External carotid artery territory ischemia impairs outcome in the endovascular filament model of middle cerebral artery occlusion in rats.
(41/215)
BACKGROUND AND PURPOSE: Middle cerebral artery occlusion (MCAO) by an intraluminal filament is a widely accepted animal model of focal cerebral ischemia. In this procedure, cutting of the external carotid artery (ECA) is a prerequisite for thread insertion. However, the implications of ECA transsection have not yet been described. METHODS: After 90 minutes of filament MCAO or sham surgery, rats were evaluated for up to 14 days in terms of body weight development, core temperature, and motor performance. Repeated in vivo MRI of the head and neck was performed for quantification of brain edema and infarct volume. The temporal muscles were histologically analyzed postmortem. RESULTS: In 47% of all rats, ischemic tissue damage to the ipsilateral ECA area, including temporal, lingual, and pharyngeal musculature, was detectable by MRI. Histology of temporal muscles confirmed acute ischemic myopathy. Animals with ECA territory ischemia (ECA-I) showed delayed body weight development and poorer recovery of motor function. There was no difference in the extent of brain edema or final cerebral lesion size between ECA-I-affected and unaffected rats. CONCLUSIONS: Filament MCAO was complicated by the consequences of ECA ischemia in approximately half of all rats. Impaired mastication and swallowing functions restricted ingestion and resulted in postsurgical body weight loss and worse motor performance. Impaired cerebral microperfusion resulting from dehydration and reduced spontaneous motor activity resulting from reduced food and water uptake might have contributed to poorer neurological recovery in ECA ischemic rats. Thus, adverse effects caused by extracerebral ischemia with potential impact on outcome have to be considered in this stroke model. (+info)
Flow-induced vascular remodeling in the mouse: a model for carotid intima-media thickening.
(42/215)
OBJECTIVE: Vascular remodeling of the carotid artery with intima-media thickness (IMT) is an important predictive factor for human cardiovascular disease. We characterized a mouse model of vascular remodeling. METHODS AND RESULTS: The left external and internal carotid branches were ligated so that left carotid blood flow was reduced to flow via the occipital artery. In response to partial ligation of the left carotid artery (LCA), blood flow significantly decreased (-90%) in the LCA and increased (+70%) in the right carotid artery (RCA). Morphometry showed that both RCA and LCA underwent outward remodeling that was maximal at one week. Remodeling was greater in the RCA with predominantly increased lumen and very little increase in media or adventitia. In the LCA there was a dramatic increase in media with adventitia growth and intima formation. Correlation analysis indicated that the outward remodeling was more likely due to primary changes in the vessel wall rather than to changes in the lumen, such as shear stress. Mechanistic studies suggested roles for macrophage infiltration, upregulation of matrix metalloproteinase (MMP)-9, extracellular matrix reorganization, and vascular smooth muscle cell proliferation in LCA remodeling. CONCLUSIONS: The mouse model described here may be useful to define genetic determinants of IMT and identify new targets for therapy based on vascular remodeling. (+info)
Effect of carotid artery stenting on the external carotid artery.
(43/215)
OBJECTIVE: We studied the fate of the ipsilateral external carotid artery (ECA) after stenting of the internal carotid artery (ICA) compared with the contralateral ECA. SUBJECTS AND METHODS: One hundred twenty-one ipsilateral ECAs in 112 consecutive patients who underwent carotid artery Wallstent placement were prospectively studied with color-coded duplex sonographic scanning (CCDS) and compared with 83 contralateral ECAs over 2 years. CCDS was scheduled for the day before (day 0), the day after (day 1) and 3, 6, 12, and 24 months after stenting. Development of ECA occlusive disease was evaluated with ECA-common carotid artery flow ratio (peak systolic velocity). For estimation of ECA stenosis 70% or greater, flow ratio 4.1 was used as the cutoff point. RESULTS: Before and after stenting, two and three (one additional) ECA occlusions were seen. Median grade of ECA stenosis on day 1 did not significantly change at angiography (P = 1.0; tendency of increase) or CCDS (P =.27; tendency of decrease).At follow-up (day 1-24 months, CCDS only), frequency of stenosis 70% or greater in the ipsilateral ECA was 21 of 120 (17.5%) on day 1 and 41 of 107 (38.32%) at 24 months, and 3 of 107 (2.5%) and 5 of 107 (4.67%) ECA occlusions were registered at the two time points. Progression of disease, as demonstrated by increase in flow ratio over time, was much more pronounced in the ipsilateral ECAs compared with the contralateral ECAs (P =.0002). In stented ICA, 2 (1.85%) asymptomatic recurrent stenoses 70% or greater were found at CCDS. One of three patients with new ECA occlusions reported jaw claudication for 10 days. Perioperative stroke (one major, four minor) occurred in 5 of 121 patients (4.46%). Two minor strokes caused by embolization occurred during the first year. CONCLUSION: The more pronounced progression of arteriosclerotic disease at the orifice of the ipsilateral ECAs during the first year after carotid stenting might be due to local factors of the ICA stent. Its clinical significance in respect to the effect of the ECA as collateral supply to the brain might depend on the incidence of carotid stent rerecurrent stenosis, which was low in the present study. (+info)
Adenoviral transfer of endothelial nitric oxide synthase attenuates lesion formation in a novel murine model of postangioplasty restenosis.
