Effect of Guglielmi detachable coils on experimental carotid artery aneurysms in primates

Therapeutic Potential of Heme Oxygenase-1 in Aneurysmal Diseases

Abdominal aortic aneurysm (AAA) and intracranial aneurysm (IA) are serious arterial diseases in the aorta and brain, respectively. AAA and IA are associated with old age in males and females, respectively, and if rupture occurs, they carry high morbidity and mortality. Aneurysmal subarachnoid hemorrhage (SAH) due to IA rupture has a high rate of complication and fatality. Despite these severe clinical outcomes, preventing or treating these devastating diseases remains an unmet medical need. Inflammation and oxidative stress are shared pathologies of these vascular diseases. Therefore, therapeutic strategies have focused on reducing inflammation and reactive oxygen species levels. Interestingly, in response to cellular stress, the inducible heme oxygenase-1 (HO-1) is highly upregulated and protects against tissue injury. HO-1 degrades the prooxidant heme and generates molecules with antioxidative and anti-inflammatory properties, resulting in decreased oxidative stress and inflammation. Therefore, increasing HO-1 activity is an attractive option for therapy. Several HO-1 inducers have been identified and tested in animal models for preventing or alleviating AAA, IA, and SAH. However, clinical trials have shown conflicting results. Further research and the development of highly selective HO-1 regulators may be needed to prevent the initiation and progression of AAA, IA, or SAH.

Preclinical extracranial aneurysm models for the study and treatment of brain aneurysms: A systematic review

Animal models make an important contribution to our basic understanding of the pathobiology of human brain aneurysms, are indispensable in testing novel treatment approaches, and are essential for training interventional neuroradiologists and neurosurgeons. Researchers are confronted with a broad diversity of models and techniques in various species. This systematic review aims to summarize and categorize extracranial aneurysm models and their characteristics, discuss advantages and disadvantages, and suggest the best use of each model. We searched the electronical Medline/PubMed database between 1950 and 2020 to identify main models and their refinements and technical modifications for creation of extracranial aneurysms. Each study included was assessed for aneurysm-specific characteristics, technical details of aneurysm creation, and histological findings. Among more than 4000 titles and abstracts screened, 473 studies underwent full-text analysis. From those, 68 different techniques/models in five different species were identified, analyzed in detail, and then grouped into one of the five main groups of experimental models as sidewall, terminal, stump, bifurcation, or complex aneurysm models. This systematic review provides a compact guide for investigators in selecting the most appropriate model from a range of techniques to best suit their experimental goals, practical considerations, and laboratory environment.

Erythropoietin Stimulates Endothelial Progenitor Cells to Induce Endothelialization in an Aneurysm Neck After Coil Embolization by Modulating Vascular Endothelial Growth Factor

: This study explored a new approach to enhance aneurysm (AN) neck endothelialization via erythropoietin (EPO)-induced endothelial progenitor cell (EPC) stimulation. Results suggest that EPO enhanced the endothelialization of a coiled embolization AN neck by stimulating EPCs via vascular endothelial growth factor modulation. Thus, the promotion of endothelialization with EPO provides an additional therapeutic option for preventing the recurrence of ANs. Endovascular coil embolization is an attractive therapy for cerebral ANs, but recurrence is a main problem affecting long-term outcomes. In this study, we explored a new approach to enhance AN neck endothelialization via EPO-induced EPC stimulation. Ninety adult male Sprague-Dawley rats were selected for an in vivo assay, and 60 of them underwent microsurgery to create a coiled embolization AN model. The animals were treated with EPO, and endothelial repair was assessed via flow cytometry, immunofluorescence, electronic microscopy, cytokine detection, and routine blood work. EPO improved the viability, migration, cytokine modulation, and gene expression of bone marrow-derived EPCs and the results showed that EPO increased the number of circulating EPCs and improved endothelialization compared with untreated rats (p < .05). EPO had no significant effect on the routine blood work parameters. In addition, the immunofluorescence analysis showed that the number of KDR(+) cells in the AN neck was elevated in the EPO-treated group (p < .05). Further study demonstrated that EPO promoted EPC viability and migration in vitro. The effects of EPO may be attributed to the modulation of vascular endothelial growth factor (VEGF). In particular, EPO enhanced the endothelialization of a coiled embolization AN neck by stimulating EPCs via VEGF modulation. Thus, the promotion of endothelialization with EPO provides an additional therapeutic option for preventing the recurrence of ANs.

SIGNIFICANCE

Erythropoietin (EPO) is involved in erythropoiesis and related conditions and is reported to enhance stem-cell mobilization from bone marrow while elevating stem-cell viability and function. In this study, EPO was also found to stimulate endothelial progenitor cells to induce the endothelialization of a coiled embolic aneurysm neck via vascular endothelial growth factor modulation. Endothelialization induction provides an additional therapeutic opportunity during vascular inner layer repair and remodeling. The results provide important information on the unique role EPO plays during vascular repair and remodeling.

Traumatic Carotid Artery Dissection and Pseudoaneurysm Treated with Endovascular Coils and Stent

Purpose:

To report a case of post-traumatic internal carotid artery dissection and pseudoaneurysm formation at the C-1 level successfully treated by a percutaneous endovascular technique.

Methods and Results:

A 20-year-old female presented 72 hours after a motor vehicle accident with incomplete occulosympathetic paresis (Horner's syndrome), carotidynia, and left-sided weakness. Arteriography confirmed the diagnosis of carotid dissection and an associated 1.5-cm × 2.5-cm pseudoaneurysm at the C-1 level. Neuroradiologists embolized the pseudoaneurysm with Guglielmi detachable coils and controlled the dissection with placement of a Wallstent.

Conclusions:

This report illustrates successful percutaneous endovascular treatment of a carotid dissection and pseudoaneurysm near the base of the skull.

Embolisation of Ruptured Cerebral Aneurysms with Interlocking Detachable Coils in Acute Stage

Twelve cases of ruptured cerebral aneurysm were treated in acute stage with interlocking detachable coils (IDC, Target Therapeutics, Fremont, California) and the outcome was assessed.

IDCs were placed intra-aneurysm for intra-aneurysmal occlusion, or intra-artery for proximal occlusion. Cases: age 36–84 (mean; 60) y.o., 11 females and 1male; 1, 5, 4 and 2 patients were categorised (Hunt and Hess) as grades 1, 2, 3 and 4 respectively. An intra-aneurysmal occlusion in ten cases and a proximal occlusion in two were performed on day 1–11 (mean 4).

On angiograms and CT findings, the ruptured point seemed to have occluded in all cases. The occlusion rate was 100% in five cases, 95% in two, 90% in three, 80% in one, and less than 50% in one.

There were two cases of technical complication, one a coil migration and the other an aneurysmal perforation with IDC.

