Accuracy of 3.0T magnetic resonance angiography for the detection of arteriovenous fistula dysfunction in hemodialysis patients requiring interventional therapy: a prospective study.

Background: Color Doppler ultrasonography (CDUS) is feasible to detect arteriovenous fistula (AVF) dysfunction in hemodialysis patients but is not sufficient to map the structure of fistula required for interventions. This study is designed to evaluate the diagnostic accuracy of three-dimensional time-of-flight magnetic resonance angiography (TOF-MRA) at 3.0T versus CDUS for AVF dysfunction, by using digital subtraction angiography (DSA) as reference. Methods: This prospective study enrolled 68 consecutive patients with dysfunctional AVF who underwent both CDUS and TOF-MRA at Shanghai Sixth People's Hospital affiliated to Shanghai Jiao Tong University School of Medicine. The analysis of the dysfunctional AVFs was divided into three regions: the feeding artery, fistula and draining veins. In the whole- and per-regional-based analyses, two observers who were blinded to the clinical and DSA results independently analyzed all CDUS and TOF-MRA datasets. The image quality and stenosis severity of the lesions on TOF-MRA were evaluated. A receiver operating characteristic curve was applied to analyze the detection of AVF dysfunction with TOF-MRA. Results: A total of 204 vessel regions were evaluated. The whole-region-based image quality of TOF-MRA was poorer in patients with a total occlusion (1.8±0.8) than in those with stenosis (2.7±0.6, P<0.001). In the whole-region analyses, TOF-MRA had higher sensitivity [99.1% (94.6-100.0%) vs. 82.9% (74.6-89.0%), P<0.001] and similar specificity [93.1% (85.0-97.1%) vs. 94.3% (86.5-97.9%), P=0.755] than CDUS. The per-region-based analyses showed that TOF-MRA yielded higher sensitivity [fistula region, 98.1% (88.4-99.9%) vs. 80.8% (67.0-89.9%); P=0.004; draining vein region, 100.0% (92.5-100.0%) vs. 85.0% (72.9-2.5%); P=0.003] and similar specificity [fistula region, 88.2% (62.3-97.8%) vs. 88.2% (62.3-97.9%); P>0.99; draining vein region, 100.0% (59.8-100.0%) vs. 87.5% (46.7-99.3%); P>0.99] than CDUS. Sensitivity and specificity of TOF-MRA were comparable to those of CDUS in feeding artery region. Conclusions: TOF-MRA is a feasible and accurate method to display AVF dysfunction in hemodialysis patients, and this method might fulfill the endovascular treatment planning requirements.

Thin-slab maximum intensity projection of CT angiography for collateral score and clot burden score evaluation: comparison with conventional CT angiography.

BACKGROUND: This study aimed to exam the effects of thin-slab maximum intensity projection (TS-MIP) of computed tomography angiography (CTA) for collateral score (CS) and clot burden score (CBS) evaluation in patients with large-vessel-occlusion (LVO) stroke in the anterior circulation. METHODS: Of 241 consecutive patients with LVO stroke admitted to our center between August 2015 and June 2020, 187 patients were enrolled. CS and CBS were evaluated on conventional CTA and TS-MIP separately. Outcome at 90 days was classified as good if modified Rankin scale (mRS) was ≤2 and as poor if mRS was >2. The correlations between CS and CBS and clinical outcomes were assessed. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic values of CS and CBS. Multivariate logistic regression analysis was performed to identify the independent predictors of 90-day good clinical outcomes. RESULTS: The correlation coefficient for clinical outcomes was significantly better for CS based on TS-MIP than that based on conventional CTA (-0.444 vs. -0.285, P=0.039); no significant difference was found in the CBS evaluation (TS-MIP: -0.356 vs. conventional CTA: -0.320, P=0.348). For predicting good clinical outcomes, TS-MIP-based CS was associated with larger area under the curve (AUC) (0.709 vs. 0.609, P=0.004) and higher sensitivity (69.1% vs. 42.0%, P=0.001) than CS based on CTA. In multivariable logistic regression analysis, the factors independently associated with good outcomes were National Institutes of Health Stroke Scale (NIHSS) score at admission (OR =1.147; P<0.001), TS-MIP-based CS (OR =0.326; P<0.001), final modified treatment in cerebral infarction (mTICI) score of 2b/3 (OR =0.098; P<0.001), and hemorrhagic transformation (OR =3.662; P<0.001). CONCLUSIONS: TS-MIP-CTA is superior to conventional CTA for evaluation CS and CBS, and TS-MIP-based CS may be a useful predictor of clinical outcome.

