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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increasing evidence suggests that higher blood velocity, by causing turbulence and high shear rates at the endothelial surfaces of arteries, may be important in the pathogenesis of atherosclerosis. In order to measure the effects of antihypertensive agents on blood velocity, an improved method has been developed for analysis of Doppler ultrasound velocity recordings. The audio signal from a Doppler velocity meter is subjected to spectral analysis; the sonagraph thus obtained is digitized with the use of a magnetic table on-line with a calculator. Four monkeys were maintained at a hypertensive baseline for six weeks by infusion of angiotensin and isoproterenol. The effects on blood velocity of 72-hour infusions of propranolol, clonidine, hydralazine, and methyldopa were studied. In doses that reduced diastolic pressure by 13--28%, propranolol decreased mean blood velocity (mv) by 17%, clonidine decreased mv by 14%, while methyldopa increased mv 12%, and hydralazine increased mv by 52% (p less than .00001). Antihypertensive drugs appear to have different effects on blood velocity; these differences may influence choice of antihypertensive drugs for the prevention of arterial disease.
Stroke
PMID:Effects of antihypertensive drugs on blood velocity in rhesus monkeys. 41 Jan 22

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

Dye flow patterns were studied in 12 glass model bifurcations with angles of 45, 90, 135, and 180 degrees, and area ratios of 0.78, 1.03 and 1.27. At the apex, the dye formed a saddle zone, and streamlines from the core which entered this region were swept over the upper and lower surfaces to enter the lateral angles. Qualitatively, the shape and size of the apex played a key role in this effect. Boundary layer separation occurred in the lateral angles, and increased as flow into the branch was reduced. If the branch was occluded, a complex vortex developed in the first few diameters of the branch, and no flow occurred beyond this, even though the occlusion was about 20 diameters downstream. The results were comparable with steady and pulsatile flow. The implications of these results for the localization of atherosclerosis are discussed.
Stroke
PMID:Flow disturbances at the apex and lateral angles of a variety of bifurcation models and their role in development and manifestations of arterial disease. 46 23

Thirteen of 1,250 patients required a second operation for recurrent stenosis following carotid endarterectomy performed at the Cleveland Clinic between 1958 and 1978. Two other patients underwent reoperation because of recurrent stenosis following primary operations at other institutions. Thirteen of the 15 patients experienced neurologic symptoms caused by recurent stenosis, while two patients remained asymptomatic. Atherosclerosis was responsible for recurrent stenosis in 12 patients and appeared to be related to hypercholesterolemia. Three of the patients had myointimal fibroplasia. Eleven of the 16 reoperations for recurrent stenosis of the carotid artery consisted of carotid endarterectomy with vein patch angioplasty. Three patients had carotid endarterectomy with closure of the primary arteriotomy. One patient with occlusion of the internal carotid artery underwent endarterectomy of the external carotid artery because of amaurosis fugax, and a saphenous vein interposition graft was used to replace a previous Dacron graft in one patient with anastomotic stenosis. One patient had a stroke during reoperation manifest as multiple retinal emboli. Fourteen patients have remained asymptomatic from one to 70 months following reoperation. One patient with occlusion of the contralateral internal carotid artery has experienced persistent vertebrobasilar symptoms.
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PMID:Recurrent stenosis after carotid endarterectomy. 47 95

Evidence of cerebrovascular disease at autopsy was compared in 2 groups of men: 186 long-time residents of Hiroshima, Japan, and 253 men of Japanese ancestry long resident in Honolulu, Hawaii. They were 45 to 71 years-of-age at death. Atherosclerosis of the circle of Willis and its major branches, sclerosis of the intraparenchymal arteries and the frequency of cerebral hemorrhage and cerebral infarct were compared in the 2 populations. The Honolulu subjects had significantly more atherosclerosis of the circle of Willis, but less intraparenchymal artery sclerosis and less cerebral infarction. Cerebral hemorrhage was equally frequent in the 2 cities. It was concluded that cerebral infarction is more frequent in Japanese men in Hiroshima than Honolulu, and that men of Japanese ancestry in Honolulu are spared an appreciable risk of cerebral infarction through decreased frequency of intraparenchymal arterial sclerosis despite higher levels of atherosclerosis of large intracranial arteries.
Stroke
PMID:Autopsy study of cerebrovascular disease in Japanese men who lived in Hiroshima, Japan, and Honolulu, Hawaii. 50 76

