187 results on '"Daniel A. Rüfenacht"'
Search Results
152. Microsurgical anatomy of the jugular foramen
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Jean H.D. Fasel, Daniel A. Rüfenacht, P. Gailloud, Michel Piotin, and M. Muster
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Microsurgical anatomy ,medicine.anatomical_structure ,business.industry ,Medicine ,Humans ,Anatomy ,Jugular Veins ,business ,Jugular foramen ,Petrous Bone ,Veins - Published
- 1996
153. Transoral Vertebroplasty for a Fractured C2 Aneurysmal Bone Cyst
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Philippe Gailloud, Daniel A. Rüfenacht, Kieran J. Murphy, Jean-Baptiste Martin, and Alessandro Olivi
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medicine.medical_specialty ,medicine.anatomical_structure ,business.industry ,Fracture fixation ,medicine ,Radiology, Nuclear Medicine and imaging ,Aneurysmal bone cyst ,Cardiology and Cardiovascular Medicine ,business ,medicine.disease ,Cervical vertebrae ,Surgery - Published
- 2002
154. Jet-Fluid Effects on the Stented-Flow Structure in the Cavity of Cerebral Aneurysm
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Makoto Ohta, Daniel A. Rüfenacht, Miki Hirabayashi, Kazuhiro Oiwa, Bastien Chopard, and Hiroaki Kojima
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0303 health sciences ,Jet (fluid) ,Materials science ,medicine.medical_treatment ,Open surgery ,Biophysics ,Stent ,Mechanics ,equipment and supplies ,medicine.disease ,eye diseases ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Flow velocity ,Flow (mathematics) ,cardiovascular system ,medicine ,Metal mesh ,sense organs ,cardiovascular diseases ,Endovascular treatment ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
The endovascular treatment of cerebral aneurysms using coils and stents, which are metal mesh cylinders, provides a promising alternative to open surgery. Although various analyses on the property of stented flow have been presented [1,2], the flow reduction mechanisms are not completely understood.Our numerical simulation indicates that the jet flow through stent struts can reduce near the aneurysm mouth but increases the flow speed far from the mouth (Fig. 1). In this work, based on this observation, we reveal the effect of the phenomenon that the pulsed jet flow drives the fluid with different velocity on the flow structure in the aneurysm cavity. As a result, we found a possibility that the shape of aneurysm may induce the self-oscillation of jet flow.We expect that our findings introduce new strategies in stent development and improve the endovascular treatment of cerebral aneurysms.[1] Biondi, A., et al., Neurosurgery, 61, 460-468 (2007)[2] Appanaboyina, S., et al., Int. J. Numer. Meth. Fluids, 57, 475-493 (2008)View Large Image | View Hi-Res Image | Download PowerPoint Slide
- Published
- 2010
155. Endovascular treatment of vertebral arteriovenous fistula
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M C Riché, D. Reizine, Jean-Jacques Merland, Armand Aymard, Rémy Beaujeux, Daniel A. Rüfenacht, Alfredo Casasco, and M H Khayata
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Adult ,Male ,congenital, hereditary, and neonatal diseases and abnormalities ,medicine.medical_specialty ,Adolescent ,medicine.medical_treatment ,Vertebral artery ,Fistula ,Arteriovenous fistula ,Physical examination ,Balloon ,Quadriplegia ,Asymptomatic ,Arteriovenous Malformations ,Tinnitus ,medicine.artery ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,cardiovascular diseases ,Embolization ,Child ,Vertebral Artery ,Aged ,Retrospective Studies ,medicine.diagnostic_test ,business.industry ,Middle Aged ,medicine.disease ,Embolization, Therapeutic ,Surgery ,Cerebral Angiography ,Female ,Radiology ,medicine.symptom ,business ,Cerebral angiography ,Follow-Up Studies - Abstract
The clinical and angiographic features of 46 vertebral arteriovenous fistulas (AVFs) seen during a 12-year period (45 patients) were reviewed. Fourteen patients were asymptomatic, with vertebral AVF discovered at routine clinical examination. Specific symptoms at presentation in the other patients were tinnitus (n = 21), vertigo (n = 6), neurologic deficit (n = 3), and pain (n = 2). Of the 46 AVFs, 19 (41%) were caused by trauma and 27 (59%) were spontaneous. The fistula was found at C-1 to C-2 in 21 (46%) cases, at C-2 to C-5 in five (11%), and below C-5 in 20 (44%). Thirty-four patients (35 vertebral AVFs) were treated with the endovascular technique. Embolization was performed with latex balloons filled with contrast medium in most cases. Endovascular therapy resulted in complete occlusion in 32 cases (91%) and partial occlusion in three (9%). The vertebral artery could not be preserved in three patients. Endovascular balloon treatment of vertebral AVFs is effective in occluding the shunt, avoids general anesthesia and surgical intervention, and results in minimal morbidity. Endovascular therapy is the treatment of choice for vertebral AVF.
