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 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of induced hypocapnia, hypothermia, and hypertension were surveyed in a primate model of acute stroke during and following a 48-hour period of intensive care. The results were compared to a group of nine control animals previously studied. Hypocapnia (PaCO2=25 torr) was examined in five animals and did not appear to alter the expected mortality, degree of neurological deficit, or frequency of infarction. There was, however, a suggestion that the size of infarction may be reduced. Hypothermia (29 degrees C) in five animals had a detrimental effect in that no animals survived following the intensive care period and all had infarction with massive edema. We speculate that hypothermia caused a sufficient increase in blood viscosity as to compromise collateral flow, thereby accounting for this detrimental effect. Induced hypertension (to 20% above control levels) was abandoned after three animals because of severe systemic effects (cardiac failure and pulmonary edema) resulting in death during the period of intensive care.
Stroke
PMID:Failure of prolonged hypocapnia, hypothermia, or hypertension to favorably alter acute stroke in primates. 40 43

White and regional gray matter distributions of water, blood flow, and the protein tracer pertechnetate were measured in five normal squirrel monkeys. A second group of five monkeys, which had undergone unilateral nephrectomy six months previously, were found at the time of study to have blood pressures similar to those of the control animals but increased brain water and altered distribution of blood flow which was increased in white matter. No alteration of capillary permeability to the protein traces attended these changes, which appeared to be influenced by blood pressure. Nephrectomy without hypertension influences brain water content, perhaps because of an effect on cerebral resistance vessels. In hypertensive encephalopathy renal lesions, as well as intraluminal pressure changes, may be related to cerebral edema.
Stroke
PMID:Brain water alterations after unilateral nephrectomy. A study of regional circulatory factors in squirrel monkeys. 40 49

Stroke is increasingly becoming a major cause of death and morbidity in African population among most of which the frequencies of hypertension are considerable, although hard data based on community surveys are lacking and most of the information available is from hospital data. The epidemiology of stroke in the Africans is reviewed. The frequencies in hospital populations varied from 0.9% to 4.0% and stroke accounted for 0.5% to 45% of neurological admissions. There is male predominance in published series. The main risk factors are hypertension, diabetes mellitus and homozygous sickle cell disease (in children only). Ischaemic stroke is by far the commonest clinical type encountered. These conclusions are further supported by experience at Ibadan, of over 1100 Africans seen over 18 years reported briefly in this communication. The results of the first community study over a 2-year period on the incidence of stroke in an African Urban (Ibadan) Community are presented. The study was carried out as part of a multinational multicentric study initiated and sponsored by the World Health Organization. The male to female ratio was five to two. Incidence rates reached peaks in the eighth decade in males and in seventh decade in females and were higher in males in all age groups, and the rates are comparable with those recorded in European populations, except in those under the age of 40 in Ibadan, in which age-specific incidence rates are considerably lower than in European and Japanese populations. Hypertension, diabetes mellitus constituted the main risk factors. Mortality and recurrence rates are described and are similar to experience in the Caucasians. Hypertension in the Nigerians predispose to a high frequency of cerebrovascular disease other than through mainly cerebral atherosclerosis. With increasing longevity of Nigerians and other Africans, the mortality and morbidity caused by cerebrovascular disease would probably become of enormous dimensions and adequate control of high blood pressure on a community basis may be the only way of preventing this: this would be desirable as myocardial infarction in contradistinction to hypertensive heart disease is an uncommon complication of high blood pressure in the Africans and prevention of hypertensive heart disease as shown by experience elsewhere can be achieved by control of high blood pressure, which does not seem to prevent ischaemic myocardial disease.
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PMID:Stroke in the Africans. 41 66

In 64 patients with ischemic strokes that occurred on the background of atherosclerosis (33) and a combination of atherosclerosis with arterial hypertension (31) using the dilution method of Evans's blue the authors studied indices of general hemodynamics compared to rheoencephalographic data. Twenty similar patients without signs of brain circulation disturbances and 20 healthy persons were taken as control groups. In 69% of the patients with ischemic strokes deep disturbances of general hemodynamics were observed. An increase of tonus, a decrease of elasticity of cerebral vessels and deficit of pulse blood repletion were determined rheoencephalographically. Insufficiency of general hemodynamics in conditions of changed autoregulation of brain circulation promotes development of ischemic disorders of brain circulation and unfavourably influences the course and outcome of the stroke.
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PMID:[State of general and cerebral hemodynamics in patients with ischemic strokes]. 42 64

