Internal Carotid Artery Siphon Research Articles

Usefulness of silent magnetic resonance angiography (MRA) for the diagnosis of atherosclerosis of the internal carotid artery siphon in comparison with time-of-flight MRA

Background and purposeFlow visualization in 3D time-of-flight MRA (3D-TOF MRA) may be limited for internal carotid artery siphon owing to turbulent artifact. The purpose of this study was to compare the usefulness of Silent MRA and 3D-TOF MRA to assess atherosclerosis of the internal carotid artery siphon.Material and methodsA total of 106 patients with suspected cerebrovascular disease were included. All patients were scanned with Silent MRA and 3D-TOF MRA sequences and also underwent DSA examination. Two observers independently assessed the TOF MRA and Silent MRA images of atherosclerosis of the internal carotid artery siphon. The diagnostic efficacy of two MRA methods in evaluating atherosclerosis of the carotid siphon was performed by using receiver operating characteristic (ROC) curve analysis. Interobserver reliability was also assessed using weighted kappa statistics.ResultsImage of Silent MRA sequence had higher subjective evaluation scores and significantly high CNR between the carotid siphon and the background tissues than the image of 3D-TOF MRA sequence (P < 0.05). The AUC was 0.928 (95% CI 0.909–0.986) for Silent MRA, which was significantly higher than that of 3D-TOF MRA (0.671, 95% CI 0.610–0.801, P < 0.05). Silent MRA had high sensitivity, specificity and accuracy than 3D-TOF MRA for visualization of the carotid siphon.ConclusionsSilent MRA as a new angiographic modality is superior to 3D-TOF MRA for visualization of the carotid siphon, and maybe an alternative to 3D-TOF MRA in the diagnosis of atherosclerosis of the carotid siphon.

Use of Distal Intracranial Catheters for Better Working View of Cerebral Aneurysms Hidden by Parent Artery or Its Branches: A Technical Note.

A good working view is critical for safe and successful endovascular treatment of cerebral aneurysms. In a few cases, endovascular treatment of cerebral aneurysms may be challenging due to difficulty in obtaining a proper working view. In this report of 6 cases, we described the advantage of using a distal intracranial catheter (DIC) to achieve better visualization of cerebral aneurysms hidden by a parent artery or its branches. Between September 2017 and January 2021, we treated 390 aneurysms with endovascular techniques. In 6 cases in which it was difficult to obtain a proper working view, the DIC was placed distally close to the aneurysm in order to remove the parent artery projection from the working view and obtain better visualization of the aneurysm. Clinical and procedural outcomes and complications were evaluated. The position of the DIC was above the internal carotid artery siphon in the 6 cases. All aneurysms were successfully embolized. Raymond–Roy class 1 occlusion was achieved in all 4 unruptured aneurysms, while the result was class 2 in the 2 ruptured aneurysms. Placement of the DIC was atraumatic without dissections or significant catheter-induced vasospasm in all patients. Transient dysphasia was seen in 2 cases and transient aphasia in 1. Using this technique, we have found it possible to better visualize the aneurysm sac or neck and thereby treat cases we otherwise would have considered untreatable.

Glucose Fluctuation and Severe Internal Carotid Artery Siphon Stenosis in Type 2 Diabetes Patients.

The impact of glucose fluctuation on intracranial artery stenosis remains to be elucidated. This study aimed to investigate the association between glucose fluctuation and intracranial artery stenosis. This was a cross-sectional study of type 2 diabetes mellitus (T2DM) patients equipped with the FreeStyle Libre Pro continuous glucose monitoring system (Abbott Laboratories) between February 2019 and June 2020. Glucose fluctuation was evaluated according to the standard deviation (SD) of blood glucose, coefficient of variation (%CV), and mean amplitude of glycemic excursions (MAGE). Magnetic resonance angiography was used to evaluate the degree of intracranial artery stenosis. Of the 103 patients, 8 patients developed severe internal carotid artery (ICA) siphon stenosis (≥70%). SD, %CV, and MAGE were significantly higher in the severe stenosis group than in the non-severe stenosis group (<70%), whereas there was no significant intergroup difference in the mean blood glucose and HbA1c. Multivariable logistic regression analysis adjusted for sex showed that SD, %CV, and MAGE were independent factors associated with severe ICA siphon stenosis. In conclusion, glucose fluctuation is significantly associated with severe ICA siphon stenosis in T2DM patients. Thus, glucose fluctuation can be a target of preventive therapies for intracranial artery stenosis and ischemic stroke.

