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

The authors measured regional cerebral 133xenon (133Xe) blood flow (rCBF), intraventricular pressure (IVP), cerebrospinal fluid (CSF) pH and lactate, systemic arterial blood pressure (SAP), and arterial blood gases during the acute phase in 23 comatose patients with severe head injuries. The IVP was kept below 45 mm Hg. The rCBF was measured repeatedly, and the response to induced hypertension and hyperventilation was tested. Most patients had reduced rCBF. No correlation was found between average CBF and clinical condition, and neither global nor regional ischemia contributed significantly to the reduced brain function. No correlation was found between CBF and IVP or CBF and cerebral perfusion pressure (CPP). The CSF lactate was elevated significantly in patients with brain-stem lesions, but not in patients with "pure" cortical lesiosn. The 133Xe clearance curves from areas of severe cortical lesions had very fast initial components called tissue peaks. The tissue peak areas correlated with areas of early veins in the angiograms, indicating a state of relative hyperemia, referred to as tissue-peak hyperemia. Tissue-peak hyperemia was found in all patients with cortical laceration or severe contusion but not in patients with brain-stem lesions without such cortical lesions. The peaks increased in number during clinical deterioration and disappeared during improvement. They could be provoked by induced hypertension and disappeared during hyperventilation. The changes in the tissue-peak areas appeared to be related to the clinical course of the cortical lesion.
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PMID:Dynamic changes in regional CBF, intraventricular pressure, CSF pH and lactate levels during the acute phase of head injury. 0 73

The middle cerebral artery (MCA) of cats was occluded permanently for 24h to study the influence of arterial hypertension during the early phase of focal ischemia upon the development of endema and changes of the blood-brain barrier (BBB). In normotensive animals MCA occlusion results in a hemispheric weight increase of about 8% and marked water and electrolyte alterations in both the grey and white matter of the MCA territory. The RISA space increases mainly in the grey matter. Hypertension aggravates these changes significantly, whereby water and electrolyte changes in the grey matter are predominantly concerned, while there is a preferential increase of the RISA space in the white matter. It is suggested that arterial hypertension aggravates the ischemic edema and enhances a vasogenic type of edema in the white matter.
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PMID:The effect of arterial hypertension of focal ischemic edema. An experimental study. 8 57

The blood flow through the anterior wall of the left ventricle has been studied during electrical stimulation of the left stellate ganglion of anesthetized dogs. The flow was continuously monitored by heated cross-thermocuple. Ganglion stimulation caused a significant increase in the flow through the outer half while producing relative ischemia of the inner half of the wall. Pretreatment with propranolol reduced regional difference of flow changes. Significantly augmented non-uniform flow changes, however, were produced by ganglion stimulation during hypertension caused by aortic constriction or by methoxamine. The results indicate non-uniform blood flow distribution which can be produced by sympathetic nerve excitation.
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PMID:Non-uniform myocardial blood flow caused by stellate ganglion stimulation. 12 85

Abdominal aortic aneurysmectomy is being performed with progressively lower operative mortality and morbidity. Three hundred thirty seven patients have had elective aneurysm repair since 1954. Factors affecting mortality and morbidity in the last 108 cases are analyzed. Seventy-four per cent of patients had pre-existing disease, either cardiac, pulmonary, renal, cerebrovascular, diabetes mellitus, or hypertension. Six patients died following operation, a mortality rate of 5.5%. One died of pulmonary and 5 of cardiac causes. No patient died of renal failure or required dialysis. A signficant feature of management is the regimen of fluid therapy using dextrose in lactated Ringer's solution during and after operation to minimize hypotensive and renal complications. No patient developed a wound infection, graft infection, wound dehiscence, stroke, or intestinal ischemia. Serious postoperative complications were largely cardiac or pulmonary. Despite recent liberalization of indications for operation, comparative figures show continued reduction in operative mortality from 17% during 1954-1961, or 7.4% during 1962-1967, to 5.5% in the 1968-1974 era. This declining mortality is related to earlier diagnosis using non-invasive methods (sonogram), simplified operative techniques, improvement in fluid management, innovations in cardiopulmonary therapy, and recognition and proper handling of unusual manifestations of aortic aneurysms.
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PMID:Surgical management of abdominal aortic aneurysms: factors influencing mortality and morbidity--a 20-year experience. 12 60

