Flow-diverting Stent Implantation Research Articles

Effects of a Novel Stereoscopic Flow-Diverting Stent on Intracranial Aneurysm Hemodynamics

Objective: To preliminarily explore the effects of a novel stereoscopic flow-diverting stent on the hemodynamics and pathophysiology of intracranial aneurysm. Methods: Three-dimensional digital subtraction angiography (3D-DSA) and transcranial Doppler ultrasound (TCD) findings and blood examination-related parameters were collected from eligible patients for clinical research. Then a model of aneurysm with its bearing artery was established, based on which a novel stereoscopic flow-diverting stent model was constructed, and hemodynamic data of fluid models with and without novel stereoscopic flow-diverting stent implantation were analyzed. Results: The novel stereoscopic flow-diverting stent could effectively decrease blood flow into the aneurysm and notably reduce blood flow velocity in the aneurysm. The time-averaged wall shear stress (TAWSS) in the aneurysm was distinctly attenuated, and the high shear stress distribution area was also markedly diminished. Conclusion: The novel stereoscopic flow-diverting stent plays an effective isolating role, which is conducive to inducing thrombosis in aneurysm, thus protecting aneurysm vessels. Furthermore, the novel stereoscopic flow-diverting stent can evidently alter the hemodynamic environment in the aneurysm, notably reduce blood flow into the aneurysm, attenuate the mechanical compression of pulsatile blood flow on the vascular wall, and slow down the blood flow velocity in the aneurysm, thus contributing to stabilizing aneurysm. Improving the hemodynamic environment guarantees arterial revascularization and stable thrombosis, thereby effectively controlling the illness.

Effects of the flow diversion technique on nucleotide levels in intra-cranial aneurysms: A feasibility study providing new research perspectives.

IntroductionThe flow diverter stent (FDS) has become a first-line treatment for numerous intra-cranial aneurysms (IAs) by promoting aneurysm thrombosis. However, the biological phenomena underlying its efficacy remain unknown. We proposed a method to collect in situ blood samples to explore the flow diversion effect within the aneurysm sac. In this feasibility study, we assessed the plasma levels of nucleotides within the aneurysm sac before and after flow diversion treatment.Materials and methodsIn total, 14 patients with unruptured IAs who were selected for FDS implantation were prospectively recruited from February 2015 to November 2015. Two catheters dedicated to (1) FDS deployment and (2) the aneurysm sac were used to collect blood samples within the parent artery (P1) and the aneurysm sac before (P2) and after (P3) flow diversion treatment. The plasma levels of adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) at each collection point were quantified with liquid chromatography and tandem mass spectrometry.ResultsThe aneurysms were extradural in nine (64.3%) patients and intra-dural in five (35.7%) patients. They presented an average diameter of 15.5 ± 7.1 mm, height of 15.8 ± 4.6 mm, and volume of 2,549 ± 2,794 ml. In all patients (100%), 16 FDS implantations and 42 in situ blood collections were performed successfully without any complications associated with the procedure. The ATP, ADP, and AMP concentrations within the aneurysm sac were decreased after flow diversion (p = 0.005, p = 0.03, and p = 0.12, respectively). Only the ATP levels within the aneurysm sac after flow diversion were significantly correlated with aneurysm volume (adjusted R2 = 0.43; p = 0.01).ConclusionIn situ blood collection within unruptured IAs during a flow diversion procedure is feasible and safe. Our results suggest that the flow diversion technique is associated with changes in the nucleotide plasma levels within the aneurysm sac.