Evaluation of hemodynamic changes in nonarteritic anterior ischemic optic neuropathy using multimodality imaging.

Nonarteritic anterior ischemic optic neuropathy (NAION) patients experience hypo-perfusion in the short posterior ciliary arteries (SPCAs), however, the cause of hypo-perfusion is unclear. Real-time dynamic hemodynamic observations may provide clues into specific NAION pathogenic mechanisms. We aim to analyze hemodynamic changes occurring in NAION using multimodality imaging. Our specific focus is identifying pathogenic mechanisms underlying SPCA insufficiency in NAION. Three-dimensional arterial spin labeling (3D ASL) magnetic resonance imaging (MRI) and three-dimensional time-of-flight (3D-TOF) magnetic resonance angiography (MRA) were performed on 25 NAION patients (50 eyes) and 22 (44 eyes) normal cases were recruited. The diameter of the initial part of the ophthalmic artery and internal carotid artery siphon were measured using MRA. Blood vessel identification and blood flow (BF) were detected using 3D ASL MRI. We measured BF values of the optic nerve head (ONH) region of the retina/choroid complex, optic nerve (ON), temporal lobe, and occipital lobe. We studied 32 NAION affected eyes, 18 NAION uninvolved eyes, and 44 normal eyes. Diameter of the initial part of ophthalmic artery in the NAION affected eyes was significantly larger than the uninvolved eyes (P=0.026). Diameter of the NAION eyes was 1.33±0.19 mm [mean ± standard deviation (SD)], uninvolved eyes were 1.15±0.21 mm. At a photolabeling delay times (PLD) of 1,500 and 2,500 ms, BF of the ONH and ON in NAION affected eyes was significantly less than uninvolved and normal eyes (pONH <0.001 both at 1,500 and 2,500 ms, pON <0.001 and pON =0.001 at 1,500 and 2,500 ms, respectively). ONH of uninvolved eyes was also significantly less than normal eyes. Additionally, BF of the ONH region correlated with temporal lobe BF, with an R2=0.3231 and 0.2397 at 1,500 and 2,500 ms, respectively. BF of the ONH region also correlated with occipital lobe BF, with an R2=0.2534 and 0.4397 at 1,500 and 2,500 ms, respectively. ON and temporal lobe BF also correlated, with an R2=0.226 and 0.1504 at 1,500 and 2,500 ms, respectively. Abnormal hemodynamics of small cerebral vessels existed prior to the onset of NAION. A candidate mechanism underlying NAION appears to be transient insufficiency of blood supply and decompensation of ocular vascular regulation.

Balloon-Assisted Coils Embolization for Ophthalmic Segment Aneurysms of the Internal Carotid Artery.