Histologic evidence of intrarenal vasomotor changes were observed in the rat in the course of acute renal failure caused by the injection of HgCl2. Male Wistar rats injected s.c. with 2.5 or 4.7 mg HgCl2 per kg b. wt. developed fibrinoid damage in the media segments of preglomerular renal vessels, mostly in the arcuate and interlobular arteries. The lesions were patchy and irregularly scattered throughout the kidneys. 24 h post-injection the lesions were very rare and of only mild degree, whereas they were fully developed and regularly seen 48 h post-injection. A high percentage of similar changes was found in certain extrarenal vascular areas especially in the mesentery and pancreas. The damaged vascular segments were usually dilated. The results of various thichrome stains and histochemical reactions suggested edema of vascular smooth muscle cells and imbibition of the media by blood plasma substances, sometimes reaching the degree of fibrinoid necrosis. These findings were confirmed by electron microscopy. The imbibition of the smooth muscle cells by blood plasma material was clearly evidenced by the demonstration of intracellular fibrin precipitations. In connection with the degeneration of smooth muscle cells, accumulations of crystal-like fibrin formations could often be shown. Subendothelial fibrin formations were not observed. 96 h after the 2.5 mg injection the changes were already regressing, but edema of the vascular wall and signs of disturbed vasotonia persisted for several days. The maximum of the vascular changes usually coincided with the maximum of azotemia and the formation of debris cylinders in the renal tubules. However, no clear relationship was recognizable in individual cases between vascular damage, extent of tubular necrosis and renal function. The pathogenesis of the vascular changes is obscure, but neurogenic factors, increased release of catecholamines and/or vasoactive agents of renal origin in connection with other factors might play a decisive role. Arterial hypertension was absent. It is assumed that the structural damage of the vascular media is mainly brought about by prolonged or recurring vasospasms, or by alternating spasm and vasodilatation with local ischemia and increased tension of the vascular wall in the dilated segments. The altered function and structure of the vascular wall might, to a certain extent, contribute to renal insufficiency.
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PMID:Intra- and extrarenal vascular changes in the acute renal failure of the rat caused by mercury chloride. 13 13

Uncontrolled hypertension increases the workload of the left ventricle causing the development of hypertrophy and an increase in myocardial oxygen consumption that may precipitate ischemia because of inadequate oxygen delivery related to accelerated coronary atherosclerosis. Control of the hypertension should prevent the further development of hypertrophy, delay the development of fibrosis and possibly also slow the rate of development of atherosclerosis. Furthermore, when myocardial function is impaired because of hypertrophy or other myocardial diseases, the level of blood pressure becomes an important determinant of left ventricular performance. Regardless of the level of arterial pressure, vasodilator drugs that lower arterial pressure may result in marked improvement in left ventricular performance and relief of symptoms of left ventricular failure. Therefore, control of blood pressure in the presence of heart disease may involve treatment of normotensive patients to bring them into a lower normotensive range as well as the more traditional treatment of hypertensives to bring them into the normotensive range. Although this scenario is consistent with conventional wisdom and clinical experience, intricacies of the relationship between hypertension, hypertrophy, myocardial oxygen delivery, atherosclerosis and intramyocardial blood flow distribution remain poorly understood. Until these aspects of the natural history of heart disease are better worked out therapy will remain largely empirical.
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PMID:Heart disease in the hypertensive patient. 14 Feb 80