Their Glasgow Outcome Scale six months after embolisation was graded as good recovery in four cases, moderately disabled state in two, severely disabled state in one, and dead in five. Follow-up angiograms taken four to six months after embolisation showed an intra-aneurysmal coil compaction in five cases. Two of these were treated by a second embolisation or by neck clipping followed by aneurysmal resection, but another two were observed without any treatment and the last one died of rebleeding. Histological examination of the resected embolised aneurysm revealed slight organization around coils but no endothelialisation over the aneurysmal orifice.

In our experience, coil embolisation with IDC for acute ruptured aneurysm is a promising means of preventing rerupture during subacute stage.

White-collar sign as a predictor of outcome after endovascular treatment for cerebral aneurysms

OBJECTIVE The white-collar sign (WCS) is known as a thick neointimal tissue formation at the aneurysm neck after endovascular coil embolization of cerebral aneurysms, which may prevent aneurysm recanalization. The purpose of this study was to evaluate factors involved in the appearance of WCS and to identify radiological and clinical outcomes of treated aneurysms with WCS. METHODS The study included 140 patients with 149 aneurysms in which it was possible to confirm the aneurysm neck between the aneurysm sac and parent artery by using conventional angiography. The WCS was defined as a radiolucent band at the aneurysm neck on the angiogram at 6 months after initial embolization. The radiological outcome was evaluated using MR angiography. RESULTS In 23 of 149 aneurysms (15.4%), a WCS appeared. The WCS-positive group had a significantly smaller neck size (3.3 ± 0.8 mm vs 4.2 ± 1.1 mm, p < 0.001) and smaller aneurysm size (4.3 ± 0.9 mm vs 6.0 ± 2.1 mm, p < 0.001) than the WCS-negative group. Multivariate analysis revealed that WCS appearance was associated with small neck size (OR 0.376, 95% CI 0.179-0.787; p = 0.009). In 106 of 149 aneurysms, the rate of complete occlusion was significantly higher in the WCS-positive group (18/18, 100%) than in the WCS-negative group (n = 54/88, 61.4%; p = 0.001) in the mean follow-up period of 31.0 ± 9.7 months (range 5-52 months). Neither major recanalization nor rupture of the aneurysm occurred in the WCS-positive group. CONCLUSIONS Appearance of the WCS was associated with complete occlusion and good clinical outcome after endovascular coil embolization. The WCS would help to determine the prognosis of cerebral aneurysms after endovascular treatment.

Rosuvastatin for enhancement of aneurysm neck endothelialization after coil embolization: promotion of endothelial progenitor cells in a rodent model

OBJECT

Coil embolization is a safe, efficient, and minimally invasive technique for the treatment of intracranial aneurysms. However, coil embolization is associated with a higher risk of recurrence than clip ligation. In this study, the authors explore a new approach through the promotion of endothelial progenitor cells (EPCs) to optimize endothelialization of the aneurysm neck and reduce the risk of recurrence.

METHODS

A coiled aneurysm model was created in 48 adult male Sprague-Dawley rats via microsurgery. Half of these animals were treated with rosuvastatin (20 mg/kg) in saline via gavage for 10, 20, or 30 days. The other half were administered saline without rosuvastatin. An additional 15 rats underwent “mock surgery” (identical anesthesia and saline gavage but no surgery). The endothelial repair process in the coiled aneurysms was evaluated via flow cytometry, im-munostaining, and electronic microscopy. The mock surgery group was used for comparison in flow cytometry studies. The effects of rosuvastatin on viability and functioning of Sprague-Dawley rat bone marrow-derived EPCs were also explored via MTT, migration, and tube formation assays.

RESULTS

The aneurysm neck repair score was significantly higher in the rosuvastatin-treated rats than in the untreated rats (p < 0.05). The circulating EPC count was increased and maintained at a higher level in rosuvastatin-treated rats compared with the aneurysm rats that did not receive rosuvastatin (p < 0.05). Immunostaining showed that the aneurysm neck endothelium was more integrated and the number of kinase insert domain receptor-positive cells was increased in the rosuvastatin-treated rats. Further study demonstrated that rosuvastatin promoted EPC proliferation, migration, and tube formation.

CONCLUSIONS

Rosuvastatin promoted endothelialization of the coiled aneurysm neck via induction of EPCs, suggesting that promoting endothelialization provides an additional therapeutic opportunity during vascular endothelium repair.

An update to the Raymond-Roy Occlusion Classification of intracranial aneurysms treated with coil embolization

BACKGROUND

The Raymond-Roy Occlusion Classification (RROC) is the standard for evaluating coiled aneurysms (Class I: complete obliteration; Class II: residual neck; Class III: residual aneurysm), but not all Class III aneurysms behave the same over time.

METHODS

This is a retrospective review of 370 patients with 390 intracranial aneurysms treated with coil embolization. A Modified Raymond-Roy Classification (MRRC), in which Class IIIa designates contrast within the coil interstices and Class IIIb contrast along the aneurysm wall, was applied retrospectively.

RESULTS

Class IIIa aneurysms were more likely to improve to Class I or II than Class IIIb aneurysms (83.34% vs 14.89%, p<0.001) and were also more likely than Class II to improve to Class I (52.78% vs 16.90%, p<0.001). Class IIIb aneurysms were more likely to remain incompletely occluded than Class IIIa aneurysms (85.11% vs 16.67%, p<0.001). Class IIIb aneurysms were larger with wider necks while Class IIIa aneurysms had higher packing density. Class IIIb aneurysms had a higher retreatment rate (33.87% vs 6.54%, p<0.001) and a trend toward higher subsequent rupture rate (3.23% vs 0.00%, p=0.068).

CONCLUSIONS

We propose the MRRC to further differentiate Class III aneurysms into those likely to progress to complete occlusion and those likely to remain incompletely occluded or to worsen. The MRRC has the potential to expand the definition of adequate coil embolization, possibly decrease procedural risk, and help endovascular neurosurgeons predict which patients need closer angiographic follow-up. These findings need to be validated in a prospective study with independent blinded angiographic grading.

Porcine brachial artery tortuosity for in vivo evaluation of neuroendovascular devices

We report a novel model of arterial tortuosity in the porcine brachial artery for testing of endovascular devices in the flexed forelimb position. This provides an ideal vascular territory for an in vivo assessment of guidewires, microcatheters, and endovascular implants because it closely mimics the challenging curvature at the carotid siphon.

Hemodynamics of cerebral aneurysms: computational analyses of aneurysm progress and treatment

The progression of a cerebral aneurysm involves degenerative arterial wall remodeling. Various hemodynamic parameters are suspected to be major mechanical factors related to the genesis and progression of vascular diseases. Flow alterations caused by the insertion of coils and stents for interventional aneurysm treatment may affect the aneurysm embolization process. Therefore, knowledge of hemodynamic parameters may provide physicians with an advanced understanding of aneurysm progression and rupture, as well as the effectiveness of endovascular treatments. Progress in medical imaging and information technology has enabled the prediction of flow fields in the patient-specific blood vessels using computational analysis. In this paper, recent computational hemodynamic studies on cerebral aneurysm initiation, progress, and rupture are reviewed. State-of-the-art computational aneurysmal flow analyses after coiling and stenting are also summarized. We expect the computational analysis of hemodynamics in cerebral aneurysms to provide valuable information for planning and follow-up decisions for treatment.