Objective: To explore the role of balloon-assisted coils technique for ophthalmic segment aneurysms (OSAS).Methods: Clinical data of 30 patients with OSAS were reviewed between December 2017 and December 2018. OSAS were defined as arising from the internal carotid artery (ICA), reaching from the distal dural ring to the origin of the posterior communicating artery. OSAS were classified into four types based on the angiographic findings. The balloon-assisted coils technique was used for the embolization of aneurysms. The duration of balloon inflation cycles, as well as difficulty and complications during the embolization procedure, were recorded. The immediate angiographic results were evaluated according to the Raymond scale. Clinical results were evaluated based on the MRS score. Follow-ups were performed at 18 months post-embolization by DSA or MRA at our institution.Results: Thirty-two aneurysms in 30 patients were detected by digital subtraction angiography (DSA), which included 30 unruptured and two ruptured cases. The patients with ruptured aneurysms were grade II status according to the Hunt-Hess scale. Three cases were type A, nine cases were type B, 17 cases were type C, and three cases were type D. According to aneurysm size, there were 19 cases of small, 11 cases of medium, two cases of large aneurysm. Thirty-two aneurysms were successfully embolized in 30 patients by balloon-assisted coils technique. The ophthalmic artery could be protected by an engorged balloon in the procedure, especially for type A aneurysms. Considering that type D aneurysm arises from the side-wall of the artery and near to tortuous ICA siphon, the balloon catheter was inflated to stabilize the microcatheter allowing for overinflation when necessary. The average duration of balloon dilatation was 4 min, and the average time was 2.5 times. Raymond class was one in 28 aneurysms and two in four aneurysms according to the immediate post-embolization angiographic results. All the patients achieved good clinical effects, except for one patient who presented with brain ischemia resulting in dizziness and contralateral limb weakness for 10 h due to prolonged temporary clamping of the responsible ICA. The follow-up angiography results were satisfactory at 18 months post-embolization.Conclusion: OSAS endovascular treatment with balloon-assisted coils has different advantages in a different classification. The technique is safe, effective, and relatively inexpensive, especially for small and medium OSAS.

Imageology of internal carotid artery siphon in non-arteritic anterior ischaemic optic neuropathy.

To evaluate whether narrowing of internal carotid artery siphon (ICAS) may increase the risk of developing non-arteritic anterior ischaemic optic neuropathy (NAION). Totally 30 consecutive patients who had unilateral NAION and 30 gender-matched control subjects were recruited in the present study. The diameter of ICAS of all the participants were measured using head-and-neck computed tomographic angiography (CTA). Color doppler flow imaging (CDI) was used to measure the haemodynamics parameters of ICAS and short posterior ciliary arteries (SPCAs) in all subjects. Comparison of parameters between the NAION patients and controls as well as between the two sides within the patients were performed. The correlation between the diameter of ICAS and NAION was analyzed. A comparison of parameters between the affected side of the NAION patients and the controls, including the diameter of ICAS, the resistance index (RI) of ICAS, the blood flow velocities of SPCAs and RI of SPCAs, showed significantly difference (P<0.01), while there was no significant difference in terms of the mean blood flow velocity (Vm) of ICAS; Similar results were found while comparing all the measurements of the affected and unaffected side of patients (P for RI of SPCAs <0.05). No marked difference was detected in nearly all parameters except for RI of ICAS and SPCAs between the unaffected side of the NAION patients and the controls (P<0.05). The diameter of ICAS were significantly positive correlated with both peak systolic velocity (PSV) of SPCAs and end diastolic velocity (EDV) of SPCAs in patients with NAION (r=0.514, P<0.01 and r=0.418, P<0.05, respectively). Narrowing of ICAS may increase the risk of developing NAION.

A Breath-Holding Index Applied to the Internal Carotid Artery Siphon in Transcranial Doppler Studies.

The breath-holding index (BHI) is a useful method to assess cerebrovascular reactivity. It is calculated based on the mean flow velocities of the middle cerebral artery (MCA) using transcranial Doppler (BHIMCA ). Therefore, it is not feasible in patients with poor temporal windows. This study tested the feasibility of a BHI using the internal carotid artery (ICA) siphon flow velocity (BHIICA ). Twenty-four patients (aged 38-79 years) with unilateral or bilateral stenosis of the cervical ICAs were prospectively recruited. The 48 examined bilateral ICAs were divided into three groups according to the stenosis degree: <50%, 50-99%, and occlusion. We investigated the reproducibility of both BHI methods (BHIMCA and BHIICA ), the correlation between the two BHI methods, and the tendency for the BHIs to decrease with increasing degree of cervical ICA stenosis. For the BHIMCA , we found a good reproducibility (intraclass correlation coefficient, rI > .9) and a significantly decreased BHI with increasing stenosis of the ICA (P = .001). For the BHIICA , good reproducibility was demonstrated (rI > or ≒ .9), but there was no significant decrease in the BHI related to the increasing degree of ICA stenosis (P = .952). Furthermore, the correlation between the two BHI methods was not robust (kappa coefficient, right .259; left .619). Our study suggests that the BHIICA is not a feasible alternative method to the BHIMCA.

