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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mortality and cerebral glycolytic metabolism were studied after bilateral ligation of the common carotid artery in normotensive Wistar rats (NTR), and spontaneously hypertensive rats (SHR) derived from Wistar strain. In the first 24 hours after occlusion of carotid arteries, 72 per cent of 108 SHR died, whereas it was fatal in only 16 per cent of 43 NTR. In SHR, cerebral lactate and cerebral lactate/pyruvate ratio (L/P ratio) increased by 12.4 and 12.1 times the control, respectively at five to six hours after ligation, and remained raised even in rats surviving for two to three days thereafter. Changes in cerebral lactate and L/P ratio were minimal in NTR. Cerebral ATP decreased markedly at five to six hours after ligation in SHR studied. These results indicate that bilateral carotid artery ligation causes severe brain damage in SHR but not in NTR, suggesting hypertension per se to be operative for the development of cerebral ischaemia.
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PMID:Mortality and cerebral metabolism after bilateral carotid artery ligation in normotensive and spontaneously hypertensive rats. 0 30

The effects of bilateral common carotid artery occlusion on brain metabolism and arterial acid-base balance were studied in normotensive and experimental renovascular hypertensive rats. One hour after carotid occlusion in hypertensive rats, supratentorial lactate increased to 383% and lactate-pyruvate ratio to 280% of the controls, while adenosine triphosphate (ATP) decreased to 69%. These metabolic changes were thought to be due to cerebral ischemia. Arterial pCO2 was lowered and the pH was raised in the hypertensive animals due to cerebral ischemia induced hyperventilation. In the normotensive rats, carotid occlusion had minimal effects on cerebral metabolism and arterial acid-base balance. These results suggest that hypertensive rats are more susceptible to cerebral ischemia caused by carotid occlusion than normotensive rats. Increased cerebrovascular resistance in hypertension is discussed as a causal factor in cerebral ischemia.
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PMID:Brain metabolism and arterial acid-base balance following bilateral carotid occlusion in normotensive and experimental hypertensive rats. 2 5

Cerebral ischemia of 15 min was produced in rats by increasing intracranial pressure above the systolic blood pressure level by infusing artificial cerebrospinal fluid into the cisterna magna. Pulmonary edema was prevented by blocking the vasomotor response with a ganglioplegic agent, and reducing the fluid load by peritoneal dialysis. The EEG flattened after 10.1 +/- 1.5 sec. followed by a dilatation of the pupils after 1--2 min. The EEG began to recover in 21 of 32 rats after 8 to 35 min of recirculation. Spectral analysis revealed an initial return of slow waves and spindles followed by continuous fast frequency activity. The EEG did not recover or was secondarily suppressed in 12 animals after a few hours. Electrophysiological recovery depended on the cardiocirculatory and respiratory state, the recovery being optimal in animals with mild hypertension and a normal acid-base status of the blood.
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PMID:Electrophysiological recovery after compression ischemia of the rat brain. 7 50

Many authors have postulated that angulation of the carotid artery is a cause of stroke and recommend corrective operation. Symptoms attributed to such lesions are often nebulous and unrelieved by the operation, and proof is lacking that unselected patients who have this condition have a risk of stroke exceeding operative risk. A review of 282 cerebral angiograms showed an incidence of elongation and potential angulation of 43 percent in children and 20 percent in adults. Acutal angulation was not found in children, however, and no child was suspected of having cerebral ischemia. Of 47 adults with potential angulation, 17 were suspected of having cerebral ischemia, the remainder having a variety of other lesions, such as tumors, aneurysm, and intracranial hemorrhage. Of the 17 having suspected cerebral ischemia, all had alternative explanations for their symptoms (hypertension, intracranial atherosclerosis), except one whose symptoms were completely inappropriate to the carotid distribution. A single patient had a completed stroke, demonstrable angulation, and only mild hypertension. Elongation and potential angulation of the carotid artery is common but usually coexists with other lesions. If the finding is postulated as the cause for neurologic morbidity the surgeon must be assured that symptoms are clearly neurologic, that no other cause exists, that angulation reduces the carotid lumen significantly and reproduces symptoms, and that the risk of operation is less than the expected risk of stroke in untreated patients.
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PMID:The significance of elongation and angulation of the carotid artery: a negative view. 16 14