Thirty-nine thrombosed arterial segments of the branches of the circle of Willis were studied by a complete serial section technique. Twenty-two patients had been hypertensive and 8 had hypercholesterolemia before the onset of cerebral artery thrombosis. The histological characteristics of the thrombosed arterial segments were intramural hemorrhage in 28 segments, superficial edema of the fibrous cap of the atheroma of fibrous plaque in 4, rupture of the atheromatous plaque in 1, superficial accumulation of foam cells in the atheroma in 1 and an atheroma or fibrous plaque without any other changes in 5. They were many intramural small blood vessels in the atheroma or fibrous plaques of 22 segments with intramural hemorrhage. Fibrinoid degeneration of these small blood vessels was noted in 5. These findings suggested that intramural hemorrhage from the intramural small blood vessels was the major cause of cerebral artery thrombosis and that persistent hypertension not only promoted cerebral atherosclerosis but also induced hemorrhage from the intramural small blood vessels.
Stroke
PMID:Cerebral artery thrombosis and intramural hemorrhage. 50 77

One hundred seventeen patients, 31 with TIA and 86 with cerebral infarction, had angiographically verified atherosclerosis within the relevant carotid artery territory and normal CSF. They were treated with anticoagulants for a mean of 11.1 months. No TIA but 1 cerebral infarction, appearing during inadequate anticoagulant therapy, was registered. Seventy-six of the patients, 20 with TIA and 56 with infarction, were followed for a mean of 4.4 months after cessation of anticoagulants or during inadequate antinecessitating re-institution of anticoagulant therapy. Long-term, anticoagulant treatment can be recommended in carefully selected patients with TIA, and also with infarction in the carotid territory.
Stroke
PMID:Prognosis in patients with infarction and TIA in carotid territory during and after anticoagulant therapy. 50 92

Ischemic optic neuropathy and retinal arterial occlusion are 2 forms of arterial occlusive disease affecting the eye. Reports in the literature suggest platelet hyperactivity in acute arterial occlusive diseases affecting other organ systems. Therefore, 14 patients with ischemic optic neuropathy and 17 patients with central or branch retinal artery occlusion were studied to determine whether platelets have a role in the pathogenesis of these vascular occlusive disorders. The results of the following investigations were no different in these patients compared with those in 18 control patients with non-vascular eye diseases: prothrombin times, partial thromboplastin times, plasma fibrinogen, factor V, factor VIII, platelet counts and threshold concentrations of ADP, epinephrine and collagen resulting in secondary platelet aggregation and serotonin release. In contrast, platelet coagulant activities concerned with the early stages of intrinsic coagulation were significantly increased in patients with retinal artery occlusion without hypertension or type IV hyperlipoproteinemia, but generally normal in patients with ischemic optic neuropathy and in patients with retinal artery occlusion associated with hypertension, type IV hyperlipoproteinemia, diabetes mellitus and generalized atherosclerosis. These results are consistent with a platelet contribution to retinal arterial occlusive disease in patients without other known contributing factors such as hypertension, serum lipid abnormalities, diabetes mellitus and generalized atherosclerosis and may have implications regarding prophylaxis.
Stroke
PMID:Platelet coagulant activities in arterial occlusive disease of the eye. 50 1

Study of the blood platelet functional activity and intensity of hemolysis in 41 patients with transient disorders of cerebral circulation and comparison of the results with the corresponding indices in healthy individuals, in 40 patients with hypertensive disease free of crisis, and in 25 patients with cerebral atherosclerosis led to the conclusion that the character of cerebral stroke is already determined in the pre-stroke period. It depends on the functional state of the blood platelets in many respects. In patients with hypertensive disease in a period clear of crisis, for instance, there is a tendency towards hypoaggregation possible associated with the presence of latent hemolysis. Platelet hypofunction progresses in the period of hypertensive encephalopathy and still more during its transformation into hemorrhagic stroke. On the contrary, in patients with atherosclerosis but no symptoms of cerebral ischemia the adhesion-aggregation activity of the platelets does not differ essentially from that in healthy individuals. With the development of signs of ischemia of the brain, the platelet activity grows considerably, particularly when transient cerebral circulatory disorders transform into ischemic stroke.
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PMID:[Importance of the thrombocytes and hemolytic syndrome in the pathogenesis of transient cerebral circulatory disorders in hypertension patients]. 63 13


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