Factors influencing blood flow resistance from a large internal carotid artery aneurysm revealed by a computational fluid dynamics model.

ABSTRACTHyperperfusion syndrome occurs after treatment of a large or giant cerebral aneurysm. Recently, flow-diverter stent placement has emerged as an effective treatment method for a large cerebral aneurysm, but postoperative ipsilateral delayed intraparenchymal hemorrhage occurs in a minority of cases. The mechanism underlying delayed intraparenchymal hemorrhage is not established, but one possibility is hyperperfusion syndrome. The incidence of delayed intraparenchymal hemorrhage appears to be higher for giant aneurysms; hence, we speculated that large/giant aneurysms may create flow resistance, and mitigation by flow-diverter stent deployment leads to hyperperfusion syndrome and delayed intraparenchymal hemorrhage. The purpose of this study was to identify aneurysm characteristics promoting flow resistance by the analysis of pressure loss in an internal carotid artery paraclinoid aneurysm model using computational fluid dynamics. A virtual U-shaped model of the internal carotid artery siphon portion was created with a spherical aneurysm of various angles, body diameters, and neck diameters. Visualization of streamlines, were calculated of pressure loss between proximal and distal sides of the aneurysm, and vorticity within the aneurysm were calculated. The pressure loss and vorticity demonstrated similar changes according to angle, peaking at 60°. In contrast, aneurysm diameter had little influence on pressure loss. Larger neck width, however, increases pressure loss. Our model predicts that aneurysm location and neck diameter can increase the flow resistance from a large internal carotid artery aneurysm. Patients with large aneurysm angles and neck diameters may be at increased risk of hyperperfusion syndrome and ensuing delayed intraparenchymal hemorrhage following flow-diverter stent treatment.

Research on Association of the Diameter of the Internal Carotid Artery Siphon and Nonarteritic Anterior Ischaemic Optic Neuropathy.

Objective To investigate the association of the diameter of the internal carotid artery siphon (ICAS) and nonarteritic anterior ischaemic optic neuropathy (NAION). Methods Thirty patients clinically diagnosed with NAION (unilateral affected) who presented to Beijing Friendship Hospital from January 2017 to October 2018 were selected. The eyes suffered from NAION were enrolled as the observation group, and the fellow healthy eyes were enrolled as the control group. The following indexes were measured: diameter of the ICAS and the ophthalmic artery (OA), intima-media thickness (IMT) of the internal carotid artery (ICA), degree of stenosis of the ICA and plaque formation, and hemodynamic parameters of the ICA and the short posterior ciliary arteries (SPCAs). All the values were compared between the two groups. Results The diameter of the ICAS in the observation group (0.30 ± 0.07 cm) significantly narrowed compared with that of the control group (0.32 ± 0.06 cm) (P < 0.05), but the diameter of the OA of the two groups had no significant difference. The detection rate of carotid atherosclerosis plaque, the average blood flow velocity (Vm), and the resistance index (RI) of the ICA in the observation group (46.67%, 26.81 ± 1.78 cm/s, and 0.72 ± 0.06) had significant differences compared with those of the control group (16.67%, 28.19 ± 2.75 cm/s, and 0.70 ± 0.05) (P < 0.05), but the gradings of ICA stenosis and IMT between the two groups had no significant differences. The peak systolic velocity (PSV) and the end diastolic velocity (EDV) of the SPCAs in the observation group (10.72 ± 2.88 cm/s and 3.43 ± 1.01 cm/s) were significantly lower than those of the control group (13.62 ± 3.93 cm/s and 4.59 ± 1.71 cm/s) (P < 0.05), but the RI of the SPCAs of the two groups had no significant differences. Conclusion The diameter of the ICAS has a close relationship with NAION.

