Nuisance bleeding complications in patients with cerebral aneurysm treated with Pipeline embolization device

Nanoarchitectonic Engineering of Thermal-Responsive Magnetic Nanorobot Collectives for Intracranial Aneurysm Therapy

Stent-assisted coiling is a main treatment modality for intracranial aneurysms (IAs) in clinics, but critical challenges remain to be overcome, such as exogenous implant-induced stenosis and reliance on antiplatelet agents. Herein, an endovascular approach is reported for IA therapy without stent grafting or microcatheter shaping, enabled by active delivery of thrombin (Th) to target aneurysms using innovative phase-change material (PCM)-coated magnetite-thrombin (Fe3O4-Th@PCM) FTP nanorobots. The nanorobots are controlled by an integrated actuation system of dynamic torque-force hybrid magnetic fields. With robust intravascular navigation guided by real-time ultrasound imaging, nanorobotic collectives can effectively accumulate and retain in model aneurysms constructed in vivo, followed by controlled release of the encapsulated Th for rapid occlusion of the aneurysm upon melting the protective PCM (thermally responsive in a tunable manner) through focused magnetic hyperthermia. Complete and stable aneurysm embolization is confirmed by postoperative examination and 2-week postembolization follow-up using digital subtraction angiography (DSA), contrast-enhanced ultrasound (CEUS), and histological analysis. The safety of the embolization therapy is assessed through biocompatibility evaluation and histopathology assays. This strategy, seamlessly integrating secure drug packaging, agile magnetic actuation, and clinical interventional imaging, avoids possible exogenous implant rejection, circumvents cumbersome microcatheter shaping, and offers a promising option for IA therapy.

Flow Diversion for Endovascular Treatment of Intracranial Aneurysms: Past, Present, and Future Directions

Flow diversion for intracranial aneurysms emerged as an efficacious and durable treatment option over the last two decades. In a paradigm shift from intrasaccular aneurysm embolization to parent vessel remodeling as the mechanism of action, the proliferation of flow-diverting devices has enabled the treatment of many aneurysms previously considered untreatable. In this review, we review the history and development of flow diverters, highlight the pivotal clinical trials leading to their regulatory approval, review current devices including endoluminal and intrasaccular flow diverters, and discuss current and expanding indications for their use. Areas of clinical equipoise, including ruptured aneurysms and wide-neck bifurcation aneurysms, are summarized with a focus on flow diverters for these pathologies. Finally, we discuss future directions in flow diversion technology including bioresorbable flow diverters, transcriptomics and radiogenomics, and machine learning and artificial intelligence.

Preclinical in vitro and in vivo results of the new silk vista flow diverter with P8RI coating

BACKGROUND

Flow diverting stents (FDS) have transformed the treatment of intracranial aneurysms; however, their metallic structure associated with their intra-luminal positioning hamper angiographic and clinical outcomes. Therefore, there is a need to develop FDS with optimized surfaces that reduce thrombogenicity while promoting the healing process and endothelialization.

METHODS

P8RI, a peptide mimicking the CD31 protein, was previously developed and grafted onto Silk Vista (SV) FDS. P8RI-SV and bare-SV were used in vitro in a blood loop model to test their hemocompatibility using human whole blood and in vivo using the rabbit elastase model for optical coherence tomography (OCT) comparisons of neointimal formation at day 5 and day 28.

RESULTS

After blood loop incubation, P8RI-SV showed significant reduction in fibrin binding (p=0.004) and platelet adhesion (p=0.041) compared with bare-SV. Similarly, derivative markers measured in blood, thromboxane B2 (platelet activation) and Thrombin-Antithrombin III complexes (coagulation activation), were also significantly reduced in the P8RI-SV group (both p=0.002). In vivo, complete or near-complete occlusion was reached in all aneurysms (n=6) at day 28. Excellent rate of stent-coverage ratio was obtained at day 5 (89.3% (79.1%-98.7%)) comparable to the observation at day 28 (91.8% (79.1%-100%); p=0.44). These rates were significantly higher compared with bare-SV at day 5 (77.8% (58.3%-86.8%); p<0.001) and at day 28 (67.7% (52.6%-88.9%); p<0.0001).