(44/215)
OBJECTIVE: Restenosis remains a major late complication of percutaneous transluminal coronary angioplasty (PTCA), for which the development of prevention strategies has thus far been hampered by the lack of a representative and practical animal model. We have, therefore, developed a murine model of PTCA-induced restenosis. METHODS AND RESULTS: Rigid probe angioplasty of pre-existing atherosclerotic lesions in the carotid arteries of ApoE-deficient mice was found to result in an increase in lesion size (0.14+/-0.04x10(5) microm2 to 0.42+/-0.09x10(5) microm2, P=0.007) with a smooth muscle cell-rich, fibrotic lesion morphology. In an additional experiment, lesions were incubated immediately after angioplasty with adenovirus bearing an endothelial nitric oxide synthase (eNOS) transgene (Ad.APT.eNOS), or an "empty" control virus (Ad.APT.empty) at a titer of 1.5x10(9) pfu/mL. Ad.APT.eNOS treatment was seen to lead to a 73.1% reduction in plaque size (0.27+/-0.04x10(5) microm2 versus 1.02+/-0.39x10(5) microm2, P=0.07), which translated to a significantly lowered average degree of stenosis (33.6+/-4.1% versus 74.6+/-14.0%, P=0.02). Ad.APT.eNOS also decreased lesional collagen content from 29.1% to 4.8% (P<0.001). CONCLUSIONS: We believe that we have established a representative murine model of postangioplasty restenosis, which may serve to elucidate the mechanisms underlying restenosis and to evaluate potential antirestenotic therapies. (+info)
Development of gold stents for the treatment of intracranial aneurysms: an experimental study in a canine model.
(45/215)
BACKGROUND AND PURPOSE: Gold has often been used in medicine because of its radiopacity and flexibility. To perform stent-supported coil embolization of intracranial aneurysms, we prepared a gold stent and examined its flexibility, radiopacity, and thrombogenic properties in comparison with a stainless steel device implanted in vitro and in vivo. METHODS: Gold stents were prepared by plating gold on stainless steel stents as a template. Their mechanical properties and trackability in vitro were determined and compared with those of stainless steel stents of the same design. Twenty gold stents and two stainless steel stents were implanted in canine external carotid, vertebral, and renal arteries, as a muscle branch of the maxillary arteries, to examine their performance in vivo. RESULTS: The gold stent exhibited much less radial force and greater flexibility than the stainless steel stent. It also demonstrated superior trackability and radiopacity in the experimental endovascular procedures in canines. Histologic examination showed good patency of the stented artery with slight endothelial hypertrophy. CONCLUSION: Although there is still room for more radial strength, less influence on intimal hypertrophy, a more suitable flexibility, and a smoother surface, the superior trackability and radiopacity of gold stents seem to support use of this device for the endovascular treatment of intracranial aneurysms. (+info)
Ultrasound morphology of carotid lesions in retinal ischaemia.
(46/215)
The extracranial carotid arteries of 165 patients with retinal ischaemic symptoms were examined with duplex ultrasound. Both the degree of stenosis and the morphological appearance of the lesions were examined. Ipsilateral carotid artery disease was found in 88% of patients. Degrees of stenosis of between 50-99% were found in 33% of patients, the majority of these lesions being complex heterogeneous in nature. Stenosis of < 50% was found in 40% of arteries. The majority of lesions causing < 20% stenosis were homogeneous in nature. However, in stenosis of 20-49%, 63% of lesions were found to be complex heterogeneous. A similar distribution of lesions was found in the contralateral carotid arteries. It is important to examine both ipsilateral and contralateral arteries, and to evaluate the morphological characteristics of all lesions causing > 20% stenosis. (+info)
A rare case of a ruptured middle meningeal aneurysm causing intracerebral hematoma in a patient with moyamoya disease.
(47/215)
Moyamoya disease is infrequently associated with intracranial aneurysms arising from the circle of Willis vessels or from "peripheral" branches of choroidal and meningeal vessels. We present a rare case of a moyamoya-related aneurysm arising along the dural junction of multiple meningeal branches from the external carotid artery causing intracerebral hemorrhage. Endovascular coil embolization of the middle meningeal artery (MMA) and occipital artery (OA) led to delayed aneurysm obliteration without rehemorrhage. (+info)
Conformity of carotid stents with vascular anatomy: evaluation in carotid models.
(48/215)
BACKGROUND AND PURPOSE: Conformity between self-expanding Wallstents and vascular anatomy is limited. Because of a lack of longitudinal flexibility, straightening effects on vascular curves occur and may result in stent-induced kinking. Our purpose was to evaluate the conformity of self-expanding stents with the course and endoluminal surface of silicone models of the normal human carotid artery. METHODS: Five different types of self-expanding carotid stents were implanted into simplified pulsatile perfused silicone models of the carotid bifurcation. The models embody elastic properties of the vessel wall similar to those of normal human arteries. All stents had the same nominal diameter and length and bridged the external carotid artery origin as well as a consecutive curve at the initial segment of the internal carotid artery. Conventional radiographs of the model were compared before and after stent placement to record changes of shape and course of the silicone artery. Dehiscences between stent filaments and arterial wall were measured on digital subtraction angiograms of the model. RESULTS: Implantation of braided Wallstents or the Expander with continuous filaments induced considerable straightening effects on the bifurcation angle, as well as on the curves of the internal carotid artery. Segmented designs of modular nitinol stents complied better with vascular tortuosity and showed improved adaption between stent and the endoluminal surface of the model. CONCLUSION: Model experiments show that segmented nitinol stents improve the conformity between the prosthesis and vascular anatomy, and confirm new carotid stent concepts as an alternative to the Wallstent. (+info)