Risk factors and preventive measures of cerebral hyperperfusion syndrome after carotid artery interventional therapy.

This study sought to investigate the risk factors for cerebral hyperperfusion syndrome (CHS) after carotid artery interventional therapy, and to explore potential preventive measures. Three hundred and eighty-two patients treated with carotid artery stenting at the Huanhu Hospital (Tianjin, China) between January 2010 and January 2016 were divided into CHS and non-CHS groups. A retrospective analysis of patient clinical data was made. The CHS group had more patients presenting coronary heart disease, diabetes, progressive neurological disease and transient recurrent cerebral hemorrhage than the non-CHS group. More patients in the CHS group presented stenosis of the internal carotid artery siphon. More CHS group patients showed plaque formation extending >3 cm to the distal end of the internal carotid artery. Finally, more CHS group patients had pressure gradients >60 mmHg (p<0.05). Logistics regression analysis showed that preoperative diabetes mellitus and carotid pressure gradient ≥60 mmHg were independent risk factors for CHS (p<0.05). The ROC curve of carotid pressure gradients ≥60 mmHg were made to predict CHS, with the area under curve being 0.949 (p<0.05). The best cut-off value was 60 mmHg. Therefore, preoperative diabetes and a carotid pressure gradient ≥60 mmHg are risk factors for CHS, and these indicators need to be examined prior to operation.

Predictors of the Aspiration Component Success of a Direct Aspiration First Pass Technique (ADAPT) for the Endovascular Treatment of Stroke Reperfusion Strategy in Anterior Circulation Acute Stroke.

A direct aspiration first pass technique (ADAPT) has been reported to be fast, safe, and effective for the treatment of acute ischemic stroke. The aim of this study is to determine the preoperative factors that affect success of the aspiration component of the technique in ischemic stroke patients with large vessel occlusion in the anterior circulation. We enrolled all 347 consecutive patients with anterior circulation acute ischemic stroke admitted for mechanical thrombectomy at our institution from August 2013 to October 2015 and treated by ADAPT for the endovascular treatment of stroke. Baseline and procedural characteristics, modified thrombolysis in cerebral infarction scores, and 3-month modified Rankin Scale were captured and analyzed. Among the 347 patients (occlusion sites: middle cerebral artery=200, 58%; internal carotid artery Siphon=89, 25%; Tandem=58, 17%), aspiration component led to successful reperfusion (modified thrombolysis in cerebral infarction 2b/3 scores) in 55.6% (193/347 patients), stent retrievers were required in 40%, and a total successful final reperfusion rate of 83% (288/347) was achieved. Overall, procedural complications occurred in 13.3% of patients (48/347). Modified Rankin Scale score of 0 to 2 at 90 days was reported in 45% (144/323). Only 2 factors positively influenced the success of the aspiration component: an isolated middle cerebral artery occlusion (P<0.001) and a shorter time from stroke onset to clot contact (P=0.018). In this large retrospective study, ADAPT was shown to be safe and effective for anterior circulation acute ischemic stroke with a final successful reperfusion achieved in 83%. The site of arterial occlusion and delay of the procedure were predictors for reperfusion. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02523261, NCT02678169, and NCT02466893.