CONCLUSION

In vitro results confirm enhanced hemocompatibility with a significant anti-thrombotic effect of the P8RI-SV. In vivo results provide evidence of rapid neo-intimal growth reaching near-complete tissue healing as early as day 5 in a rabbit model.

Flow diverter surface modifications for aneurysm treatment: A review of the mechanisms and data behind existing technologies

Flow diversion (FD) has become a mainstay treatment for large wide-necked aneurysms. Despite excellent safety and efficacy, the risk of thromboembolic complications necessitates the use of dual antiplatelet therapy (DAPT). The use of DAPT makes hemorrhagic complications of stenting carry high morbidity and mortality. Additionally, DAPT usage carries a risk of "nuisance" complications that do not directly impact intracranial circulation but need to be managed nonetheless. To circumvent this issue, the most recent generation of flow diverters have undergone surface modification with various compounds to confer blood compatibility to limit clotting and thrombosis. While these newer generation flow diverters are marketed to enhance ease of deployment, the goal is to eventually facilitate single antiplatelet use with flow diverter treatment. This generation of FDs have potential to expand indications beyond unruptured wide-necked aneurysms to include ruptured intracranial aneurysms without the necessity of DAPT. Currently, no comprehensive review details the molecular mechanisms and pre-clinical and clinical data on these modifications. We seek to fill this gap in the literature by consolidating information on the coating technology for four major FDs currently in clinical use-PipelineTM Flex and Vantage Shield TechnologyTM, FREDTMX, p48/64 hydrophilic coating, and Acandis Dervio® 2heal-to serve as a reference guide in neurointerventional aneurysm treatment. Although the Balt silkTM was one of the first FDs, it is uncoated, thus we will not cover this device in our review. A literature review was performed to obtain information on each coating technology for the major flow diverters currently on the market using international databases (PUBMED, Embase, Medline, Google Scholar). The search criteria used the keywords for each coating technology of interest "phosphorylcholine," "poly 2-methoxyethyl acrylate," "hydrophilic polymer coating," and "fibrin-heparin" Keywords related to the device names "Pipeline Shield," "Pipeline Shield with Flex Technology," "FRED," "FREDX," "p64," "p64-HPC," "Derivo 2heal" were also used. Studies that detailed the mechanism of action of the coating, any pre-clinical studies with surface-modified intravascular devices, and any clinical retrospective series, prospective series, or randomized clinical trials with surface-modified devices for aneurysm treatment were included.

Early Termination versus Standard Regimen Duration of Dual Antiplatelet Therapy in Intracranial Aneurysm Patients Treated With Pipeline Embolization Device Flex With Shield Technology: Preliminary Experience of 3 U.S. Centers

BACKGROUND

Pipeline Flex Embolization Device with Shield Technology (PED-Shield) is a third-generation flow diverter with reduced thromboembolic potential. However, safety profile and dual antiplatelet therapy (DAPT) recommendations with PED-Shield is not well -established. We aim to assess the safety and complication profile with early termination of DAPT with use of PED-Shield.

METHODS

Databases of 3 high-volume cerebrovascular centers were retrospectively reviewed. We identified patients with unruptured and ruptured intracranial aneurysms treated with PED-Shield. Patient demographics, aneurysm characteristics, complications, and angiographic outcomes were extracted. All patients who had early termination of DAPT, defined as <180 days, as well as standard duration were included.