A comparison of experimental aneurysm occlusion determination by angiography, scanning electron microscopy, MICROFIL perfusion, and histology

In clinical practice, occlusion of embolized, intracerebral aneurysms is evaluated using angiography. Standard, two-dimensional digital subtract angiography (DSA) is unable to quantify irregular aneurysm remnants, and even three-dimensional rotational angiography cannot quantify the degree of occlusion. To better understand occlusion at the aneurysm neck, we compared angiographic results with MICROFIL perfusion, histology, and scanning electron microscopy (SEM) results in 20 elastase-induced saccular aneurysms in rabbits. Aneurysms were embolized with HydroCoil devices (n = 12) or platinum coils (n = 8). Aneurysm follow-up occurred at 2 (n = 10) and 6 (n = 10) weeks. Aneurysm occlusion was evaluated using DSA, MICROFIL perfusion, histological ground sections, and SEM. Groups were compared statistically using ANOVA and chi(2) tests. The MICROFIL perfusion results were not concordant with the angiographic results for the HydroCoil and platinum coil groups. Both increased and decreased occlusion was observed on the MICROFIL-perfused aneurysms when compared with angiography. The histologic occlusion results of the HydroCoil group were concordant with the angiographic results; however, unoccluded areas not visible on angiography were routinely observed on the ground sections in the platinum coil group. SEM imaging of the aneurysm neck consistently showed decreased occlusion than angiographic results for both the HydroCoil and platinum coil groups. Although histology and MICROFIL-perfusion analyses provided additional details of aneurysm occlusion when compared with angiography, complete visualization of the entire neck of the aneurysm and accurate assessment of aneurysm occlusion was possible only with SEM.

In vivo experimental intracranial aneurysm models: a systematic review

Animal models are necessary to develop and test innovations in aneurysm therapy before clinical introduction. This review aims at identifying the most likely candidates for standardizing preclinical testing of aneurysm devices. We systematically searched electronic databases for publications on animal aneurysm models from 1961-2008 to assess the methodologic quality of the studies and collect data on the patency and angiographic and pathologic outcomes of treatments. There has been a steady increase in the annual number of publications with time. Species that were most frequently used were dogs, rabbits, and rodents, followed by swine. Most publications are single-laboratory studies with variables and poorly validated outcome measures, a small number of subjects, and limited standardization of techniques. The most appropriate models to test for recurrences after endovascular occlusion were the surgical bifurcation model in dogs, and the elastase-induced aneurysm model in rabbits. A standardized multicenter study is needed to improve the preclinical evaluation of endovascular devices in aneurysm therapy.

Surgical construction of a novel simulated carotid siphon in dogs

Object

The development and preclinical assessment of new endovascular devices necessitate readily available and reproducible animal models. The purpose of this study was to develop an in vivo carotid siphon model for testing the properties of covered stents specially designed for the intracranial vasculature.

Methods

Six carotid siphon–shaped devices were created. Six dogs underwent surgery to expose and isolate both common carotid arteries (CCAs). The right CCA origin was ligated and incised distal to the ligation point after temporary constriction of the distal right CCA. The distal left CCA was ligated and incised proximal to the ligation point after the left CCA origin was temporarily clamped. The proximal isolated left CCA was passed through the shaped device and then anastomosed end-to-end to the distal isolated right CCA. Finally, the shaped device was fixed and embedded in the neck. Intraarterial digital subtraction angiography was performed at 7 days, 2 weeks, and 1 month postprocedure. All models underwent endovascular interventional simulation. The carotid siphon models were evaluated.

Results

The animals tolerated the surgical procedure well. The mean time for surgical construction of the model was 90 minutes. The morphology and endovascular manipulation of the siphon models were similar to those in humans. Stenosis of anastomotic stoma occurred in 2 models, and mural thrombosis of anastomotic stoma occurred in 1 model; however, all models were patent at postprocedural follow-up angiography.

Conclusions

Surgical construction of an in vivo carotid siphon model in dogs with carotid siphon–shaped devices is feasible and potentially useful for testing neurovascular devices.

Morbidity and mortality associated with creation of elastase-induced saccular aneurysms in a rabbit model

BACKGROUND AND PURPOSE

Elastase-induced aneurysms in rabbits have been proposed as a useful preclinical tool for device development. The object of this study was to report rates of morbidity and mortality associated with the creation and embolization of elastase-induced rabbit aneurysms and to assess the impact of operator experience on these rates.

MATERIALS AND METHODS

Elastase-induced model aneurysms were created in New Zealand white rabbits (n = 700). One neuroradiologist/investigator, naive to the aneurysm-creation procedure at the outset of the experiments, performed all surgeries. All morbidity and deaths related to aneurysm creation (n = 700) and embolization procedures (n = 529) were categorized into acute and chronic deaths. Data were analyzed with single-regression analysis and analysis of variance. To assess the impact of increasing operator experience, we broke the number of animals into 50-animal increments.

RESULTS

There were 121 (17%) deaths among 700 subjects. Among 700 aneurysm-creation procedures, 59 deaths (8.4%) were noted. Among 529 aneurysm-embolization procedures, 43 deaths (8.1%) were noted. Nineteen additional deaths (2.7% of 700 subjects) were unrelated to the procedures. Simple regression-indicated mortality associated with procedures diminished with increasing operator experience (R(2) = 0.38, P = .0180), and that for each 50-rabbit increment mortality was reduced, on average, by 0.6%.

CONCLUSIONS

Mortality rates of approximately 8% are associated with both experimental aneurysm creation and with embolization in the rabbit elastase-induced aneurysm model. Increasing operator experience is inversely correlated with mortality, and the age of the rabbit is positively associated with morbidity.

Isolated progressive visual loss after coiling of paraclinoid aneurysms

BACKGROUND AND PURPOSE

The proximity of the paraclinoid segment of the internal carotid artery to the visual pathways may result in visual deficits when patients present with aneurysms in this segment. Although surgical clip ligation of these aneurysms has been the standard of care for decades, the advent of coil embolization has permitted endovascular therapy in those aneurysms with favorable dome-to-neck ratios. Although immediate nonprogressive visual loss after coil embolization of paraclinoid aneurysms has been well described, isolated progressive visual loss immediately or shortly following coil embolization, to our knowledge, has not. We have identified 8 patients who experienced progressive loss of vision, unassociated with any other neurologic deficits, developing immediately or shortly after apparently uncomplicated coil embolization of a paraclinoid aneurysm.

MATERIALS AND METHODS

This study is a retrospective case series of 8 patients seen at 4 separate academic institutions. Inpatient and outpatient records were examined to determine patient demographics, previous ocular and medical history, and ophthalmic status before endovascular embolization. In addition, details of the primary endovascular therapy and subsequent surgical and nonsurgical interventions were recorded. Follow-up data, including most recent best-corrected visual acuity, postoperative course, and duration of follow-up were documented.

