Cerecyte versus platinum coils in the treatment of intracranial aneurysms: packing attenuation and clinical and angiographic midterm results

Flow Diverter Performance Comparison of Different Wire Materials for Effective Intracranial Aneurysm Treatment

A flow diverter (FD) is an effective method for treating wide-necked intracranial aneurysms by inducing hemodynamic changes in aneurysms. However, the procedural technique remains challenging, and it is often not performed properly in many cases of deployment or placements. In this study, three types of FDs that changed the material of the wire were prepared within the same structure. Differences in physical properties, such as before and after delivery loading stent size, radial force, and radiopacity, were evaluated. The performances in terms of deployment and trackability force were also evaluated in a simulated model using these FDs. Furthermore, changes of deployment patterns when these FDs were applied to a 3D-printed aneurysm model were determined. The NiTi FD using only nitinol (NiTi) wire showed 100% size recovery and 42% to 45% metal coverage after loading. The low trackability force (10.9 to 22.9 gf) allows smooth movement within the delivery system. However, NiTi FD cannot be used in actual surgeries due to difficulties in X-ray identification. NiTi-Pt/W FD, a combination of NiTi wire and platinum/tungsten (Pt/W) wire, had the highest radiopacity and compression force (6.03 ± 0.29 gf) among the three FDs. However, it suffered from high trackability force (22.4 to 39.9 gf) and the end part braiding mesh tended to loosen easily, so the procedure became more challenging. The NiTi(Pt) FD using a platinum core nitinol (NiTi(Pt)) wire had similar trackability force (11.3 to 22.1 gf) to NiTi FD and uniform deployment, enhancing procedural convenience. However, concerns about low expansion force (1.79 ± 0.30 gf) and the potential for migration remained. This comparative analysis contributes to a comprehensive understanding of how different wire materials influence the performance of FDs. While this study is still in its early stages and requires further research, its development has the potential to guide clinicians and researchers in optimizing the selection and development of FDs for the effective treatment of intracranial aneurysms.

Intracranial wide neck aneurysms: clinical and angiographic outcomes of endovascular management

Background

The treatment of intracranial wide neck aneurysms (WNAs) is usually difficult, hence several endovascular techniques were developed. This study aims to assess the clinical and angiographic imaging outcome of endovascular management of intracranial wide neck aneurysm. Forty patients were referred to the neuro-endovascular unit, at our hospital, each with a wide neck aneurysm. They were assessed regarding clinical presentation, aneurysm size, the character of the aneurysm, and the age and sex of the patient. Post-procedural, clinical, and angiographic outcomes of the patients who underwent endovascular intervention were reviewed.

Results

In this study, the mean aneurysmal neck was 5.4 ± 1.6 mm (mm). Endovascular intervention was carried out in all 40 patients in the form of simple coiling in 3 patients, double-catheter technique in 5 patients, balloon-assisted coiling (BAC) in 16 patients, stent-assisted coiling (SAC) in 13 patients, and flow diverter (FD) in 3 patients. Regarding clinical outcome, 4 patients had unfavorable outcome (the modified Rankin Scale, mRS > 2) at presentation and 3 patients at discharge. There was no unfavorable clinical outcome at 6- and 12-month follow-ups. Overall angiographic outcome at 1-year follow-up, 37/40 aneurysms (92.5%) had complete occlusion while two aneurysms had neck recurrence and one aneurysm had neck recanalization.

Conclusion

The current endovascular techniques in the treatment of WNAs are considered effective, feasible, and safe.

TARGET® Intracranial Aneurysm Coiling Prospective Multicenter Registry: Final Analysis of Peri-Procedural and Long-Term Safety and Efficacy Results

Background and Purpose: To describe the final results of the TARGET Registry, a multicenter, real-world study of patients with intracranial aneurysms treated with new generation TARGET Coils.

Methods: The TARGET Registry is a prospective, single-arm study with independent medical event monitoring and core-lab adjudication. Patients with de novo intracranial aneurysms were embolized with either TARGET-360° or helical coils in 12 US centers. The primary outcome was aneurysm packing density (PD), which was assessed immediately post-procedure. The secondary outcomes were immediate and long-term aneurysm occlusion rate using the Raymond Scale, and independent functional outcome using the modified Rankin Scale (mRS). A secondary analysis investigated the influence of the use of 100% 360-complex coils on clinical and angiographic outcomes.

