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Satoshi Tateshima, Fernando Viñuela, J. Pablo Villablanca, Yuichi Murayama, Taku Morino, Kiyoe Nomura, and Kazuo Tanishita

the cerebral aneurysm, and Dr. Yih Lin Nien Shy for his great assistance in the preparation of this manuscript. Abbreviations used in this paper ACA = anterior cerebral artery ; CT = computerized tomography ; DS = digital subtraction ; ICA = internal carotid artery ; LDV = laser Doppler velocimetry ; MCA = middle cerebral artery ; OphA = ophthalmic artery ; PIV = particle image velocimetry ; 3D = three-dimensional . References 1. Burleson AC

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Vertebrobasilar occlusion therapy of giant aneurysms

Significance of angiographic morphology of the posterior communicating arteries

David M. Pelz, Fernando Viñuela, Allan J. Fox, and Charles G. Drake

G iant intracranial aneurysms have arbitrarily been defined as aneurysms greater than 2.5 cm in diameter, and they comprise approximately 5% of all intracranial aneurysms. 8 They are most commonly located in the intracavernous portion of the internal carotid artery, and in the supraclinoid carotid artery. 10 Giant aneurysms of the vertebrobasilar system are uncommon, representing only 8% of all giant intracranial aneurysms. 7 A thorough angiographic evaluation is essential in all aneurysm cases, and this is particularly true of giant aneurysms. Multiple

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Fernando Viñuela, Allan J. Fox, David M. Pelz, and Charles G. Drake

hemorrhage. The source of bleeding is not always evident but, in some cases at least, hemorrhage results from rupture of aneurysmally dilated veins rather than from rupture of the AVM itself. 8 The use of superselective angiography, with catheterization of individual branches of the external carotid artery and identification of the meningeal branches from internal carotid and vertebral arteries, has helped the neurosurgeon and neuroradiologist to better identify and separate these lesions from the more common intracranial arachnoid AVM's. 13 The arterial supply to dural

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Electrothrombosis of saccular aneurysms via endovascular approach

Part 1: Electrochemical basis, technique, and experimental results

Guido Guglielmi, Fernando Viñuela, Ivan Sepetka, and Velio Macellari

immersed end of the positive wire dissolves, and the other wire recruits the migrating ferrous ions from the anode to the cathode. Noble metals such as platinum are not affected by this phenomenon. 23 Electrolysis is the process that will detach the platinum coil from the stainless steel delivery wire within an aneurysm. Materials and Methods Since February, 1989, experimental saccular aneurysms were surgically created in swine by grafting a vein pouch onto the common carotid artery (this surgical technique will be described in a separate communication). Swine

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Fernando Viñuela, Gary Duckwiler, and Michel Mawad

.4  posterior communicating/anterior choroidal 53 13.2  middle cerebral artery bifurcation 11 2.7  internal carotid artery bifurcation 8 2.0 Hunt and Hess Grading Eighty-two patients (20.3%) were classified as Grade I, 105 (26.1%) as Grade II, 121 (30%) as Grade III, 69 (17.1%) as Grade IV, and 26 patients (6.5%) as Grade V. Timing of Treatment One hundred forty-seven patients (36.5%) underwent GDC aneurysm occlusion within 48 hours after the primary hemorrhage; 156 (38.7%) underwent GDC aneurysm occlusion between 3 and 6

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Gyula Gács, Fernando Viñuela, Allan J. Fox, and Charles G. Drake

= anterior inferior cerebellar artery; AVM = arteriovenous malformation; hemis = hemisphere; ICA = internal carotid artery; angio = angiography. † Preoperative neurological grading according to the Botterell classification system. TABLE 1 (continued) * Case No. Age (yrs), Sex Clinical Syndrome Interval to SAH & Angio Preop. Grade † Site & Size of Aneurysm Vasospasm Other Anomalies Surgery Outcome 13 69, M 2 × SAH, rt cerebellar signs 4 wks I rt SCA, on hemis branch; 7 × 4 mm none AVM

