for a prolonged period of time.

Treatment of dural arteriovenous malformations and fistulas

Dural arteriovenous fistulas (DAVFs) or malformations consist of pathological vascular channels located within the substance of the dura mater and usually involve the walls of a dural sinus or adjacent cortical vein. DAVFs can affect a variety of cerebral venous structures and can present at various clinical stages. Although some fistulas can spontaneously thrombose, the clinical course usually involves progression from venous sinus pressurization to occlusion and retrograde cortical venous drainage. The spectrum of clinical presentation ranges from an irritating pulse-synchronous bruit to a disabling neurologic ischemic deficit or life-threatening intracranial hemorrhage from venous hypertension. The authors present their clinical experience in the radiographic diagnosis and endovascular treatment of these potentially dangerous lesions.

Carotid artery cavernous fistulas

The treatment of carotid cavernous fistulas has undergone a fundamental transformation during the preceding 30 years. Endovascular techniques have not only largely replaced surgical management of this disease, but have also resulted in substantially lower rates of procedure-associated morbidity and mortality. Percutaneous transarterial occlusion of direct cavernous carotid fistulas with preservation of the carotid artery using detachable balloons is now considered the current preferred therapeutic objective. Concurrent progress in percutaneous transvenous embolization techniques and materials has led to more effective and better-tailored therapies for indirect (dural) carotid cavernous fistulas. The current understanding of the clinicopathologic mechanisms associated with carotid cavernous fistulas and the endovascular therapies used in the contemporary management of this condition are reviewed.

Hemodynamic shear stress and its role in atherosclerosis

Atherosclerosis, the leading cause of death in the developed world and nearly the leading cause in the developing world, is associated with systemic risk factors including hypertension, smoking, hyperlipidemia, and diabetes mellitus, among others. Nonetheless, atherosclerosis remains a geometrically focal disease, preferentially affecting the outer edges of vessel bifurcations. In these predisposed areas, hemodynamic shear stress, the frictional force acting on the endothelial cell surface as a result of blood flow, is weaker than in protected regions. Studies have identified hemodynamic shear stress as an important determinant of endothelial function and phenotype. Arterial-level shear stress (>15 dyne/cm2) induces endothelial quiescence and an atheroprotective gene expression profile, while low shear stress (<4 dyne/cm2), which is prevalent at atherosclerosis-prone sites, stimulates an atherogenic phenotype. The functional regulation of the endothelium by local hemodynamic shear stress provides a model for understanding the focal propensity of atherosclerosis in the setting of systemic factors and may help guide future therapeutic strategies.

Embolization of non-ruptured aneurysms

Options for treatment of intracranial aneurysms have expanded with the advent of the Guglielmi Detachable Coil (GDC) eight years ago. We have reviewed 435 cases of intracranial aneurysms treated at UCSF by endovascular means using the GDC system. Of these, 55% represent anterior circulation aneurysms, and 45% are located in the posterior circulation. Additionally, 55% of the aneurysms presented with subarachnoid hemorrhage (SAH) and 45% were unruptured. Factors which hindered optimal coiling include the following: wide aneurysm neck in relation to the overall aneurysm size, mural thrombus, giant aneurysm, arteries originating from the aneurysm sac, and middle cerebral location. After initial experience was gained, we tended to avoid these aneurysms especially in the non-ruptured group. This may be especially important in light of new epidemiological data suggesting that the natural history of unruptured aneurysms is significantly lower than previously thought. New technical developments which may reduce the risk of treating unruptured aneurysms include the two-dimensional coil, the three-dimensional coil, the balloon-assist technique for wide-necked aneurysms, and combined stent-coil procedures.

Acquired pial arteriovenous fistula following cerebral vein thrombosis

BACKGROUND

We report a unique case of an acquired pial arteriovenous fistula occurring after an asymptomatic thrombosis of a superficial cerebral vein.