RESULTS

A total of 37 patients, totaling 37 aneurysms, had early termination of DAPT and 24 patients with 24 aneurysms received standard duration (>180 days) of DAPT. There was no difference in pre-procedural DAPT regimens between the groups (P = 0.503). Following DAPT termination, o1ne major thromboembolic complication was observed in the early termination group while no major or minor thromboembolic or hemorrhagic complication was noted in the standard duration group. Time of angiographic follow-up was not statistically different (P = 0.063) between the early termination (343 days, interquartile range [IQR] 114-371 days) and the standard duration (175 days, IQR 111-224.5 days) groups. There were no statistically significant differences in complete aneurysm occlusion (P = 0.857), residual neck (P = 0.582), and aneurysm remnant (P = 0.352) rates between the groups on angiography.

CONCLUSIONS

Early termination of DAPT proves safe after PED-Shield treatment of intracranial aneurysms with comparable complete occlusion rates.

Analysis of reported adverse events of pipeline stents for intracranial aneurysms using the FDA MAUDE database

OBJECTIVE

Flow diverting stents (FDS) are a validated device in the treatment of intracranial aneurysms, allowing for minimally invasive intervention. However, after its approval for use in the United States in 2011, post-market surveillance of adverse events is limited. This study aims to address this critical knowledge gap by analyzing the FDA Manufacturer and User Facility Device Experience (MAUDE) database for patient and device related (PR and DR) reports of adverse events and malfunctions.

METHODS

Using post-market surveillance data from the MAUDE database, PR and DR reports from January 2012-December 2021 were extracted, compiled, and analyzed with R-Studio version 2021.09.2. PR and DR reports with insufficient information were excluded. Raw information was organized, and further author generated classifications were created for both PR and DR reports.

RESULTS

A total of 2203 PR and 4017 DR events were recorded. The most frequently reported PR adverse event categories were cerebrovascular (60%), death (11%), and neurological (8%). The most frequent PR adverse event reports were death (11%), thrombosis/thrombus (9%) cerebral infarction (8%), decreased therapeutic response (7%), stroke/cerebrovascular accident (6%), intracranial hemorrhage (5%), aneurysm (4%), occlusion (4%), headache (4%), neurological deficit/dysfunction (3%). The most frequent DR reports were activation/positioning/separation problems (52%), break (9%), device operates differently than expected (4%), difficult to open or close (4%), material deformation (3%), migration or expulsion of device (3%), detachment of device or device component (2%).

CONCLUSIONS

Post-market surveillance is important to guide patient counselling and identify adverse events and device problems that were not identified in initial trials. We present frequent reports of several types of cerebrovascular and neurological adverse events as well as the most common device shortcomings that should be explored by manufacturers and future studies. Although inherent limitations to the MAUDE database are present, our results highlight important PR and DR complications that can help optimize patient counseling and device development.

Ticagrelor is related to nuisance bleeding after flow diversion of unruptured intracranial aneurysms

Nuisance bleeding (NB) without urgent medical attention is rarely characterized despite its frequent occurrence in patients with cerebral aneurysms undergoing flow diversion (FD) who are maintained on dual antiplatelet therapy (DAPT). This study explored the risk factors for NB. Patients with unruptured cerebral aneurysms who underwent intervention using FD (July 2018 to May 2022) and had follow-up data were enrolled. Patient demographics, clinical characteristics, aneurysm features and follow-up data were analysed. Bleeding complications were classified as NB, internal bleeding and alarming bleeding. NB was characterized by easy bruising, bleeding from small cuts and nonfatal petechiae and ecchymosis. Univariate and multivariate logistic regression analyses were performed to determine risk factors for NB. This study assessed 121 patients. Of these, 52 (43.0%) patients had NB. Compared with the non-bleeding group, the NB group had more females (82.7% vs. 56.5%; p = 0.003), lower smoking rate (7.7% vs. 23.2%; p = 0.027) and smaller aneurysms (6.65 mm [4.60-9.60 mm] vs. 8.82 mm [5.65-15.65 mm]; p = 0.007) and had more patients maintained on ticagrelor-containing DAPT regimen (90.4% vs. 66.7%; p = 0.002). Multivariate logistic regression revealed that ticagrelor-containing DAPT regimen (odds ratio, 3.91; 95% confidence interval, 1.29-11.87; p = 0.016) was associated with NB. These results suggest that NB is a common bleeding complaint in patients on DAPT. In patients undergoing FD, DAPT with ticagrelor was the only independent risk factor for NB.