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- 1992
156. Remote congenital cerebral arteriovenous fistulae associated with aortic coarctation. Case report
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Francis H. Tomlinson, Sue C. Kaste, Douglas A. Nichols, David G. Piepgras, and Daniel A. Rüfenacht
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Intracranial Arteriovenous Malformations ,Male ,medicine.medical_specialty ,Left subclavian ,Varix ,business.industry ,medicine.medical_treatment ,Coarctation of the aorta ,Infant, Newborn ,Arteriovenous fistula ,medicine.disease ,Pathophysiology ,Aortic Coarctation ,Surgery ,Prenatal ultrasound ,Arteriovenous Fistula ,medicine ,Cerebellar vermis ,Humans ,Caesarean section ,Abnormalities, Multiple ,Radiology ,business - Abstract
✓ A neonate presented with anatomically discrete cerebral arteriovenous fistulae located in the right sylvian fissure and the cerebellar vermis that were initially detected by prenatal ultrasonography. Following delivery of the baby by Caesarean section, both malformations were treated by surgical obliteration. These intracranial vascular lesions were associated with cardiac anomalies and a periductal coarctation of the aorta, which was treated with a left subclavian rotational arterial pedicle repair. Follow-up examination of the infant at age 13 months demonstrated an excellent clinical result with normalization of the circulation. The pathophysiology of this syndrome is discussed and the literature reviewed.
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- 1992
157. Salle d’opération combinée avec angiographie intraopératoire rotationnelle : une note technique sur l’expérience de Genève
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Shahan Momjian, Daniel A. Rüfenacht, I. Radovanovic, C. Schaller, M. Kotowski, B. Schatlo, O. Brina, Philippe Bijlenga, and L. Slegers
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Surgery ,Neurology (clinical) - Published
- 2009
158. 028 Revascularization of large vessel occlusion by the Penumbra System in acute ischemic stroke contributes to good functional outcome
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Michael T. Madison, R Bellon, Christophe Bonvin, Daniel A. Rüfenacht, Robert W Tarr, Donald Frei, Tobias Struffert, D Hsu, Anton Haass, I. Q. Grunwald, K. Alfke, Arnd Dörfler, Olav Jansen, Robert Stingele, Zsolt Kulcsar, and Wolfgang Reith
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medicine.medical_specialty ,business.industry ,medicine.medical_treatment ,Penumbra ,Large vessel ,General Medicine ,Revascularization ,Surgery ,Internal medicine ,medicine ,Cardiology ,Neurology (clinical) ,business ,Acute ischemic stroke ,Mechanical devices ,Large vessel occlusion ,Acute stroke - Abstract
Purpose: The purpose of this study was to assess the post-market experience of the Penumbra System at several academic and community hospitals. The Penumbra System is a new generation of mechanical devices designed to reduce clot burden in acute stroke due to large vessel thromboembolism. It was recently approved for commercial use in the US and Europe, indicated for the revascularization of occluded large vessels in acute ischemic stroke. Methods and Materials: This study …
- Published
- 2009
159. Endovascular occlusion of intracranial vessels for curative treatment of unclippable aneurysms: report of 16 cases
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J E Hodes, Jean-Jacques Merland, D. Reizine, Daniel A. Rüfenacht, S. Bien, Armand Aymard, Y. P. Gobin, and Gaston A
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Male ,medicine.medical_specialty ,medicine.medical_treatment ,Posterior cerebral artery ,Aneurysm ,medicine.artery ,Occlusion ,medicine ,Humans ,cardiovascular diseases ,Embolization ,Aged ,Retrospective Studies ,medicine.diagnostic_test ,business.industry ,Intracranial Aneurysm ,Middle Aged ,medicine.disease ,Embolization, Therapeutic ,Surgery ,Radiography ,Posterior inferior cerebellar artery ,Cerebral blood flow ,Cerebrovascular Circulation ,Angiography ,Middle cerebral artery ,cardiovascular system ,Radiology ,business ,Follow-Up Studies - Abstract
✓ Among 121 intracerebral aneurysms presenting at one institution between 1984 and 1989, 16 were treated by endovascular means. All 16 lesions were intradural and intracranial, and had failed either surgical or endovascular attempts at selective exclusion with parent vessel preservation. The lesions included four giant middle cerebral artery (MCA) aneurysms, one giant anterior communicating artery aneurysm, six giant posterior cerebral artery aneurysms, one posterior inferior cerebellar artery aneurysm, one giant mid-basilar artery aneurysm, two giant fusiform basilar artery aneurysms, and one dissecting vertebral artery aneurysm. One of the 16 patients failed an MCA test occlusion and was approached surgically after attempted endovascular selective occlusion. Treatment involved pretreatment evaluation of cerebral blood flow followed by a preliminary parent vessel test occlusion under neuroleptic analgesia with vigilant neurological monitoring. If the test occlusion was tolerated, it was immediately followed by permanent occlusion of the parent vessel with either detachable or nondetachable balloon or coils. The follow-up period ranged from 1 to 8 years. Excellent outcomes were obtained in 12 cases with complete angiographic obliteration of the aneurysm and no new neurological deficits and/or improvement of the pre-embolization symptoms. Four patients died: two related to the procedure, one secondary to rupture of another untreated aneurysm, and the fourth from a postoperative MCA thrombosis after having failed endovascular test occlusion. The angiographic, clinical, and cerebral blood flow criteria for occlusion tolerance are discussed.