CASE DESCRIPTION

A cerebral angiogram performed in a 51-year-old man with subarachnoid hemorrhage revealed a 10-mm ruptured anterior communicating artery aneurysm and a thrombosed left superficial middle cerebral vein. Coil embolization of the anterior communicating aneurysm was performed. Follow-up angiography 18 months later revealed a new, asymptomatic, pial arteriovenous fistula between the previously thrombosed left superficial middle cerebral vein and a small sylvian branch of the left middle cerebral artery.

CONCLUSIONS

This case provides evidence that pial arteriovenous fistulas may develop as acquired lesions and furthermore may rarely follow cerebral vein thrombosis. Several cases of dural arteriovenous fistulas, as well as a single case of a mixed pial-dural arteriovenous fistula, occurring after dural sinus thrombosis have been reported previously. However, to our knowledge, this is the first report of an acquired pial arteriovenous fistula following a cerebral vein thrombosis.

Clinical use of stents for carotid artery disease

Over the last 5 years, the clinical use of intravascular stents for treatment of carotid artery pathology has become more prevalent and the spectrum of potential indications has widened. Endovascular stenting is providing an alternative to surgical endarterectomy for treatment of cervical carotid artery atherosclerotic disease. This has prompted a North American, randomized, controlled clinical trial directly comparing these two therapies. In this article we review the major surgical endarterectomy trials that currently provide the scientific rationale for revascularization of carotid artery occlusive disease, critically evaluate the evidence supporting the application of endovascular stenting procedures for the treatment of occlusive and nonocclusive disease of the extracranial and intracranial carotid artery, consider the current clinical indications for use of stents in the carotid artery, and discuss current equipment, technique, and potential procedure-related complications.

Treatment of posterior circulation ischemia with extracranial percutaneous balloon angioplasty and stent placement

BACKGROUND AND PURPOSE

Vertebrobasilar territory ischemia (VBI) leads to disabling neurological symptoms and poses a risk for stroke by an embolic or flow-related mechanism. We present our clinical experience in the endovascular treatment of patients with symptomatic VBI from severe atherosclerosis or dissection of the vertebral and subclavian arteries that was unresponsive to medical therapy.

METHODS

Twenty-one patients (9 female, 12 male) with a mean age of 65.7 years (range 47 to 81 years) underwent treatment with percutaneous endovascular balloon angioplasty and stent placement. Sixteen patients (76.2%) had evidence of contralateral involvement, and 9 (42.8%) demonstrated severe anterior-circulation atherosclerosis. Nine patients had a previous infarct in the occipital lobe, cerebellum, or pons before treatment. Follow-up was available for all patients.

RESULTS

Balloon angioplasty with intravascular stent placement was performed in 13 vertebral artery lesions (10 at the origin, 3 in the cervical segment) and in 8 subclavian lesions. The prestenting stenosis was 75% (50% to 100%) and was reduced to 4.5% (0% to 20%) after stenting. Six of the patients with proximal subclavian stenosis demonstrated angiographic evidence of subclavian steal, which resolved in all cases after treatment. All patients showed improvement in symptoms after the procedure except for 1 who developed a hemispheric stroke after thrombotic occlusion of an untreated cavernous carotid artery stenosis (rate of major stroke and mortality=4.8%). One patient (4.8%) had a periprocedural transient ischemic attack (TIA), and none had minor stroke. At long-term follow-up (mean=20.7+/-3.6 months) of the surviving 20 patients, 12 (57.1%) remained symptom-free, 4 (19%) had at most 1 TIA over a 3-month period, 2 (9.5%) had at most 1 TIA per month, and 2 (9.5%) had persistent symptoms. There were no clinically evident infarcts during the follow-up period.

CONCLUSIONS

Endovascular treatment using balloon angioplasty with intravascular stent placement for symptomatic stenotic lesions resulting in VBI that is unresponsive to medical therapy appears to be of benefit in this high-risk subset of patients with poor collateral flow.

Tandem intracranial stent deployment for treatment of an iatrogenic, flow-limiting, basilar artery dissection: technical case report

OBJECTIVE AND IMPORTANCE

Intimal dissection constitutes one of the complications associated with angioplasty of intracranial vessels. We present a case of iatrogenic dissection of the entire basilar artery, which was induced by angioplasty and stenting of symptomatic, focal, intracranial vertebral artery stenosis, and its successful treatment with tandem deployment of a downstream stent.