No permanent neurologic deficit results from a transient ischemic attack, but patients with these episodes are at risk of stroke. Successful treatment depends on identifying the source of the problem--the heart, blood, or vessel wall. However, anticoagulants and antiplatelet agglutinating agents will reduce only the incidence of TIA's, not the incidence of stroke. Prompt vigorous treatment of progressive stroke may avert completed stroke. Heparin is recommended, unless a specific etiologic factor, such as polycythemia or hypertension, is identified.
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PMID:Current concepts in managing TIAs and stroke. 44 70

Regional cerebral blood flow (rCBF) was measured by 133Xe inhalation in 46 normal volunteers, aged 21 to 63 years, and 14 neurologically asymptomatic subjects above age 40 with risk factors for atherothrombotic stroke, including hypertension, diabetes mellitus, and hyperlipidemia. In normal volunteers, there was diffuse and progresive reduction of gray matter flow and weight as well as increases of cerebrovascular resistance (CVR) with advancing age. Reduction of gray matter flow with advancing age appears to be attributed in part to neuronal atrophy and in part to cerebral arteriosclerosis. Regional increases of CVR and reduction of gray matter flow with advancing age were most evident in the middle cerebral arterial (MCA) distribution and were enhanced by the association of risk factors. Development of cerebral arteriosclerosis with age and/or risk factors appears to be most evident in MCA distribution.
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PMID:Effects of advancing age on regional cerebral blood flow. Studies in normal subjects and subjects with risk factors for atherothrombotic stroke. 45 46

Hypertension was produced in 8 cats by nephrectomy and wrapping the opposite kidney. Subsequent occlusion of one middle cerebral artery caused ischemic infarcts that were larger than those of 8 normotensive cats. The larger infarcts may have been caused by increases of ischemic cerebral edema resulting from changes in the cerebral endothelial barrier induced by hypertension. In addition to increasing the likelihood of strokes, hypertension in humans may predispose toward larger cerebral infarcts.
Stroke
PMID:Hypertension and acute focal cerebral ischemia. Infarction and edema after occlusion of a middle cerebral artery in cats. 46 12

In ten hypertensive late pregnant women with passing crises of hypertension cardiovascular analysis with the method of quantitative sphygmometry, the unbloody recording of the blood pressure and the direct electronic measuring of the pulse wave velocity were made before and after the intravenous injection of 300 mg Diazoxid (Hypertonalum). This drug is recommended to the treatment of severe preeclampsia and eclampsia because of lessening the arterial blood pressure and the total peripheral resistance, increasing the heart rate, stroke volume and cardiac output.
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PMID:[The haemodynamic principle of action of diazoxide (hypertonalum) in the treatment of acute hypertensive crises in late pregnant women (author's transl)]. 46 55

The handling of patients with cerebral ischemia is reviewed, taking into consideration recent concepts regarding etiopathogenesis along with new diagnostic and therapeutic methods. A particularly important new diagnostic method is computerized axial tomography. The subject is divided into four sections in order to present a practical outline. The first section deals with the arterial circulatory system. Evaluation of patients with arteriosclerosis of the vessels in the neck and/or intracranial are reviewed in some detail, according to whether the clinical manifestation was transitory ischemia, progressive cerebral infarction, or complete cerebral infarction. Emphasis is placed on the proper selection of diagnostic tests and application of therapy in each case. The second part is a discussion of the changes in arterial blood pressure in the etipathogenesis of stroke. Arterial hypertension is an important factor in production of small infarctions. In the third section a review is made of the role of the heart in transitory ischemia and as a cause of cerebral infarctions. Lastly, the hematologic factors which might contribute to the development of cerebral ischemia, along with the other causes, are mentioned.
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PMID:[Practical considerations in dealing with cerebral ischemia (author's transl)]. 47 Apr 90

In two experimental models of established hypertension in the rat (two kidney, one clip renal and genetic hypertension), the maximum by which stroke volume and cardiac output could be increased during an acute preload stress was significantly reduced despite the concomitant development of left ventricular hypertrophy. Reversal of cardiac hypertrophy by prolonged treatment with methyldopa (range 3 to 6 weeks) during the established phase of spontaneous hypertension normalized arterial blood pressure and improved ventricular pumping ability. The improved performance was in part due to reduced impedance to ventricular ejection because it did not persist when peripheral resistance was increased by an acute administration of phenylephrine hydrochloride. Thus, hemodynamic as well as structural factors contribute to alterations in cardiac function during the chronic established phase of arterial hypertension.
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PMID:Cardiac pumping ability in rats with experimental renal and genetic hypertension. 49 96


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