Effects of intracarotid infusion of prostaglandins (PG) E1 and Fza on the circulation to the dog brain were examined by fluorescein angiography, by measuring diameter changes in the epicerebral vessels, and by measuring microregional cerebral blood flow with ~33xenon and lithium-drift silicon detectors. PGE~ at doses of 0.5 .I~g/min constricted the epicerebral arteries 700 [~ or less in diameter, arrested fluorescein dye injected into the carotid system, and reduced rCBF by 42% with increase of collateral flow to the brain by the vertebrobasilar system. This effect was not obtained by PGE~ to which 0.08% ethanol had been added. PGF2~ at doses of 25 ~g/min constricted epicerebral arterial vessels less than 200 .I~ in diameter, reduced rCBF by 35%, and decreased fluorescein dye in the cortical microcirculation with lengthening of the cerebral circulation time. Selective clipping of external and internal carotid arteries indicated that PGE~ acts by constricting these vessels as well as the epicerebral arteries. Since prostaglandins are released from platelets as well as from stimulation of the cerebral cortex they should be considered as factors involved in the regulation of cerebral blood flow and in the mechanism of cerebral vasospasm. These properties of PGEa and PGF2~ also imply the need for caution when these substances are used for clinical investigation. KEY WORDS cerebral microcireulation mieroregional cerebral blood flow xenon vasospasm ethanol fluoreseeln anglography prostaglandins ? Anesthesia machine was from Stanton Scientitle Equipment Company, California. Saran Wrap made by Dow Chemical
✓ The circulation through an arteriovenous malformation and the microcirculation of the surrounding brain were examined during craniotomy by fluorescein angiography and by microregional blood flow measurements using xenon133 and Neohydrin-Hg197. The evidence indicates that occluding the arterial supply to the angioma obliterated the cerebral steal by reducing the shunt or non-nutritional flow and improving the perfusion flow through the cortical microcirculation. The features characterizing the cerebral steal syndrome are described.
✓ In dogs, while the middle cerebral artery (MCA) was clipped, an apparent ischemia was demonstrated with fluorescein angiography when the dye was injected through the lingual artery. Injection of fluorescein into the femoral artery or perfusion of carbon black particles through the heart demonstrated considerable collateral blood supply to the affected area. Water, sodium, and potassium content of cerebral tissues normally supplied by the occluded artery remained unchanged. At 48 hours after clipping, focal areas of infarction developed in 70% of the animals; edema could then be demonstrated in tissue surrounding the infarction. The collateral blood supply was compromised by subjecting the dogs with clipped MCA to hemorrhagic hypotension for 1 hour. Following restoration of the systemic blood pressure by infusion of the shed blood, an area of ischemia in the territory normally supplied by the clipped artery could be easily demarcated by fluorescein angiography through the femoral and lingual arteries and by carbon perfusion. The involved cerebral cortex tissue showed marked changes that started immediately after restoration of the blood pressure, and which consisted of a fall in percentage dry weight and potassium content and an increase in sodium content. These findings were clearly correlated with gross and histological evidence of massive necrosis and were interpreted as indicating cell death rather than tissue swelling. In the underlying white matter, moderate delayed changes in water and electrolyte content were compatible with the development of vasogenic edema.
Fluorescein angiography and xenon-133 (133Xe) clearance studies were performed during surgery on 15 patients who were undergoing superficial temporal artery (STA) to middle cerebral artery (MCA) anastomosis. Fourteen patients had occlusive disease of the internal carotid artery (ICA), and one patient had severe stenosis of the MCA. Before anastomosis, fluorescein angiography showed slow filling of the MCA branches through collateral channels. Focal areas of impaired microcirculatory filling and washout were seen in the territory of severely sclerotic cortical arteries. The findings of preanastomotic 133Xe clearance studies were variable and a uniform pattern of regional cerebral blood flow (rCBF) changes was not defined. In 55% of the patients, rCBF was reduced to 25 ml/100 gm/min or less at one or more detector sites. Fluorescein angiography provided an immediate assessment of anastomotic patency and clearly displayed the distribution of blood entering the epicerebral circulation through the STA. In 67% of patients, multiple MCA cortical branches filled with fluorescein, whereas in 33% filling was restricted to the receptor artery territory. An immediate, substantial (greater than or equal to 15 ml/100 gm/min) increase in rCBF was demonstrated in 73% of patients after anastomosis. The rCBF changes were consistently better in patients with donor and receptor arteries greater than 1 mm in diameter. Redistribution of collateral input acted to increase rCBF in areas distant from the anastomotic site. Some improvement in fluorescein circulation and rCBF also was seen in cortex supplied by sclerotic MCA branches.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.