Acute Intraprocedural Thrombosis After Flow Diverter Stent Implantation: Risk Factors and Relevance of Standard Observation Time for Early Detection and Management

PurposeAcute intraprocedural thrombosis (AIT) is a severe complication of flow diverter stent (FDS) implantation for the treatment of intracranial aneurysms. Even though device-related thromboembolic complications are well known, there are no acknowledged risk factors nor defined surveillance protocols for their early detection. This study aimed to demonstrate that an angiographic active surveillance is effective to detect and treat AIT. Furthermore, we investigated risk factors for the occurrence of AIT.MethodsA prospective institutional protocol consisting of a defined observation period of 30 min following FDS deployment was established to detect AIT. Overall incidence, as well as the efficacy and safety of AIT treatment were assessed. Moreover, radiological and clinical outcomes of patients with AIT were analyzed. The influence of various patient- and procedure-related factors on the occurrence of AIT was investigated using multivariable forward logistic regression.ResultsDuring active surveillance twelve cases of AIT were observed among a total of 161 procedures (incidence: 7.5%). The median time of first observation was 15.5 min (IQR 9.5) after FDS implantation. The early recognition of AIT ensured a prompt treatment with intravenous application of a glycoprotein IIb/IIIa inhibitor, which led to complete thrombus resolution in all cases without hemorrhagic complications. Patients with pre-existing arterial hypertension and side branches originating from the aneurysmal sac had a higher risk of AIT (respectively OR, 9.844; OR, 3.553). There were two cases of re-thrombosis in the short-term postoperative period, of whom one died. The remaining patients with AIT had a good clinical outcome.ConclusionActive surveillance for 30 min after FDS implantation is an effective strategy for early detection and ensuing treatment of AIT and can thus prevent secondary sequalae. Hypertension and side branches originating from the aneurysmal sac may increase the risk of AIT.

Clinical evaluation of high-resolution cone-beam computed tomography for the implantation of flow-diverter stents in intracranial aneurysms

It is well-established that complete expansion and proper apposition to the vessel wall of flow-diverter stents are critical for optimizing endovascular aneurysm outcomes by using flow diversion techniques. We aimed to evaluate the clinical value of high-resolution cone-beam CT (HR-CBCT) upon flow-diverter stent implantation in intracranial aneurysms. In this study, we retrospectively analyzed the clinical data of eighty-one patients (101 intracranial aneurysms) who underwent flow-diverter stent implantation (Pipeline™ or Tubridge™). Images were reconstructed using conventional cone-beam CT (CBCT)(voxel size 0.43 mm isotropic) and HR-CBCT(voxel size 0.15 mm isotropic). Immediately after stent deployment, dual volume 3D fusion images were obtained from 3D-digital subtraction angiography (DSA) and HR-CBCT. The image quality for stent visualization was graded from 0 to 2 (0:not able to assess, 1:limited, but able to assess; 2:clear visualization), and the stent expansion status (full, under-expanded or poor apposition) was also recorded. Finally, patients were treated using flow-diverter stents (n = 92: 17 Pipeline and 75 Tubridge). Compared to CBCT, HR-CBCT led to improved visualization of the structures of the stents and significantly improved the image quality (mean score: 0.59 ± 0.67 vs. 1.6 ± 0.63, P < 0.001). For 28 stents (seven Pipeline and 21 Tubridge), partially incomplete apposition was observed by HR-CBCT but not by conventional CBCT and resolved by microguidewire looping dilation or balloon dilation. High-resolution cone-beam CT could better display flow-diverter stent details and yielded an improved image quality, which facilitated the assessment of stent deployment, potentially reducing the incidence of complications.

And don't forget your anti in-stent stenosis pill! Commentary on 'Factors associated with in-stent stenosis after cerebral aneurysm embolization using a Pipeline embolization device' by Flores-Milan et al.

In their INR study, Flores-Milan et al. present a retrospective single-centre study that aimed to investigate and determine some of the factors associated with in-stent stenosis (ISS) after intracranial aneurysm (IA) embolization using a commercially available flow diverter stent (FD). The retrospective analyses included ruptured and unruptured intracranial aneurysms treated with standalone flow diverter stent implantation or initial coil obliteration with the FD device placed subsequently two weeks after initial treatment. The article's methodology was carefully tailored to demystify the unknown pathophysiological mechanism behind the entity of interest called in-stent stenosis. Study outcomes also included angiographic evaluation of aneurysm occlusion thrombotic and hemorrhagic events. The authors reported excellent technical and clinical results altogether. The achieved angiographic occlusion rates resonate with the current obliteration results reported in the literature. Mortality and morbidity are congruent with previously published results and were 5.3% and 1.1%, respectively.

