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At least 19 recordsLinked to original sources
PubMed1989

Renovascular hypertension: etiology and pathophysiology.

Evidence from animal studies demonstrates that the renin-angiotensin (ANG II) system and sodium retention play major roles in experimental renovascular hypertension (RVH). Two basic models have been described. In the first, one-clip two-kidney Goldblatt hypertension, the ischemic kidney secretes renin, which leads to increased ANG II formation and hence elevation of blood pressure (BP). As BP rises, sodium excretion by the intact contralateral kidney increases (pressure natriuresis); therefore, there is no sodium retention. In the second, one-clip one-kidney Goldblatt hypertension, the contralateral kidney is removed. In this case the pressure natriuresis can no longer occur, and sodium retention occurs. The ensuing expansion of plasma volume inhibits renin secretion, so that in this model the renin level is normal or low. Following the clipping of the renal artery, renal blood flow and pressure are maintained distal to the stenosis by an ANG II-mediated vasoconstriction. This acts preferentially on the efferent glomerular arterioles, so that the ratio of preglomerular to postglomerular resistance is reduced, which helps to maintain glomerular filtration despite the reduced renal perfusion pressure. In the contralateral kidney the afferent arteriolar resistance is increased, probably as a direct result of exposure to the higher intrarenal arterial pressure. ANG II constricts the efferent arterioles in the same way as in the ischemic kidney, so that the ratio of preglomerular to postglomerular resistance is unchanged. When an angiotensin converting enzyme (ACE) inhibitor is given, the efferent arterioles vasodilate. In the ischemic kidney this may produce a reduction of glomerular filtration rate (GFR), which is not seen in the contralateral kidney. Unilateral RVH in humans corresponds closely to the animal model of one-clip two-kidney hypertension. Plasma renin activity is usually high, and converting enzyme inhibitors lower BP effectively. The increased renin is due exclusively to increased secretion of renin by the ischemic kidney, and is completely suppressed in the contralateral kidney. It is not clear whether bilateral RVH corresponds to the one-clip one-kidney model, but there is circumstantial evidence to suggest that both renin and volume factors may be involved. The majority of cases of human RVH are caused by atheroma, which is commonly bilateral, or by fibromuscular dysplasia. The former tends to be associated with atheroma elsewhere in the arterial tree, and often progresses to complete occlusion and renal failure. The latter occurs in younger patients, and almost never progresses to complete occlusion.

Animals↗
PubMed1990

Aldosterone-producing tumors (Conn's syndrome).

Adenomas of the adrenal cortex which produce aldosterone (APA) are among the surgically correctible causes of hypertension accounting for 0.5 to 1.0% of all hypertensive etiologies. The adenomas have a 5:1 predilection for women and generally present with hypertension or profound hypokalemia. A low plasma renin activity completes the triad for primary hyperaldosteronism which could be caused by adrenocortical cancer, a neoplasm with an average diameter of 12 cm, or idiopathic hyperaldosteronism (IHA), a bilateral hyperplasia of the zona glomerulosa of the adrenal cortex which responds poorly to surgical resection. The adenomas are small (2 cm) but can be localized by imaging or selective venous sampling. Resection has a high success rate with minimal morbidity.

Adenoma↗
PubMed1989

Chronic cor pulmonale.

