Haemodynamic Effect on the Growth of Experimentally Induced Saccular Aneurysms in Rats (original) (raw)
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Arterial saccular aneurysm model in the rabbit
AJNR. American journal of neuroradiology, 1996
Saccular aneurysms arising from the common carotid artery in the neck at the origin of the internal carotid artery were created in male rabbits using the stump of a ligated external carotid artery. These stumps were intraluminally perfused with varying concentrations of porcine pancreatic elastase for 45 minutes via a microcatheter introduced into the femoral artery. The aneurysms were allowed to mature for 2 to 12 weeks. Gross examination and histologic studies confirmed the presence of an aneurysm in all 15 experiments. Ninety-two percent (12 of 13) of the aneurysms studied by postoperative angiography were shown to be angiographically patent: 40% of all aneurysms were noted to be patent at harvest; and the remainder showed evidence of intraluminal thrombus. On histologic examination, all aneurysms showed complete loss of elastic lamina without evidence of fibrosis or scarring.
Brain Research, 2009
Establishing a simple and comprehensive experimental model is one of the most important issues in the study of cerebral aneurysms. Previous models in the rat required two stage surgeries and observations were limited to a few branching sites. The present study aimed to introduce a simplified model in rats and to provide a comprehensive evaluation of induced arterial changes in the circle of Willis. Sprague-Dawley rats underwent ligation of the right common carotid artery, and posterior and inferior (group 2, n = 9) or only posterior (group 3, n = 12) branches of the bilateral renal arteries, and bilateral oophorectomy. Dahl salt-sensitive rats underwent only carotid ligation and bilateral oophorectomy (group 5, n = 11). All surgical procedures were completed in one procedure instead of two in the original method. Salt loading was started after the surgery. Five rats of each strain without treatment served as controls (groups 1 and 4, respectively). Three months later, vascular corrosion casts of the cerebral arteries were examined by scanning electron microscopy. Experimental rats in groups 2, 3, and 5 developed 43 aneurysmal lesions at branching sites. Forty-eight arterial changes including dilatation, tortuosity, and fusiform or lateral wall aneurysms were observed at non-branching sites. Group 3 appeared to be superior to the other groups for experimental studies. The frequency and degree of the induced lesions were comparable with previous studies even after the surgical simplification. The present model may be more practical for the study of experimental cerebral aneurysms.
Revista do Colégio Brasileiro de Cirurgiões
To develop an experimental model of stable saccular aneurysm in carotid of pigs using the internal jugular vein. In 12 healthy pigs, weighing between 25 and 5 0kg, five males and seven females, we made a right common carotid artery aneurysm. After elliptical arteriotomy, we carried out a terminolateral anastomosis with the distal stump of the internal jugular vein. Aneurysm volume was calculated so that the value did not exceed 27 times the area of the arteriotomy. After six days angiography and microscopic examination were performed to assess patency of the aneurysm and the presence of total or partial thrombosis. There was a significant weight gain of pigs in the time interval between the manufacture of the aneurysm and angiography (p = 0.04). Aneurysmal patency was observed in ten pigs (83%). Operative wound infections occurred in two animals (16.6%), both with early onset, three days after the making of the aneurysm. Histological analysis showed aneurysm thrombus partially occlu...
Neuroradiology
Introduction Experimental saccular aneurysms can be created with surgical techniques of the arterial wall or by injecting pancreatic elastase. Papain is an enzyme with properties similar to those of elastase, and it has not been tested for this purpose. The objective of this study was to determine whether papain produces saccular aneurysms. Methods Eleven New Zealand white rabbits (1.9–3.0 kg) were divided into two groups: group I (n = 8)—papain, and group II (n = 3)—sham. The animals underwent surgical exposure of the neck; the right common carotid artery was used as the test and the left common carotid artery as the control. On the 21st day after surgery, animals were sacrificed for removal of the arteries, measurements, and histological analysis. We determine formation of aneurysm to occur when the test artery dilated compared to the control. Results There was no aneurysm formation in the sham group. The papain group showed aneurysm formation in all cases (100%). The average diameter of the aneurysms was 3.8 ± 1.4 mm and the average length was 16.7 ± 6.0 mm. The histological analysis showed a destruction of the elastic fibers in 100% of cases, mild inflammation in 62.5%, intimal fibrosis in 50%, endothelial injury in 100%, and thrombosis in 100% of cases. Conclusion Papain was capable of forming aneurysms with histological characteristics similar to those of elastase-induced aneurysms; however, a comparative study is necessary to determine whether the papain is superior to elastase in the production of experimental saccular aneurysms.