Sixty-two autopsied hearts, with left ventricular hypertrophy (LVH) caused by mitral regurgitation (MR), aortic failure (AR), combined valvular disease (CVD), hypertension (HHD), or ischemia (IHD), and 23 control hearts with normal left ventricles were studied morphologically for analysis of modes of hypertrophy and for ECG-pathology correlation. Basic disorders modify the mode of hypertrophy; that is, elongated AR-type LV makes muscle fiber orientation in the outer layer more vertical, and globular MR-type LV makes it more horizontal than normal. High-voltage QRS correlates with hypertrophy of the outer layer which is often associated with that of the inner layer. ST depression and T changes correspond to relative deterioration of the inner and median layers, respectively.
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PMID:Histopathological study of hypertrophied myocardium of known etiologies with special reference to correlation of ECG changes. 14 36

Fibromuscular dysplasia of renal arteries was the cause of hypertension in four consecutive children with renal artery stenosis. Two were asymptomatic, the third had had hypertension for seven years but had not been treated, and the fourth, a 9-month-old infant, presented with cardiac failure. Heart enlargement and left ventricular hypertrophy were present in all. Rapid sequence urograms demonstrated a smaller kidney and delayed appearance and disappearance of the contrast medium on the affected side in all. Angiograms showed left RAS in all. Peripheral plasma renin activity was elevated in only three of the four patients. Antihypertensive and diuretic drugs were not very effective therapeutically. Ischemia of the ipsilateral kidney probably prevented normal growth and led to shrinkage of the kidney in one patient. Following nephrectomy the BP has remained normal without any therapy for 24 to 64 months. With normalization of BP, accelerated growth ensued, the cardiomegaly regressed and the hypertensive retinopathy resolved. These patients demonstrate that: (1) FMD is an important cause of RAS. (2) the well-known radiologic feature of FMD, the beaded appearance, is usually not seen in children. (3) control of BP leads to normalization of linear growth, usually impaired in severe hypertension, and (4) target organ complications such as cardiomegaly, LVH, and hypertensive retinopathy are reversible in one to 10 months.
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PMID:Fibromuscular dysplasia of renal arteries: an important cause of renovascular hypertension in children. 15 54

Hypertension during pregnancy and its complications are the most important cause of maternal and foetal death and morbidity. The chronic primary hypertension can be differentiated from the dysgravidia by anamnestic, biological, clinical and technical investigations. However the diagnosis remains difficult and the renal needle biopsy can help to ascertain it. The pathogenesis of dysgravidia is still obscure: the placental ischemia leads to a slow disseminated intravascular coagulation state with renal injury, while a vascular hyperreactivity leads to an increase of the resistance, a relative hypovolemia and lowering of cardiac output. The treatment and remote prognosis of the hypertensive disease associated with the pregnancy are summarized. The antihypertensive drugs improve the maternal prognosis while jeopardize the foetal outcome.
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PMID:[Hypertension and pregnancy]. 30 56

71 patients undergo myocardial revascularisation for Prinzmetal's angina; among them, 50 p. cent are operated upon in emergency according to three ways of anaesthesia: neuroleptanalgesia, analgesic anaesthesia, combined anaesthesia. The authors lay stress on the importance of per- and post-operative complications: electrocardiographic ischemia in 22 p. cent of the cases, severe ventricular excitability perturbations were observed in 21 p. cent, myocardial necrosis in 14 p. cent, cardiovascular collapse in 21 p. cent and hypertensions in 22 p cent. These complications are often associated. In the discussion, the authors underline anesthetic induction as a cause of Prinzmetal's angina in 50 p. cent of the cases. They put the accent on the severity of peroperative crisis followed in 50 p. cent of the cases by serious ventricular excitability perturbations. In 25 p. cent of the cases myocardial necrosis is a complication of the spasm of a coronary artery. In this field, posterior necrosis are more frequent and correspond to the spasm of the right coronary artery. All the patients of this series, except one, develop necrosis in the spastic area (by-passed or not). Per-operative hypertension has no incidence on the occurrence of post-operative complications. Lastly, continuous per-operative infusions of nitroglycerine has been performed in several patients in order to reduce morbidity of this type of surgery.
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PMID:[Prinzmetal's angina during myocardial revascularisation. Cardiovascular complications in 71 patients (author's transl)]. 31 82


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