Endovascular treatment of wide-necked paraophthalmic aneurysms with flow diverter stent implantation

Amaç: Bu çalışmada, amacımız geniş boyunlu paraoftalmik anevrizmaların tedavisi için kullanılan akım çevirici stentlerin erken ve orta dönem klinik sonuçlarını sunmak idi. &#x0D; Gereç ve Yöntem: Hastanemizin girişimsel radyoloji ünitesinde Ekim 2008-Ocak 2020 tarihleri arasında internal karotid arterin paraoftalmik segmentinde yer alan geniş boyunlu anevrizma nedeniyle akım çevirici stent ile tedavi edilen toplam 87 hastanın verileri retrospektif olarak analiz edildi. &#x0D; Bulgular: Bu çalışmada yaş ortalaması 51,1 ± 8 olan 66’sı (% 75,8) kadın toplam 87 hasta yer aldı. Otuz dört (% 39) hastada birden fazla olmak üzere, toplam 100 paraoftalmik segment yerleşimli anevrizma, akım çevirici stentler ile tedavi edildi. Kırk (% 40) paraoftalmik segment anevrizmanın tedavisi için akım çevirici stente ek olarak koil embolizasyonu da yapıldı. Tüm stentler istenilen lokalizasyona yerleştirildi (Teknik başarı % 100). Bir hastada tedaviden sonra 5. günde intrakraniyal kanama nedeniyle ölüm gerçekleşti (Mortalite oranı: % 1,1). Uzun dönem takiplerde 3 hastada ileri düzeyde (stent lümenin %50 nin üzerinde daralaması) stent stenozu gelişti ve tedavi gerektirdi. Hastalar ortalama 29,8 ± 3 ay takip edildi. Yapılan kontrollerde ilk 3-6. ayda 77 (%81,9) anevrizma ve 6. ay sonrası kontrollerde 88 (%92,6) anevrizma kapalı idi. &#x0D; Sonuç: Paraoftalmik anevrizmaların endovasküler tedavisinde akım çevirici stent implantasyonu tek başına veya koil embolizasyonu ile birlikte güvenilir ve etkin bir yöntemdir.

Endovascular treatment of extracranial dissecting aneurysms of cervical arteries

Dissecting aneurysms of extracranial cervical arteries are a rare vascular pathology. To date, there is no consensus on the choice of optimal surgical approach for these aneurysms. To evaluate the effectiveness of endovascular treatment of various extracranial dissecting aneurysms. There were 19 patients with 21 extracranial dissecting aneurysms for the period from January 1, 2013 to October 19, 2020. Clinical examination, ultrasound and neuroimaging data were considered to determine surgical intervention. Nineteen patients underwent 20 intravascular interventions: aneurysm embolization with detachable coils with stent-assistance (n=9), flow-diverting stent implantation (n=5), arterial reconstruction with a stent for carotid stenting (n=3), aneurysm embolization with balloon assistance (n=1), aneurysm embolization with detachable coils without assistance (n=2). There were no complications. All patients were discharged without neurological impairment after 1-5 days. Long-term results of control angiography were analyzed within 1-19 months in 12 patients. All aneurysms were completely occluded. Asymptomatic occlusion of flow-diverting stent together with aneurysm occurred in 1 patient with low compliance to antiplatelet therapy. Other 6 patients are scheduled for elective angiography. Extracranial dissecting aneurysms of cervical arteries require vigilance due to their rare occurrence and risk of severe complications. In our opinion, intravascular interventions are advisable for these patients as effective and safe procedures.