CLINICAL PRESENTATION

A 61-year-old, hypertensive, renal transplant recipient presented with orthostatic vertebrobasilar insufficiency that was refractory to medical management, including anticoagulation therapy. Angiography revealed an occluded right vertebral artery and focal, high-grade, left intracranial vertebral artery stenosis. Magnetic resonance imaging showed multiple posterior fossa infarctions. The left intracranial vertebral artery stenosis was successfully treated with primary stent deployment and balloon angioplasty, with symptom resolution. On postprocedure Day 2, the patient noted worsening right hemiparesis.

INTERVENTION

Subsequent angiography revealed a flow-limiting, windsock-type, basilar artery dissection beginning at the distal end of the left vertebral artery stent and extending to the origin of the left posterior cerebral artery. A tandem stent was navigated intracranially and deployed past the first one, successfully sealing the dissection inflow zone and reconstituting normal flow to the top of the basilar artery. A clinical follow-up examination at 3 months revealed no further orthostatic symptoms and only mild residual right-sided weakness.

CONCLUSION

This is the first description of iatrogenic stent-induced dissection of the entire basilar artery that was successfully treated by inflow zone control via tandem intracranial stent deployment.

Modulation by pathophysiological stimuli of the shear stress-induced up-regulation of endothelial nitric oxide synthase expression in endothelial cells

OBJECTIVE

Fluid shear stress (the frictional force resulting from blood flow) is a principal regulator of endothelial nitric oxide synthase (eNOS) expression. We examined the responses of eNOS messenger ribonucleic acid (mRNA) levels to dynamic shear stimuli in the presence of pathological risk modifiers.

METHODS

Confluent bovine aortic endothelial cells were subjected in vitro to shear stress (using a cone-plate viscometer) and to hydrostatic pressure (using a custom-built pressure chamber device). eNOS mRNA levels were quantitated by densitometric analysis of Northern blots.

RESULTS

In contrast to steady laminar shear stress, which elevated eNOS mRNA levels in a time- and dose-dependent manner (2.9- and 3.6-fold after 6 h at 4 and 20 dyn/cm2, respectively), steady hydrostatic pressure of 150 mm Hg decreased eNOS mRNA levels by 46%. eNOS mRNA up-regulation by shear stress was reversible after cessation of flow, although it was not influenced by previous shear exposure, and it was not mediated by a stable transferable factor. eNOS mRNA up-regulation by sinusoidal shear stress was frequency-dependent, with a moderate response at 1-Hz oscillating shear and no change at 0.3 Hz. Hypoxia (3% O2) suppressed eNOS mRNA expression by 78% under static conditions and by 72% under shear conditions but did not alter the fold induction by shear. Elevated glucose concentrations reduced eNOS mRNA levels in both resting and shear stress-exposed cells but did not reduce the fold induction by shear; the protein kinase C inhibitor calphostin C was without effect. Shear-induced up-regulation of eNOS mRNA was unaffected by changes in the medium partial pressure of CO2/pH, by the Na+/H+-exchanger inhibitor HOE694, or by aspirin. In contrast, the shear response was potentiated by homocysteine.

CONCLUSION

Both physical and chemical stimuli regulate eNOS mRNA levels in endothelial cells. Although eNOS mRNA expression is increased by shear stress, it is decreased by hydrostatic pressure, hypoxia, and elevated glucose levels. The effect of shear on eNOS mRNA expression involves a reversible, frequency-dependent process. These in vitro findings suggest possible contributions of the eNOS flow response to atherosclerosis, in the presence of systemic risk factors.

