Morphology of cerebral arteries

Lee, Robert M.K.W.

doi:10.1016/0163-7258(94)00071-a

Cited by 226 publications

(177 citation statements)

References 75 publications

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“…Optimal oxygenation of the retinal tissue is ensured by the presence of a dual vascular supply, widespread intracranial anastomoses, 30 and the ability of the chorioretinal vascular circuit to regulate blood flow by means of both intrinsic autoregulatory and extrinsic autonomic feedback loops. 31 Because vascular pO 2 is dependent on both the supply of oxygenated blood and the extraction of oxygen by the retinal tissue, technologies that provide direct measurement of chorioretinal pO 2 can be invaluable to supplement knowledge of normal retinal vascular function and retinal pathologies associated with hypoxia or lowered blood flow.…”

Section: Discussionmentioning

confidence: 99%

A Method for Chorioretinal Oxygen Tension Measurement

Shahidi¹,

Shakoor²,

Blair³

et al. 2006

Current Eye Research

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Purpose-To report an optical imaging system that was developed to measure oxygen tension (pO 2 ) in the chorioretinal vasculatures. The feasibility of the system for the measurement of changes in pO 2 separately in the retinal and choroidal vasculatures was established in rat eyes by varying the fraction of inspired oxygen and inhibiting nitric oxide activity.Methods-Our optical section phosphorescence imaging system was modified to provide quantitative measurements of pO 2 separately in the retinal and choroidal vasculatures. A narrow laser line was projected at an angle on the retina after intravenous injection of an oxygen-sensitive probe (Pd-porphyrin), and phosphorescence emission was imaged. A frequency-domain approach allowed measurements of the phosphorescence lifetime by varying the phase relationship between the modulated excitation laser light and sensitivity of the imaging camera. Chorioretinal pO 2 was measured while varying the fraction of inspired oxygen and during intravenous infusion of N ω -nitro-L-arginine (N ω -NLA), a nonselective nitric oxide synthase inhibitor.Results-The systemic arterial pO 2 varied according to the fraction of inspired oxygen. The pO 2 in the retinal and choroidal vasculatures increased as the fraction of inspired oxygen was increased. Compared with base-line, choroidal pO 2 decreased during infusion of N ω -NLA, whereas the pO 2 in the retinal vasculatures remained relatively unchanged. The choroidal pO 2 decreased markedly with each incremental increase in N ω -NLA infusion rate, in the range 1-6 mg/min, and there was no additional change in the choroidal pO 2 at N ω -NLA infusion rates above 6 mg/min.Conclusions-An optical method combining pO 2 phosphorescence imaging with chorioretinal optical sectioning was established that can potentially be applied for better understanding of retinal and choroidal oxygen dynamics in physiologic and pathologic states.

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Section: Discussionmentioning

confidence: 99%

A Method for Chorioretinal Oxygen Tension Measurement

Shahidi¹,

Shakoor²,

Blair³

et al. 2006

Current Eye Research

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“…In human stroke, there exists a highly variable clinical state; in the development of animal models of focal ischemia, however, achieving reproducibility of experimentally induced infarct volume is essential. The rat is a widely used animal model for stroke due to its relatively low animal husbandry costs and to the similarity of its cranial circulation to that of humans 2,3 . In humans, the middle cerebral artery (MCA) is most commonly affected in stroke syndromes and multiple methods of MCA occlusion (MCAO) have been described to mimic this clinical syndrome in animal models.…”

Section: Introductionmentioning

confidence: 99%

Focal Cerebral Ischemia Model by Endovascular Suture Occlusion of the Middle Cerebral Artery in the Rat