Atherosclerosis in intracranial or extracranial vessels in diabetic patients and the association with stroke subtype.

BACKGROUND: Diabetes mellitus (DM) is associated with increased prevalence and severity of atherosclerosis. This study aimed to assess the prevalence and location of atherosclerosis in intracranial and extracranial vessels in diabetic patients and to investigate their association with ischemic stroke subtype. METHODS: Diabetes patients (n=128) and nondiabetic patients (n=195) were enrolled. Brain MRI, MR angiography, and digital subtraction angiography (DSA) imaging findings in the two groups were retrospectively compared. The characteristics of atherosclerosis (prevalence, location, severity) and collateral flow in diabetic and nondiabetic patients and their association with stroke subtype were analyzed. RESULTS: Atherosclerosis in extracranial vessels was more common in diabetes patients than in nondiabetic patients (43.8% vs. 23.1%; P<0.001). Symptomatic stenoses were commonly in the proximal internal carotid artery (ICA) and proximal vertebral artery (pVA). Diabetes patients were more likely to have lacunar infarction (49.2% vs. 32.3%; P=0.002) and less likely to have large artery infarct (36.7% vs. 48.2%; P=0.042). DM (OR, 2.03; 95% CI, 1.96-4.30; P=0.006) and age >65 years (OR, 2.55; 95% CI, 1.24-5.22; P=0.011) were independent risk factors for lacunar infarct. Diabetes patients with symptomatic extracranial stenosis or occlusion, combined with good collateral circulation, had significantly higher risk of lacunar infarction than nondiabetic patients (47.8% vs. 30.5%; P=0.045). CONCLUSIONS: DM aggravates the severity of extracranial atherosclerosis. Lacunar stroke is relatively common in diabetic patients and could even be due to large artery disease (LAD).

Integrated application of antegrade and retrograde recanalization for femoral-popliteal artery chronic total occlusions: outcomes compared with antegrade recanalization.

BACKGROUND: To investigate the efficacy of retrograde recanalization for chronic total occlusion (CTO) of femoral-popliteal artery in patients with peripheral arterial disease. METHODS: In this single-center retrospective study, all patients who had undergone endovascular recanalization for femoral-popliteal CTOs at our center from June 2011 to October 2014 were included. Patients' demographics, immediate and follow-up outcomes were analyzed. RESULTS: A total of 205 patients with 238 CTOs were enrolled. In total, successful recanalization was achieved in 228 CTOs (95.8%). The antegrade procedure was successful in 196 CTOs. The retrograde procedure was successfully performed in 32 CTOs after failed antegrade procedure. Ankle-brachial index increased from 0.48±0.18 to 0.79±0.16 in antegrade group vs. 0.41±0.13 to 0.76±0.13 in retrograde group (P=0.438). Pulse score increased from 0.48±0.50 to 2.30±0.76 in antegrade group vs. 0.48±0.51 to 2.30±0.79 in retrograde group (P=0.771). At 12 and 24 months, primary patency rate was 86.2% (169/196) and 51.5% (101/196) in the antegrade group, and 75.0% (24/32) and 43.8% (14/32) in the retrograde group, respectively (P=0.346). Kaplan-Meier analysis showed limb salvage rates of 85.7% in the antegrade group vs. 78.1% in the retrograde group (P=0.198). CONCLUSIONS: Retrograde recanalization is effective for CTO of femoral-popliteal artery after the failure of an antegrade procedure; immediate outcomes and mid-term patency and limb salvage rate are comparable with that of antegrade procedure.

No inferiority of Tonbridge thrombectomy device for acute thrombus retrial compared with Solitaire device: an experimental evaluation with a canine distal external carotid-maxillary artery occlusion model.