Intraventricular contrast medium leakage during ethanol embolization of an arteriovenous malformation

We report the unusual phenomenon of abrupt intraventricular contrast medium leakage from the choroid plexus occurring during ethanol embolization of a periventricular arteriovenous malformation. There was no evidence of any associated intraventricular hemorrhage to suggest that leakage arose from a vessel perforation, as was first suspected. Intraventricular contrast medium leakage has been reported previously in the setting of ependymitis, and it is likely that similar pathogenetic mechanisms apply in this case. To our knowledge, this is the first reported case of intraventricular contrast medium leakage occurring during an embolization procedure.

Embolization of the meningohypophyseal trunk as a cause of diabetes insipidus

We present an unusual case of diabetes insipidus occurring after selective embolization of 50% dextrose and pure ethanol into an enlarged left meningohypophyseal trunk (MHT) supplying a dural carotid cavernous fistula. The inferior hypophyseal artery was not opacified during the selective preembolization MHT injection; however, diabetes insipidus developed abruptly a few hours after the procedure. The patient required intranasal 1-deamino-(8-D-arginine)-vasopressin for approximately 3 months, after which his symptoms resolved. The hazards of using liquid embolic agents, especially ethanol, in the cavernous branches of the internal carotid artery should always be borne in mind.

Simultaneous subarachnoid hemorrhage and carotid cavernous fistula after rupture of a paraclinoid aneurysm during balloon-assisted coil embolization

We describe an iatrogenic perforation of a paraclinoid aneurysm during balloon-assisted coil embolization that resulted in simultaneous subarachnoid contrast extravasation and a carotid cavernous fistula. The causative factors specifically related to the balloon-assisted method that led to aneurysm rupture are discussed as well as strategies for dealing with this complication.

Treatment of an intracranial aneurysm using a new three-dimensional-shape Guglielmi detachable coil: technical case report

OBJECTIVE AND IMPORTANCE

Coil embolization of wide-necked aneurysms is currently difficult, when using a conventional endovascular approach without resorting to complex adjunctive techniques.

CLINICAL PRESENTATION

A 41-year-old woman with a history of systemic lupus erythematosus and hypertension refractory to treatment presented with an unruptured right ophthalmic segment aneurysm of the internal carotid artery having an unfavorable neck-to-fundus ratio.

INTERVENTION

A new type of Guglielmi detachable coil (Target Therapeutics, Fremont, CA), consisting of a series of omega loops, spontaneously forms a three-dimensional cage after deployment and was used to successfully treat the aneurysm, which was angiographically stable at the 3-month follow-up.

CONCLUSION

The new Guglielmi detachable coil may be useful in the embolization of aneurysms having an unfavorable geometry, which would otherwise not be amenable to endovascular treatment without adjunctive techniques.

Detection of vertebral artery injury after cervical spine trauma using magnetic resonance angiography

BACKGROUND

We prospectively describe the incidence, magnetic resonance-based diagnosis, and treatment of vertebral artery (VA) injury resulting from closed cervical spine trauma.

METHODS

Patients with fracture or dislocation on plain radiographic studies underwent computed tomography. Among these patients, the subset with computed tomographic evidence of foramen transversarium (FT) fracture underwent magnetic resonance angiography as early as possible.

RESULTS

During a 16-month period, 38 patients with closed cervical trauma were treated. Twelve patients demonstrated fracture extension through at least one FT by computed tomography. Among these patients, four showed unilateral VA injury by magnetic resonance angiography, all ipsilateral to the fractured FT. Three cases of VA occlusion and one of focal narrowing were demonstrated. All four patients were initially treated with aspirin, and two were systemically anticoagulated. None developed irreversible neurologic deficits from the VA compromise.

CONCLUSION

Our data suggest that the incidence of VA injury in closed cervical spine trauma is significant and that FT fractures warrant flow-sensitive magnetic resonance imaging.

