Creation of four experimental aneurysms with different hemodynamics in one dog (original) (raw)
Related papers
In Vivo Experimental Intracranial Aneurysm Models: A Systematic Review
American Journal of Neuroradiology, 2009
Animal models are necessary to develop and test innovations in aneurysm therapy before clinical introduction. This review aims at identifying the most likely candidates for standardizing preclinical testing of aneurysm devices. We systematically searched electronic databases for publications on animal aneurysm models from 1961-2008 to assess the methodologic quality of the studies and collect data on the patency and angiographic and pathologic outcomes of treatments. There has been a steady increase in the annual number of publications with time. Species that were most frequently used were dogs, rabbits, and rodents, followed by swine. Most publications are single-laboratory studies with variables and poorly validated outcome measures, a small number of subjects, and limited standardization of techniques. The most appropriate models to test for recurrences after endovascular occlusion were the surgical bifurcation model in dogs, and the elastase-induced aneurysm model in rabbits. A standardized multicenter study is needed to improve the preclinical evaluation of endovascular devices in aneurysm therapy. ABBREVIATIONS: Angio ϭ angiography; ICA ϭ intracranial aneurysms; IHC ϭ immunohistochemistry; SEM ϭ scanning electron microscope; w ϭ width
A New Canine Carotid Artery Bifurcation Aneurysm Model for the Evaluation of Neurovascular Devices
American Journal of Neuroradiology, 2010
BACKGROUND AND PURPOSE: Stents are increasingly used for coiling of difficult aneurysms, to reduce the risk of recurrences, or to modify blood flow. Currently available bifurcation aneurysm models are ill-suited to assess stent performance before clinical use. We designed a new wide-neck canine T-type bifurcation aneurysm model. Its potential value as a training tool as well as in the evaluation of new techniques or embolic agents was assessed. Our first task was to verify that recurrences occurred after satisfactory coiling. A second aim of this preliminary work was to assess if the new model could recreate the technical challenges involved in bifurcation aneurysms.
Novel Methodologies for Investigating the Pathophysiology of Cerebral Aneurysms
2011
An intracranial aneurysm (IA) is a pathological state of a cerebral artery in which the elastin and smooth muscle cells found in the healthy arterial wall are absent. Rupture of an IA is a major cause of subarachnoid hemorrhage. Hemodynamics is believed to play an important role in initiation, development and rupture of the IA. However, the coupling between hemodynamics and aneurysm pathophysiology remains poorly understood. The initiation of cerebral aneurysms is believed to be caused by a breakdown in the homeostatic mechanism of healthy arteries, leading to destructive wall remodeling and damage. Due to its complex nature, there is a need for both controlled in vitro and in vivo studies of IA initiation. We have designed an in vitro flow chamber that can be used to reproduce specific magnitudes of wall shear stress and wall shear stress gradients found at the apices of arterial bifurcations, where aneurysms tend to form. Animal models provide a mechanism for fundamental studies of the coupling between hemodynamics and pathophysiology in cerebral aneurysms. We conducted a sensitivity study to develop an accurate CFD model for an elastase-induced rabbit aneurysm model. We then used this computational model to evaluate the capability of the rabbit model to reproduce hemodynamic features typical of human IAs. Geometric and hemodynamic features of 51 rabbit aneurysm models were analyzed and shown to fall within the range reported for human IAs. This model was also used to study the relationship between aspect ratio and hemodynamics in the v aneurysm sac. An-in silico design‖ approach was then used to explore the possibility of extending the rabbit model to capture more of the flow categories identified in human IAs. Based on a previously developed parametric model for human arterial bifurcations, we created and validated a parametric model for IAs. This parametric model captures important geometric and flow features of both the aneurysm and neighboring vasculature. The model is currently being used for studies of the coupling between geometry and hemodynamics in IAs. It can also be used to guide 3D reconstruction of poor quality clinical data or construct in vitro experimental models. vi TABLE OF CONTENTS
Basic principles of hemodynamics and cerebral aneurysms
World Neurosurgery, 2016
Rupture is the most serious consequence of cerebral aneurysms, and its likelihood depends on non-modifiable and modifiable risk factors. Recent efforts have focused on analyzing the effects of hemodynamic forces on the initiation, growth and rupture of cerebral aneurysms. Studies of role of hemodynamics on the physiopathology of intracranial aneurysms fall between mechanical engineering and molecular biology. This review is intended to summarize the basic principles of the effect of hemodynamic forces on the cerebral vascular wall. Nowadays, the size of the aneurysm dome is the most common parameter used in clinical practice to estimate the risk of rupture. However, relying only on aneurysm size means excessively simplifying a more complicated reality. Aneurysms emerge in areas of the vascular wall exposed to high wall shear stress. The direction that blood flows once an aneurysm forms depends on aspects such as neck diameter, its angle with respect to the parent artery, the parent vessel caliber, the caliber or the angle of efferent vessels, and aneurysm shape. The progression and rupture of aneurysms have been associated with zones of the aneurysm wall exposed to both high and low wall shear stresses. Advances in this challenging and growing field are intended to predict more precisely the risk of rupture of aneurysms and to better understand the mechanisms of origin and growth of aneurysms.