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- 1991
160. Endovascular occlusion of vertebral arteries in the treatment of unclippable vertebrobasilar aneurysms
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B. George, Jean-Jacques Merland, J E Hodes, Daniel A. Rüfenacht, Armand Aymard, S. Bien, Y. P. Gobin, and D. Reizine
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Adult ,Male ,medicine.medical_specialty ,Subarachnoid hemorrhage ,Adolescent ,Vertebral artery ,Endovascular occlusion ,Catheterization ,Aneurysm ,medicine.artery ,Occlusion ,Basilar artery ,Medicine ,Effective treatment ,Humans ,cardiovascular diseases ,Child ,Stroke ,Vertebral Artery ,Aged ,business.industry ,Middle Aged ,medicine.disease ,nervous system diseases ,Surgery ,Basilar Artery ,cardiovascular system ,Female ,Radiology ,business - Abstract
✓ Twenty-one patients with aneurysms of the vertebrobasilar circulation underwent unilateral or bilateral endovascular occlusion of the vertebral artery. Six patients presented with subarachnoid hemorrhage (SAH), 10 with mass effect, four with mass effect and SAH, and one with ischemic symptoms. Thirteen patients had good outcomes with complete clinical and angiographic cure. Six patients had partial thrombosis of their aneurysms. There was one death and one treatment failure. One patient suffered transient stroke. It is concluded that endovascular occlusion of the vertebral artery following test occlusion is a safe and effective treatment for proximal aneurysms of the vertebrobasilar circulation.
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- 1991
161. EFFECT OF CRYOPRESERVATION ON THE MECHANICAL PROPERTIES OF DECELLULARIZED ARTERIES
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Edouard Fonck, Sylvain Roy, Daniel A. Rüfenacht, and Nikos Stergiopulos
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Decellularization ,Chemistry ,Rehabilitation ,Biomedical Engineering ,Biophysics ,Orthopedics and Sports Medicine ,Cryopreservation ,Biomedical engineering - Published
- 2008
162. Concept d'harmonie musculaire paraspinale
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Jean-Marc Constans, Daniel A. Rüfenacht, Alfredo Casasco, T. Sola, Jacques Theron, Patrick Courtheoux, and Leopoldo Guimaraens
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Radiological and Ultrasound Technology ,Radiology, Nuclear Medicine and imaging ,Neurology (clinical) - Published
- 2007
163. La hernie discale: conséquence d'une faiblesse posturale et musculaire locorégionale. Diagnostic et propositions thérapeutiques
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Leopoldo Guimaraens, Patrick Courtheoux, Daniel A. Rüfenacht, Alfredo Casasco, Jacques Theron, and T. Sola
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Radiological and Ultrasound Technology ,Radiology, Nuclear Medicine and imaging ,Neurology (clinical) - Published
- 2007
164. Dr Becker and colleagues respond
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Jacqueline Delavelle, C. Egger, Minerva Becker, Anne-Marie Kurt, Peter Zbären, Daniel A. Rüfenacht, and François Terrier
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Psychoanalysis ,business.industry ,Medicine ,Radiology, Nuclear Medicine and imaging ,business - Published
- 1998
165. The supraisthmic anastomotic arch: a potential pitfall in Doppler sonography of the thyroid gland
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Daniel A. Rüfenacht, N. Khaw, Philippe Gailloud, Jean H.D. Fasel, and H. G. Khan
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endocrine system ,medicine.medical_specialty ,endocrine system diseases ,Thyroid Gland ,Anastomosis ,Superior thyroid artery ,medicine.artery ,medicine ,Humans ,Carotid Stenosis ,Radiology, Nuclear Medicine and imaging ,Ultrasonography, Doppler, Color ,medicine.diagnostic_test ,Vascular disease ,business.industry ,Thyroid ,Ultrasonography, Doppler ,Arteries ,General Medicine ,Middle Aged ,medicine.disease ,Doppler sonography ,medicine.anatomical_structure ,Angiography ,Female ,Radiology ,Thyroid function ,business ,Artery - Abstract
C onventional B-mode sonography is commonly used in the imaging of thyroid diseases. Recently, Doppler analysis of the superior thyroid artery has shown some promise in the evaluation of thyroid function [1, 2]. We report angiographic and sonographic findings concerning an anatomic variant of the superior thyroid artery that may represent a pitfall in the Doppler analysis of thyroid vascularization.
