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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A model for studying changes in local CBF and evoked potentials in selective thalamic ischaemia has been developed. The arterial supply to the posterior thalamus (mainly from the posterior choroidal arteries) was occluded in the baboon using a transorbital approach to the region of prepontine and ambient cisterns. Local CBF was measured by the hydrogen clearance method using electrodes introduced into the nucleus ventralis posterior lateralis of thalamus as well as cortex on both sides. The production of focal ischaemia was demonstrated by a significant decrease in thalamic CBF and confirmed by examination of the brain perfused with carbon particles.
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PMID:A model of selective experimental ischaemia in the primate thalamus. 400 65

The effects of nimodipine, a calcium antagonist with preferential cerebrovascular activity, on the global and regional cerebral blood flow (CBF and rCBF), the intracranial pressure (ICP), and the cerebral perfusion pressure (CPP), were investigated in an acute study. The rCBF of 54 patients was measured by the Xe133 inhalation method under identical conditions before and 60 min after oral administration of nimodipine. 12 patients with focal cerebral circulation disturbances of arteriosclerotic origin, who had suffered a cerebral accident (TIA, PRIND, minor stroke) no more than 3 weeks previously, were given a placebo (test-retest controls) and 25 patients of the same diagnosis and age group were given 40-80 mg nimodipine orally. 11 patients with acute subarachnoid hemorrhage (SAH) from ruptured anterior communicating artery aneurysms and clinical and angiographic signs of vasospasm (Hunt- and Hess grade 3) were likewise treated with nimodipine by the oral route. 6 patients with cerebral vasospasm received nimodipine in i.v. doses of 0.5-2 mg/h. The cerebral blood flow, assessed on the basis of the initial slope index (ISI), before and after the medication, was compared by statistical methods. 12 patients with head injury were given nimodipine intravenously in a dose of 0.5-2 mg with continuous monitoring of the ICP and the blood pressure. The pressure values were evaluated continuously by computer, with calculation of the perfusion pressure, and tested for statistical significance. Oral nimodipine therapy resulted in a significant (14%) increased of the CBF (taking account of the arterial pCO2), the improvement of blood flow being even more pronounced in the hypoperfused regions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Acute effects of nimodipine on the cerebral blood flow and intracranial pressure. 401 Aug 72

A modified collimator and standard gamma camera have been used to measure regional cerebral blood flow following inhalation of radioactive xenon. The collimator and a simplified analysis technique enables excellent statistical accuracy to be achieved with acceptable precision in the measurement of grey matter blood flow. The validity of the analysis was supported by computer modelling and patient measurements. Sixty-one patients with subarachnoid haemorrhage, cerebrovascular disease or dementia were retested to determine the reproducibility of our method. The measured coefficient of variation was 6.5%. Of forty-six patients who had a proven subarachnoid haemorrhage, 15 subsequently developed cerebral ischaemia. These showed a CBF of 42 +/- 6 ml X minute-1 X 100 g brain-1 compared with 49 +/- 11 ml X minute-1 X 100 g brain-1 for the remainder. There is evidence that decreasing blood flow and low initial flow correlate with the subsequent onset of cerebral ischaemia.
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PMID:Regional cerebral blood flow utilizing the gamma camera and xenon inhalation: reproducibility and clinical applications. 408 19

The effect of perfusion of the cerebral ventricles with artificial cerebrospinal fluid containing carbachol on the blood flow in the caudate nucleus of the cat and the possibility to inhibit this effect by anticholinergic drugs was studied by means of the hydrogen clearance technique. After a control period during which both lateral ventricles were perfused with artificial CSF of identical composition, the drug under study was added on one side (experimental side) while the other side continued to be perfused with the control artificial CSF (control side). The blood flow on the experimental side and on the control side were compared. A dose dependent response to carbachol was observed. Lower concentrations of carbachol (10(-6) up to 10(-4)M) caused vasodilatation whereas high concentrations (10(-3)M) caused local vasoconstriction. The increase in the local blood flow caused by the low carbachol concentrations was reduced by both atropine (10(-5)M) and hexamethonium (10(-3)M). The fall in CBF observed with the high carbachol concentration was prevented by atropine (10(-5)M). It may be concluded that low, physiologically more meaningful, carbachol concentrations cause a local vasodilatation due to interaction with both muscarinic and nicotinic receptors.
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PMID:Response of local blood flow in the caudate nucleus of the cat to intraventricular administration of carbachol. 614 38