ORIGINAL RESEARCH A Large and Giant Bifurcation Aneurysm Model in Canines: Proof of Feasibility
2016
BACKGROUND AND PURPOSE: To our knowledge, no reproducible animal model of a giant bifurcation type aneurysm has been described. It was our aim to develop a 1-stage and reproducible model of a venous pouch giant aneurysm in canines. MATERIALS AND METHODS: Nine canines were involved. Bilateral CCAs were exposed. The left CCA was divided and its distal segment was swung to the right side. Using the right CCA and the distal segment of the left CCA, either a bifurcation or a terminal arterial structure was constructed. Bilateral external jugular veins were also exposed. A 30-mm vein segment was harvested from each side. Each vein graft was split and unfolded to make 2 venous sheets. These sheets were then joined top-to-bottom so as to form a single cylinder in such a way that original adventitial side of the venous sheets was on the exterior surface. In 2 instances, pieces of polytetrafluoroethylene were employed along with the venous sheets. The combined vein graft was then incorporated...
A Large and Giant Bifurcation Aneurysm Model in Canines: Proof of Feasibility
American Journal of Neuroradiology, 2011
BACKGROUND AND PURPOSE: To our knowledge, no reproducible animal model of a giant bifurcation type aneurysm has been described. It was our aim to develop a 1-stage and reproducible model of a venous pouch giant aneurysm in canines. MATERIALS AND METHODS: Nine canines were involved. Bilateral CCAs were exposed. The left CCA was divided and its distal segment was swung to the right side. Using the right CCA and the distal segment of the left CCA, either a bifurcation or a terminal arterial structure was constructed. Bilateral external jugular veins were also exposed. A 30-mm vein segment was harvested from each side. Each vein graft was split and unfolded to make 2 venous sheets. These sheets were then joined top-tobottom so as to form a single cylinder in such a way that original adventitial side of the venous sheets was on the exterior surface. In 2 instances, pieces of polytetrafluoroethylene were employed along with the venous sheets. The combined vein graft was then incorporated into the arterial anastomosis. Lastly, the top of the venous pouch was closed. No medications for anticoagulant or antiplatelet were used throughout the study period. Follow-up imaging studies were performed. RESULTS: It took 2.5 hours on average for 2 operators to create an aneurysm. Eight of the 9 aneurysms were patent at follow-up. The cause of the spontaneous thrombosis was unclear despite autopsy. All the aneurysms had a maximum diameter Ͼ20 mm. CONCLUSIONS: We demonstrated and illustrated a 1-stage and reproducible procedure to create a model of a venous pouch bifurcation giant aneurysm in canines. ABBREVIATIONS: CCA ϭ common carotid artery; EJV ϭ external jugular vein; IA ϭ intra-arterial; PTFE ϭ polytetrafluoroethylene; VOR ϭ volume to the area of the ostium
Stroke, 2010
Background and Purpose-Hemodynamic insult by bilateral common carotid artery ligation has been shown to induce aneurysmal remodeling at the basilar terminus in a rabbit model. To characterize critical hemodynamics that initiate this remodeling, we applied a novel hemodynamics-histology comapping technique. Methods-Eight rabbits received bilateral common carotid artery ligation to increase basilar artery flow. Three underwent sham operations. Hemodynamic insult at the basilar terminus was assessed by computational fluid dynamics. Bifurcation tissue was harvested on day 5; histology was comapped with initial postligation hemodynamic fields of wall shear stress (WSS) and WSS gradient. Results-All bifurcations showed internal elastic lamina loss in periapical regions exposed to accelerating flow with high WSS and positive WSS gradient. Internal elastic lamina damage happened 100% of the time at locations where WSS was Ͼ122 Pa and WSS gradient was Ͼ530 Pa/mm. The degree of destructive remodeling accounting for internal elastic lamina loss, medial thinning, and luminal bulging correlated with the magnitude of the hemodynamic insult. Conclusions-Aneurysmal remodeling initiates when local hemodynamic forces exceed specific limits at the rabbit basilar terminus. A combination of high WSS and positive WSS gradient represents dangerous hemodynamics likely to induce aneurysmal remodeling. (Stroke. 2010;41:00-00.)