Application of a rheolytic thrombectomy device in the treatment of dural sinus thrombosis: a new technique

We present a novel application of a transvascular rheolytic thrombectomy system in the treatment of symptomatic dural sinus thrombosis in a 54-year-old woman with somnolence and left-sided weakness. The diagnosis of bilateral transverse and superior sagittal sinus thrombosis was made and the patient was treated with anticoagulant therapy. After an initial period of improvement, she became comatose and hemiplegic 8 days after presentation. After excluding intracerebral hemorrhage by MR imaging, we performed angiography and transfemoral venous thrombolysis with a hydrodynamic thrombectomy catheter, followed by intrasinus urokinase thrombolytic therapy over the course of 2 days. This technique resulted in dramatic sinus thrombolysis and near total neurologic recovery. Six months after treatment, the patient showed mild cognitive impairment and no focal neurologic deficit. Our preliminary experience suggests that this technique may play a significant role in the endovascular treatment of this potentially devastating disease.

Endovascular recanalization with balloon angioplasty and stenting of an occluded occipital sinus for treatment of intracranial venous hypertension: technical case report

OBJECTIVE AND IMPORTANCE

Dural sinus thrombosis can lead to intracranial venous hypertension and can be complicated by intracranial hemorrhage. We present a case report of a patient who underwent endovascular recanalization and stenting of a thrombosed occipital sinus.

CLINICAL PRESENTATION

A 13-year-old patient with a history of chronic sinus thrombosis refractory to anticoagulant therapy presented with acute onset of aphasia and hemiparesis. Computed tomography and magnetic resonance imaging revealed hydrocephalus and cerebral edema. Angiography delineated multiple dural arteriovenous fistulae and persistent occlusion of the posterior sagittal, occipital, and bilateral transverse dural sinuses with retrograde cortical venous drainage.

INTERVENTION

After embolization of the dural arteriovenous fistulae, a transvenous approach was used to recanalize and perform balloon angioplasty of the right internal jugular vein and the occipital and left transverse sinuses, resulting in subsequent clinical improvement. The patient's condition deteriorated 3 days later with reocclusion of both balloon-dilated sinuses. Repeat angioplasty and then deployment of an endovascular stent in the occipital sinus were performed, and reestablishment of venous outflow was achieved, resulting in a decrease of intracranial venous pressure from 41 to 14 mm Hg and neurological improvement. At the 3-month follow-up examination, the stented occipital sinus remained patent and served as the only conduit for extracranial venous outflow; the patient remained neurologically intact at the 12-month follow-up examination.

CONCLUSION

This is the first report of mechanical recanalization, balloon angioplasty, and stent deployment in the occipital sinus to provide sustained venous outflow for the treatment of venous hypertension with retrograde cortical venous drainage in a patient with dural pansinus thrombosis refractory to anticoagulant therapy.

Spinal dural arteriovenous fistula with an associated feeding artery aneurysm: case report

OBJECTIVE AND IMPORTANCE

A case of a spinal dural arteriovenous fistula (DAVF) with two associated feeding artery aneurysms is reported. Intradural spinal arteriovenous malformations have been associated with aneurysms that present with subarachnoid hemorrhage and with venous varices that produce mass effect, but spinal DAVFs have not previously been described in association with feeding artery aneurysms.

CLINICAL PRESENTATION

A 71-year-old man presented with progressive spastic paraparesis, constipation, and overflow incontinence. Magnetic resonance imaging demonstrated a spinal vascular lesion and venous ischemia in the lower spinal cord. Diagnostic spinal angiography revealed a DAVF originating from the left T11 radicular artery and having the unusual feature of two proximal feeding artery aneurysms.

INTERVENTION

The patient deteriorated neurologically after undergoing angiography, prompting emergent surgery. The DAVF was resected through a T11 transpedicular approach. One aneurysm was dolichoectatic and therefore unclippable, requiring proximal occlusion of the parent artery after establishing tolerance of test occlusion using somatosensory evoked potentials; the second aneurysm was adjacent to the fistula and was resected with the DAVF.

CONCLUSION

Feeding artery aneurysms in association with spinal DAVFs have not been previously reported. They present additional risk to patients and, with simple modifications of the standard operative approaches, can easily be treated as part of the surgery for the DAVF.