Clinical analysis of difficult intraarterial mechanical thrombectomy in patients with acute ischemic stroke

To investigate the causes and strategy of difficult intraarterial mechanical thrombectomy (≥3 times) in patients with acute ischemic stroke (AIS). The clinical data of 8 cases of AIS with thrombectomy ≥3 times admitted in Department of Neurology, the 306(th) Hospital of People's Liberation Army from June to October in 2015 was analyzed retrospectively. There were 7 male and 1 female patients, aged from 38 to 86 years with an average age of (70±15) years, in which 5 cases were cardiogenic cerebral embolism and 3 cases were large artery atherosclerotic infarction. The National Institute of Health stroke scale (NIHSS) score (M (QR)) was 16 (12) before procedure and modified thrombolysis in cerebral infarction (mTICI)score were 0 in all the patients. Solitaire AB was used in thrombectomy in the occlusion of the arteries. The causes of difficult intraarterial thrombectomy included multiple thrombus, tortuosity in vascular paths, guiding catheter being placed below the internal carotid artery siphon leading to weak strength of suction and support of stent, embolus dropping in the thrombectomy and inadequate anesthesia. After successful thrombectomy 3 cases had mTICI score of 2a, 4 cases of 2b, 1 case of 3. The NIHSS score was 5 (24) at 7(th) day after treatment. At the 90-day follow-up 5 patients had good prognosis (modified Rankin score 0 to 2) and 3 had disability (modified Rankin score 3 to 4). Cases of AIS with difficult intraarterial thrombectomy can be treated by improving thrombectomy materials and technique, reasonable anesthesia and perioperative medication in decision-making strategy.

Ascertain the Safe Range From Foramen Rotundum to the Siphon of Internal Carotid Artery for Operation Through Pterygopalatine Fossa With Thin-Section Computed Tomographic Image.

This study aimed to ascertain the safe range from foramen rotundum to the siphon of internal carotid artery using three-dimensional reconstruction technique. We scanned skulls of 121 volunteers to get the final results with thin-section computed tomographic image. The distance of AC was measured as 13.22 (3.79) mm (range, 8.33-105.67 mm; 95% CI [confidence interval], 8.55-21.39 mm). The angle to the sagittal plane was measured as 33.54 (9.23) mm (range, 5.38-66.58; 95% CI, 30.88-34.20). The angle to the coronal plane was measured as 53.17 (10.48) mm (range, 5.60-75.02; 95% CI, 51.29-55.06). The angle to the horizontal plane was measured as 9.43 (12.91) mm (range, -28.44 to 82.22; 95% CI, 7.11-11.76). These above-mentioned results can help locate these structures to help in minimizing surgical trauma to the nerves and blood vessels of the operation through pterygopalatine fossa under nasoendoscope.

Analysis of flow and LDL concentration polarization in siphon of internal carotid artery: Non-Newtonian effects

Carotid siphon is known as one of the risky sites among the human intracranial arteries, which is prone to formation of atherosclerotic lesions. Indeed, scientists believe that accumulation of low density lipoprotein (LDL) inside the lumen is the major cause of atherosclerosis. To this aim, three types of internal carotid artery (ICA) siphon have been constructed to examine variations of hemodynamic parameters in different regions of the arteries. Providing real physiological conditions, blood considered as non-Newtonian fluid and real velocity and pressure waveforms have been employed as flow boundary conditions. Moreover, to have a better estimation of risky sites, the accumulation of LDL particles has been considered, which has been usually ignored in previous relevant studies. Governing equations have been discretized and solved via open source OpenFOAM software. A new solver has been built to meet essential parameters related to the flow and mass transfer phenomena. In contrast to the common belief regarding negligible effect of blood non-Newtonian behavior inside large arteries, current study suggests that the non-Newtonian blood behavior is notable, especially on the velocity field of the U-type model. In addition, it is concluded that neglecting non-Newtonian effects underestimates the LDL accumulation up to 3% in the U-type model at the inner side of both its bends. However, in the V and C type models, non-Newtonian effects become relatively small. Results also emphasize that the outer part of the second bend at the downstream is also at risk similar to the inner part of the carotid bends. Furthermore, from findings it can be implied that the risky sites strongly depend on the ICA shape since the extension of the risky sites are relatively larger for the V-type model, while the LDL concentrations are higher for the C-type model.