A comparison of antiplatelet therapy during the peri- and post-operative periods following flow-diverting stent insertion for unruptured intracranial aneurysms: A systematic review

BACKGROUND

Flow diverters (FDs) are neuroendovascular stents indicated for the management of unruptured intracranial aneurysms. Due to their composition, dual antiplatelet therapy (DAPT) is essential during the peri- and post-operative periods to prevent thromboembolic events. However, there is limited consensus within the scientific community regarding which antiplatelets to use and dosing following neuroendovascular treatment of aneurysms.

METHOD

A systematic search of four electronic databases was conducted during November 2020 that included studies published between January 2010 and November 2020. Eligibility for inclusion included primary research articles, published in the English language and use of flow-diverting intracranial stents. Studies were excluded if they utilised combined therapies (e.g. FD with stent-assisted coiling), animal studies, clinical trial protocols and study population of less than 10 subjects.

RESULTS

Eighteen studies were identified for inclusion with a total of 1312 patients with 1355 unruptured intracranial aneurysms treated with FDs. Of these, 13 studies primarily investigated the use of clopidogrel with aspirin with low rates of haemorrhagic and thromboembolic complications. A forest plot of nine of these studies showed average efficacy of 88% at 95% confidence interval (CI) (SD + 5%) with 63% heterogeneity.

CONCLUSIONS

The large proportion of studies investigating clopidogrel and aspirin antiplatelet therapy presents a challenge in comparing antiplatelet regimens. Although prasugrel and ticagrelor have been identified as suitable alternatives to clopidogrel, these were based on studies with small cohort sizes. Glycoprotein IIb/IIIa inhibitors may be efficacious as rescue therapy for intra-procedural thrombosis. Further research is required to determine which antiplatelet is most suitable.

Intrasaccular flow disruption for brain aneurysms: a systematic review of long-term outcomes

OBJECTIVE

The long-term safety and efficacy of intrasaccular flow disruption (IFD) for the treatment of brain aneurysms remain unclear. With accumulating experience and increasing use of IFD devices, recent studies have provided additional data regarding their outcomes. This review summarizes the long-term outcomes of IFD-treated brain aneurysms.

METHODS

A systematic literature review was performed on May 23, 2021, in PubMed, Web of Science, and Ovid MEDLINE for aneurysm treatment outcomes with IFD devices. Procedural details, including use of adjunctive devices and complications, were collected. The quality of studies was assessed using the Downs and Black checklist. Angiographic outcomes were classified as complete occlusion, residual neck, and residual aneurysm. Other outcomes included need for retreatment, permanent neurological deficit, and mortality. Pooled analyses were performed.

RESULTS

The final analysis comprised 1217 patients with 1249 aneurysms from 22 studies. The mean aneurysm diameter and neck width were 6.9 and 4.5 mm, respectively, and 27.6% of aneurysms were ruptured. The complete occlusion rates at 12 months and final follow-up (pooled mean duration 15.7 months) were 50.1% and 58.2%, respectively. Adjunctive devices were used in 6.4% of cases. The rates of hemorrhage, symptomatic infarction, permanent neurological deficit, and mortality were 1.2%, 2.8%, 1.0%, and 2.6%, respectively.

CONCLUSIONS

IFD is a very safe treatment for appropriately selected brain aneurysms with low complication and neurological deterioration rates. However, complete occlusion is achieved in only half of IFD-treated aneurysms at 1 year with a modest increase beyond this time point. As the majority of the studies were single arm, the pooled data are subject to selection and reporting biases. Future device developments, increased operator experience, and direct comparisons with alternative endovascular strategies and surgical clipping may clarify the role of IFD in aneurysm management.