INTRODUCTION: Mechanical thrombectomy (MT) has been widely accepted as a safe and effective treatment for acute ischemic stroke (AIS). Development of stent retriever devices has been intensively developed over the past two decades. In this study, we compared the effectiveness and safety of a new thrombectomy device with Solitaire FR for the treatment of AIS models. METHODS: Mechanical performance of stent retrievers was tested in vitro. Thrombin-induced thrombus was pre-injected into the right distal external carotid-maxillary artery in 18 dogs to create an acute thrombus occlusion model, and these animals were divided into a Tonbridge group (n=9, with Tonbridge stent Tonbridge Medical Technology) and a Solitaire group as control (n=9, with Solitaire stent, ev3 Neurovascular). Final flow restoration, side branches, recanalization time, distal vessel embolism, and device-related complications were recorded and compared. A post-procedure angiogram was obtained at 30 and 90 days after thrombectomy. Device manipulation-related damage to the arterial walls was evaluated histologically. RESULTS: In vitro test showed that the maximum friction within the microcatheter was 0.763 for the Tonbridge device and 0.784 n for the Solitaire (P>0.05). Slight increase in radial force was noticed for the Tonbridge (0.035 N/mm vs 0.031 N/mm of Solitaire, P>0.05). Eighteen and 16 retriever attempts were done in the Tonbridge (mean 2.0 attempts) and the Solitaire (mean 1.8 attempts) groups (P=0.74). The Tonbridge device led to good flow restoration in all nine (100%) models compared with eight (88.9%) in the Solitaire group (P=0.30). Side branches' influence (P=0.39), distal thromboembolism (P=0.60), and device-related complications (P=1.00) found no difference between the two groups. The rates of disruption of the internal elastic lamina (IEL) were 8.3% (2/24) and 4.2% (1/24) of the specimens, respectively (P=0.683). TICI 2b/3 flow of the right CCA were similar between the two groups at 1 (6/6 vs 6/6) and 3 months (6/6 vs 6/6) follow-up (P>0.05). CONCLUSION: Our preliminary study indicated this new device was technically feasible and effective to be used in thrombectomy for the treatment of acute thrombus occlusion in canine models.

Concomitant aneurysm detection in an intracranial dolichoectasia mouse model using a MicroFil polymer perfusion technique.

OBJECTIVE: To assess the feasibility of using MicroFil polymer perfusion to detect concomitant saccular aneurysms in an intracranial arterial dolichoectasia (IADE) model in mice, and to report detailed histomorphometric features of these aneurysms. MATERIALS AND METHODS: IADE models were created in C57/BL6 mice via microsurgical injection of 25 mU elastase into the cisterna magna. The cerebral vasculature was perfused with MicroFil polymer and harvested at 1, 3, and 7 days, and 2 and 4 weeks (n=8 for each group). IADE was defined by a tortuosity index >10 combined with a 25% increase in diameter of the A1 segment of the anterior cerebral artery (ACA), internal carotid artery (ICA), or basilar artery compared with the baseline of controls, which received heat-inactivated elastase. Saccular aneurysm occurrence rate, location, and morphological parameters were investigated using macroscopic and microscopic analysis. RESULTS: IADE was present in 95% (36/38) of the subjects, with a mortality rate of 5% (2/40). Fifteen concomitant saccular aneurysms were detected in 8 (21%) of the 38 surviving mice, including 6 at the posterior communicating artery, 1 along the ACA, 2 along the anterior communicating artery complex, 3 along the ICA, and 3 along the middle cerebral artery. Rupture was confirmed in two aneurysms. Histological examination indicated that the aneurysms develop via arterial-wall remodelling, which is characterized by internal elastic lamina disruptions and muscular layer discontinuity in the media. CONCLUSIONS: The proportion of subjects developing saccular aneurysms in addition to IADE in our mouse model is similar to the 15% of patients with IADE who have concomitant saccular aneurysms.

Arterial wall degeneration plus hemodynamic insult cause arterial wall remodeling and nascent aneurysm formation at specific sites in dogs.

To determine whether arterial wall degeneration, in combination with hemodynamic insult, causes cerebral artery aneurysms in a dog model, we simulated the geometry and hemodynamics of a human artery by surgical reconstruction of both common carotid arteries in 12 dogs. The dogs were then randomly assigned to one of the following groups: hemodynamic insult + elastase insult group ( n = 6), hemodynamic insult group (n = 6), or elastase control group (n = 3), in which the straight common carotid arteries were subjected to elastase alone. Angiography and hemodynamic analysis were performed immediately and at 12 weeks after surgery; the animals were then killed for histologic evaluation. The 12 surgically reconstructed distal internal carotid arteries simulated the human artery well with respect to geometric and hemodynamic measurements, with the intended aneurysm sites exposed to higher wall shear stress and velocity, lower pressure, turbulent flow, and changes in wall shear stress gradient. Nascent aneurysms developed in 4 hemodynamic insult + elastase insult group dogs at 12 weeks; blood flow analysis demonstrated decreased wall shear stress, increased pressure, and wall shear stress gradient from the neck to the dome. Arterial wall remodeling or nascent aneurysm formation in the hemodynamic insult + elastase insult group versus the other groups was indicated by internal elastic lamina/elastic fiber disruption, muscular layer thinning, increased smooth muscle cell proliferation, macrophage infiltration, and high expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 in the media. These data suggest that nascent aneurysms were caused by the combination of arterial wall degeneration and hemodynamic perturbations in this distal internal carotid artery dog model.

