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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Removal of a rectus muscle results in permanent interruption of blood flow in the corresponding anterior ciliary artery, predisposing to anterior segment ischemia (ASI). A subhuman primate model of ASI was developed in order to study a novel muscle tuck procedure designed to preserve anterior ciliary artery circulation. Fluorescein angiograms were obtained before and after surgery to determine the effect of the muscle surgery on iris circulation. A total of 12 eyes from 12 cynomolgus monkeys underwent strabismus surgery consisting of tenectomy of all 4 rectus muscles in 3 eyes, tenectomy of 3 rectus muscles in 3 eyes, and tenectomy of 3 rectus muscles and muscle to sclera tuck of the remaining recti in 6 eyes. Postoperative angiograms documented preservation of perfusion in the distribution of the tucked muscle in all cases except one, in which there was iatrogenic trauma and disruption of anterior ciliary arteries. The modified tuck procedure thus appears to preserve anterior ciliary artery blood flow, and may be useful as a muscle strengthening procedure in patients predisposed to developing ASI.
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PMID:Effect of a modified rectus tuck on anterior segment circulation in monkeys. 205 Dec 93

A 51 year-old woman presented with sudden loss of vision secondary to serous neuroretinal detachments of both maculas. Fluorescein angiography revealed multiple hyperfluorescent pin-point dots in the early phases. The areas of fluorescein hyperfluorescence became more diffuse as dye leaked into the subretinal space. The diagnostic of acute monoblastic leukemia was made. Following treatment, her vision improved. Fundus examination at that time showed resolution of the bilateral serous retinal detachment. She died one month after the onset of visual complaints and autopsy was refused. There have been 14 previous reports of acute leukemia with serous retinal detachment. In most cases, retinal detachment occurred as the presenting sign or during relapse of the systemic disease. It was often bilateral and located in the posterior pole. Histopathologic studies showed leukemic infiltration of the choroid with areas of degeneration and proliferation of the retinal pigment epithelium. Angiographic findings are similar to what is observed in choroidal ischemia. The relationships with macular serous retinal detachment and choriocapillaris occlusion are discussed.
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PMID:[Bilateral serous detachment of neuroepithelium of the posterior pole disclosing acute leukemia]. 208 49

Carotid artery obstructive disease, although infrequently diagnosed as a primary or contributing cause of neovascular glaucoma, can produce distinctive characteristics. Decreased perfusion of the ciliary body may decrease aqueous humor production. As a result, such eyes with neovascular glaucoma may occasionally be normotensive or even hypotensive. Fluorescein angiography may show an increased arm-to-retina time and leakage from the major retinal arterioles. Panretinal photocoagulation may not eliminate the anterior segment neovascularization because of anterior segment ischemia. Endarterectomy can significantly increase intraocular pressure as perfusion to the ciliary body returns to normal. These characteristics were found in two patients, a 67-year-old woman and a 49-year-old man, with diabetes and hypertension. In both cases cyclocryotherapy significantly reduced the intraocular pressure and the rubeosis iridis regressed.
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PMID:Neovascular glaucoma and carotid artery obstructive disease. 240 76

The authors describe in seven eyes of four patients a form of serpiginous choroiditis beginning in the macula without initial peripapillary activity. Eyes with macular serpiginous choroiditis often had a poor visual prognosis and sometimes developed subretinal neovascularization. Fluorescein angiography of the acute lesions showed hypofluorescence; some cases were thus initially diagnosed as having choroidal ischemia. Fluorescein angiography in one eye, however, suggested that at least some of the hypofluorescence seen acutely in eyes with serpiginous choroiditis is secondary to blocked fluorescence from "opaque" retinal pigment epithelium.
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PMID:Macular serpiginous choroiditis. 245 20