Clinical Usage of Different Doses of Cis-Atracurium in Intracranial Aneurysm Surgery and Its Effect on Motor-Evoked Potentials

The objective of this work was to investigate the effect of different doses of cis-atracurium on patients undergoing general anesthesia induction (GAI) during intracranial aneurysm surgery (ICAS). In this work, 90 patients who underwent ICAS under the elective motor-evoked potential (MEP) monitoring in the First Affiliated Hospital of Northwest University (Xi'an No. 1 Hospital) from January 2021 to May 2022 were enrolled as the research objects. Randomly, they were rolled into a S1 group (30 cases, 2 times 95% effective dose (ED95) cis-atracurium), a S2 group (30 cases, 3 times ED95 cis-atracurium), and a S3 group (30 cases, 4 times ED95 cis-atracurium). The endotracheal intubation conditions, the train-of-four (TOF) rate (TOFR), body movement, and spontaneous breathing were compared among the three groups of patients. The results showed that the MEP inhibition time of the patients in the S3 group was much longer than that of the S1 and S2 groups, but it showed no significant difference between the S1 group and S2 group (P > 0.05). The good rates of endotracheal intubation conditions in the S2 group (100%) and S3 group (100%) were obviously higher than the rate in the S1 group (43.33%). The TOFRs of patients in S2 and S3 groups at time t2 and t3 were lower obviously to that at time t0, while the TOFRs of patients in S3 group at time t2 and t3 were still lower in contrast to the S2 group (P < 0.05). The mean arterial pressure (MAP) and heart rate (HR) of patients in all groups were lower at t1, t2, and t3 than at t0 (P < 0.05), while the differences among different groups were not remarkable (P > 0.05). Finally, using 3 times ED95 cis-atracurium for GAI could reduce the risk of intraoperative body movement and spontaneous breathing, as well as the residual degree of muscle relaxation, in patients with ICAS, without affecting MEP monitoring, improving endotracheal intubation conditions, and increasing safety during open neurosurgery operations.

A systematic review and meta-analysis of the Derivo Embolization Device: a novel surface-modified flow diverter for intracranial aneurysm treatment

BACKGROUND

Surface-modified flow diverters (FDs) designed to reduce thrombogenicity represent the next frontier for intracranial aneurysm treatment. The Derivo Embolization Device (DED) is a novel FD with titanium oxide and titanium oxynitride finishing of the struts. We performed a systematic review of pertinent literature, aiming to evaluate the device's effectiveness and safety.

METHODS

A literature search of PubMed, Embase, and MEDLINE was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Five studies comprising 481 aneurysms were included. These studies were conducted in Turkey, Brazil, Germany, Poland, and Italy; two were prospective and three were retrospective. Twenty-six aneurysms (5.4%) were ruptured. The antiplatelet regimens were heterogeneous, but dual antiplatelet therapy was administered preprocedurally in all studies and maintained for 3-12 months before a switch to single antiplatelet therapy. The rate of periprocedural ischemic and hemorrhagic complications was 4.9% (95% CI 2.9% to 7%). Adjunctive coiling was used in 25.6% (95% CI 11.4% to 39.8%) of aneurysms. The complete angiographic occlusion rate was 81.4% (95% CI 71.3% to 91.5%), mortality rate was 2.1% (95% CI 0.4% to 3.9%), with follow-up ranging from 9 to 18 months. Delayed aneurysm rupture was reported in one patient.

CONCLUSIONS

The DED has been increasingly used in other countries. We identified low rates of periprocedural complications and mortality and a high rate of complete occlusion.