Fentanyl (mean dose 109 micrograms X kg-1) and oxygen were given to ten patients having coronary vein grafts. Serial studies were done before, during and after operation, of central and mean arterial pressures (MAP), cardiac index (CI) and coronary sinus flow (CBF) by thermodilution, myocardial oxygen consumption (MVO2) and lactate extraction (MLE). On induction CI and stroke work index decreased, but heart rate and MAP were unchanged as systemic resistance increased. Mean MAP and heart rate remained at the awake levels. Mean CBF remained unchanged along with stable MAP and coronary resistance. Oxygen content of CS blood increased on induction and remained elevated until the incision; it was above the awake level early postoperatively. MVO2 was low normal when the patients were awake and remained so. Normal MLE continued with a few exceptions. High-dose fentanyl did not uniformly abolish autonomic reflexes. Heavy premedication, complete beta adrenergic blockade and a high initial doses of fentanyl plus its continued infusion, aided in retaining a hypodynamic circulation and myocardial oxygenation.
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PMID:Myocardial metabolism and haemodynamic responses during high-dose fentanyl anaesthesia for coronary patients. 633 15

Glucose-insulin-potassium (GIK) has beneficial effects during endotoxin shock, possibly through improvement of myocardial function, but the mechanism is not clear. We have studied the effects of GIK on left ventricular function, coronary flow, and oxygen consumption in controls and dogs treated with endotoxin (1.5 mg/kg-1). The animals were anaesthetized (etomidate 4 mg/kg-1/hr-1) and ventilated (N2O:O2 = 2:1). We have measured left ventricular pressure, left ventricular end-diastolic pressure (LVEDP) and LVdP/dt, systemic blood pressure, cardiac output (CO; thermodilution), coronary blood flow (CBF; radioactive microspheres), and oxygen content and lactate in arterial and coronary sinus blood. Endotoxin caused a rapid fall of CO and blood pressure with a temporary recovery followed by gradual circulatory collapse. GIK infusion (50% glucose, 2 g/kg-1 bw, 8 mmol KCl, and 3 U insulin/kg-1 bw) increased CO (56%), CBF (61%), blood pressure (21%), LVEDP (77%), and LVdP/dt (28%), and systemic vascular resistance decreased (23%). Stroke work (80%) and tension time index (42%) decreased during shock, but GIK temporarily improved these variables. The ratio of stroke work, respectively tension time index to oxygen consumption, suggests that myocardial efficiency decreased during shock and improved after GIK. Endotoxin decreased the ratio of endo- to epicardial flow. GIK did not change this ratio. However, for the same endo to epi ratio, increased CBF implies increased flow to endocardium.
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PMID:Effects of glucose-insulin-potassium (GIK) on myocardial blood flow and metabolism in canine endotoxin shock. 638 52

Thirty six small hydrogen sensitive electrodes were inserted into the brains of 6 cats to evaluate the local vascular response to change in PaCO2, of cortex, subcortical white matter, and caudate nucleus. Repeated measurements (617) of local cerebral blood flow (ICBF) were performed over a period of 12 weeks. Within a PaCO2 range from 19 to 96 mmHg the local response of CBF was linear in most of the regions measured. The absolute local CO2 reactivity (CO2-R) showed a positive correlation to ICBF at PaCO2 = 40 mmHg (ICBF40) with the regression line: absolute CO2-R = 0.02 ICBF40 + 0.22, r = 0.71 (p less than 0.01). Therefore relative ICBF change was calculated in relation to ICBF40 to make comparisons between the CO2 response of different measuring days and of different regions examined. No significant change in relative CO2-R was observed during the 12 weeks interval. Differences of relative CO2-R between investigated regions were insignificant. The uniformity of relative CO2 response might support the hypothesis of a direct effect of PaCO2 or pH on the vessel wall. For comparison of CBF, the individual determination of CBF40 and relative CO2-R would be necessary.
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PMID:Local vascular response to change in carbon dioxide tension. Long term observation in the cat's brain by means of the hydrogen clearance technique. 642 Sep 42