Results: 148 patients with 157 aneurysms met the inclusion and exclusion criteria. 58 (39.2%) patients with ruptured and 90 (61.8%) with unruptured aneurysms were treated using TARGET 360°, helical Coils, or both. Median age was 58.3 (IQR 48.1–67.4), 73% female, and 71.6% were Caucasian. Median follow-up time was 5.9 (IQR 4.0–6.9) months. The majority were treated with TARGET 360-coils (63.7%), followed by mixed and helical coils only. Peri-procedural morbidity and mortality was seen in 2.7% of patients. A good outcome at discharge (mRS 0–2) was seen in 89.9% of the full cohort, and in 84.5 and 93.3% in the ruptured and unruptured patients, respectively. The median packing density was 28.8% (IQR 20.3–41.1). Long-term complete and near complete occlusion rate was seen in 90.4% of aneurysms and complete obliteration was seen in 66.2% of the aneurysms. No significant difference in clinical and angiographic outcomes were noted between the pure 360-complex coiling vs. mixed 360-complex/Helical coiling strategies. In a multivariate analysis, predictors for long-term aneurysm occlusion were aneurysm location, immediate occlusion grade, and aneurysm size. The long-term independent functional outcome was achieved in 128/135 (94.8%) patients and all-cause mortality was seen in 3/148 (2%) patients.

Conclusion: In the multicenter TARGET Registry, two-thirds of aneurysms achieved long-term complete occlusion and 91.0% achieved complete or near complete occlusion with excellent independent functional outcome.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT01748903

Autologous adipose-derived mesenchymal stem cells improve healing of coiled experimental saccular aneurysms: an angiographic and histopathological study

PURPOSE

Long-term occlusion of coiled aneurysms frequently fails, probably because of poor intrasaccular healing and inadequate endothelialization across the aneurysm neck. The purpose of this study was to determine if attachment of autologous mesenchymal stem cells (MSCs) to platinum coils would improve the healing response in an elastase-induced aneurysm model in rabbits.

MATERIALS AND METHODS

With approval from the institutional animal care and use committee, aneurysms were created in rabbits and embolized with control platinum coils (Axium; Medtronic) (n=6) or coils seeded ex vivo with autologous adipose-tissue MSCs (n=7). Aneurysmal occlusion after embolization was evaluated at 1 month with angiography. Histological samples were analyzed by gross imaging and graded on the basis of neck and dome healing on H&E staining. Fibrosis was evaluated using a ratio of the total area presenting collagen. Endothelialization of the neck was quantitatively analyzed using CD31 immunohistochemistry. χ² and Student's t-test were used to compare groups.

RESULTS

Healing score (11.5 vs 8.0, p=0.019), fibrosis ratio (10.3 vs 0.13, p=0.006) and endothelialization (902 262 μm² vs 31 810 μm², p=0.041) were significantly greater in the MSC group. The MSC group showed marked cellular proliferation and thrombus organization, with a continuous membrane bridging the neck of the aneurysm. Angiographic stable or progressive occlusion rate was significantly lower in the MSC group (0.00, 95% CI 0.00 to 0.41) compared with controls (0.67, 95% CI 0.22 to 0.96) (p=0.02).

CONCLUSIONS

Autologous MSCs attached to platinum coils significantly improve histological healing, as they result in improved neck endothelialization and collagen matrix formation within the aneurysm sac.

Endovascular treatment of bifurcation intracranial aneurysms with the WEB SL/SLS: 6-month clinical and angiographic results

BACKGROUND

The WEB device is a recent intrasaccular flow disruption technique developed for the treatment of wide-necked intracranial aneurysms. To date, a single report on the WEB Single-Layer (SL) treatment of intracranial aneurysms has been published with 1-months' safety results. The aim of this study is to report our experience and 6-month clinical and angiographic follow-up of endovascular treatment of wide-neck aneurysm with the WEB SL.

METHODS

Ten patients with 10 unruptured wide-necked aneurysms were prospectively enrolled in this study. Feasibility, intraoperative and postoperative complications, and outcomes were recorded. Immediate and 6-month clinical and angiographic results were evaluated.