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- 1998
166. 822 Three Dimensional Geometry Measurements of Cerebral Aneurysms and Vessel Sizes for Analytical Geometry(1)
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Daniel A. Rüfenacht and Makoto Ohta
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Materials science ,Analytic geometry ,Geometry ,Three dimensional geometry - Published
- 2006
167. Flow-related aspects of cerebral aneurysms
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Daniel A. Rüfenacht, Rod Hose, Nikos Stergiopulos, Bastien Chopard, Alejandro F. Frangi, Juan R. Cebral, and Pedro Lylyk
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medicine.medical_specialty ,Flow (mathematics) ,business.industry ,Internal medicine ,Rehabilitation ,Biomedical Engineering ,Biophysics ,Cardiology ,Medicine ,Orthopedics and Sports Medicine ,business - Published
- 2006
168. 822 Three Dimensional Geometry Measurements of Cerebral Aneurysms and Vessel Sizes for Analytical Geometry(2)
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Makoto Ohta and Daniel A. Rüfenacht
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Materials science ,Analytic geometry ,Geometry ,Three dimensional geometry - Published
- 2006
169. Mechanical properties of elastase treated arteries
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Daniel A. Rüfenacht, E. Fonck, Sylvain Roy, Gilles Prod'hom, Nikolaos Stergiopulos, and Luca Augsburger
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Pathology ,medicine.medical_specialty ,Chemistry ,Rehabilitation ,Elastase ,Biomedical Engineering ,Biophysics ,medicine ,Orthopedics and Sports Medicine - Published
- 2006
170. Biomechanical study of structural changes of human cerebral arteries
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E. Fonck, Daniel A. Rüfenacht, Luca Augsburger, G. Feigl, and Nikolaos Stergiopulos
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Materials science ,Rehabilitation ,Cerebral arteries ,Biomedical Engineering ,Biophysics ,Orthopedics and Sports Medicine ,Anatomy - Published
- 2006
171. Three dimensional measurements of cerebral aneurysms and vessel size
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Hasan Yilmaz, P. Lylyk, D. Babic, Luca Augsburger, Makoto Ohta, German Abdo, Naoko Fujimura, Daniel A. Rüfenacht, and Y. Lachenal
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Vessel diameter ,Materials science ,Rehabilitation ,Biomedical Engineering ,Biophysics ,Orthopedics and Sports Medicine ,Biomedical engineering - Published
- 2006
172. Towards the integration of heterogeneous data: computational fluid dynamics as part of a processing chain in the context of risk assessment for cerebral aneurysms
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Juan R. Cebral, Rod Hose, Daniel A. Rüfenacht, and Alejandro F. Frangi
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Theoretical computer science ,Chain (algebraic topology) ,Computer science ,business.industry ,Rehabilitation ,Biomedical Engineering ,Biophysics ,Orthopedics and Sports Medicine ,Context (language use) ,Computational fluid dynamics ,Risk assessment ,business ,Data science - Published
- 2006
173. Un modèle anatomiquein vitro des artères cérébrales humaines avec anévrysmes artériels sacciformes
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Michel Piotin, J. R. Pray, P. Gailloud, Daniel A. Rüfenacht, M. Muster, and Jean H.D. Fasel
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Gynecology ,medicine.medical_specialty ,business.industry ,medicine ,Radiology, Nuclear Medicine and imaging ,Surgery ,Anatomy ,business ,Pathology and Forensic Medicine - Abstract
Un modele anatomique in vitro des arteres cerebrales est presente. Ce modele est hautement reproductible et restitue l'arbre arteriel humain dans sa complexite. Des anevrysmes sacciformes secondairement implantes sur le moulage arteriel sont presentes comme exemple de pathologies qui peuvent etre simulees sur ce modele.
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- 1997
174. Fully multisensor 5D biomedical imaging for the assessment of neurological (Dys-)function
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Margitta Seeck, Daniel A. Rüfenacht, Roberto D. Pascual-Marqui, Jacqueline Delavelle, Daniel O. Slosman, François Lazeyras, and Luc Bidaut
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Neurology ,business.industry ,Cognitive Neuroscience ,media_common.quotation_subject ,Medical imaging ,Medicine ,Function (engineering) ,business ,Neuroscience ,media_common - Published
- 1996
175. A simple propulsion-chamber-system for the 16 gauge approach
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Jean-Jacques Merland, D. Reizine, Daniel A. Rüfenacht, and L. Guimaraens
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business.industry ,Equipment Design ,Anatomy ,Propulsion ,Gauge (firearms) ,Catheterization ,Catheter ,Evaluation Studies as Topic ,Coaxial catheter ,Blood Vessels ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,Neurology (clinical) ,Endovascular treatment ,Coaxial system ,Cardiology and Cardiovascular Medicine ,business ,Biomedical engineering - Abstract
The construction of a propulsion chamber system is simplified by separating the different eelements of its functions. For injections of the propulsive fluid the coiling chamber is bypassed, leaving its contents untouched. The diameter of the coaxial system is reduced by minimizing the space between the two catheters. Consequently the puncture site becomes small (a balloon-catheter may be introduced through a 16 G catheter needle) allowing punctures proximal to lesions (e.g. puncture of the axillary a. or the carotid a.) and thus shortening the length of the coaxial catheter system. The risk of thrombus formation diminishes and renders heparinization dispensable. Control angiographies are separated from the coaxial system.
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- 1986
176. Pre-operative embolization of naso-pharyngeal angiofibromas. Report of 58 cases
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D. Reizine, J J Merland, E. Garcia-Cervigon, Daniel A. Rüfenacht, P. Tran Ba Huy, C. Thurel, and S. Bien
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Adult ,Male ,medicine.medical_specialty ,Adolescent ,Juvenile nasopharyngeal angiofibroma ,Carotid arteries ,medicine.medical_treatment ,Preoperative Care ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Embolization ,Child ,Neuroradiology ,Histiocytoma, Benign Fibrous ,business.industry ,Nasopharyngeal Neoplasms ,Angiofibromas ,Combined Modality Therapy ,Embolization, Therapeutic ,Pre operative ,Surgery ,Carotid Artery, External ,cardiovascular system ,Neurology (clinical) ,Radiology ,Neurosurgery ,Cardiology and Cardiovascular Medicine ,business - Abstract
58 patients with a juvenile nasopharyngeal angiofibroma have been treated by a combined neuroradiological-surgical method. In the cases with smaller turmor extension, fed only by the external carotid arteries or with only slight participation of the internal carotid arteries, the external carotid arteries alone have been embolized using particles. In the cases with marked participation of the internal carotid arteries these vessels were also embolized. In the first group there have been no complications and no recurrences. In the latter (31 cases) there have been three temporary minor complications and 11 recurrences.