Fluorescein-isothiocyanate dextran (FITC-dextran), a dye confined to the vascular space, was infused via the hepatic artery and portal vein into perfused livers from fed rats treated with diethylnitrosamine for 4 to 5 months. Fluorescence due to FITC-dextran was detected with fiberoptic microlight guides placed on surface nodules of about 5 mm in diameter. Nodules were categorized into groups with normal and compromised microcirculation based on their fluorescence following infusion of FITC-dextran. Similar results were obtained when nodules were classified based on reflectance of trypan blue. Despite compromised microcirculation, ATP and ADP levels as well as ATP/ADP ratios were comparable in both groups of nodules; however, AMP was elevated in FITC-dextran-negative nodules (i.e., those with compromised microcirculation). Nodules with compromised microcirculation also contained higher glucose and lactate levels than nodules that were well perfused; however, glycogen was five times lower than in FITC-dextran-positive nodules. Fasting reduced ATP/ADP ratios in poorly perfused nodules in comparison to well-perfused nodules. In perfused livers from fed rats where glycogen was high, however, ATP/ADP ratios and rates of ATP depletion during ischemia were the same in well-perfused and poorly perfused nodules. Products of glycogen breakdown (e.g., glucose and lactate) were elevated in nodules from livers of fed but not fasted rats. The results indicate that alteration of perfusion of hepatic nodules does not change ATP levels nor the capacity of nodules to utilize high energy phosphate during anoxia. Thus, near normal energy status is maintained from glycogen metabolism in poorly perfused nodules via glycolysis. Since basal ATP content and utilization is comparable in well and poorly perfused nodules, compromised energy status is unlikely to explain selection of nodules that regress to near normal hepatocytes.
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PMID:Adenine nucleotides and carbohydrates in subpopulations of hepatic nodules with normal and compromised microcirculation. 247 May 3

Thirty-five Sprague-Dawley rats were divided into control (non-exsanguinated) groups of 8 and 10 hr of ischemia, and exsanguinated groups of 8, 10, 14, 16, and 18 hr of ischemia. Free flaps based on the superficial inferior epigastric artery were anastomosed to the contralateral femoral vessels after their designated ischemia period. Reperfusion was assessed by measuring fluorescein uptake in the free flaps after clamp release. In the exsanguinated groups, 100 percent (5/5) of the 8-hr, 10-hr, and 14-hr ischemia groups survived; 80 percent (4/5) of the 16-hr ischemia group free flaps survived; and none (0/5) of the 18-hr ischemia flaps survived. In the control groups, 100 percent (5/5) of the 8-hr ischemia flaps survived, while none (0/5) of the control 10-hr ischemia flaps survived. Fluorescein uptake correlated well with flap survival. By exsanguinating an experimental microvascular free flap prior to its ischemia period, it is possible to dramatically increase flap tolerance to ischemia.
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PMID:Perfusion washout: increasing a microvascular free flap tolerance to ischemia. 272 27

We produced experimental renovascular malignant arterial hypertension by modified Goldblatt's procedures, in 60 rhesus monkeys. Hypertensive retinopathy was studied in detail (by ophthalmoscopy, and stereoscopic color fundus photography and fluorescein fundus angiography on long-term follow-up). Cotton-wool spots (CWSs) were found to be an important, early retinal lesion. On ophthalmoscopy, they had a characteristic appearance. Fluorescein fundus angiography of these lesions revealed focal retinal capillary nonperfusion. The CWSs usually lasted for over 3 weeks and resolved within 6 weeks, leaving permanent obliteration of the retinal capillaries in their distribution, secondary intraretinal microvascular abnormalities, and retinal nerve fiber loss. We discuss pathogenesis and other features of CWSs. There is overwhelming evidence that CWSs are due to occlusion of the terminal retinal arterioles, resulting in acute focal inner retinal ischemia; hence the scientifically valid term for them would be 'inner retinal ischemic spots'.
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PMID:Cotton-wool spots (inner retinal ischemic spots) in malignant arterial hypertension. 274 98