Temporary placement of a paclitaxel or rapamycin-eluting stent is effective to reduce stenting induced inflammatory reaction and scaring in benign cardia stricture models.

BACKGROUND/AIMS: To investigate whether temporary placement of a paclitaxel or rapamycin eluting stent is more effective to reduce stenting induced inflammatory reaction and scaring than a bared stent in benign cardia stricture models. MATERIALS AND METHODS: Eighty dog models of stricture were randomly divided into a control group (CG, n=20, no stent insertion), a bare stent group (BSG, n=20), a paclitaxel eluting (Pacl-ESG, n=20) and a rapamycin eluting stent group (Rapa-ESG, n=20), with one-week stent retention. Lower-oesophageal-sphincter pressure (LOSP), 5-minute barium height (5-mBH) and cardia diameter were assessed before, immediately after the procedure, and regularly for 6 months. Five dogs in each group were euthanized for histological examination at each follow-up assessment. RESULTS: Stent insertion was well tolerated, with similar migration rates in three groups. At 6 months, LOSP and 5-mBH improved in Pacl-ESG and Rapa-ESG compared to BSG (p<0.05), with no difference between Pacl-ESG and Rapa-ESG (p>0.05). Cardia kept more patency in the Pacl-ESG and Rapa-ESG than in BSG (p<0.05). Reduced peak inflammatory reactions and scarring occurred in the Pacl-ESG and Rapa-ESG compared to BSG (p<0.05), with a similar outcome in the Pacl-ESG and Rapa-ESG (p>0.05). CONCLUSION: Paclitaxel or rapamycin-eluting stents insertion led to better outcomes than bare stents in benign cardia stricture models.

Frequency and predictors of endoleaks and long-term patency after covered stent placement for the treatment of intracranial aneurysms: a prospective, non-randomised multicentre experience.

OBJECTIVE: We investigated immediate/late endoleaks and long-term patency following stent-graft placement for treatment of intracranial aneurysms located within the distal internal carotid artery (ICA) or vertebral artery (VA). METHODS: Forty-five aneurysms in 41 patients receiving covered stents in three centres were followed. Outcome measures included aneurysm occlusion rate, endoleaks, late in-stent stenosis rate, clinical improvement, neurological deficiencies and death. RESULTS: Total aneurysm exclusion was achieved in 69.2% (n = 27), with 30.8% (n = 12) experiencing immediate residual endoleaks. Angiographic follow-up (mean 43.5 ± 14.3 months) revealed that 87.2% (n = 34) were completely occluded with only 12.8% (n = 5) showing residual endoleaks. Predictors of immediate endoleaks in our patient group were stent number (P = 0.023) and stent diameter (P = 0.022), while predictors of late endoleaks in our patient group were stent diameter (P = 0.035) and stent angulation (P = 0.021). Late in-stent stenosis rates were 18.0 ± 13.3 and 29.0 ± 18.5% compared with the period immediately following implantation at 2- and 6-year follow-ups respectively. Smoking (P = 0.017) and stent angulation (P = 0.020) were predictors of late in-stent stenosis. CONCLUSION: Treating intracranial aneurysms with Willis stent-grafts has an acceptable immediate and late occlusion rate and long-term stented artery patency rate.

Safety, feasibility, and mid-term follow-up of Willis stent graft placement in the treatment of symptomatic complicated intra- or extra-cranial aneurysms: a multicenter experience.