RESULTS

Failure of WEB SL placement occurred in two cases. Eight aneurysms were successfully treated using one WEB SL without additional treatment. Three middle cerebral artery, four anterior communicating artery, and one basilar artery aneurysms were treated. Average dome width was 7.5 mm (range 5.4-10.7 mm), and average neck size was 4.9 mm (range 2.6-6.5 mm). No periprocedural complication was observed, and morbi-mortality at discharge and 6 months was 0.0%. Angiographic follow-up at 6 months demonstrated complete aneurysm occlusion in 2/8 aneurysms, neck remnant in 5/8 aneurysms, and aneurysm remnant in 1/8 aneurysm.

CONCLUSIONS

From this preliminary study, treatment of bifurcation intracranial aneurysms using WEB SL is feasible. WEB SL treatment seems safe at 6 months; however, the rate of neck remnants is not negligible due to compression of the WEB SL. Further technical improvements may be needed in order to ameliorate the occlusion in the WEB SL treatment.

Comparison of Intracranial Aneurysms Treated by 2-D Versus 3-D Coils: A Matched-Pairs Analysis

OBJECTIVE

Knowledge on the influence of 2D and 3D coils to occlude intracranial aneurysms is poor. Therefore, aim of our analysis was to evaluate whether the use of 3-D versus 2-D coils alone may improve the efficacy of endovascular aneurysm treatment.

PATIENTS AND METHODS

We performed a matched pair analysis comparing aneurysms treated by 3-D coils as initial "framing" coils to aneurysms treated exclusively by 2-D coils. Number of coils, implanted coil length/volume, and associated packing density were calculated. Aneurysmal occlusion was assessed and monitored 6 months (DSA; magnetic resonance angiography (MRA)) and 18 months (MRA) after embolization. Periprocedural complications and retreatment rate of each group were analyzed.

RESULTS

Our retrospective analysis revealed 50 pairs. Concerning the 3-D group, number of coils (353 in total, median 7; p = 0.002), implanted coil length (55.69  ± 48.4 cm), implanted coil length per volume (5.92 mm/mm³), and packing density (30 %; p = 0.017) was higher than in the 2-D group (259 in total, median 5 coils; 38.52 ± 43.13 cm; 4.54 mm/mm³; 23 %). Occlusion was not significantly different immediately after treatment but at 6 and 18 months follow-up in favor of 3-D coils. Retreatment was performed in 2 cases of the 3-D group and in 3 cases of the 2-D group and therefore in a similar range (p = 0.564).

CONCLUSION

Initial use of 3-D coils revealed a higher packing density and a higher long-term occlusion. Therefore, we recommend initial use of 3-D coils.

A decade after International Subarachnoid Aneurysm Trial: Coiling as a first choice treatment in the management of intracranial aneurysms - Technical feasibility and early management outcomes

Purpose:

The technique of coiling has evolved in the last decade with evolution in both equipment and material. The preferable treatment of intracranial aneurysms at our center is endovascular coiling. We discuss the technical and management outcomes of consecutive patients treated with this approach and compare our results with a decade old International Subarachnoid Aneurysm Trial.

Materials and Methods:

Between January 2006 and November 2011, a total of 324 aneurysms in 304 consecutive patients were treated. Endovascular treatment was done in 308 aneurysms (95.0%) in 288 patients while 16 patients (5%) underwent surgical clipping. Of the 308 aneurysms treated endovascularly, 269 (87.3%) were ruptured, and 39 (12.7%) were unruptured aneurysms.

Results:

The endovascular coiling was feasible in all (99.6%) but 1 case. The immediate postoperative occlusion status was complete occlusion in 240 aneurysms (77.9%), neck remnant in 57 aneurysms (18.5%), and aneurysm remnant in 11 aneurysms (3.6%). Technical issues – with or without clinical effect–were encountered in 20 patients (6.9%). They included 18 thromboembolic events (6.2%) and intraprocedural aneurysmal rupture in 2 cases (0.7%). In “good grade” patients, H and H grade 1-3, a good outcome (modified Rankin score [mRS] 0-2) was in 87.6% patients while the bad outcome (mRS 3-5) was in 10.2% patients and mortality of 2.2%. In “bad grade” patients, H and H grade 3-5, a good outcome was in 29.2%, and bad outcome was in 41.7% patients with mortality was 29.1%. In the unruptured aneurysm group, the good outcome was seen in 97.7% and bad outcome in 2.3% with no mortality.