In order to clarify the pathophysiology of intestinal ischemic lesions and to make a useful method for the prediction of fate of the ischemic bowel, we devised an experimental model to produce the disorder. Microbarium of 0.5 micrometer in diameter was injected into a branch of the superior mesenteric artery of adult mongrel dogs. The severity of the ischemic lesions depended on the amount of microbarium injected, and lesions could be classified into three types; transient, stricturing and gangrenous, similar to clinical cases. Endoscopic examination was performed, accompanied with fluorescence endoscopy. Fluorescein could not be observed in all types soon after microbarium injection. In the transient type, fluorescein was observed after only a few days in an evenly distributed pattern. However in the stricturing type, the appearance of fluorescein was delayed, and an irregular pattern was observed in about 1 week. The submucosal blood flow was measured by hydrogen clearance method. The fluorescence endoscopic findings were nearly compatible with changes of submucosal blood flow. Fluorescence endoscopy is easily performed and appears to be highly useful in the differentiation of these three types of ischemia in the early stages.
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PMID:[An experimental endoscopic study on intestinal ischemic lesions in dogs with special reference to fluorescence endoscopy]. 322 23

Epidural spinal cord electrical stimulation (ESES) was performed on 10 patients with severe limb ischemia due to atherosclerotic disease. Microcirculatory parameters were assessed before and after ESES. Bright field microscopy was used to assess capillary diameters and red blood cell (RBC) velocity in the dorsum of the foot. Fluorescein microscopy was used with intravenously injected sodium fluorescein to study capillary density and sodium fluorescein appearance time in the dorsum of the toe. The systolic ankle/arm pressure ratio and toe pressure measurements were used as macrocirculatory parameters. After ESES, clinical improvement was confirmed by intravital microscopy. Capillary density increased (p less than 0.001), RBC velocity in capillaries already perfused before ESES increased from 0.054 mm/sec to 0.762 mm/sec (p less than 0.001), and sodium fluorescein appearance time decreased from 72 to 45 seconds (p less than 0.001). Capillary diameter did not change significantly so that the increase in RBC velocity may be interpreted as enhanced volume flow. Systolic ankle/arm pressure ratios and digital arterial pressure did not change significantly. The current results show that in patients with severe occlusive arterial disease of the lower limbs, ESES recruits capillaries not perfused in the control situation and enhances skin blood flow, improvements that may explain the beneficial clinical effects of ESES.
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PMID:Epidural spinal cord electrical stimulation improves microvascular blood flow in severe limb ischemia. 325 79

Cutaneous circulation in 4 X 10 cm skin samples and delayed and acute random skin flaps constructed on the flanks of castrated Yorkshire pigs (13.3 +/- 0.7 kg; n = 12) were studied during intravenous infusion (0.5 ml per minute) of 5% dextrose solution (vehicle) and 5% dextrose containing norepinephrine (1 microgram/kg per minute). Total and capillary blood flow and A-V shunt flow were measured by the radioactive microsphere technique 6 hours after the raising of 4 X 10 cm single-pedicle acute and delayed random skin flaps using the technique and calculations published previously. Fluorescein dye test was also performed to assess vascular perfusion. It was observed that the capillary blood flow in the single-pedicle delayed skin flaps was similar to that in the normal skin, and the maintenance of this normal skin blood flow was not due to the closing of A-V shunt flow in the delayed skin flaps. Similarly, the significant (p less than 0.01) decrease in capillary blood flow and distal perfusion in the acute skin flaps compared with the delayed skin flaps was not due to the opening of A-V shunts in the acute skin flaps. There was no evidence to indicate that A-V shunt flow per se was the primary factor for the regulation of capillary blood flow in the acute and delayed skin flaps in the pig. Our data seemed to indicate that tissue ischemia in the distal portion of acute skin flaps was likely the result of vasoconstriction of the small random arteries which supplied blood to arterioles and A-V shunts, and locally released neurohumoral substances may play an important role in the pathogenesis of vascular resistance and ischemia in the acute skin flaps.
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PMID:Hemodynamics and vascular sensitivity to circulating norepinephrine in normal skin and delayed and acute random skin flaps in the pig. 372 57


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