In vivo cerebral aneurysm models
Neurosurgical Focus, 2019
Cerebral aneurysm rupture is a devastating event resulting in subarachnoid hemorrhage and is associated with significant morbidity and death. Up to 50% of individuals do not survive aneurysm rupture, with the majority of survivors suffering some degree of neurological deficit. Therefore, prior to aneurysm rupture, a large number of diagnosed patients are treated either microsurgically via clipping or endovascularly to prevent aneurysm filling. With the advancement of endovascular surgical techniques and devices, endovascular treatment of cerebral aneurysms is becoming the first-line therapy at many hospitals. Despite this fact, a large number of endovascularly treated patients will have aneurysm recanalization and progression and will require retreatment. The lack of approved pharmacological interventions for cerebral aneurysms and the need for retreatment have led to a growing interest in understanding the molecular, cellular, and physiological determinants of cerebral aneurysm pat...
A novel two-stage technique for construction of experimental aneurysms
AJNR. American journal of neuroradiology, 2004
A two-staged technique for construction of experimental aneurysms in swine is described. The jugular vein is initially anastomosed to the carotid artery. Spontaneous hypertrophy of the vein is modeled by placing restraining sutures to create a fusiform aneurysm. Subsequent endovascular closure of this aneurysm leaves a sidewall aneurysm pouch. Staging allows maturation of the anastomosis, and the technique provides additional targets for endovascular training. Trial has been successful in three animals.
2012
BACKGROUND AND PURPOSE: EL associated with ruptured aneurysms is higher than that for unruptured aneurysms. In this study, the effect of arterial morphologic variation of bifurcation aneurysms on EL was investigated in idealized models of middle cerebral artery aneurysms. MATERIALS AND METHODS: Bifurcation angle configuration and DA ratio were evaluated in 6 idealized numeric models. Type A and B bifurcation models were defined with symmetric and asymmetric bifurcation angles of 136°, and 57°and 79°, respectively. Three models with DA ratios of 1, 1.3, and 2 were constructed for each type. EL was calculated as the energy difference between aneurysm inflow and outflow at the aneurysm neck. Three growth paths (R1, R2, and R3) were proposed. RESULTS: The highest EL and influx occurred in bifurcations with DA ratios of 1 for both types A and B. As the DA ratio increases, flow distribution between branches becomes more asymmetric, resulting in a reduction of EL and intra-aneurysmal flow. No strong relation was found between bifurcation angle configuration, inflow flux, and EL. EL decreased with an increase in the AR and DA ratio and increased with an increase in the AR and reduction of DA ratio. CONCLUSIONS: EL determined in idealized models is less dependent on bifurcation angle configuration than on DA ratio, and the stability of the aneurysm strongly depends on variation of the daughter artery morphology after aneurysm growth. ABBREVIATIONS: AR ϭ aspect ratio; DA ϭ daughter artery diameter; EL ϭ energy loss; LSA ϭ low shear stress area; R1 ϭ increasing the AR and DA ratio; R2 ϭ increasing the AR and reducing the DA ratio; R3 ϭ increasing the AR with a constant DA ratio; WSS ϭ wall shear stress