Conclusions:

In the current era, the favorable results of coiling demonstrated in previous studies may be applicable to the larger proportion of patients. In our series of consecutively treated patients using latest advances, such as three-dimensional imaging and the interventional material, endovascular management as first choice was feasible in 95% of patients with good technical and management outcomes.

Hemodynamic impact of cerebral aneurysm endovascular treatment devices: coils and flow diverters

Coils and flow diverters or stents are devices successfully used to treat cerebral aneurysms. Treatment aims to reduce intra-aneurysmal flow, thereby separating the aneurysmal sac from the blood circulation. The focus and this manuscript combining literature review and our original research is an analysis of changes in aneurysmal hemodynamics caused by endovascular treatment devices. Knowledge of post-treatment hemodynamics is a path to successful long-term treatment. Summarizing findings on hemodynamic impact of treatment devices, we conclude: coiling and stenting do not affect post-treatment intra-aneurysmal pressure, but significantly alter aneurysmal hemodynamics through flow reduction and a change in flow structure. The impact of treatment devices on aneurysmal flow depends, however, on a set of parameters including device geometry, course of placement, parent vessel and aneurysm geometry.

[Neuroimaging follow-up of cerebral aneurysms treated with endovascular techniques]

There are no specific recommendations in clinical guidelines about the best time, imaging tests, or intervals for following up patients with intracranial aneurysms treated with endovascular techniques. We reviewed the literature, using the following keywords to search in the main medical databases: cerebral aneurysm, coils, endovascular procedure, and follow-up. Within the Cerebrovascular Disease Group of the Spanish Society of Neuroradiology, we aimed to propose recommendations and an orientative protocol based on the scientific evidence for using neuroimaging to monitor intracranial aneurysms that have been treated with endovascular techniques. We aimed to specify the most appropriate neuroimaging techniques, the interval, the time of follow-up, and the best approach to defining the imaging findings, with the ultimate goal of improving clinical outcomes while optimizing and rationalizing the use of available resources.

Reactive tissue proliferation and damage of elastic lamina caused by hydrogel coated coils in experimental rat aneurysms

BACKGROUND AND OBJECTIVE

The HydroCoil Endovascular Aneurysm Occlusion and Packing Study clinical trial, comparing HydroCoil with platinum coils, reported an 8.6% reduction in significant recurrence following cerebral aneurysm coil embolization. We sought to better understand the mechanism of aneurysmal healing following HydroCoil implantation using the rat external carotid artery (ECA) sidewall aneurysm model.

METHODS

We ligated the proximal ECA, creating a blind pouch in our rat model. HydroCoil or bare platinum coil segments (5 mm) were inserted into aneurysms. Sham operated rats underwent identical procedures without coil insertion. 14 days after coil embolization, animals were sacrificed and the common carotid artery/internal carotid artery/ECA complex removed. Sac and surrounding vasculature underwent microscopic and histopathologic evaluation. Cellular and fibrotic components within the sac were defined as the organized area. Percentage of organized area and residual length of internal elastic lamina were calculated.

RESULTS

Organized tissue area in ECA sac 2 weeks following coil embolization was significantly greater in the HydroCoil group than the bare coil (60.42±22.58% vs 15.62±19.24%; p=0.01) and sham (60.42±22.58% vs 4.61±3.86%; p=0.002) groups. Elastic lamina was significantly reduced in the HydroCoil group compared with the sham and bare coil groups (21.67±16.50% vs 100% and 96.06±8.78%; both p<0.001). No significant difference was found between the bare coil and sham groups for organized tissue formation or reduction in elastic lamina. Greater numbers of B cells, T cells, and neutrophils were present within HydroCoil induced organized tissue compared with the platinum group; this difference was not statistically significant.

CONCLUSIONS

In the rat ECA sidewall aneurysm model, hydrogel coated coils cause more tissue reaction and organization compared with bare platinum coils, possibly attributed to observed elastic lamina damage and vascular smooth muscle cell proliferation.

Long-term outcomes of coil packing for visceral aneurysms: correlation between packing density and incidence of coil compaction or recanalization

PURPOSE

To evaluate the correlation between packing density and the incidence of coil compaction or recanalization of visceral artery aneurysms (VAAs) after coil packing.