Flow-diverting stent and delayed intracranial bleeding: the case for discussing acquired von Willebrand disease

A unique feature of the flow-diverting stent (FDS) has rendered it useful in the endovascular treatment of selected intracranial aneurysms for the last decade. Delayed aneurysmal rupture and intracranial parenchymal bleeding are two leading hemorrhagic complications after FDS. It has recently been shown for the first time that there is a relationship between FDS and reduced level of vWF activity in patients undergoing endovascular cerebral aneurysm treatment. Here, the current literature is reviewed in the context of this novel finding to propose an illustrative scenario that conceptually links implantation of FDS to delayed intracranial bleeding, through the mechanism of shear-induced activation of vWF. In this scenario, after FDS implantation, sustained release of activated vWF in association with platelets plays a pivotal role in the mechanisms of delayed intracranial hemorrhages.

Petrous Internal Carotid Artery Aneurysm: A Systematic Review.

Petrous internal carotid aneurysm (PA) concomitant with a mass lesion and cranial nerve palsy is relatively rare. Flow-diverter stent implantation is now widely used as an alternative treatment for PA. However, alternative treatments sometimes cannot be used because of tortuosity of the carotid artery, allergies to contrast material, and high costs. The outcomes of different treatment methods should therefore be assessed. Here, we review the available literature on treatments for PA. In a search using the terms "aneurysm", "carotid artery", and "petrous" on PubMed, MEDLINE, and databases such as OvidSP, 221 articles were identified. We also performed a literature review and discuss and compare the causes, symptoms, treatment methods, and clinical outcomes of PA. Onset of secondary aneurysm was generally heralded by bleeding (p<0.001), while onset of primary aneurysm was heralded by cranial nerve deficit (p= 0.0014). Outcomes after treatment of 34 cranial nerve palsies in 25 patients are reported.

Reduced Activity of von Willebrand Factor after Flow-Diverting Stent Implantation for Intracranial Aneurysms: A Link to Acquired von Willebrand Disease?

Vascular devices generating high shear stress can cause type 2A acquired von Willebrand disease, which is characterized by low von Willebrand factor activity accompanied by hemorrhagic complications. The braided mesh structure of flow-diverting stents with a relatively small strut size can create abnormally high shear stress while arterial blood flows through the stent struts into the aneurysm, and flow-diverting stent may be associated with reduced von Willebrand factor activity. Aneurysmal morphologic parameters and patient data were examined retrospectively among patients who had an unruptured intracranial aneurysm treated with a flow-diverting stent. The RISTOtest (test for whole blood ristocetin-induced platelet aggregation) for von Willebrand factor activity, as well as tests for aspirin and clopidogrel/prasugrel effectiveness, were performed immediately before the endovascular procedure and 24 hours later by multiple electrode aggregometry. A total of 39 patients with 56 aneurysms were recruited, and statistical analyses were performed in 32 patents with 49 aneurysms. Compared with the baseline values, von Willebrand factor activity was reduced in 16 patients but increased in 23 patients. Aneurysmal variables (eg, neck area, volume, volume-to-neck area ratio, size ratio, and morphologic index) clearly distinguished patients with reduced von Willebrand factor activity from those with nonreduced von Willebrand factor activity. The receiver operating characteristic curve showed that the morphologic index and volume had the highest discriminative power, with an area under the curve of 0.99. In high-volume/large-neck aneurysms, flow-diverting stent implantation can cause reduced von Willebrand factor activity, which may be linked causally to acquired von Willebrand disease.

How Flow Reduction Influences the Intracranial Aneurysm Occlusion: A Prospective 4D Phase-Contrast MRI Study.