- Published
- 1988
177. Effect of elastin degradation on carotid wall mechanics as assessed by a constituent-based biomechanical model
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Luca Augsburger, Edouard Fonck, Daniel A. Rüfenacht, Nikos Stergiopulos, Sylvain Roy, and Gilles Prod'hom
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Male ,Vascular smooth muscle ,Carotid Artery, Common ,Physiology ,Blood Pressure ,In Vitro Techniques ,Mechanotransduction, Cellular ,Tensile Strength ,Physiology (medical) ,medicine ,Animals ,Mechanotransduction ,Elastic modulus ,Pancreatic Elastase ,biology ,Chemistry ,Elastase ,Models, Cardiovascular ,Anatomy ,Elasticity ,Elastin ,medicine.anatomical_structure ,Research Design ,Circulatory system ,biology.protein ,Biophysics ,cardiovascular system ,Collagen ,Rabbits ,Cardiology and Cardiovascular Medicine ,Compliance ,Blood vessel ,Artery - Abstract
Arteries display a nonlinear anisotropic behavior dictated by the elastic properties and structural arrangement of its main constituents, elastin, collagen, and vascular smooth muscle. Elastin provides for structural integrity and for the compliance of the vessel at low pressure, whereas collagen gives the tensile resistance required at high pressures. Based on the model of Zulliger et al. (Zulliger MA, Rachev A, Stergiopulos N. Am J Physiol Heart Circ Physiol 287: H1335–H1343, 2004), which considers the contributions of elastin, collagen, and vascular smooth muscle cells (VSM) in an explicit form, we assessed the effects of enzymatic degradation of elastin on biomechanical properties of rabbit carotids. Pressure-diameter curves were obtained for controls and after elastin degradation, from which elastic and structural properties were derived. Data were fitted into the model of Zulliger et al. to assess elastic constants of elastin and collagen as well as the characteristics of the collagen engagement profile. The arterial segments were also prepared for histology to visualize and quantify elastin and collagen. Elastase treatment leads to a diameter enlargement, suggesting the existence of significant compressive prestresses within the wall. The elastic modulus was more ductile in treated arteries at low circumferential stretches and significantly greater at elevated circumferential stretches. Abrupt collagen fiber recruitment in elastase-treated arteries leads to a much stiffer vessel at high extensions. This change in collagen engagement properties results from structural alterations provoked by the degradation of elastin, suggesting a clear interaction between elastin and collagen, often neglected in previous constituent-based models of the arterial wall.
178. An in vitro anatomic model of the human cerebral arteries with saccular arterial aneurysms
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Jean H.D. Fasel, J. R. Pray, Daniel A. Rüfenacht, Michel Piotin, M. Muster, and P. Gailloud
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medicine.diagnostic_test ,business.industry ,Cerebral arteries ,Liquid resin ,Magnetic resonance imaging ,Anatomy ,Pathology and Forensic Medicine ,Transcranial Doppler ,In vitro model ,Arterial aneurysms ,Medicine ,Radiology, Nuclear Medicine and imaging ,Surgery ,business - Abstract
Summary: Anin vitro model of the main human cerebral arteries with or without saccular arterial aneurysms is presented. A cast of the cerebral arteries was obtained in a human specimen. Three aneurysms were simulated and added to the cast. Wax copies of the cast were produced, and embedded with liquid resin solidifying into solid blocks. After evacuation of the wax, a model consisting of a hollow reproduction of the cast within the resin block was obtained. The model is reproducible and anatomically accurate. Since it is transparent to visible light, and compatible with x-ray, magnetic resonance and transcranial doppler techniques, it should prove useful for a wide range of haemodynamic and radiologic investigations. The reported technique may be adapted to any structure with a hollow configuration, allowing for the preparation of arterial and venous models from other vascular areas, as well as models from other anatomic systems, such as the biliary or urinary tracts
179. Biomaterials for injectable therapeutic implants
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Christophe Iselin, Eric Doelker, Olivier Jordan, and Daniel A. Rüfenacht
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Injectable biomaterials ,medicine.diagnostic_test ,business.industry ,Urology ,Interventional radiology ,General Medicine ,General Chemistry ,Embolization ,Chemistry ,Oncology ,medicine ,Interventional procedures ,Polymeric implants ,business ,QD1-999 ,Biomedical engineering - Abstract
Injectable biomaterials that have the ability to form semi-solid implants in situ are of keen interest for therapeutic applications. The materials may be used to fill in pathological vascular spaces or be designed to possess functional properties such as being radiopaque for an improved visibility during image-guided minimally invasive interventions, or induce a localized biological activity. Among the variety of solidification principles that may be used to produce implants in situ, the precipitation of water-insoluble polymers driven by solubility changes shows some particular features that may be valuable for specific therapeutic applications. This paper reviews some of the applications of these implant-forming biomaterials in interventional radiology, urology, and oncology.