Endovascular stenting of an acutely thrombosed basilar artery: technical case report and review of the literature

OBJECTIVE AND IMPORTANCE

The goal of this report was to describe the successful percutaneous endovascular use of a Gianturco-Roubin-2 coronary stent in the treatment of an acute atherothrombotic occlusion of the basilar artery. To our knowledge, the percutaneous endovascular deployment of an intra-arterial stent for the treatment of an acute atherothrombotic occlusion of the basilar artery and the percutaneous endovascular placement of a Gianturco-Roubin-2 stent in the basilar artery have not been previously reported.

CLINICAL PRESENTATION

An 83-year-old man presented with a recurrent, transient, locked-in syndrome resulting from a lower basilar artery occlusion caused by vertebrobasilar thrombosis superimposed on severe proximal basilar artery atheromatous stenosis.

INTERVENTION

After successful superselective intra-arterial thrombolysis of the vertebrobasilar clot, balloon angioplasty of the underlying basilar artery stenosis was performed, without significant angiographic improvement. Percutaneous endovascular deployment of a Gianturco-Roubin-2 coronary stent of 4-mm diameter was subsequently performed, with excellent angiographic results.

CONCLUSION

The patient made a very good neurological recovery but unfortunately died as a result of cardiogenic shock and sepsis. Detailed neuropathological follow-up results are presented; stent patency was revealed in the postmortem examination. The anatomic and pathophysiological considerations of basilar artery stent placement for the treatment of acute basilar artery occlusion related to atherosclerotic stenosis are discussed.

Endothelin-1 gene suppression by shear stress: pharmacological evaluation of the role of tyrosine kinase, intracellular calcium, cytoskeleton, and mechanosensitive channels

Physiological fluid shear stress regulates endothelin-1 (ET-1) gene expression in endothelial cells by inducing an early transient upregulation followed by a sustained suppression, at times greater than 2 h in duration. We evaluated the mechanism of ET-1 mRNA downregulation in confluent monolayers of bovine aortic endothelial (BAE) cells by applying a 6 h steady laminar shear stress of magnitude 20 dyn/cm2. Inhibition of tyrosine kinases using herbimycin A (875 nM) abolished the shear-induced decrease in ET-1 mRNA expression. Similarly, chelation of intracellular calcium ([Ca2+]i) with quin 2-AM (10 microM) blocked the suppression of ET-1 mRNA by shear. To examine the role of the endothelial cytoskeleton in the response to flow, cytochalasin D was used to disrupt F-actin microfilaments. This treatment induced cell retraction and detachment under flow, whereas stabilization of F-actin with phalloidin (1 microM) did not affect shear-induced ET-1 downregulation. In contrast, disruption of the microtubule network with nocodazole (10 micrograms/ml) completely prevented, while microtubule stabilization with taxol (10 microM) did not affect the suppression of ET-1 mRNA by flow. To determine the possible contributions of mechanosensitive channels, barium (1 mM BaCl2), was added to confluent BAE monolayers in a low-sulfate/low-phosphate modified medium and was noted to abrogate the downregulation of ET-1 gene expression and to attenuate the shear-induced increase in cytoplasmic free calcium concentration. Tetraethylammonium (3 mM TEA) partially inhibited the suppression of ET-1 mRNA by shear; in contrast, gadolinium (10 microM GdCl3), an inhibitor of the stretch-activated cation channel ISA, had no effect. Membrane depolarization by elevated extracellular potassium ([K+]o) also attenuated the suppression of ET-1 mRNA by flow at [K+]o = 70 mM and completely inhibited it at [K+]o = 135 mM. In summary, the steady-state downregulation of ET-1 mRNA by physiological levels of fluid shear stress shares signaling features with the morphological and cytoskeletal response to shear stress. These include requirement for intracellular calcium, tyrosine kinase activity, an intact microtubule network, and independence from a Gd(3+)-sensitive ISA. Unlike shear-induced changes in cell morphology and the actin cytoskeleton, the shear-induced decrease in ET-1 mRNA level is blocked by cell depolarization and by Ba2+, a blocker of the shear-activated IKS which also decreases shear-induced cytoplasmic calcium increase.