RESULTS

Eight patients developed progressive visual loss in 1 or both eyes immediately or shortly after apparently uncomplicated coiling of a paraclinoid aneurysm. MR imaging findings suggested that the visual loss was most likely caused by perianeurysmal inflammation related to the coils used to embolize the aneurysm, enlargement or persistence of the aneurysm despite coiling, or a combination of these mechanisms. Most patients experienced improvement in vision, 2 apparently related to treatment with systemic corticosteroids.

CONCLUSION

Patients in whom endovascular treatment of a paraclinoid aneurysm is contemplated should be warned about the potential for both isolated nonprogressive and progressive visual loss in 1 or both eyes. Patients in whom progressive visual loss occurs may benefit from treatment with systemic corticosteroids.

The implantation of non-cell-based materials to prevent the recurrent disc herniation: an in vivo porcine model using quantitative discomanometry examination

Recurrent disc herniation is frequently observed due to leakage of nucleus pulposus through injured anulus fibrosus. There is no effective treatment to prevent recurrent disc herniation yet. In this study, we proposed to implant non-cell-based materials into the porcine disc to stimulate the growth of fibrous tissue and thereby increase the disc functional integrity. The disc herniation was simulated by anular punctures using the spinal needles. Four clinically used implantation materials, i.e., gelfoam, platinum coil, bone cement and tissue glue, were delivered into the discs via percutaneous spinal needles. Two months after the surgery, the swine were killed. The degree of disc integrity of intact, naturally healed and implanted discs, was examined by quantitative discomanometry apparatus. We found the disc injury could not recover after 2 months of healing, and the disc implantation affected the degree of disc integrity. The disc integrity of gelfoam-implanted discs was better than that of coil-, bone cement-, and glue-implanted discs. The implantation of non-cell-based material was proved to be a potentially clinically applicable method to recover the integrity of injured discs and to prevent recurrent disc herniation.

Morphologic changes in neo-intimal proliferation in an experimental aneurysm after coil embolization: effect of factor XIII administration

We investigated histological changes in aneurysmal orifices after embolization with Guglielmi detachable coils (GDCs) and determined the effects of the wound-healing factor, factor XIII, on promoting intimal proliferation by scanning electron microscopy (SEM). GDC embolization was performed in an experimental model of aneurysm in swine. In the control group (17 aneurysms), the aneurysms were resected immediately after surgery, at 1 and 3 weeks after the procedure. In the factor XIII-administered group (13 aneurysms), the swine received factor XIII postoperatively, and the aneurysms were excised at 1 and 3 weeks. The endothelial cell proliferation changes in the aneurysm orifices in both groups were evaluated by SEM. The histological changes at the orifices began immediately after the procedure, and endothelialization was observed at 1 week. One week after the procedure, the rate of endothelial cell proliferation was significantly higher in the factor XIII group (P<0.05). But no difference was observed at 3 weeks, when endothelialization of the orifices was essentially completed. The process of intimal proliferation after coil embolization was similar to the wound-healing process after vascular intimal injury. Administration of the wound-healing factor, factor XIII, would contribute rapid intimal proliferation and may be effective to facilitate complete obliteration of aneurysms after coil embolization.

In vitro and in vivo Studies of the Extent of Electrothrombotic Deposition of Blood Elements on the Surface of Electrolytically Detachable Coils

SUMMARY

Endovascular treatment of intracranial aneurysms with electrolytically detachable coils is often claimed to be based on electrothrombosis, i.e. intra-aneurysmal thrombus formation through applied direct current. Despite the fact that this concept was described more than a century ago, the significance of electrothrombosis in the endovascular treatment of aneurysms remains debatable. Apart from electrothrombosis, mechanical obliteration of the aneurysmal lumen might be one of the many possible mechanisms to explain why and how detachable coils are effective in preventing aneurysms from (re-)rupture. The purpose of this experimental study was to investigate to what extent direct current comparable to that used for coil detachment would influence the adhesion of cellular and liquid blood components to the surface of electrolytically detachable platinum coils. For the in vitro study, electrolytically detachable platinum coils of various types were exposed to stagnant heparinised blood for a total of 16 h, without or with applied direct current for 30 or 90 s (1 mA, 4-6 V, coil as anode). For the in vivo study, electrolytically detachable platinum coils were exposed to flowing blood for 180 s, without or with applied direct current (2 mA, 4-6 V, coil as either anode or cathode), without anti-coagulation and after intravenous administration of 5000 U Heparin and again after the intravenous administration of 500 mg Aspisol in addition to Heparin. After exposure to blood according to these different experimental protocols, the coils were fixed in formalin solution, gold coated and examined by scanning electron microscopy. Thrombus formation on the surface of all unfibred coils was thin and highly variable both from coil to coil, and on different areas of any given coil. The application of direct current minimally enhanced thrombus formation in stagnant blood in vitro, but not in vivo. The cellular and fibrin adhesions on the coil surfaces without and with applied current did not effectively increase the diameter or volume of unfibred coils. Coils with attached nylon fibres, however, proved to be highly thrombogenic without or with application of current. In fibred coils, surface adhesions without and with applied current were voluminous enough to effectively increase the diameter of the coil, potentially important for the process of endosaccular aneurysm occlusion. Electrothrombosis plays no role in the endovascular treatment of intracranial aneurysms with electrolytically detachable coils. This explains why platinum coils with non-electrolytic detachment mechanisms show a similar efficiency and recurrence rate.

The Underlying Mechanisms of Endovascular Exclusion of Intracranial Aneurysms by Coils. How Important is Electrothrombosis?

SUMMARY

Endovascular coil treatment of intracranial aneurysms is now widely accepted. We discuss some of the arguments for the relative roles of electrothrombosis, spontaneous thrombosis, mechanical filling, haemodynamic effects and surface properties in successful coil treatment. Despite an enormous body of literature, with many theories and much data, there is limited evidence for, or understanding of, the mechanisms by which coil treatment protects against aneurysm rupture. It seems likely that electrothrombosis plays no part.Dense packing is probably important in preventing recurrence. New technologies aiming to encourage endothelialisation and increased connective tissue formation appear promising.