180. Treatment of renal artery aneurysm with the multilayer stent
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Patricia Gruffaz, Maurice Bonneau, Rafik Ouared, Michèle Hugel, Matthieu De Beule, Bastien Chopard, Noureddine Frid, Antonios Polydorou, Daniel A. Rüfenacht, Alain Cavet, Luca Augsburger, Isabelle Henry, Michel Henry, Chantal Kang, and Pascal Verdonck
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Male ,medicine.medical_specialty ,medicine.medical_treatment ,fluid modulating stent ,Coil ,Prosthesis Design ,hemodynamics ,Multilayer stent ,Renal artery aneurysm ,Embolization ,Aneurysm ,Endovascular Repair ,medicine.artery ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,cardiovascular diseases ,Renal artery ,Vascular Patency ,Aged ,renal artery ,business.industry ,stent design ,Angiography ,Stent ,medicine.disease ,Surgery ,aneurysm ,Stents ,stent ,Radiology ,Cardiology and Cardiovascular Medicine ,business ,Stent design - Abstract
To describe a new type of stent consisting of a 3-dimensional (3D) braided tube made of 2 interconnected layers without any covering to treat a renal artery aneurysm.A 78-year-old hypertensive man with multiple comorbidities was incidentally found to have a large (28- x 30 mm) saccular aneurysm in the main right renal artery involving the inferior renal artery. Via a percutaneous femoral approach, a 6- x 30-mm Multilayer stent was deployed easily in front of the aneurysm neck covering the inferior renal artery. Blood flow inside the sac was immediately and significantly reduced. All the renal artery branches remained patent. Blood pressure returned to normal after the procedure. At 6 months, angiography showed complete shrinkage of the aneurysm wall; all the inferior renal artery branches remained patent.The 3D multilayer fluid modulating stent concept appears to be a viable alternative for renal aneurysm exclusion. A larger study is underway to evaluate this new stent in other peripheral aneurysms.
181. Multisensor and multidimensional biomedical imaging (including volumetric electro-magnetic tomography) for the visualization and assessment of neurological (dys-)function
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Luc Bidaut, Daniel A. Rüfenacht, Roberto D. Pascual-Marqui, François Terrier, and Jean-Raoul Scherrer
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Engineering ,medicine.diagnostic_test ,business.industry ,Image registration ,Context (language use) ,Iterative reconstruction ,Sensor fusion ,Visualization ,Positron emission tomography ,Medical imaging ,medicine ,Computer vision ,Tomography ,Artificial intelligence ,business - Abstract
We have implemented a global system consisting of techniques and protocols for the combination (registration, visualization, navigation and processing) of various multidimensional biomedical imaging sensors, including all current modalities and also electro-magnetic tomography (EMT), to study, assess, and localize neurological (dys-)function for both clinical and research applications. The already well described interest for this combination stems from the broad variety of complementary information brought out by modern biomedical imaging modalities. In this context, the input of volumetric EMT permits direct sighting, in near real-time, of any EM (dys-)functional behavior. Besides allowing morphology, metabolism and function to be studied simultaneously and from different points of view, the global combination permitted by our approach is expected to show its best value when studying pathologies reflected by metabolic or electromagnetic dysfunctions such as drug-resistant epilepsy.
182. Validation of a one-dimensional model of the systemic arterial tree
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Fabrice Merenda, Nikos Stergiopulos, Fabienne Perren, Philippe Reymond, and Daniel A. Rüfenacht
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Models, Anatomic ,Physiology ,Constitutive equation ,Arteries/anatomy & histology/physiology ,Blood Pressure ,Human Aorta ,nonlinear viscoelasticity ,Wave Reflections ,Time-Varying Elastance ,Blood Pressure/physiology ,Mathematics ,education.field_of_study ,Ultrasonography, Doppler, Duplex ,Viscosity ,ultrasound ,Distributed element model ,cerebral circulation ,Heart ,Mechanics ,Anatomy ,Arteries ,Arterial tree ,Heart/physiology ,Cerebral blood flow ,Cerebrovascular Circulation ,Mathematical-Model ,Cardiology and Cardiovascular Medicine ,Shear Strength ,Input Impedance ,Algorithms ,Adult ,Coronary Circulation/physiology ,Manometry ,Theoretical-Analysis ,Population ,Acceleration ,Cerebrovascular Circulation/physiology ,heart model ,wave propagation ,Viscoelasticity ,Physiology (medical) ,Coronary Circulation ,Shear stress ,Coronary-Arteries ,Humans ,education ,ventricular-vascular coupling ,Models, Statistical ,Computer-Simulation ,Reproducibility of Results ,Elasticity ,ddc:616.8 ,Nonlinear system ,Nonlinear Dynamics ,noninvasive vascular imaging ,Pulse Pressure Method ,Cerebral-Blood-Flow ,Forecasting - Abstract
A distributed model of the human arterial tree including all main systemic arteries coupled to a heart model is developed. The one-dimensional (1-D) form of the momentum and continuity equations is solved numerically to obtain pressures and flows throughout the systemic arterial tree. Intimal shear is modeled using the Witzig-Womersley theory. A nonlinear viscoelastic constitutive law for the arterial wall is considered. The left ventricle is modeled using the varying elastance model. Distal vessels are terminated with three-element windkessels. Coronaries are modeled assuming a systolic flow impediment proportional to ventricular varying elastance. Arterial dimensions were taken from previous 1-D models and were extended to include a detailed description of cerebral vasculature. Elastic properties were taken from the literature. To validate model predictions, noninvasive measurements of pressure and flow were performed in young volunteers. Flow in large arteries was measured with MRI, cerebral flow with ultrasound Doppler, and pressure with tonometry. The resulting 1-D model is the most complete, because it encompasses all major segments of the arterial tree, accounts for ventricular-vascular interaction, and includes an improved description of shear stress and wall viscoelasticity. Model predictions at different arterial locations compared well with measured flow and pressure waves at the same anatomical points, reflecting the agreement in the general characteristics of the “generic 1-D model” and the “average subject” of our volunteer population. The study constitutes a first validation of the complete 1-D model using human pressure and flow data and supports the applicability of the 1-D model in the human circulation.