Induction of nitric oxide synthase mRNA by shear stress requires intracellular calcium and G-protein signals and is modulated by PI 3 kinase

We have investigated the signaling pathways by which shear stress induces accumulation of endothelial nitric oxide synthase (eNOS) mRNA in bovine aortic endothelial cells (BAEC). Steady laminar fluid shear stress (20 dyn/cm2) induced a time-dependent increase in eNOS mRNA levels that did not require de novo protein synthesis and was in part transcriptional. Shear responsiveness was conferred on a luciferase reporter by a portion of the eNOS gene promoter encoding the 5'-flanking region between nt -1600 and -779. Shear-mediated induction of eNOS mRNA was abolished by chelation of intracellular calcium ([Ca2+]i) with BAPTA-AM, and inhibited by blockade of calcium entry with SKF96535. In contrast, eNOS mRNA upregulation by shear was potentiated by thapsigargin-mediated depletion of Ca2+i stores. Pertussis toxin (PTX) inhibited both the shear-induced elevation in [Ca2+]i and the subsequent increase in eNOS mRNA, implicating a PTX-sensitive G-protein in both responses. Shear-induced upregulation of eNOS mRNA was unaffected by the calmodulin inhibitor W-7 and by the tyrosine kinase inhibitor herbimycin A, suggesting that neither calmodulin nor tyrosine kinases are required. However, eNOS mRNA upregulation was potentiated by the PI 3-kinase inhibitors wortmannin and LY294002, suggesting that PI 3-kinase inhibits the shear response. Although microtubule integrity is required for the shear-induced regulation of endothelin-1 mRNA and the morphological and cytoskeletal responses to flow, neither microtubule dissolution with nocodazole nor microtubule stabilization with taxol altered shear-induced [Ca2+]i elevation or upregulation of eNOS mRNA. In conclusion, shear stress of BAEC increases eNOS transcriptional rate and upregulates eNOS mRNA levels by a process that requires calmodulin-independent [Ca2+]i signaling and a PTX-sensitive G-protein, is inhibited by PI 3-kinase, and is independent of microtubule integrity and tyrosine kinase activity.

Mannitol at clinical concentrations activates multiple signaling pathways and induces apoptosis in endothelial cells

BACKGROUND AND PURPOSE

Hyperosmotic mannitol therapy is widely used in the clinical setting for acute and subacute reduction in brain edema, to decrease muscle damage in compartment syndrome, and to improve renal perfusion. Though beneficial rheological effects commonly are attributed to mannitol, its direct effects on endothelial cells are poorly understood.

METHODS

We studied the effect of hypertonic and hypotonic stress on bovine aortic endothelial (BAE) cells, using mannitol, urea, and sodium chloride and medium dilution in vitro.

RESULTS

Exposure to incremental osmolar concentrations of 300 mOsm of each osmotic agent increased apoptosis in BAE cells (mannitol congruent withNaCl>urea). Induced programmed cell death was detected by DAPI staining of intact cell nuclei, and by TUNEL and DNA fragmentation ladder assays. Mannitol-induced apoptosis exhibited dose dependence (42% of cells at 300 mOsm [P<0.0001] compared with 1.2% of control cells) and was also observed in bovine smooth muscle cells. Mannitol-induced apoptosis was attenuated approximately 50% in the presence of cycloheximide or actinomycin D. Hypertonic mannitol and NaCl, but not urea, increased tyrosine phosphorylation of the focal adhesion contact-associated proteins paxillin and FAK. Hypotonic medium, which did not lead to apoptosis, increased protein tyrosine phosphorylation of FAK but not of paxillin. Addition of mannitol or NaCl also produced sustained increases in c-Jun NH2-terminal kinase (JNK) activity. In addition, hypertonic mannitol increased intracellular free [Ca2+] in a dose-dependent manner. Chelation of intracellular Ca2+ with quin2-AM (10 micromol/L) inhibited mannitol-induced apoptosis approximately 50%, as to a lesser extent did inhibition of tyrosine kinase activity with herbimycin (1 micromol/L).