Flow-diverter stents are widely used for the treatment of wide-neck intracranial aneurysms. Various parameters may influence intracranial aneurysm thrombosis, including the flow reduction induced by flow-diverter stent implantation, which is assumed to play a leading role. However, its actual impact remains unclear due to the lack of detailed intra-aneurysmal flow measurements. This study aimed to clarify this relationship by quantitatively measuring the intra-aneurysmal flow using 4D phase-contrast MR imaging. We acquired prospective pre- and post-stent implantation 4D phase-contrast MR imaging data of a consecutive series of 23 patients treated with flow-diverter stents. Velocity field data were combined with the intraprocedural 3D angiogram vessel geometries for precise intracranial aneurysm extraction and partial volume correction. Intra-aneurysmal hemodynamic modifications were compared with occlusion outcomes at 6 and 12 months. The averaged velocities at systole were lower after flow-diverter stent implantation for all patients and ranged from 21.7 ± 7.1 cm/s before to 7.2 ± 2.9 cm/s after stent placement. The velocity reduction was more important for the group of patients with aneurysm thrombosis at 6 months (68.8%) and decreased gradually from 66.2% to 55% for 12-month thrombosis and no thrombosis, respectively (P = .08). We propose an innovative approach to measure intracranial flow changes after flow-diverter stent implantation. We identified a trend between flow reduction and thrombosis outcome that brings a new insight into current understanding of the flow-diversion treatment response.

Aggregometry Response to Half-dose Prasugrel inFlow-diverting Stent Implantation.

The aim of this study was to determine whether half-dose loading (30 mg) of prasugrel is sufficient to achieve adequate platelet inhibition, and whether such aloading dose of prasugrel together with aspirin followed by a10 mg/day prasugrel maintenance, could serve as afirst-line antiplatelet strategy for patients undergoing flow-diverting stent (FDS) implantation. Data from agroup of consecutive patients treated for intracranial aneurysm with FDS were retrospectively collected. Platelet P2Y12 receptor responsiveness was assessed by arapid platelet function test just prior to the procedure. All ischemic and hemorrhagic complications as well as morbidity and mortality rates were documented. Atotal of 138 patients with 153 aneurysms (32were symptomatic and 121 were incidental) underwent FDS treatment in atotal of 147 loading sessions. Adequate platelet inhibition was obtained in 136/138 (98.5%) patients and 145/147 (98.6%) loading sessions. Overall, there was one case of (hemorrhagic) mortality (0.7%), one of (ischemic) morbidity (0.7%), one of symptomatic (hemorrhagic) clinical complications without permanent deficits (0.7%), and six transient ischemic attacks (4.1%). The 6‑month control angiography, available for all patients, revealed a95.4% aneurysm occlusion rate. Half-dose (30 mg) prasugrel loading results in effective platelet P2Y12 receptor inhibition in more than 98% of patients. Dual antiaggregant loading with half dose prasugrel followed by prasugrel maintenance as afirst-line therapy appears to be feasible in patients treated with FDS implantation for intracranial aneurysm.

Massive subarachnoid hemorrhage after implantation of flow-diverter stent: clinical case and literature review

The study objective is to present a clinical case of massive subarachnoid hemorrhage after flow-diverter stent implantation for giant aneurysm and to review the literature on complication rate after use of flow diverter devices. Materials and methods. Forty two patients with large and giant cerebral aneurysms underwent surgical treatment with the use of flow-diverter stents in the department of neurosurgery of the Interregional Clinical Diagnostic Center (Kazan) from 2010 to 2018. In 1 case, massive subarachnoid hemorrhage as a result of aneurysm rupture with fatal outcome developed on the day 4 postoperatively. Results. Causes of aneurysm rupture after the installation of flow-diverter stents are still poorly understood. Possible causes include redirection of blood flow towards the part of the aneurysm, that has not been earlier exposed to high blood pressure; release of a large amount of enzymes from the thrombus formed in the aneurysm, which results in inflammation in the vessel wall; mechanical impact of the forming thrombus on the thinned aneurysm wall; reperfusion syndrome caused by artery stenosis developed before surgery; and administration of antiplatelets. The data on their effectiveness remain controversial. We report a case of aneurysm rupture, which was not prevented by steroid and nonsteroidal anti-inflammatory therapy received by a patients during the postoperative period. Conclusion. Aneurysm rupture after flow diverter implantation remains unpredictable and threatening complication which requires maximum awareness. Further studies and recommendations are needed to prevent this complication.