Histological evaluation of endothelial reactions after endovascular coil embolization for intracranial aneurysm. Clinical and experimental studies and review of the literature

SUMMARY

The purpose of this study was to evaluate the role of the endothelial cell reaction after endovascular coil embolization for the treatment of intracranial aneurysms. A scanning electron microscopic (SEM) study of the platinum coil, embolized into a middle cerebral aneurysm in a 35-year-old woman and subsequently removed surgically eight months later, revealed no endothelial coverage on the coil. This finding prompted us to perform experimental studies. In the first in vitro study, endothelial cells from gerbil brain microvessels and canine carotid arteries were co-cultured with either bare-form platinum coils or type-1 collagen-coated coils for up to three weeks, and the endothelial cell population on the coils was ascertained. In the second in vivo study, platinum coils coated with type-1 collagen were delivered endovascularly into canine carotid arteries, while the contralateral side was treated with bare-form coils, and endothelialization over the coil was investigated. SEM studies revealed that no endothelial cells, either from gerbil brain microvessels or from canine carotid artery, were found on the uncoated coils, whereas gerbil endothelial cells began to proliferate on the collagen-coated coils in three days, covering extensively in one week and reaching confluence in two weeks in vitro. The in vivo canine study demonstrated that bare-form platinum coils did not show endothelial coverage until two weeks, but endothelial cells proliferated directly on the collagen-coated coils in three days, and coils were completely covered in two weeks. These results supported the SEM study of our case and several human histopathological reports in the literature in that endothelial cell coverage in the orifice of the intracranial aneurysm is exceptional after endovascular treatment. But if some extracellular matrix, like collagen in our study, is prepared, coverage could be possible, as is seen in a few human cases. Biological modification of the platinum coils, such as collagen coating, is awaited for the better long-term results of endovascular coil embolization without recanalization of the treated intracranial aneurysms.

Post-mortem pathological examination of two patients after intraaneurysmal embolization using guglielmi detachable coils

SUMMARY

We report the histological findings in two patients treated using Guglielmi detachable coils with almost complete occlusion of the aneurysms.Autopsies of these patients were performed one week and one year after GDC embolization respectively. In one aneurysm that was obtained at autopsy one week after embolization, the histological findings revealed coils and an unorganized thrombus-filled aneurysm sac; an incomplete cell-lining on the luminal side of fibrin thrombi in the region of the neck of the aneurysm was recognized. In the other aneurysm in which autopsy was performed one year after embolization, an organized fibrous tissue at the margin of the aneurysmal wall and vascular granulation tissue at the center of the aneurysm were observed. There is a single layer of endothelium covering fibrous tissue in the neck of the aneurysm. We discuss the healing process after GDC treatment.

Histological findings in coil-packed experimental aneurysms 3 months after embolization

OBJECTIVE

Knowledge regarding tissue reactions within coil-packed aneurysms is poor. The purpose of this study was to analyze histological changes in a chronic experimental bifurcation aneurysm model that might explain the protective effect of Guglielmi detachable coils.

METHODS

The aneurysms were produced by means of a venous graft pouch at a surgically created bifurcation of the carotid artery in the neck of rabbits. After 3 weeks, embolization with Guglielmi detachable coils was performed in the treatment group but not in the control group (seven rabbits each). At the time of embolization, six of seven treated aneurysms were completely occluded according to radiological criteria. Twelve weeks later, all aneurysms were explanted after final angiography. Histological examinations were performed with coils in situ.

RESULTS

Six of seven embolized aneurysms demonstrated complete occlusion in final angiography. But gross pathology revealed that all specimens had differently sized open cavities between the coils. In only two cases, these spaces were very small and the aneurysmal sacs were filled with coils and tissue by more than 90%. Light microscopy demonstrated intraluminal granulation tissue and strong chronic inflammatory wall thickening with numerous foreign body cells at the interface between coils and tissue. Coils were partially incorporated into the aneurysmal wall, sometimes close to the surface and occasionally even outside the wall within the surrounding tissue.

CONCLUSION

The protective effect of Guglielmi detachable coil treatment in our chronic experimental bifurcation aneurysms results from formation of intraluminal granulation tissue and wall thickening attributable to chronic inflammation.

Three-dimensional pulsatile flow simulation before and after endovascular coil embolization of a terminal cerebral aneurysm

The effect of different percentages of coil mesh in a cerebral aneurysm on the pulsatile flow and pressure in the parent vessel and aneurysm lumen was evaluated. Geometric data on a basilar tip aneurysm and vertebrobasilar arteries after subarachnoid hemorrhage was obtained by computer tomographic angiography. Intraarterial pressure was measured at four vertebrobasilar points before and after treatment with detachable coils. Pulsatile flow was documented by transcranial ultrasonography. A three-dimensional computer simulation was created using a commercial fluid dynamics solver for four aneurysm conditions: (1) before intervention; (2) with a 20% filling showing a complete cessation of the inflow through the aneurysm neck; (3) with a 12% filling showing an incomplete deceleration of inflow through the aneurysm neck, with a remaining flow around the embedded platinum coils; and (4) with a 12% filling and simulation of clotted aneurysm dome, which did not inhibit persisting flow phenomena. The relative pressure amplitudes neither increased nor decreased under the different simulated aneurysm filling conditions. Inserted platinum coils can immediately and decisively relieve the influx of pulsating blood and allow for initial clotting. To reach this effect, a volume density of 20% platinum coil mesh in the aneurysm neck is needed.

Histological Investigation of Endothelial Cell Proliferation on the Coil Surface after Endovascular Treatment Using FactorXIII. Preliminary Results in Swine Model

SUMMARY

Recently, endovascular treatment of coil embolisation has been widely used for obliterating cerebral aneurysms. However, the process of endothelial cell growth within aneurysms to prevent aneurysmal rupture associated with endovascular coil embolisation remains unclear. Fourteen aneurysms were produced in seven matured swine and embolised with Guglielmi Detachable coils (GDCs). The aneurysms were resected either immediately or three weeks after coil embolisation, and subjected to histological and scanning electron microscopic examinations. Blood coagulation factor XIII was administered in four animals on the day of embolisation and on the following four days. These aneurysms were also resected three weeks after the embolisation and investigated histologically. Marked fibroblast proliferation and growth of endothelial cells on the intraluminal surface of the coil were observed more often in the group administered factor XIII than in those not given factor XIII. These results suggest that administration of factor XIII may contribute to more effective aneurysm obliteration during coil embolisation.

Bioabsorbable polymeric material coils for embolization of intracranial aneurysms: a preliminary experimental study

OBJECT

A new embolic agent, bioabsorbable polymeric material (BPM), was incorporated into Guglielmi detachable coils (GDCs) to improve long-term anatomical results in the endovascular treatment of intracranial aneurysms. The authors investigated whether BPM-mounted GDCs (BPM/GDCs) accelerated the histopathological transformation of unorganized blood clot into fibrous connective tissue in experimental aneurysms created in swine.