Uluç¹,

Miranpuri²,

Kujoth³

et al. 2011

JoVE

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Stroke is the leading cause of disability and the third leading cause of death in adults worldwide 1 . In human stroke, there exists a highly variable clinical state; in the development of animal models of focal ischemia, however, achieving reproducibility of experimentally induced infarct volume is essential. The rat is a widely used animal model for stroke due to its relatively low animal husbandry costs and to the similarity of its cranial circulation to that of humans 2,3 . In humans, the middle cerebral artery (MCA) is most commonly affected in stroke syndromes and multiple methods of MCA occlusion (MCAO) have been described to mimic this clinical syndrome in animal models. Because recanalization commonly occurs following an acute stroke in the human, reperfusion after a period of occlusion has been included in many of these models. In this video, we demonstrate the transient endovascular suture MCAO model in the spontaneously hypertensive rat (SHR). A filament with a silicon tip coating is placed intraluminally at the MCA origin for 60 minutes, followed by reperfusion. Note that the optimal occlusion period may vary in other rat strains, such as Wistar or Sprague-Dawley. Several behavioral indicators of stroke in the rat are shown. Focal ischemia is confirmed using T2-weighted magnetic resonance images and by staining brain sections with 2,3,5-triphenyltetrazolium chloride (TTC) 24 hours after MCAO. Video LinkThe video component of this article can be found at https://www.jove.com/video/1978/ Protocol MCAO Rat Model Presurgical PreparationsAseptic technique should be used for all survival surgical procedures. Disinfect the surgical work surface with commercial disinfectant and prepare sterile surgical packs of instruments, drapes, gauze, swabs, sutures, and scalpel blades by autoclaving. A surgical mask, hair bonnet and sterile gloves should be worn. A Germinator dry bead sterilizer is also used to resterilize surgical instruments between procedures if multiple rat surgeries will be done during one session. Prewarm a water-jacketed homeothermic blanket and place under an absorbent pad in order to prevent hypothermia of the rat during surgery.1. Place spontaneously hypertensive rat (or other rat strain of choice) into an induction chamber and induce anesthesia with 5% isoflurane (anesthesia machine should be set to 1.0 L/min O 2 and 1.0 L/min N 2 O). Lower to 1-2% isoflurane to maintain anesthesia. 2. Apply Artificial Tears ointment to both eyes. 3. Shave the throat and left neck region beyond the prospective incision site using clippers (Oster A5 with #10 blade). 4. Apply Betadine to a gauze pad and disinfect the skin starting from the center of the surgical region, spiraling outward. Rinse with sterile gauze pad containing 70% ethanol, moving pad in a similar pattern. Repeat both steps for a total of three cycles. 5. Inject 0.2 mL of 0.5% bupivacaine subcutaneously along the prospective incision site. 6. Place rat in sterile stockinette or cover with a sterile surgical drape.

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“…Both an increase in WSS amplitude at the impingement point and a double amplitude peak at the opposite bifurcation region are observed due to local recirculation effects. The impingement sites of the incoming parent artery flow also shift toward the apex of the bifurcation region along the A2-ACOM adjoining wall where the median muscular layer of the arterial wall is least developed [1]. This leads to greater hemodynamic stresses at locations that are least able to withstand them and a possible mechanism for mechanical deformation from cyclic fatigue stresses.…”

Section: Discussionmentioning

confidence: 99%

“…It is known that over 85% of aneurysms occur in the anterior circulation and form predominantly at the apex of vessel bifurcations and around sharp bends. It is at these locations where hemodynamic stresses are the greatest and the structural protein assembly of the muscular layer of the vessel wall is most underdeveloped [1]. A generally accepted theory is that an anomalous response of the vascular endothelium to oscillating wall shear stresses leads to progressive and unstable degradation of the arterial wall and consequent aneurysm formation [2].…”

Section: Introductionmentioning

confidence: 99%

Hemodynamic Effect of Unequal Anterior Cerebral Artery Flow Rates on the Anterior Communicating Artery Bifurcation: A Computational Fluid Dynamics Study

Rau

Venugopal

et al. 2008

Modelling and Simulation in Engineering

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Recommended by Ewa PietkaComputational fluid dynamics techniques were used to investigate the hemodynamic effect of unequal anterior cerebral artery flow rates on the anterior cerebral and anterior communicating artery (ACA-ACOM) bifurcation. Hemodynamics have long been implicated as a major factor in cerebrovascular disease. Using an idealized 2D symmetric model of the ACA-ACOM geometry, the flow field and wall shear stress (WSS) at the bifurcation regions are assessed for pulsatile inflows with left to right flow ratios of 1 : 1, 2 : 1, 3 : 1, and 4 : 1. Unequal flow rates through the ACA parent arteries result in bifurcation of the higher flow parent stream and a shifting of the impingement points along the A2-ACOM adjoining wall toward the contralateral ACA. Cross-flow through the ACOM is generally unstable and results in increased WSS at the impingement region from the higher flow parent artery and a double amplitude peak in the WSS at the contralateral bifurcation region from local recirculation effects. These results suggest that asymmetry in ACA flow rates result in increased hemodynamic stresses at the ACA-ACOM bifurcation regions and suggest a possible factor for vessel weakening and aneurysm formation.

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Morphology of cerebral arteries

Cited by 226 publications

References 75 publications

A Method for Chorioretinal Oxygen Tension Measurement

A Method for Chorioretinal Oxygen Tension Measurement

Focal Cerebral Ischemia Model by Endovascular Suture Occlusion of the Middle Cerebral Artery in the Rat

Hemodynamic Effect of Unequal Anterior Cerebral Artery Flow Rates on the Anterior Communicating Artery Bifurcation: A Computational Fluid Dynamics Study

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