Reversible Brain Edema Associated with Flow Diverter Stent Procedures: A Retrospective Single- Center Study to Evaluate Frequency, Clinical Evolution, and Possible Mechanism

Hemorrhage and ischemia after flow diverter stent (FDS) procedures for intracranial aneurysms are the most common complications and have been extensively described. Temporary brain edema (TBE) is an unknown complication that could be associated with particular FDS procedures. To estimate the frequency, clinical presentation, imaging findings, and possible mechanisms associating TBE with FDS. Unruptured aneurysms treated with FDS implantation performed in our service from June 2015 to March 2018 were reviewed. Medical antecedents, endovascular procedure, clinical assessments before and after treatment, aneurysm characteristics, and image records were collected. Artery diameters of patients in whom TEB developed were also calculated to investigate any correlation between TBE and anatomic descriptors. A total of 179 FDS procedures in 176 patients were reviewed. Six patients (3.4%) presented with symptomatic TBE, and all TBE patients had undergone FDS implantation from the middle cerebral artery (MCA) to the internal carotid artery (ICA). A Pearson product-moment correlation coefficient (PPCC) found smaller MCA diameters and MCA/ICA ratios in these 6 patients (respectively PPCC=-0.619, P < 0.04; PPCC=-0.647, P < 0.03). Hemorrhagic and ischemic complications were less frequent than TBE (2.3% and 1.1% vs. 3.4%). TBE was more frequent than ischemic or hemorrhagic complications after FDS in this study. TBE seemed to be associated with a particular FDS positioning in small arteries, inducing flow changes and disruption of the blood-brain barrier.

Nationwide Mortality Data after Flow-Diverting Stent Implantation in Korea.

ObjectiveTo investigate nationwide statistics on flow-diverting stent usage for cerebral aneurysm treatment and related mortality data.MethodsWe requested data extraction from the National Health Insurance Service claims database using electronic data interchange codes (J3207064, J3207073). Patient and hospital information as well as death statistics were collected from the database.ResultsA total of 169 procedures were performed using flow-diverting stents for cerebral aneurysm treatment from November 2014 to December 2016 in Korea. The majority of primary diagnosis was unruptured intracranial aneurysm. During the study period, nine subjects died, including one patient initially diagnosed with subarachnoid hemorrhage. The crude mortality rate was 5.3%. Five patients died within one month after the procedure; therefore, the estimated periprocedural mortality rate was 3.0±1.3%. The mortality rate as of the last day of 2016 was 6.3±2.1%.ConclusionIn a 171 person-year follow-up in a Korean series, nine deaths occurred after flow-diverting stent treatment. The crude mortality rate in Korea (5.3%) was higher than that reported in a previous meta-analysis (3.8%).

Determination of a shear rate threshold for thrombus formation in intracranial aneurysms

BackgroundParticular intra-aneurysmal blood flow conditions, created naturally by the growth of an aneurysm or induced artificially by implantation of a flow diverter stent (FDS), can potentiate intra-aneurysmal thrombosis. The aim...

Tailoring platelet inhibition according to multiple electrode aggregometry decreases the rate of thrombotic complications after intracranial flow-diverting stent implantation

Background and purposePretreatment with dual antiaggregant drugs is accepted as a standard step in intracranial stent implantation. The aim of this study was to determine whether tailored antiaggregant medication based...