METHODS

Twenty-four experimental aneurysms were created in 12 swine. In each animal, one aneurysm was embolized using BPM/GDCs and the other aneurysm was embolized using standard GDCs. Comparative angiographic and histopathological data were analyzed at 2 weeks and 3 months postembolization. At 14 days postembolization, angiograms revealed evidence of neck neointima in six of eight aneurysms treated with BPM/GDCs compared with zero of eight aneurysms treated with standard GDCs (p < 0.05). At 3 months postembolization, angiograms demonstrated that four of four aneurysms treated with BPM/GDC were smaller and had neck neointima compared with zero of four aneurysms treated with standard GDCs (p = 0.05). At 14 days, histological analysis of aneurysm healing favored BPM/GDC treatment (all p < 0.05): the grade of cellular reaction around the coils was 3 +/- 0.9 (mean +/- standard deviation) for aneurysms treated using BPM/GDCs compared with 1.6 +/- 0.7 for aneurysms treated using GDCs alone; the percentage of unorganized thrombus was 16 +/- 12% compared with 37 +/- 15%, and the neck neointima thickness was 0.65 +/- 0.26 mm compared with 0.24 +/- 0.21 mm, respectively. At 3 months postembolization, only neck neointima thickness was significantly different (p < 0.05): 0.73 +/- 0.37 mm in aneurysms filled with BPM/GDCs compared with 0.16 +/- 0.14 mm in aneurysms filled with standard GDCs.

CONCLUSIONS

In experimental aneurysms in swine, BPM/GDCs accelerated aneurysm fibrosis and intensified neck neointima formation without causing parent artery stenosis or thrombosis. The use of BPM/GDCs may improve long-term anatomical outcomes by decreasing aneurysm recanalization due to stronger in situ anchoring of coils by organized fibrous tissue. The retraction of this scar tissue may also decrease the size of aneurysms and clinical manifestations of mass effect observed in large or giant aneurysms.

Re-evaluation of cellulose acetate polymer: angiographic findings and histological studies

BACKGROUND

Cellulose acetate polymer (CAP) is a new liquid embolic material that has been used experimentally in intravascular treatment of intracranial aneurysms. But this compound is still controversial in some aspects such as safety, efficiency, and histological changes. In this study, we re-evaluated the material with regard to intravascular treatment of aneurysms.

METHODS

The carotid arteries of rats and experimental aneurysms in canines were embolized with CAP. The effects of CAP were evaluated according to angiographic and histological results.

RESULTS

A strong chemo-corrosive effect was observed. This led to severe damage to vessels and rupture of two thrombosed canine aneurysm models. There were significant technical difficulties including out-flow of CAP and a high rate of occlusion of the parent arteries.

CONCLUSIONS

We conclude that currently CAP is not an ideal embolic material for intracranial aneurysms. Further tests and improvements are needed before it can be widely used clinically.

Electromicroscopic Investigation of the Efficacy of FactorXIII for Coil Embolization in Experimental Aneurysms. Preliminary Report

SUMMARY

In recent years, endovascular treatment has often been used to treat cerebral aneurysms. Basic investigation to elucidate the process of endothelial cell growth within aneurysms is a crucial problem.We performed elecrtro-detachable coil embolization in aneurysms under administration of blood coagulation factorXIII, a wound-healing accelerator, and examined changes in endothelial cells on the surface of the inserted coil with a scanning electron microscope. Experimental aneurysms produced in animals were treated by coil embolization and histological changes in embolized coil after the treatment of factorXIII were investigated. Aneurysms were produced in four matured swines under general anesthesia and coil embolization was performed with a elecrtro-detachable coil. The aneurysms were resected immediately and 3 weeks after coil embolization, and investigated histologically with a scanning electron microscope. Seven animals were administrated with blood coagulation factorXIII on the day of embolized and the following 4 consecutive days. These aneurysms were also resected 3 weeks after embolization and investigated histologically. More marked fibroblast proliferation and growth of endothelial cells on the surface of luminal side of embolized coil were seen in the aneurysms in the group administrated with factorXIII than in aneurysms treated without factorXIII. More effective and sufficient coil embolization can be obtained by administration of factorXIII.

1999 ARRS Executive Council Award. Creation of saccular aneurysms in the rabbit: a model suitable for testing endovascular devices. American Roentgen Ray Society

OBJECTIVE

This study developed an animal model of intracranial aneurysms suitable for evaluating emerging endovascular devices for aneurysmal therapy. We characterized the short-, medium-, and long-term attributes of this endovascular technique for saccular aneurysmal creation in the rabbit.

MATERIALS AND METHODS

The right common carotid artery was surgically exposed in nine New Zealand white rabbits. Using endovascular techniques, we occluded the origin of the right common carotid artery with a pliable balloon. Elastase was incubated endoluminally in the proximal common carotid artery above the balloon. The common carotid artery was ligated distally. Animals were studied angiographically and sacrificed at 2 weeks (n = 3), 10 weeks (n = 3), and 24 weeks (n = 3) after aneurysm creation. Histology was obtained.

RESULTS

Saccular aneurysms formed in eight of the nine rabbits. The aneurysm projected from the apex of an approximately 90 degree curve of the parent vessel, the brachiocephalic artery. Mean aneurysm diameter was 4.5 mm (SD, 1.2 mm), and mean height was 7.5 mm (SD, 1.6 mm). All samples showed thinned elastic lamina and no evidence of inflammation. In four of eight aneurysms, unorganized thrombus was present in the dome of the aneurysm.

CONCLUSION

Arterial aneurysms with intact endothelium and deficient elastic lamina were reliably created in an area of high shear stress in New Zealand white rabbits. Three of these aneurysms remained patent for at least 6 months. We found a simple procedure that can be readily applied to the testing of new endovascular devices for a reliable creation of aneurysms in rabbits.

Long-term histopathology of intracranial aneurysms after endovascular treatment with coils. Report of two cases with ultrastructural evaluations by scanning electron microscopy

We describe the results of electron microscopic examination in two patients with ruptured intracranial aneurysms who were successfully treated by endovascular coil embolization. The aneurysms were seen completely occluded on the follow-up angiograms. Autopsies of these patients were performed five and 26 months after endovascular treatment when they died of pneumonia and thalamic hemorrhage, respectively. The aneurysms were densely filled with the coils, which were readily identified through the thin and transparent wall of the aneurysmal dome. The orifice of the aneurysm was completely occluded so that macroscopically the coils were not directly visualized through the orifice. To examine any evidence of endothelialization across the orifice of the aneurysms, scanning electron microscopic examination was performed. In both cases, evidence of well regenerative endothelialization was observed across the aneurysmal orifice, being contiguous with the endothelial layer of the adjacent parent vessels. These ultrastructural findings indicate that the aneurysms are completely isolated from the lumen of the parent artery by a continuous lining of the regenerated endothelial cells following the endo vascular treatment with coils, and further suggest that aneurysms have a potential of being cured permanently by this treatment modality. This is, to the best of our knowledge, the first report in humans verifying a complete endothelialization of the luminal surface at the aneurysmal neck after coil embolization, as evidenced by scanning electron microscopy.

Endovascular creation of an in vivo bifurcation aneurysm model in rabbits

PURPOSE

To develop a rabbit model of an intracranial bifurcation aneurysm to test new endovascular therapies.

MATERIALS AND METHODS

An experimental aneurysm model was created in rabbits by means of endovascular balloon occlusion of the left common carotid artery, which created an aneurysm at the bifurcation formed by the aortic arch and the brachiocephalic trunk. A total of 18 aneurysms were created. In eight rabbits, the aneurysms were incubated with intraluminal elastase to induce degeneration of the elastic laminae. The animals were followed up with angiography for as long as 3 months. The animals were sacrificed at various times, and histologic evaluation of the aneurysm was performed.