Journal of Biomechanics, 2011
Clinical studies suggest aneurysm aspect ratio (AR) is an important indicator of rupture likelihood. The importance of AR is hypothesized to arise from its influence on intra-aneurysmal hemodynamics. It has been conjectured that the flow in the domes of high AR sacs is slower than in low AR sacs and some aspect and leads to a cascade of enzymatic activities that weaken the aneurysm wall. However, the connection between AR, hemodynamics and wall weakening has never been proven. Animal models of saccular aneurysms provide a venue for evaluating this conjecture. The focus of this work was to evaluate whether a commonly used elastase induced aneurysm model in rabbits is suitable for a study of this kind from a hemodynamic perspective. In particular, to assess whether hemodynamic factors in low and high AR sacs are statistically different. To achieve this objective, saccular aneurysms were created in 51 rabbits and pulsatile computational fluid dynamics (CFD) studies were performed using rabbit specific inflows. Distinct hemodynamics were found in the low AR (AR<1.8, n=25), and high AR (AR>2.2, n=18) models. A single, stable recirculation zone was present in all low AR aneurysms, whereas a
Creation of four experimental aneurysms with different hemodynamics in one dog
AJNR. American journal of neuroradiology, 2005
We developed an experimental canine model in which four types of aneurysm--bifurcation, side-wall, small branch-artery, and arterial-stump--were surgically created in the same animal. These experimental aneurysms are exposed to simultaneous but different hemodynamic stresses correlating to human intracranial aneurysms in different locations. Because this model allowed for the creation of four aneurysms, each with different hemodynamic features, it seems to offer advantages from ones previously described. This model may foster investigation of new and current endovascular devices.
A Modification to a Murine Model for Intracranial Aneurysm Formation and Rupture
Cureus
Between 3.6% and 6.0% of the population has an intracranial aneurysm. The mechanisms underlying intracranial aneurysm formation and rupture are not fully known. Several rodent models have been developed to better understand intracranial aneurysm pathophysiology. Hypertension, hemodynamic changes, and vessel injury are all necessary for aneurysm induction; however, multiple invasive procedures may disrupt an animal's physiology. Therefore, we hypothesized that our method for inducing hypertension could be modified to create a simpler model. We previously developed a highly reproducible murine model of intracranial aneurysm formation and rupture that involves hemodynamic changes through ligation of the left common carotid artery, vessel wall degradation using elastase and a lysyl oxidase inhibitor, and hypertension through a high-salt diet, continuous angiotensin II infusion, and right renal artery ligation. In order to create a simpler model, we sought to eliminate renal artery ligation. We assessed aneurysm formation, aneurysm rupture, and blood pressure in two separate cohorts of C57BL/6 mice: one cohort underwent our model as above, while another cohort did not receive right renal artery ligation. Our results demonstrate that intracranial aneurysm formation and rupture rates did not differ between each group. Further, the blood pressures between cohorts did not differ at various timepoints in the model. Both cohorts, however, did have a significant increase in blood pressure from baseline, suggesting that renal artery ligation is not needed for inducing hypertension. These findings demonstrate that our murine model can be modified to eliminate right renal artery ligation. Thus, we propose this modification to our murine model for studying intracranial aneurysm pathophysiology.
Neurologia medico-chirurgica, 2020
Hemodynamic stress and chronic inflammation are closely associated with the pathogenesis of intracranial aneurysms (IAs). However, the hemodynamic and biological mechanisms triggering IA formation remain to be elucidated. To clarify them, computational fluid dynamics (CFD) and histopathological analyses in the early phase of IA development using an experimentally induced IA model in rats were conducted. Histological changes in the early phase of IA development were observed under a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Using data from 7-T magnetic resonance angiography (7T-MRA), CFD analyses were performed to determine wall shear stress (WSS) and wall pressure (WP) at the prospective site of IA. A bump-like protrusion named an "intimal pad" was located in the anterior cerebral artery (ACA) immediately distal to the apex of the bifurcation. TEM showed the degeneration of the internal elastic lamina (IEL) and longitudinally elongated smooth muscle cells (SMCs) that switched from the contractile to the proliferative phenotype and penetrated between two divided layers of the degenerated IEL in the prospective site of the IA. However, no inflammatory cells were observed. CFD analyses showed no particular pattern of WSS and WP at the prospective IA site. IEL degeneration and the phenotypic change and longitudinal elongation of SMCs were identified as the early events in IA development. CFD analyses and TEM data suggest that these biological events may be derived from increased circumferential wall stress due to increased blood pressure and increased longitudinal wall strain due to the existence of the intimal pad.