MATERIALS AND METHODS

Between July 2004 and April 2012, coil packing was performed for 46 true visceral aneurysms (16 splenic, 11 pancreaticoduodenal, eight renal, six hepatic, three superior mesenteric, one right gastric, and one gastroepiploic) in 42 patients. The size and volume of the aneurysm, packing density, and the incidences of compaction and recanalization were evaluated retrospectively.

RESULTS

The mean follow-up period was 37 months ± 8 (range, 11-80 mo). The mean packing density was 19% ± 8 (range, 5%-42%), mean aneurysm size was 19 mm ± 8 (range, 5-40 mm), and mean volume was 4,108 mm(3) ± 5,435 (range, 72-26,235 mm(3)). Compaction and recanalization occurred in two (4%) and 12 aneurysms (26%), respectively. The mean packing density was significantly lower in aneurysms with compaction or recanalization than in unaffected aneurysms (12% vs 22%; P = .00014). There was a significant difference in mean packing density between small (< 20 mm; 22%) and large (≥ 20 mm) aneurysms (15%; P = .0045). The mean size and volume were significantly larger for coil-compacted or recanalized aneurysms than for unaffected aneurysms (P < .05). In aneurysms with a packing density of at least 24%, no compaction or recanalization occurred.

CONCLUSIONS

Coil compaction or recanalization after coil packing for VAAs more often occurs after insufficient embolization with low packing density and in patients with large aneurysms.

Pipeline for uncoilable or failed aneurysms: results from a multicenter clinical trial

PURPOSE

To evaluate the safety and effectiveness of the Pipeline Embolization Device (PED; ev3/Covidien, Irvine, Calif) in the treatment of complex intracranial aneurysms.

MATERIALS AND METHODS

The Pipeline for Uncoilable or Failed Aneurysms is a multicenter, prospective, interventional, single-arm trial of PED for the treatment of uncoilable or failed aneurysms of the internal carotid artery. Institutional review board approval of the HIPAA-compliant study protocol was obtained from each center. After providing informed consent, 108 patients with recently unruptured large and giant wide-necked aneurysms were enrolled in the study. The primary effectiveness endpoint was angiographic evaluation that demonstrated complete aneurysm occlusion and absence of major stenosis at 180 days. The primary safety endpoint was occurrence of major ipsilateral stroke or neurologic death at 180 days.

RESULTS

PED placement was technically successful in 107 of 108 patients (99.1%). Mean aneurysm size was 18.2 mm; 22 aneurysms (20.4%) were giant (>25 mm). Of the 106 aneurysms, 78 met the study's primary effectiveness endpoint (73.6%; 95% posterior probability interval: 64.4%-81.0%). Six of the 107 patients in the safety cohort experienced a major ipsilateral stroke or neurologic death (5.6%; 95% posterior probability interval: 2.6%-11.7%).

CONCLUSION

PED offers a reasonably safe and effective treatment of large or giant intracranial internal carotid artery aneurysms, demonstrated by high rates of complete aneurysm occlusion and low rates of adverse neurologic events; even in aneurysms failing previous alternative treatments.

Initial experience with an extremely soft bare platinum coil, ED coil-10 Extra Soft, for endovascular treatment of cerebral aneurysms

BACKGROUND AND PURPOSE

The ED coil-10 Extra Soft (EDC-10 ES) is an extremely soft coil with excellent operability for embolization of cerebral aneurysms and is frequently used as a 'finishing coil'. The aim of this study was to evaluate the efficacy and safety of this coil.

METHODS

Clinical data were analyzed retrospectively for 92 consecutive aneurysms for which at least one EDC-10 ES was used. Follow-up angiography at 6 months was available for 69 aneurysms. Initial and follow-up outcomes were evaluated using three-category occlusion grading. Factors that affect the packing density were also investigated.

RESULTS

Of the 92 aneurysms, 63 (68.5%) were classified as complete occlusion, 11 (12.0%) as having a neck remnant and 18 (19.6%) with dome filling immediately after the embolization procedure. The mean ± SD packing density was 29.5 ± 10.6%. Periprocedural complications were observed in three cases (3.3%). At 6 months the rate of completely occluded cases increased to 78.3% (54/69) and those for neck remnant and dome filling decreased to 11.8% (8/69) and 10.1% (7/69), respectively. Recanalization occurred in six aneurysms and one aneurysm was retreated during the follow-up period, giving an overall recurrence rate of 10.0% (7/70). Linear regression analysis showed a significant association of packing density with the percentage EDC-10 ES volume (p<0.001) and with the maximum aneurysm size (p<0.001).