The use of k-t PCA accelerated dual-venc 3D flow MRI to assess hemodynamics before and after flow diverting stent implantation in cerebral aneurysm models

Background Hemodynamic parameters are known to play a crucial role in the growth and rupture of intracranial aneurysms [Appanaboyina IntJNumerMethodsFluids2008]. Flow diverting stents have emerged as an alternative to coiling by using fine meshes to divert flow away from the aneurysm sac to promote thrombus formation and remodeling of the aneurysm while keeping side branches and perforating arteries patent. However, the post procedural course of these aneurysms is not fully predictable. Time-resolved 3D phase-contrast MRI allows for the assessment of three-directional velocity fields. Due to intrinsic long acquisition times, a single velocity encoding step (venc) is typically used [Acevedo-Bolton JCMR2013]. In this work, we use k-t Principal Component Analysis (PCA) [Pedersen MRM2009] in combination with a dual-venc acquisition to acquire highly undersampled 3D flow data for improved accuracy of lower velocities. Flow patterns within the aneurysms are analysed for different stent sizes, including optimal and oversized stents, and compared to the native models.

Implantation of Pipeline Flow-Diverting Stents Reduces Aneurysm Inflow Without Relevantly Affecting Static Intra-aneurysmal Pressure

Flow-diverting stent (FDS) implantation is an endovascular treatment option for intracranial aneurysms. However, little is known about the hemodynamic effects. To assess the effect of stent compression on FDS porosity, to evaluate the influence of single and overlapping implantation of FDS on intra-aneurysmal flow profiles, and to correlate stent porosity with changes in static mean intra-aneurysmal pressure. Intra-aneurysmal time-density curves were recorded in a pulsatile in vitro flow model before and after implantation of FDSs (Pipeline Embolization Device; ev3) in 7 different types of aneurysm models. Reductions in the maximum contrast inflow and time to maximum intra-aneurysmal contrast were calculated. Micro--computed tomography was performed, and compression-related FDS porosity was measured. The influence of FDS placement on mean static intra-aneurysmal pressure was measured. FDS compression resulted in an almost linear reduction in stent porosity. Stent porosity (struts per 1 mm) correlated significantly with the reduction of aneurysm contrast inflow (R = 0.81, P < .001) and delay until maximum contrast (R = 0.34, P = .001). Circulating intra-aneurysmal high-velocity flow was terminated in all sidewall models after implantation of a single stent. Superimposition of 2 stents reduced maximum intra-aneurysmal contrast by 69.1 ± 3.1% (mean ± SD) in narrow-necked sidewall aneurysm models, whereas no substantial reduction in maximum intra-aneurysmal contrast was observed in wide-necked sidewall aneurysm models. Intra-aneurysmal mean static pressure did not correlate with FDS porosity or number of implanted stents. Implantation of FDS effectively reduces aneurysm inflow in a porosity-dependent way without relevantly affecting static mean intra-aneurysmal pressure. FDS, flow-diverting stentMAP, mean arterial pressurePED, Pipeline Embolization Device.

Correlation of aneurysm occlusion with actual metal coverage at neck after implantation of flow-diverting stent in rabbit models

A remarkable curing rate has been achieved in the treatment of intracranial intractable aneurysms by using flow-diverting stents (FDS). An appropriate metal coverage (MC) of this device influences the hemodynamics of aneurysm significantly but little to branches in vitro. The MC changes after elongation or compression and the actual changes are still unknown in vivo. In this paper, we analyzed the correlation of aneurysm occlusion with actual MC after implantation of FDS in rabbit models. FDS was implanted across the necks of 22 elastase-induced aneurysms in rabbits. Animals were performed for angiography at 4weeks and sacrificed at 3months after angiography for pathology. Tissue was explanted with stent for micro-computed tomography scan, and local shape of stent at neck was reconstructed. Actual MC at neck was calculated, and the correlations of aneurysm occlusion with effective factors were analyzed. Greater than 95% angiographic aneurysm occlusion rates for the FDS, which covered the neck of aneurysms, were 61.9% at 4weeks and 57.9% by angiography at 3months. Aneurysm occlusion was positively correlated with local MC of stent at neck (r (s) = 0.486; P = 0.026). A 35% actual MC at the neck predicted greater than 95% angiographic aneurysm occlusion with a specificity of 100% and sensitivity of 53.8%. Aneurysm occlusion was positively correlated with local MC of stent at the neck. The FDS with 35% MC can predict greater than 95% angiographic aneurysm occlusion.