CONCLUSIONS

We have shown that hypertonic mannitol exposure induces endothelial cell apoptosis, accompanied by activation of tyrosine and stress kinases, phosphorylation of FAK and paxillin, and elevation of intracellular free [Ca2+]. The apoptosis is attenuated by inhibition of transcription or translation, by inhibition of tyrosine kinases, or by intracellular Ca2+ buffering. These data suggest that clinical use of the osmotic diuretic mannitol may exert direct deleterious effects on vascular endothelium.

Diagnosis and treatment of dural arteriovenous fistulas

Dural arteriovenous fistulas (DAVFs) are abnormal vascular connections located within the dura mater which are thought to be promoted by venous hypertension and venous sinus thrombosis. The symptoms associated with DAVFs depend on the direction and adequacy of venous drainage pathways, the amount of arteriovenous shunting and specific location of the fistula. Our experience over a period of eight years with 268 patients suffering from cranial DAVFs in the transverse, sigmoid, superior sagittal, ethmoidal, inferior and superior petrosal, cavernous, and marginal sinuses are presented. The clinical presentation, radiographic evaluation, and treatment modalities for DAVFs in each of these locations are summarized.

Regulation of endothelin-1 gene expression by cell shape and the microfilament network in vascular endothelium

Endothelial synthesis and release of endothelin-1 (ET-1) are exquisitely regulated by external shear and strain. We tested the hypothesis that manipulation of endothelial cell shape can regulate ET-1 gene expression. Treatment of bovine aortic endothelial cell (BAEC) monolayers with cytochalasin D disrupted F-actin and induced cell retraction and rounding, in parallel with time- and dose-dependent specific decreases in ET-1 mRNA levels. Treatments with forskolin, phorbol 12-myristate 13-acetate, staurosporine, and genistein also induced cell shape change and decreased F-actin staining and ET-1 mRNA levels. BAEC plated onto nonadhesive petri dishes coated with decreasing concentrations of synthetic RGD polymer showed RGD dose-dependent decreases in cell spreading and in F-actin microfilament elaboration. These changes were specifically accompanied by decreases in ET-1 peptide secretion (60%) and, via posttranscriptional mechanisms, ET-1 mRNA (94%) and were not due to decreased cell-cell contact. We conclude that the shape and microfilament network of endothelial cells are potent posttranscriptional regulators of ET-1 gene expression.

Elevation of cerebrospinal fluid levels of basic fibroblast growth factor in moyamoya and central nervous system disorders

Moyamoya syndrome is a vaso-occlusive disease involving the intracranial vessels of the circle of Willis which is accompanied by an intense compensatory recruitment of new vessels. Angiogenic substances such as basic fibroblast growth factor (bFGF) present in the cerebrospinal fluid (CSF) have been proposed as possible mediators of the neovascular response. We analyzed CSF samples collected intraoperatively from predominantly pediatric patients with moyamoya and other conditions such as Chiari malformation (Ch), tethered cord (TC), arteriovenous malformation (AVM), brain tumor (BT) and hydrocephalus (HCP). We found that CSF bFGF was significantly elevated in patients with moyamoya (141 pg/ml, n = 37), Ch (56.7 pg/ml, n = 22), TC (55.1 pg/ml, n = 23), AVM (354 pg/ml, n = 5), and BT (208 pg/ml, n = 5) compared to patients with HCP (5.5 pg/ml, n = 7) and controls (1.6 pg/ml, n = 25; p < 0.05). There was no dependence of CSF bFGF on patient age or gender. Although CSF bFGF in the moyamoya group showed no correlation with the Suzuki radiographic stage at either pre- or post-operative (1-year follow-up) angiography, it showed a trend with the Matsushima angiographic score with increasing collateral vascularization from the synangiosis developing at higher levels of CSF bFGF. Our findings suggest that CSF bFGF may be playing a wide-ranging role in a number of central nervous system conditions associated with ischemia and hypervascularity. Although not a specific marker for moyamoya, elevated CSF bFGF may serve as a weak predictor of the extent of angiogenesis to be expected in indirect revascularization procedures.