CONCLUSIONS

Use of the EDC-10 ES permits safe and effective embolization of a cerebral aneurysm and contributes to a reduction in the rate of recanalization.

The Orbit Galaxy XTRASOFT Coils: A Multicenter Study of Coil Safety and Efficacy in Both Ruptured and Unruptured Cerebral Aneurysms

Increase packing density with the use of softer three-dimensional (3D) coils has been indicated in reducing aneurysm recurrence. We are reporting a multicenter initial experience of using the Orbit Galaxy XTRASOFT which is a stretch-resistant, softer 3D coil in both ruptured and unruptured aneurysms. A total of 57 consecutive patients from five high-volume neurointerventional centers were reported where at least one Galaxy XTRASOFT coil was used during a procedure. There were 25 patients with ruptured aneurysm and 32 with elective coiling. The overall complication rate was 3.5%, one patient with nonoperative retroperitoneal hematoma and one patient with intraoperative rupture but with no neurological deficit. The occlusion rate of 90% or greater was achieved in 86% of the cases. The discharge modified Rankin score of 0 or 1 was achieved in 100% of the elective coiling and 65% in the ruptured cases. Early experience with Galaxy XTRASOFT coils for both ruptured and unruptured aneurysms appears to be safe with good aneurysm obliteration and low complication rate.

Cerecyte coil trial: procedural safety and clinical outcomes in patients with ruptured and unruptured intracranial aneurysms

BACKGROUND AND PURPOSE

This study arose from a need to systematically evaluate the clinical and angiographic outcomes of intracranial aneurysms treated with modified coils. We report the procedural safety and clinical outcomes in a prospective randomized controlled trial of endovascular coiling for ruptured and unruptured intracranial aneurysms, comparing polymer-loaded Cerecyte coils with bare platinum coils in 23 centers worldwide.

MATERIALS AND METHODS

Five hundred patients between 18 and 70 years of age with a ruptured or unruptured target aneurysm planning to undergo endovascular coiling were randomized to receive Cerecyte or bare platinum coils. Analysis was by intention to treat.

RESULTS

Two hundred forty-nine patients were allocated to Cerecyte coils and 251 to bare platinum coils. Baseline characteristics were balanced. For ruptured aneurysms, in-hospital mortality was 2/114 (1.8%) with Cerecyte versus 0/119 (0%) bare platinum coils. There were 8 (3.4%) adverse procedural events resulting in neurological deterioration: 5/114 (4.4%) with Cerecyte versus 3/119 (2.5%) with bare platinum coils (P = .22). The 6-month mRS score of ≤2 was not significantly different in 103/109 (94.5%) patients with Cerecyte and 110/112 (98.2%) patients with bare platinum coils. Poor outcome (mRS score of ≥3 or death) was 6/109 (5.5%) with Cerecyte versus 2/112 (1.8%) with bare platinum coils (P = .070). For UIAs, there was no in-hospital mortality. There were 7 (2.7%) adverse procedural events with neurological deterioration, 5/133 (3.8%) with Cerecyte versus 2/131 (1.5%) with bare platinum coils (P = .13). There was a 6-month mRS score of ≤2 in 114/119 (95.8%) patients with Cerecyte versus 123/123 (100%) patients with bare platinum coils. There was poor outcome (mRS ≥3 and 1 death) in 5/119 (4.2%) patients with Cerecyte versus 0/123 (0%) patients with bare platinum coils (P = .011).

CONCLUSIONS

There was a statistical excess of poor outcomes in the Cerecyte arm at discharge in the ruptured aneurysm group and at 6-month follow-up in the unruptured group. Overall adverse clinical outcomes and in-hospital mortality were exceptionally low in both groups.

High shear stress and flow velocity in partially occluded aneurysms prone to recanalization

BACKGROUND AND PURPOSE

Hemodynamic factors are thought to play an important role in the initiation, growth, and rupture of cerebral aneurysms. However, the hemodynamic features in the residual neck of the partially embolized aneurysms and their influences on recanalization are rarely reported. In this study, we characterized the hemodynamics of partially occluded aneurysms, which were proven to undergo recanalization during follow-up using computational fluid dynamic analysis.