RESULTS

Ten aneurysms created without elastase infusion were all very small or completely closed at 1-3 months. Six aneurysms created with elastase infusion had long-term patency (two were patent at 1 month and four, at 3 months). The elastase aneurysms had a mean width of 3 mm (range, 2-3.5 mm) and a mean length of 5 mm (range, 3-7 mm). Histologic evaluation revealed destruction of the normal elastin layers, which allowed the artery to become aneurysmal.

CONCLUSION

This aneurysm model re-created the hemodynamic forces and size of human cerebral bifurcation aneurysms and maintained the integrity of the endothelium. The creation of the aneurysms was rapid, reliable, and reproducible.

Histologic evaluation of platinum coil embolization in an aneurysm model in rabbits

PURPOSE

To characterize the histologic response to platinum coil embolization by using a rabbit aneurysm model.

MATERIALS AND METHODS

Saccular aneurysms were created in New Zealand White rabbits by using vessel ligation with intraluminal elastase incubation. Aneurysms were subsequently embolized by using platinum coils. Subjects were sacrificed at various intervals up to 12 weeks following coil embolization. The aneurysm cavities and adjacent vessels were embedded in methylmethacrylate, were sectioned, and were stained for histologic examination.

RESULTS

Two weeks following coil implantation, aneurysms were filled predominantly with unorganized thrombus. Six weeks following coil implantation, histologic features included complete filling of the aneurysm lumen with either prominent laminated but unorganized thrombus or areas of unorganized thrombus interspersed among areas of cellular infiltration. At 12 weeks following coil implantation, aneurysms were filled with the loosely packed, disordered cells contained within the extracellular matrix. Fibrosis or smooth muscle cell infiltration was not present in any of the 6- or 12-week samples.

CONCLUSION

Platinum coils placed into experimental saccular aneurysms in New Zealand White rabbits failed to elicit a fibrotic response. This model can be used for the testing of biologic modifications of platinum coils aimed at increasing intra-aneurysmal fibrosis.

Acute histologic and ultrastructural study in one case of human basilar tip aneurysm embolised with guglielmi detachable coils

SUMMARY

Histologic findings after Guglielmi detachable coils endovascular embolisation have been studied in experimental aneurysms. Few reports describe histopathologic reactions to platinum coils in humans. In this report we describe gross, light microscopic pathology and scanning electron microscopy study of a ruptured basilar tip artery aneurysm in a patient who died 16 hours following coiling.

Balloon-assisted Guglielmi detachable coiling of wide-necked aneurysms: Part I--experimental evaluation

OBJECTIVE

Balloon-assisted technique is a promising technical adjunct to use of Guglielmi detachable coils for embolization of wide-necked aneurysms. In this study using experimental aneurysms in swine, the safety and long-term efficacy of this technique were evaluated.

METHODS

Sixteen wide-necked aneurysms (sidewall model) were surgically created in common carotid arteries of swine. In the acute study of eight aneurysms, intra-aneurysmal pressure changes were recorded during balloon inflation in different positions of the balloon relative to the neck of the aneurysm. In the chronic study, eight aneurysms were treated with this technique, and follow-up angiography was performed 14 days postembolization. The animals were then killed for macroscopic evaluation.

RESULTS

In the acute study, the systolic intra-aneurysmal blood pressure increased with balloon inflation at the distal portion of the neck and with balloon inflation/occlusion across the entire neck of the aneurysm. In the chronic study, seven of eight cases were embolized with satisfactory occlusion, and six showed no coil displacement on the follow-up angiogram. In five cases, macroscopic evaluation of the aneurysm showed that the coils were compacted at the neck of the aneurysm with a concave shape consistent with the shape of the inflated balloon across its neck.

CONCLUSION

This preliminary study indicates that balloon-assisted Guglielmi detachable coiling technology may produce a temporary increase of pressure within the aneurysm while occluding the aneurysmal neck during coil delivery. This sudden change of intra-aneurysmal pressure may potentially be the cause-of aneurysm rupture in the clinical setting. The balloon must be inflated and deflated very slowly to minimize these potentially risky hemodynamic changes. Although angiographic follow-up showed successful obliteration of aneurysms, further long-term angiographic studies are necessary to establish the durability of this technique.

Gross and microscopic histopathological findings in aneurysms of the human brain treated with Guglielmi detachable coils

OBJECT

The histopathological characteristics of aneurysms obtained at autopsy or surgery 3 days to 54 months after being treated with Guglielmi detachable coils (GDCs) were assessed.

METHODS

Seventeen aneurysms were obtained at autopsy and one was removed at surgery. Fourteen were examined histologically with the coils in situ. Naked coils embedded in an unorganized thrombus were found in those aneurysms that had been treated with coils within 1 week earlier. An incomplete replacement of the intraluminal blood clot by fibrous tissue and a partial membranous covering at the aneurysm orifice were observed in those aneurysms that had been treated with coils between 2 and 3 weeks prior to examination. One small aneurysm treated 6 weeks before harvesting showed formation of an endothelium-lined layer of connective tissue at the orifice. Collagen-rich vascularized tissue surrounding the coils was found in an aneurysm removed at surgery 54 months after coil implantation. Interestingly, six (50%) of 12 aneurysms (two small, three large, and one giant) that had been deemed 100% occluded on initial angiography showed tiny open spaces between the coils at the neck on gross examination.

CONCLUSIONS

Endothelialization of the aneurysm orifice following placement of GDCs can occur; however, it appears to be the exception rather than the rule. In large aneurysms the process of intraaneurysm clot organization seems to be delayed and incomplete; tiny open spaces between the coils and an incomplete membranous covering in the region of the neck are frequently encountered. Further longitudinal studies are required to establish the spectrum of healing profiles that may direct our efforts in modifying the GDC system to produce a more stable long-term result.

Acute human histopathology of an intracranial aneurysm treated using Guglielmi detachable coils: case report and review of the literature

OBJECTIVE AND IMPORTANCE

This case study provided us with the opportunity to explore the histopathological effects of Guglielmi detachable coil (GDC) therapy on the aneurysm orifice and parent vessel-aneurysm neck interface. This type of study is important to the understanding of the mechanisms of obliteration of aneurysms by GDCs.

CLINICAL PRESENTATION

The patient presented with a Hunt and Hess Grade III subarachnoid hemorrhage that occurred secondary to the rupture of a small anterior communicating artery aneurysm.

INTERVENTION

The aneurysm was successfully coiled without complication, but the patient died 36 hours later. We examined the gross and microscopic pathological findings of this GDC-treated anterior communicating artery aneurysm 36 hours after coiling. A discrete membrane composed of fibrin had formed completely across the aneurysm orifice, excluding the aneurysm sac from the circulation. This membrane was contiguous with the parent vessel.