183. Impact of stent design on intra-aneurysmal flow. A computer simulation study
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S. Wetzel, P. Lylyk, Daniel A. Rüfenacht, Sadami Tsutsumi, Miki Hirabayashi, Makoto Ohta, and H. Wata
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0301 basic medicine ,medicine.medical_specialty ,medicine.medical_treatment ,Flow (psychology) ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Aneurysm treatment ,medicine ,Perpendicular ,cardiovascular diseases ,Cell shape ,business.industry ,Stent ,General Medicine ,Original Articles ,medicine.disease ,equipment and supplies ,Surgery ,030104 developmental biology ,surgical procedures, operative ,cardiovascular system ,Outflow ,business ,Stent design ,030217 neurology & neurosurgery ,Biomedical engineering - Abstract
In addition to providing a skeleton for vessel reconstruction, stent implantation as used for cerebral aneurysm treatment can induce flow redirection, thus reducing vortical flow velocities within the aneurysm cavity. Further, stent characteristics such as strut size, porosity and cell shape influence the changes in intra-aneurysmal flow by analog simulations. The purpose of this computer simulation study was to visualize the flow pattern over the entire neck area of a side wall aneurysm while changing the stent parameters. A 3-D computer model aneurysm was constructed to have a parent artery of 5 mm diameter and an aneurysm of 10 mm diameter. The distance between the midline of main artery and center point of the aneurysm was 6.8 mm, providing a neck length of 5 mm, a width of 3.6 mm, and a neck area of 14 mm 2. The simulations were carried out with a Finite Element Method based flow simulation package. The incompressible Navier -Stokes equation was solved for a steady flow with a mean speed of 290 mm/s, steady viscosity of 3.83 cp, and density of 1.0 g/cm3. Two parallel stent struts (dimensions: 100 μm m 100 μm m 2.0 mm) were introduced into the plane of the aneurysm neck. The fraction of the aneurysm neck cross-section occupied by the stent was 2.83% in all cases. The velocity distribution through the neck of the aneurysm was calculated for three different choices of separation between the struts for each of two orientations of the struts (parallel and perpendicular) relative to the vessel axis. The flow pattern in the aneurysm was composed of an inflow zone at the distal neck and of an outflow zone at the proximal neck. The placement of stent struts at the aneurysm neck resulted in a decrease in the mean speed in the aneurysm. The degree of reduction and the distribution of flow through the neck did depend on the orientation of the stent struts. The struts, when placed parallel or perpendicular to the parent vessel axis affected the mean speed through the aneurysm neck differently.
184. The POST trial: initial post-market experience of the Penumbra system: revascularization of large vessel occlusion in acute ischemic stroke in the United States and Europe
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Christophe Bonvin, Michael T. Madison, R Bellon, Anton Haass, K. Alfke, Daniel A. Rüfenacht, Zsolt Kulcsar, Wolfgang Reith, Robert Stingele, Iris Q. Grunwald, Donald Frei, D Hsu, Olav Jansen, Robert W Tarr, Tobias Struffert, Arnd Dörfler, University of Zurich, and Tarr, Robert
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Male ,medicine.medical_specialty ,Mechanical Thrombolysis ,medicine.medical_treatment ,610 Medicine & health ,Suction ,Revascularization ,Brain Ischemia ,Modified Rankin Scale ,10043 Clinic for Neuroradiology ,Internal medicine ,Product Surveillance, Postmarketing ,medicine ,Humans ,Adverse effect ,Stroke ,Thrombectomy ,Aged ,Retrospective Studies ,Aged, 80 and over ,Cerebral Revascularization ,business.industry ,Penumbra ,Incidence (epidemiology) ,General Medicine ,Middle Aged ,medicine.disease ,United States ,Surgery ,2746 Surgery ,Europe ,Cerebrovascular Disorders ,Treatment Outcome ,medicine.anatomical_structure ,2728 Neurology (clinical) ,Cardiology ,Female ,Neurology (clinical) ,business ,Vascular Access Devices ,TIMI ,Artery - Abstract
Background and purposeThe purpose of this study was to assess the initial post-market experience of the device and how it is compared with the Penumbra Pivotal trial used to support the 510k application.MethodsA retrospective case review of 157 consecutive patients treated with the Penumbra system at seven international centers was performed. Primary endpoints were revascularization of the target vessel (TIMI score of 2 or 3), good functional outcome as defined by a modified Rankin scale (mRS) score of ≤2 and incidence of procedural serious adverse events. Results were compared with those of the Penumbra pivotal trial.ResultsA total of 157 vessels were treated. Mean baseline values at enrollment were: age 65 years, NIHSS score 16. After use of the Penumbra system, 87% of the treated vessels were revascularized to TIMI 2 (54%) or 3 (33%) as compared with 82% reported in the Pivotal trial. Nine procedural serious adverse events were reported in 157 patients (5.7%). All-cause mortality was 20% (32/157), and 41% had a mRS of ≤2 at 90-day follow-up as compared with only 25% in the Pivotal trial. Patients who were successfully revascularized by the Penumbra system had significantly better outcomes than those who were not.ConclusionInitial post-market experience of the Penumbra system revealed that the revascularization rate and safety profile of the device are comparable to those reported in the Pivotal trial. However, the proportion of patients who had good functional outcome was higher than expected.