The number of patients with cerebral infarctions increases as the population ages, despite campaigns against hypertension, the greatest risk factor. Cerebral ischemia initiates events that are presumed to defer the stage of irreversible injury. These events cause an increase of perfusion around the central ischemic zone and trigger the Bohr effect, both of which preserve tissue viability. Almost simultaneously, mitochondrial function fails, resulting in insufficient energy for the enzyme systems to control Na and K ion equilibrium. At the same time, protein synthesis slows and cellular respiratory enzymes decrease their activity, initiating an irreversible state of tissue change. Tissue fatty acids increase as a result of dissolution of cell membrane lipoprotein structure. Barbiturates reduce the extent of experimental infarction. Resperine and aminophylline are also effective, but there are no corroborative clinical trials. That ischemic brain damage may be the result of toxic substances in the ischemic tissue represents a new concept.
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PMID:Survival of the ischemic brain: a progress report. 22 19

Of 26,294 consecutive patients monitored in a comprehensive drug surveillance program, 1067 (4 per cent) received methyldopa for treatment of hypertension. Adverse reactions attributed to methyldopa were reported in 149 patients (14 per cent), the most frequent being hypotension. Life-threatening adverse effects were reported in nine patients (6 per cent of reactors)--the major problems being hypotension associated in several patients with signs of cardiac or cerebral ischemia. Hypotension attributed to methyldopa was more frequent in younger patients, in those with uremia, in lighter subjects, and in those receiving a high daily dose. Marked interaction between these factors was demonstrated and eightfold differences in the frequency of hypotension were observed in different sub-groups of methyldopa recipients. Adverse effects other than hypotension were reported infrequently and did not correlate well with the previously mentioned factors. The findings suggest that methyldopa therapy should be commenced cautiously in younger patients, in the non-obese, and in those with impairment of renal function as manifest by elevated blood urea nitrogen levels.
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PMID:Adverse reactions to methyldopa with particular reference to hypotension. 26 90

Time-compressed Fourier analysis of the electroencephalogram has proven to be a useful analytical procedure during anesthesia and surgery which simplifies data interpretation by presenting the EEG in a time-compressed frequency domain rather than the conventional time domain. This method of data analysis graphically accentuates the electroencephalographic correlates of ischemia-induced cerebral dysfunction and other cerebral oxygen consumption abnormalities. The ability to accentuate trends in frequency and power is derived from sequential plotting of spectra to produce a graph with three dimensional axes of frequency, time, and power. In carotid endarterectomies the system has proven more useful than the conventional EEG in assessing the need for a vascular shunt to maintain internal carotid flow during endarterectomy. In open-heart surgery time-compressed EEG spectral analysis has allowed early recognition of cerebral ischemia resulting from arterial hypotension and venous hypertension. Five cases are presented which demonstrate the ability of our system to reflect developing cerebral ischemia.
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PMID:Monitoring of cerebral perfusion during anesthesia by time-compressed Fourier analysis of the electroencephalogram. 32 37

The presented work is founded on the analysis of the results of the surgical treatment of 43 patients with combined injuries to the brachycephalic and renal arteries, manifested clinically as syndromes of cerebral ischemia and vasorenal hypertension. 50 operations were carried out upon 43 patients. 45 of these 50 operations were reconstructive ones. 6 patients were subjected to several-stages operations both upon the brachycephalic and renal arteries. 80% of the patients showed good long-term results. An active surgical tactics allowed to diminish dramatically the percentage of nephrectomy in non-specific aorto-arteritis.
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PMID:[Principles of the surgical treatment of combined lesions of the brachiocephalic and renal arteries in nonspecific aorto-arteritis]. 37 72

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

The effects of antihypertensive treatment on brain metabolism after bilateral carotid occlusion were studied in spontaneously hypertensive rats. The results indicate that an increase in metabolites of ischaemic brain such as lactate and the lactate/pyruvate ratio after carotid occlusion in spontaneously hypertensive rats is apparently suppressed by treating hypertension. This suggests that hypertension may play an important role in susceptibility to cerebral ischaemia.
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PMID:Effects of long-term antihypertensive treatment on brain metabolism after bilateral carotid artery occlusion in spontaneously hypertensive rats. 53 53


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