CONCLUSION

This case represents one of the first examples in humans of the formation of a membrane over the aneurysm orifice after GDC therapy. The formation of this membrane, shown to be composed of fibrin, was found at 36 hours after coiling, which is the earliest time frame at which membrane formation has been noted in either humans or animal models. This fibrin membrane may function both as a scaffold for subsequent endothelialization across the aneurysm neck as well as to isolate the aneurysm from the parent circulation, permitting thrombus within the aneurysm sac to mature to an endovascular scar. The factors contributing to the formation of this membrane and its clinical implications are discussed.

Materials and biomaterials for interventional radiology

Devices used in interventional radiology have significantly developed in the past few years. In order to understand the trends of this development, we analyzed how new interventional devices are progressively incorporating materials having original physical properties, and how developers are today progressively turning towards biomaterials, with respect to the new regulatory environment, and the requirements of biocompatibility.

Demonstration of platinum microcoils in embolized blood vessels in-situ using a modified methyl methacrylate embedding method, and a special cutting and grinding technique

With current paraffin embedding techniques it is not possible to demonstrate metal particles in vascular lumens. We used a modified methyl methacrylate embedding method for obtaining plastic blocks which were cut with a precision diamond saw, and subsequently ground and polished to preserve the interface of reactive tissue surrounding platinum microcoils in arteriovenous malformations. Artifact-free interfaces could be achieved by slow embedding under vacuum conditions, slow polymerization in a water bath, and very gentle cutting, grinding and polishing techniques. The method produces good preservation of tissue and cells directly adjacent to metal coils. Our method is useful for the histomorphological interpretation of vascular pathologies in which metal particles have been introduced.

Rerupture of coil-embolized aneurysm during long-term observation. Case report

The authors describe the histopathological findings in a case involving rerupture of a recanalized aneurysm of the internal carotid artery 8 months after partial (95%) embolization with interlocking detachable coils. The aneurysm was filled with poorly organized thrombus, and its orifice was devoid of endothelial cells. It appears likely that a long period of observation may be required to confirm the complete thrombotic organization of coil-embolized aneurysms. This indicates that caution is needed because rupture may follow recanalization of the aneurysm.

Long-term results of ruptured cerebral aneurysms embolized in acute stage with interlocking detachable coils

SUMMARY

We report on a series of eight patients presenting with SAH secondary to ruptured saccular (n=7) or dissecting (n=l) aneurysm, treated in the acute stage (within 14 days) by embolization with interlocking detachable coils (IDCs) who survived at least 3 months following initial hemorrhage. Embolization resulted in complete occlusion in 2 of 7 cases of saccular aneurysm, 90-95% occlusion was obtained in the remaining 5 cases of saccular aneurysm. Proximal occlusion with intra-aneurysmal coil packing was achieved in 1 case of dissecting aneurysm. In all 5 cases with partial occlusion, follow-up angiograms taken 2-4 months after the embolization showed partial recanalization due to coil compaction, while no recanalization was recognized in cases with complete occlusion in follow-up angiograms at 5 and 9 months respectively. Clinical disability, at 9 months after the embolization was rated as none in 4 cases, moderate in 1, and severe in 1. Two patients died of re-rupture at 4 and 8 months respectively after the embolization. Of the other 3 cases with partial recanalization, 2 were retreated by re-embolization or surgical clipping, one has been followed clinically and angiographically. Histological findings of the re-ruptured aneurysm showed neither endothelialization of the aneurysmal orifice nor organization of the clot around the coils. Aneurysmal re-rupture secondary to coil compaction related recanalization remains a critical factor in long-term clinical outcome and prognosis.

Traumatic carotid artery dissection and pseudoaneurysm treated with endovascular coils and stent

PURPOSE

To report a case of post-traumatic internal carotid artery dissection and pseudoaneurysm formation at the C-1 level successfully treated by a percutaneous endovascular technique.

METHODS AND RESULTS

A 20-year-old female presented 72 hours after a motor vehicle accident with incomplete occulosympathetic paresis (Horner's syndrome), carotidynia, and leftsided 1.5-cm x 2.5-cm pseudoaneurysm at the C-1 level. Neuroradiologists embolized the pseudoaneurysm with Guglielmi detachable coils and controlled the dissection with placement of a Wallstent.

CONCLUSIONS

This report illustrates successful percutaneous endovascular treatment of a carotid dissection and pseudoaneurysm near the base of the skull.

Ion implantation and protein coating of detachable coils for endovascular treatment of cerebral aneurysms: concepts and preliminary results in swine models

OBJECTIVE

Complete anatomic obliteration remains difficult to achieve with endovascular treatment of wide-necked aneurysms using Guglielmi detachable platinum coils (GDCs). Ion implantation is a physicochemical surface modification process resulting from the impingement of a high-energy ion beam. Ion implantation and protein coating were used to alter the surface properties (thrombogenicity, endothelial cellular migration, and adhesion) of GDCs. These modified coils were compared with standard GDCs in the treatment of experimental swine aneurysms.

METHODS

In an initial study, straight platinum coils were used to compare the acute thrombogenicity of standard and modified coils. Modified coils were coated with albumin, fibronectin, or collagen and underwent Ne+ ion implantation at a dose of 1 x 10(15) ions/cm2 and an energy of 150 keV. Coils were placed in common iliac arteries of 17 swine for 1 hour, to evaluate their acute interactions with circulating blood. In a second study, GDCs were used to treat 34 aneurysms in an additional 17 swine. GDCs were coated with fibronectin, albumin, collagen, laminin, fibrinogen, or vitronectin and then implanted with ions as described above. Bilateral experimental swine aneurysms were embolized with standard GDCs on one side and with ion-implanted, protein-coated GDCs on the other side. The necks of aneurysms were evaluated macroscopically at autopsy, by using post-treatment Day 14 specimens. The dimensions of the orifice and the white fibrous membrane that covered the orifice were measured as the fibrous membrane to orifice proportion. Histopathological evaluation of the neck region was performed by light microscopy and scanning electron microscopy.

RESULTS

Fibronectin-coated, ion-implanted coils showed the greatest acute thrombogenicity (average thrombus weight for standard coils, 1.9 +/- 1.5 mg; weight for fibronectin-coated coils, 8.6 +/- 6.2 mg; P < 0.0001). By using scanning electron microscopy, an intensive blood cellular response was observed on ion-implanted coil surfaces, whereas this was rare with standard coils. At Day 14, greater fibrous coverage of the necks of aneurysms was observed in the ion-implanted coil group (mean fibrous membrane to orifice proportion of 69.8 +/- 6.2% for the ion-implanted coil group, compared with 46.8 +/- 15.9% for the standard coil group; P = 0.0143).

CONCLUSION

The results of this preliminary experimental study indicate that ion implantation combined with protein coating of GDCs improved cellular adhesion and proliferation. Future application of this technology may provide early wound healing at the necks of embolized, wide-necked, cerebral aneurysms.