We report the technical success rate and mid-term follow-up results after deploying stent-grafts to treat a cohort of patients with symptomatic complicated intra- or extracranial aneurysms (SCIEAs). This study was a retrospective review of 58 patients (39 male; mean age 40.4 ± 12.3 years) with 60 SCIEAs treated by 67 Willis covered stents at three medical centers in China between April 2005 and January 2010. The locations of the SCIEAs were as follows: Intracranial internal carotid artery (ICA) in 54 patients, extracranial ICA in one, intracranial vertebral artery (VA) in three and extra-cranial VA in two. Surgery was successful in 59 (98.3%) SCIEAs. Total exclusion was immediately achieved in 48 SCIEAs, and minor endoleaks were present in 11. Acute thrombosis occurred in two patients and hemorrhage in one. Follow-up angiography (mean 13.8 ± 8.9 months) revealed that 49 of 52 (94.2%) aneurysms were completely isolated, with mild in-stent stenosis in only two patients and in-stent occlusion in one patient. Willis stent-graft application is an alternative therapy to treat SCIEAs in either intra- or extracranial ICAs or VAs. In the case of a tortuous intracranial ICA or potential side branch coverage, however, it is still not a first choice.

Combined endovascular and vascular surgical therapy of a blister-like distal internal carotid aneurysm in a patient with a right-sided aortic arch.

Blood blister-like aneurysms (BBAs) are rare but challenging to treat owing to their fragile, thin walls and poorly defined necks. A right-sided aortic arch is an uncommon congenital cardiac anomaly with an estimated incidence of only 0.1% and presents a challenge to intubation at vessels above the aortic arch. This represents an extremely rare case of a BBA at the left internal carotid artery with a right-sided aortic arch treated with combined endovascular and vascular surgical therapy. We report the case and provide a short review of the relevant literature.

Batroxobin for prevention of restenosis in diabetic patients after infrapopliteal arterial angioplasty: a small randomized pilot trial.

BACKGROUND: We designed a small randomized clinical trial to prospectively test the hypothesis that batroxobin is more effective than aspirin alone to prevent restenosis in patients with diabetes undergoing angioplasty of infrapopliteal arteries. METHODS: After a successful angioplasty, a total of 52 diabetic patients with symptomatic infrapopliteal obstructions were randomized to either the treated group (n = 26) or the control group (n = 26). Patients in the treated group received 5 IU batroxobin through an intravenous drip once every alternate day, for a total of six doses. The primary end point was restenosis and reocclusion, which was documented by magnetic resonance angiography or duplex scanning at 12-month follow-up. The clinical symptoms relief and ankle-brachial index (ABI) were compared before and after the procedure, and during follow-up. Kaplan-Meier curves were constructed to evaluate restenosis or reocclusion-free, limb salvage, and amputation-free rates. RESULTS: Restenosis and reocclusion occurred in 22.0% and 34.5% lesions in the treated and the control group, respectively (p = 0.0307). Statistical differences were observed between the ABI before the angioplasty procedure(p < 0.05) and the ABI at the 12-month follow-up (p = 0.0094) of the two groups. Clinical symptoms improvement and tissue healing occurred in 23 and 19 patients in the batroxobin group and the control group, respectively (p = 0.0544). Twelve months after angioplasty, Kaplan-Meier analysis showed that the restenosis and reocclusion-free rate was 74.0% and 54.8%, the limb salvage rate was 96.2% and 92.3%, and the amputation-free rate was 84.6% and 84.6%, in the treated and control group, respectively. CONCLUSION: This pilot trial revealed that batroxobin usage was effective in preventing restenosis and reocclusion after infrapopliteal arterial angioplasty, and it might provide better clinical symptoms relief; however, it did not report preferable limb salvage or amputation-free rates.

The effectiveness and feasibility of endovascular coil embolization for very small cerebral aneurysms: mid- and long-term follow-up.