First U.S. Experience Using the Pipeline Flex Embolization Device with Shield Technology for Treatment of Intracranial Aneurysms

BACKGROUND

The Pipeline Flex Embolization Device with Shield technology (PED-Shield [Medtronic, Dublin, Ireland]) is a third-generation flow diverter. Surface modification of the mesh with phosphorylcholine covalently bound to the metal struts aims to reduce thrombogenicity. In the present study, we report the results from the first U.S. series of patients with intracranial aneurysms treated with the PED-Shield and a comprehensive systematic literature review.

METHODS

We retrospectively collected the patient demographics, aneurysm characteristics, procedural details, and periprocedural complications from our prospectively maintained endovascular database (April 2021 to July 2021). Our literature review encompassed 3 databases (PubMed, Embase, and MEDLINE).

RESULTS

Ten patients with 11 anterior circulation unruptured wide-necked aneurysms (10 saccular, 1 fusiform) were included. The average patient age was 64.7 years (range, 45-86 years), and 9 were women. One device demonstrated insufficient distal opening. No other technical issues or intraprocedural complications had occurred. After the procedure, 1 patient had developed a groin hematoma and 1 had experienced a small intracranial hemorrhage, with no clinical repercussions. All patients were discharged with dual-antiplatelet therapy. In the review, we identified 15 studies. Most had been conducted in Europe and South America and 3 were U.S. case reports of compassionate use of the device.

CONCLUSIONS

In our initial periprocedural experience with the PED-Shield for intracranial aneurysm treatment, the device demonstrated an excellent performance and no major complications. Further studies are required to evaluate the long-term follow-up results and the safety of different antiplatelet regimens.

P2Y12 inhibitors for the neurointerventionalist

The use of antiplatelets is widespread in clinical practice. However, for neurointerventional procedures, protocols for antiplatelet use are scarce and practice varies between individuals and institutions. This is further complicated by the quantity of antiplatelet agents which differ in route of administration, dosage, onset of action, efficacy and ischemic and hemorrhagic complications. Clarifying the individual characteristics for each antiplatelet agent, and their associated risks, will increasingly become relevant as the practice of mechanical thrombectomy, stenting, coiling and flow diversion procedures grows. The aim of this review is to summarize the existing literature for the use of P2Y12 inhibitors in neurointerventional procedures, examine the quality of the evidence, and highlight areas in need of further research.

Flow diverter stents in the treatment of recanalized intracranial aneurysms

BACKGROUND

We assessed the safety and efficacy of flow diverter stents (FDSs) in the treatment of recanalized or residual intracranial aneurysms treated endovascularly.

MATERIALS & METHODS

Patients whose recanalized or residual aneurysms were treated with FDSs in five tertiary hospitals were reviewed retrospectively. The patients' demographic data, aneurysm characteristics, types of previous treatment, and clinical complications, or serious adverse events associated with FDSs, as well as the results of neurological and angiographic follow-up assessments, were recorded.

RESULTS

Eighty-six patients (37 males) with 87 aneurysms were included in this study. Eighty (91.9%) aneurysms were in the anterior and seven (8.1%) in the posterior circulation. The initial treatment methods were the primary coiling or balloon remodeling technique in 69 (79.3%) and stent-assisted coiling in 18 (20.7%) aneurysms. The endovascular procedure was successful in all patients. Complications occurred in four patients, for a total complication rate of 4.6%. A technical complication developed in one patient (1.2%). An in-stent thrombosis treated with tirofiban was seen in two cases. Late in-stent stenosis exceeding 50% was treated with balloon angioplasty in one patient. The mean length of follow-up was 21.0 months. The first angiographic follow-up (3-6 months) revealed the complete occlusion of 74 aneurysms (85.1%). While 76 aneurysms (87.4%) were occluded at the last angiographic follow-up (mean: 26.0 months), 11 aneurysms (12.6%) were still filling. Morbimortality was zero.

CONCLUSION

The drawback of endovascular treatment is aneurysmal remnants or recurrences, which is safely and durably amenable to flow diversion.