Fast 4D flow MRI intracranial segmentation and quantification in tortuous arteries.

To describe, validate, and implement a centerline processing scheme (CPS) for semiautomated segmentation and quantification in carotid siphons of healthy subjects. 4D flow MRI enables blood flow measurement in all major cerebral arteries with one scan. Clinical translational hurdles are time demanding postprocessing and user-dependence induced variability during analysis. A CPS for 4D flow data was developed to automatically separate cerebral artery trees. Flow parameters were quantified at planes along the centerline oriented perpendicular to the vessel path. At 3T, validation against 2D phase-contrast (PC) magnetic resonance imaging (MRI) and 4D flow manual processing was performed on an intracranial flow phantom for constant flow, while pulsatile flow validation was performed in the internal carotid artery (ICA) of 10 healthy volunteers. The CPS and 4D manual processing times were measured and compared. Flow and area measurements were also demonstrated along the length of the ICA siphon. Phantom measurements for area and flow were highly correlated between the CPS and 2D measurements (area: R = 0.95, flow: R = 0.94), while in vivo waveforms were highly correlated (R = 0.93). Processing time was reduced by a factor of 4.6 compared with manual processing. Whole ICA measurements revealed a significantly decreased area in the most distal segment of the carotid siphon (P = 0.0017), with flow unchanged (P = 0.84). This study exhibits fast semiautomated analysis of intracranial 4D flow MRI. Internal consistency was shown through flow conservation along the tortuous ICA siphon, which is typically difficult to assess.

Curvature effect on hemodynamic conditions at the inner bend of the carotid siphon and its relation to aneurysm formation

Although high-impact hemodynamic forces are thought to lead to cerebral aneurysmal change, little is known about the aneurysm formation on the inner aspect of vascular bends such as the internal carotid artery (ICA) siphon where wall shear stress (WSS) is expected to be low. This study evaluates the effect of vessel curvature and hemodynamics on aneurysm formation along the inner carotid siphon. Catheter 3D-rotational angiographic volumes of 35 ICA (10 aneurysms, 25 controls) were evaluated in 3D for radius of curvature and peak curvature of the siphon bend, followed by univariate statistical analysis. Computational fluid dynamic (CFD) simulations were performed on patient-derived models after aneurysm removal and on synthetic variants of increasing curvature. Peak focal siphon curvature was significantly higher in aneurysm bearing ICAs (0.36±0.045 vs. 0.30±0.048mm−1, p=0.003), with no difference in global radius of curvature (p=0.36). In CFD simulations, increasing parametric curvature tightness (from 5 to 3mm radius) resulted in dramatic increase of WSS and WSS gradient magnitude (WSSG) on the inner wall of the bend. In patient-derived data, the location of aneurysms coincided with regions of low WSS (<4Pa) flanked by high WSS and WSSG peaks. WSS peaks correlated with the aneurysm neck. In contrast, control siphon bends displayed low, almost constant, WSS and WSSG profiles with little spatial variation. High bend curvature induces dynamically fluctuating high proximal WSS and WSSG followed by regions of flow stasis and recirculation, leading to local conditions known to induce destructive vessel wall remodeling and aneurysmal initiation.

O-017 Reduction in distal emboli with proximal flow control during mechanical thrombectomy: a quantitative in vitro study

PurposeThe hypothesis is that proximal flow control with a balloon guide catheter (BGC) in the cervical internal carotid artery (ICA) during mechanical thrombectomy will reduce the amount of distal emboli.Materials...