BACKGROUND: Endovascular embolization for very small cerebral aneurysms (VSCAs) is still controversial. We report our experience with endovascular coil embolization for these lesions and assess the feasibility and effectiveness. METHODS: We conducted a review of our experience with endovascular treatment of a series of 19 patients with 20 VSCAs, located at the supraclinoid segment of the internal cranial artery (ICA) in seven, the cavernous ICA segment in three, the anterior communicating artery in five, vertebral artery-posterior inferior cerebellar artery in two, bifurcation of the middle cerebral artery in one, the pericallosal artery in one, and the P2 segment in one. The World Federation of Neurosurgical Societies classification before treatment was grade I in 14 patients and grade II in five patients. The strategy of endovascular treatment included coil occlusion, balloon-assisted coiling, and stent-assisted coiling. Occlusion rate was divided into (1) total/near total, occlusion rate 95-100%; (2) subtotal, occlusion rate 80-95%; and (3) partial, occlusion rate<80%. Clinical outcome of patients with ruptured aneurysm was ascertained according to the Glasgow Outcomes Scale. RESULTS: All patients were successfully treated with coil embolization; immediate angiography determined occlusion of the aneurysm, including total occlusion in five, subtotal occlusion in nine, and partial occlusion in six. During 1-2 years of follow-up, all aneurysms were confirmed as complete occlusion by control angiography. No recurrence or coil compaction occurred. No rehemorrhage or ischemic stroke occurred. CONCLUSION: Endovascular coil embolization for VSCAs is effective and feasible. Initial subtotal or partial aneurysm occlusion might progress to total occlusion.

Subintimal angioplasty for below-the-ankle arterial occlusions in diabetic patients with chronic critical limb ischemia.

PURPOSE: To assess the feasibility and efficacy of subintimal angioplasty (SA) in the treatment of below-the-ankle arterial occlusion in diabetic patients with chronic critical limb ischemia (CLI). METHODS: SA was applied in 37 diabetic patients (24 men; mean age 70.9+/-8.5 years, range 52-88) with chronic CLI and occlusive disease of the dorsalis pedis artery (DPA) and/or plantar artery (PA) but were poor candidates for intraluminal angioplasty or bypass surgery. Tissue loss was present in 31 (54.4%) of 57 afflicted limbs, and rest pain was reported in 51 (89.5%) limbs. SA was performed to create continuous arterial flow to the foot for limb salvage. The clinical symptoms, DPA or PA pulse volume scores, and ankle-brachial index (ABI) were compared before and after SA. Wound healing, amputation, and restenosis of target vessels were also evaluated at follow-up. Kaplan-Meier curves were constructed to evaluate limb salvage, survival, and freedom from amputation. RESULTS: Below-the-ankle SA was performed successfully in 55 (83.3%) of 66 arteries in 57 limbs. Median pulse volume scores and ABIs were 0.33+/-0.55 and 0.31+/-0.19 before SA and 2.04+/-1.05 and 0.80+/-0.14 after SA, respectively (p<0.0001 for both). The 30-day mortality was 2.7%. Median follow-up was 9.1+/-6.1 months (range 1-18). Major complications occurred in 1 (2.7%) patient and minor complications in 3 (8.1%). Twelve months after SA, Kaplan-Meier analysis showed that the limb salvage rate was 94.6%, the freedom from amputation was 89.2%, and the survival rate was 97.3%. CONCLUSION: SA of the dorsalis pedis artery and/or plantar artery is a useful technique for lower limb salvage in diabetic patients with chronic CLI who are not candidates for bypass surgery.

Surgical construction of a novel simulated carotid siphon in dogs.

OBJECT: The development and preclinical assessment of new endovascular devices necessitate readily available and reproducible animal models. The purpose of this study was to develop an in vivo carotid siphon model for testing the properties of covered stents specially designed for the intracranial vasculature. METHODS: Six carotid siphon-shaped devices were created. Six dogs underwent surgery to expose and isolate both common carotid arteries (CCAs). The right CCA origin was ligated and incised distal to the ligation point after temporary constriction of the distal right CCA. The distal left CCA was ligated and incised proximal to the ligation point after the left CCA origin was temporarily clamped. The proximal isolated left CCA was passed through the shaped device and then anastomosed end-to-end to the distal isolated right CCA. Finally, the shaped device was fixed and embedded in the neck. Intraarterial digital subtraction angiography was performed at 7 days, 2 weeks, and 1 month postprocedure. All models underwent endovascular interventional simulation. The carotid siphon models were evaluated. RESULTS: The animals tolerated the surgical procedure well. The mean time for surgical construction of the model was 90 minutes. The morphology and endovascular manipulation of the siphon models were similar to those in humans. Stenosis of anastomotic stoma occurred in 2 models, and mural thrombosis of anastomotic stoma occurred in 1 model; however, all models were patent at postprocedural follow-up angiography. CONCLUSIONS: Surgical construction of an in vivo carotid siphon model in dogs with carotid siphon-shaped devices is feasible and potentially useful for testing neurovascular devices.