Cross-sectional analysis of CBF values was carried out among 668 volunteers and patients. Subjects were subdivided according to age, gender, and degree of cerebrovascular disease, ranging from healthy volunteers with or without risk factors for stroke to patients with multi-infarct dementia. Four-year longitudinal analysis was also carried out on 230 individuals from the original sample. Decrements in CBF values were evidenced by both cross-sectional and longitudinal analysis in relation to advancing age, progressive cerebrovascular disease, and dementia. Regional, age-related CBF declines in healthy volunteers were heterogeneous, possibly related to changes in levels of functional activity within different brain regions.
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PMID:Cerebral blood flow changes in benign aging and cerebrovascular disease. 653 61

Repeated CBF-measurements can be performed after inhalation or intravenous injection of 133Xe. After the development of a bicompartmental model by Obrist et al. in 1975 atraumatic CBF-measurements became widely used but there were still some difficulties concerning the sensitivity of different flow-indices towards CBF changes in normals under test conditions or ischemia in stroke patients. Due to the "slippage phenomenon" mostly noncompartmental flow-indices are used for the detection of ischemic brain areas. In this study a scintillation camera, that is usually available in every nuclear medicine department, was used for atraumatic CBF-studies. A collimator consisting of hexagonal lead tubes (septa 0.2 mm thick; FWHM 1.7 cm in 10 cm) was constructed for this purpose. The obtained counting rate varied between 2432 and 9081 cps over the whole hemisphere and 116-1094 cps in regions of approximately 2.5 X 2.5 cm. In 31 patients with CVD CBF was measured with the intracarotid (i.c.) technique and 1 hour later after i.v. 133Xe-injection. Intravenous flow values were comparable to those obtained after i.c. 133Xe injection (fB X MFr = 0.904; p less than 0.001). In 12 of the used 13 regions also significant correlation coefficients were found. In order to estimate the reproducibility of the intravenous injection method CBF-measurements were performed in both hemispheres of 10 patients on two consecutive days. Highly significant correlation coefficients were found for hemispheric blood flow (r = 0.933; p less than 0.001) and temporal, frontotemporal, temporoparietal and praecentral regions, while in the high parietal, frontal and occipital region lower reporducibility was found. Normal CBF-values were obtained from 12 healthy volunteers (MF right hemisphere: 50.7 +/- 4.6 ml/100 g/min; MF left hemisphere: 50.6 +/- 4.6 ml/100 g/min). MF did not show any hyperfrontality, while F1 and the ISI gave highest flow values in frontal regions. The clinical status of 76 patients suffering from cerebral ischemia (68 with flow disturbances in one hemisphere, 8 with vertebrobasilar insufficiency) was estimated by a semiquantitative scorescale at time of admission and after an observation period lasting from 6 to 35 months. In each case CBF was measured twice: once in the subacute stage after onset of symptoms and once after the observation period. The duration of neurologic symptoms (TIA, RIND, CS) was compared to the obtained flow values. A significant relationship was found between the duration of symptoms and impairment of CBF, thus showing the prognostic value of intravenous CBF measurements.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Noninvasive measurement of cerebrovascular circulation with the scintillation camera. A neurologic nuclear medicine study]. 659 71

Cerebral blood flow CBF was studied in 14 patients with transient ischemic attacks TIA and arteriosclerotic neck vessel disease. CBF was measured by a rapidly rotating single photon emission computerized tomograph using Xenon-133 inhalation. This method yields images of 3 brain slices depicting CBF with a spatial resolution of 1.7 cm. Based primarily on the clinical evidence and on the angiographical findings embolism was considered the pathogenetic factor in 10 cases, whereas chronic hemodynamic insufficiency rendered symptomatic by postural factors probably accounted for the symptoms in 4 patients. Of the 14 patients, all studied days to weeks after the most recent TIA, four showed hypoperfused areas on the CBF-tomograms and with roughly the same location hypodense areas on CT-scanning, i.e. areas of complete infarction. However, an additional five patients showed reduction of CBF in areas with no abnormality on the CT-scan. The abnormal blood flow pattern was found to be unchanged after clinically successful reconstructive vascular surgery. This suggests the presence of irreversible ischemic tissue damage without gross emollition (incomplete infarction). It is concluded, that TIAs are often harmful events, as no less than 9 of the 14 patients studied had evidence of complete and/or incomplete infarction. Thorough examination and rational therapy should be instituted as soon as possible to prevent further ischemic lesions.
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PMID:Regional cerebral blood flow in patients with transient ischemic attacks studied by Xenon-133 inhalation and emission tomography. 660 72


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