185. Lattice Boltzmann analysis of the flow reduction mechanism in stented cerebral aneurysms for the endovascular treatment
- Author
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Makoto Ohta, Miki Hirabayashi, Daniel A. Rüfenacht, and Bastien Chopard
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medicine.medical_specialty ,Materials science ,medicine.medical_treatment ,Lattice Boltzmann methods ,Stent ,equipment and supplies ,medicine.disease ,Flow reduction ,Aneurysm rupture ,Aneurysm ,Aneurysm treatment ,cardiovascular system ,medicine ,Stent implantation ,cardiovascular diseases ,Radiology ,Endovascular treatment - Abstract
Two-dimensional numerical analysis of local hemodynamics on flow-reduction mechanism by stent implantation in cerebral aneurysms is presented to understand these interesting hydrodynamic phenomena and improve this promising minimally invasive treatment. Recently in the cerebral aneurysm treatment, this new endovascular occlusion technique using a porous tubular shaped stent or coils sometimes replaces invasive open surgeries. It is thought that the flow reduction by the stent implantation prevents the aneurysm rupture, however its mechanism is not well understood. We reveal the fundamental flow reduction mechanism by the stent implantation in dependence of the aneurysm size using the lattice Boltzmann approach.
186. Effect of Flow Diverter Porosity on Intra-aneurysmal Blood Flow
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Luca, Augsburger, Mohamed, Farhat, Philippe, Reymond, Edouard, Fonck, Zsolt, Kulcsar, Nikos, Stergiopulos, and Daniel A., Rüfenacht
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Shear-driven flow ,Inertia-driven flow ,Intracranial aneurysms ,Particle image velocimetry ,Porosity ,Experimental setup - Abstract
Background and Purpose: Growth and rupture, the two events that dominate the evolution of an intracranial aneurysm, are both dependent on intraaneurysmal flow. Decrease of intraaneurysmal flow is considered an attractive alternative for treating intracranial aneurysms by minimally invasive techniques. Such modification can be achieved by inserting stents or flow diverters alone. In the present paper, the effect of different commercial and innovative flow diverters’ porosity was studied in intracranial aneurysm models. Material and Methods: Single and stent-in-stent combination of Neuroform II as well as single and stent-in-stent combination of a new innovative, low-porosity, intracranial stent device (D1, D2, D1 + D2) were inserted in models of intracranial aneurysms under shear-driven flow and inertia-driven flow configurations. Steady and pulsating flow rates were applied using a blood- like fluid. Particle image velocimetry was used to measure velocity vector fields in the aneurysm midplane along the vessel axis. Flow and vorticity patterns, velocity and vorticity magnitudes were quantified and their value compared with the same flows in absence of the flow diverter. Results: In absence of flow diverters, a solid- like rotation could be observed in both shear-driven and inertia-driven models under steady and pulsatile flow conditions. The flow effects due to the insertion of low- porous devices such as D1 or D2 provoked a complete alteration of the flow patterns and massive reduction of velocity or vorticity magnitudes, whereas the introduction of clinically adopted high-porous devices provoked less effect in the aneurysm cavity. As expected, results showed that the lower the porosity the larger the reduction in velocity and vorticity within the aneurysm cavity. The lowest-porosity device combination (D1 and D2) reached an averaged reduction of flow parameters of 80% and 88% under steady and pulsatile flow conditions, respectively. The reduction in mean velocity and vorticity was much more significant in the shear-driven flows as compared to the inertia-driven flows. Conclusion: Although device porosity is the main parameter influencing flow reduction, other parameters such as device design and local flow conditions may influence the level of flow reduction within intracranial aneurysms.
187. Biomaterials for Injectable Therapeutic Implants
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Olivier Jordan, Daniel A. Rufenacht, Christophe Iselin, and Eric Doelker
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Embolization ,Injectable biomaterials ,Interventional procedures ,Oncology ,Polymeric implants ,Urology ,Chemistry ,QD1-999 - Abstract
Injectable biomaterials that have the ability to form semi-solid implants in situ are of keen interest for therapeutic applications. The materials may be used to fill in pathological vascular spaces or be designed to possess functional properties such as being radiopaque for an improved visibility during image-guided minimally invasive interventions, or induce a localized biological activity. Among the variety of solidification principles that may be used to produce implants in situ, the precipitation of water-insoluble polymers driven by solubility changes shows some particular features that may be valuable for specific therapeutic applications. This paper reviews some of the applications of these implant-forming biomaterials in interventional radiology, urology, and oncology.
- Published
- 2005
- Full Text
- View/download PDF
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