Flow patterns and wall shear stress distribution in human internal carotid arteries: The geometric effect on the risk for stenoses

It has been widely observed that atherosclerotic stenosis occurs at sites with complex hemodynamics, such as arteries with high curvature or bifurcations. These regions usually have very low or highly oscillatory wall shear stress (WSS). In the present study, 3D sinusoidally pulsatile blood flow through the models of internal carotid artery (ICA) with different geometries was investigated with computational simulation. Three preferred sites of stenoses were found along the carotid siphon with low and highly oscillatory WSS. The risk for stenoses at these sites was scaled with the values of time-averaged WSS and oscillating shear index (OSI). The local risk for stenoses at every preferred site of stenoses was found different between 3 types of ICA, indicating that the geometry of the blood vessel plays significant roles in the atherogenesis. Specifically, the large curvature and planarity of the vessel were found to increase the risk for stenoses, because they tend to lower WSS and elevate OSI. Therefore, the geometric study makes it possible to estimate the stenosis location in the ICA siphon as long as the shape of ICA was measured.

Transvenous embolization of dural carotid cavernous fistula through the facial and ophthalmic vein

Dural carotid cavernous fistula is acquired, relatively rare, condition comprising of numerous small-caliber meningeal arterial branches, draining directly into cavernous sinus. Endovascular therapy is the treatment of choice, preferably by a transvenous approach. In the case of inaccessible inferior petrosal sinus, other alternative routes are considered. We presented a case of dural carotid cavernous fistula completely occluded with Guglielmi detachable coils, using a transvenous approach through facial and superior ophthalmic vein. A 62-year-old man was referred with a gradual worsening proptosis, red eye, and decreased visual acuity, on the right side. Digital subtraction an giography revealed the presence of a right dural carotid cavernous fistula, predominantly supplied from dural branches of the right internal carotid artery siphon, with minimal contribution from the right middle meningeal artery and contra lateral dural branches of the left internal carotid artery siphon. The fistula was drainaged through the dilated superior ophthalmic vein, and via the facial to the internal jugular vein. There was neither pacification of pterygoid and petrous sinuses, nor cortical venous reflux. Endovascular treatment was performed by a transvenous approach. A guiding catheter was placed in the right facial vein. A microcatheter was advanced through the dilated angular and superior ophthalmic vein, and its tip positioned into the right cavernous sinus. Coils were deployed, until a complete angiographic occlusion of the fistula had been achieved. The patient experienced rapid improvement in the symptoms, with complete normalization of his condition one month after the treatment. Coil embolization of dural carotid cavernous fistula by transvenous catheterization, through the facial and superior ophthalmic vein, can be considered as safe and effective treatment option in the presence of marked anterior drainage.

TCD Diastolic Velocity Decay and Pulsatility Index Increment in PVS Cases

Functional neuroimaging has provided new insights for assessing cerebral function in persistent vegetative state patients (PVS). Compared to controls, positron emission tomography and single photon emission tomography have shown a substantial reduction of global brain cerebral glucose metabolism and perfusion in PVS. Doppler ultrasonography (TCD) assesses local blood flow velocity and direction in the proximal portions of large intracranial arteries; it is a noninvasive technique, and it can be carried out at the bedside. To date, few studies have applied TCD to study PVS. We assessed intracranial circulation by TCD in five PVS patients. The cause of brain insult was hypoxic encephalopathy in four cases, and the other suffered an embolic cerebral infarct causing a top of the basilar artery syndrome. The sample volume was set at 12 mm; power output and gain settings were maximized as needed. The temporal bone acoustic window was not suitable for intracranial vessel insonation in all patients. As an alternative, the internal carotid artery siphon was assessed by orbital insonation between 55-70 mm. Systolic velocity was within a normal range, between 44 and 62 cm/second in all cases. However, the diastolic amplitude was reduced, as well as the end diastolic velocity, and the pulsatility index was increased in all patients. We conclude that TCD diastolic velocity decrement and PI augmentation in our cases might be related to uncoupling of cerebral blood flow and cerebral metabolic rate, arising from reduced cerebral glucose consumption and oxygen uptake, after extensive brain injury.