METHODS

From May 2007 to June 2009, we identified 11 partial aneurysms during follow-up, including 5 recanalized cases and 6 stable cases with 3-dimensional digital subtraction angiography. We retrospectively characterized the hemodynamic features around the residual aneurysmal pouch using the available postprocedural digital subtraction angiography image data. The occluded part of the aneurysm was regarded as completely separated from the circulation.

RESULTS

The overall blood flow patterns before embolization were almost the same in the recanalized and stable groups. After occlusion, the flow pattern changes, wall shear stress (WSS), and velocity at the remnant neck demonstrated different changes between the 2 groups. Specifically, in the recanalized group, high WSS regions were found near the neck in all 5 cases, with 4 of them being even higher than those before occlusion. Interestingly, in all cases, the high WSS area of the remnant neck coincided with the location where the aneurysm recanalization occurred. In the stable group, 5 out of 6 cases demonstrated lower WSS and velocity at the remnant neck after occlusion.

CONCLUSIONS

High WSS and blood flow velocity were consistently observed near the remnant neck of partially embolized aneurysms prone to future recanalization, suggesting that hemodynamic factors may have an important role in aneurysmal recurrence after endovascular treatment. The difference in flow pattern could be caused by the incomplete occlusion of the aneurysms.

Differential gene expression in well-healed and poorly healed experimental aneurysms after coil treatment

PURPOSE

To compare gene expression patterns between well-healed and poorly healed aneurysms following coil embolization in a rabbit model.

MATERIALS AND METHODS

The Institutional Animal Care and Use Committee approved all procedures before initiation of the study. Elastase-induced, saccular aneurysms were created in rabbits and embolized by using platinum microcoils. Group 1 aneurysms were densely packed (volumetric packing density, >30%) to achieve good healing, whereas group 2 aneurysms were loosely packed (volumetric packing density, <20%), which yields poor healing. At 2 or 4 weeks after implantation, samples were harvested. RNA was isolated separately from the necks and domes of the aneurysms and analyzed by using a microarray containing 294 rabbit genes. Genes with significant differences between groups (P < .05; false discovery rate, <0.1; fold change, ≥1.2 and ≤0.8) were considered differentially expressed.

RESULTS

At 2 weeks, of 294 genes, 22 (7.5%) genes in the neck and 14 (4.8%) genes in the dome were differentially expressed between groups; at 4 weeks, of 294 genes, 25 (8.5%) genes in the neck and 17 (5.8%) genes in the dome were differentially expressed between groups. Genes overexpressed in group 1 as compared with group 2 aneurysms included those encoding proteases, adhesion molecules, and chemoattractant molecules. Conversely, group 2 aneurysms had increased expression of genes encoding structural molecules, including collagens, as compared with expression in group 1 aneurysms.

CONCLUSION

Robust healing after coil embolization is associated with substantial biological activity, as evidenced by overexpression of proteases, adhesion molecules, and chemoattractants. However, contrary to prior hypotheses, structural molecules such as collagen were not associated with the healing response in the rabbit model.

In vitro study of near-wall flow in a cerebral aneurysm model with and without coils

BACKGROUND AND PURPOSE

Coil embolization procedures change the flow conditions in the cerebral aneurysm and, therefore, in the near-wall region. Knowledge of these flow changes may be helpful to optimize therapy. The goal of this study was to investigate the effect of the coil-packing attenuation on the near-wall flow and its variability due to differences in the coil structure.

MATERIALS AND METHODS

An enlarged transparent model of an ACA aneurysm was fabricated on the basis of CT angiography. The near-wall flow was visualized by using a recently proposed technique called Wall-PIV. Coil-packing attenuation of 10%, 15%, and 20% were investigated and compared with an aneurysmal flow without coils. Then the flow variability due to the coil introduction was analyzed in 10 experiments by using a packing attenuation of 15%.

RESULTS

A small packing attenuation of 10% already alters the near-wall flow significantly in a large part of the aneurysmal sac. These flow changes are characterized by a slow flow with short (interrupted) path lines. An increased packing attenuation expands the wall area exposed to the altered flow conditions. This area, however, depends on the coil position and/or on the 3D coil structure in the aneurysm.

CONCLUSIONS

To our knowledge, this is the first time the near-wall flow changes caused by coils in an aneurysm model have been visualized. It can be concluded that future hydrodynamic studies of coil therapy should include an investigation of the coil structure in addition to the coil-packing attenuation.