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Guido Guglielmi, Fernando Viñuela, Jacques Dion, and Gary Duckwiler

15 57, F SAH basilar small previous attempt failed 1 40 cm, 8-mm mem. 11/5/90 none 11/9/90 100% occlusion good bifurcation 1 15 cm, 5-mm mem. * CC fistula = carotid-cavernous fistula; mem. = circular memory; SAH = subarachnoid hemorrhage; PICA = posterior inferior cerebellar artery; PCA = posterior cerebral artery; SCA = superior cerebellar artery; ICA = internal carotid artery; ACA = anterior cerebral artery; VB junction = vertebrobasilar junction; ACoA = anterior communicating artery; MCA = middle

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Fernando Viñuela, Allan J. Fox, Gerard M. Debrun, Sydney J. Peerless, and Charles G. Drake

T he extensive vascular collateral pathways between the internal carotid artery (ICA) and the external carotid artery (ECA) in the region of the cavernous sinus have been well documented. The first angiographic demonstration of these important vascular pathways was reported by Marx in 1949. 16 In 1963, Hayes 8 described ECA-ICA anastomosis as the cause of recurrent carotid-cavernous fistulas after performance of a Dandy trapping procedure. In 1965, Parkinson 20 described a surgical approach to the cavernous portion of the ICA for the treatment of carotid

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Allan J. Fox, Fernando Viñuela, David M. Pelz, Sydney J. Peerless, Gary G. Ferguson, Charles G. Drake, and Gerard Debrun

T he accepted method of treatment for cerebral aneurysms is surgical clipping of the aneurysm neck. However, because of location, size, or wall thickness, it is not always possible to surgically clip these aneurysms. For unclippable carotid artery aneurysms, occlusion of the carotid artery is still an accepted treatment, 11 with the occlusion being performed by surgical ligation, Selverstone clamp, 8, 11, 13 Drake tourniquet, 4 or detachable balloon. 1, 2, 12 The use of parent vessel occlusion has been expanded to include one or both vertebral arteries as

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Satoshi Tateshima, Kazuo Tanishita, Yasuhiro Hakata, Shin-ya Tanoue, and Fernando Viñuela

Object

Development of a flexible self-expanding stent system and stent-assisted coiling technique facilitates endovascular treatment of wide-necked brain aneurysms. The hemodynamic effect of self-expandable stent placement across the neck of a brain aneurysm has not been well documented in patient-specific aneurysm models.

Methods

Three patient-specific silicone aneurysm models based on clinical images were used in this study. Model 1 was constructed from a wide-necked internal carotid artery–ophthalmic artery aneurysm, and Models 2 and 3 were constructed from small wide-necked middle cerebral artery aneurysms. Neuroform stents were placed in the in vitro aneurysm models, and flow structures were compared before and after the stent placements. Flow velocity fields were acquired with particle imaging velocimetry.

Results

In Model 1, a clockwise, single-vortex flow pattern was observed in the aneurysm dome before stenting was performed. There were multiple vortices, and a very small fast flow stream was newly formed in the aneurysm dome after stenting. The mean intraaneurysmal flow velocity was reduced by ~ 23–40%. In Model 2, there was a clockwise vortex flow in the aneurysm dome and another small counterclockwise vortex in the tip of the aneurysm dome before stenting. The small vortex area disappeared after stenting, and the mean flow velocity in the aneurysm dome was reduced by 43–64%. In Model 3, a large, counterclockwise, single vortex was seen in the aneurysm dome before stenting. Multiple small vortices appeared in the aneurysm dome after stenting, and the mean flow velocity became slower by 22–51%.

Conclusions

The flexible self-expandable stents significantly altered flow velocity and also flow structure in these aneurysms. Overall flow alterations by the stent appeared favorable for the long-term durability of aneurysm embolization. The possibility that the placement of a low-profile self-expandable stent might induce unfavorable flow patterns such as a fast flow stream in the aneurysm dome cannot be excluded.