Chronic cor pulmonale is defined as right heart hypertrophy and/or chronic right heart failure. There are many etiologies, but the common cause is increased right heart work from pulmonary hypertension. Etiology can be conveniently discussed by assuming two prototypes, the asphyxial or hypoxic type and the vascular obliterative type. A common cause of the asphyxial type is chronic obstructive pulmonary disease, and the obliterative type is represented by chronic pulmonary thromboembolic disease or primary pulmonary hypertension. Pathology is discussed, emphasizing the cardiac manifestations of chronic cor pulmonale including data of specific cardiac chamber size. An overview of hemodynamics is given, and the use and limitation of electrocardiography and chest x-rays are discussed. The exciting potential use of echocardiography for the serial non-invasive measurement of anatomical and pathophysiological features is outlined, along with the value of a careful physical examination and the proper utilization of laboratory tests in the diagnosis of chronic cor pulmonale. In the patient with the asphyxial type, the treatment of pulmonary infectious exacerbations, the role of corticosteroids, digoxin, diuretics, phlebotomy, bronchodilators (theophylline, beta adrenergic agonists, and anticholinergics), and long-term oxygen therapy is noted. The controversy surrounding the use of vasodilators and calcium blockers in these patients is discussed. Treatment aspects of the vascular obliterative type, including the role of vasodilators, calcium blockers, prostacyclin, anticoagulants, and overall strategy are discussed. A brief note is mentioned of the promising role of surgical therapy in chronic thromboembolic disease causing chronic cor pulmonale.

Adult↗
PubMed1977

Pulmonary arteriovenous fistulas with pulmonary hypertension.

Two cases of pulmonary arteriovenous fistulas associated with pulmonary hypertension occurring in young multiparous women are described. Both cases suggest the development of pulmonary arteriovenous fistulas subsequent to and as a consequence of the onset of pulmonary hypertension. Etiologic factors resulting in the development of the pulmonary hypertension in these patients, including the possible role of estrogens, are considered. The possible causal relationship of the pulmonary hypertension to the development of the pulmonary arteriovenous fistulas is discussed, and the importance of detecting the presence of pulmonary hypertension is stressed, since resection of the arteriovenous fistulas would be contraindicated in this situation.

Adult↗
PubMed1990

[Age-related features of the functional state of the brain in patients with circulatory encephalopathy].

Complex clinico-physiological examinations was performed in 300 patients of middle and old ages with early and pronounced dyscirculatory encephalopathy of atherosclerotic and, in most cases, hypertensive etiologies. The cerebral hemodynamics was found to be relatively independent of the central one in patients with early atherosclerotic encephalopathy; the level of the systemic circulation and that of the median regional cerebral flow were found to correlate in early and advanced hypertensive encephalopathy cases. The cerebral function was shown to be more associated with the cerebral flow in the early encephalopathy in elderly patients than in middle-aged ones. The individual and personal traits of the patients were largely related to the disease stage rather than to the predominant etiological factor.

Adult↗
PubMed1991

Pulse rate and sodium intake interact to determine blood pressure. A population study.

It has been suggested that certain factors need to be present for the pressor effect of sodium to become apparent. The present population study investigated whether pulse rate (PR) and salt intake interact to determine blood pressure (BP). Twenty-four hour urinary sodium (UNaV) was used as a measure of salt intake. A random population sample, including 2081 subjects with a minimum age of 18 years, was stratified on tertiles of PR. In subjects with a slow PR(less than 68 beats/min) and in those with a fast PR (greater than 78 beats/min), a significant curvilinear relationship between BP and UNaV was found, while in subjects with an intermediate PR the BP-UNaV correlation was not significant. There was also a significant interaction between PR and UNaV, indicating that when UNaV increased from 160 to 300 mmol/24 h, systolic/diastolic BP rose by 2/1 mm Hg in the fast PR third, but declined by 1/1 mm Hg in the slow PR third. These divergent trends could not be explained by smoking habits or alcohol consumption and were still present after cumulative adjustment for other important correlates of BP, ie, gender, age, body weight, urinary potassium, and contraceptive pill intake in women. In conclusion, the present data suggest that in subjects with a pulse rate greater than 78 beats/min a high salt intake may be associated with blood pressure elevation, whereas the opposite tendency is observed in individuals with a pulse rate less than 68 beats/min.

Adolescent↗
PubMed1975

Oral contraceptives.

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Contraceptives, Oral↗
PubMed1976

[Changes of the renin-angiotensin-aldosterone system under contraceptive steroids. Contribution to the etiology of hypertension under hormonal contraceptives].

Treatment with hormonal contraceptives leads to a considerable stimulation of the renin-angiotensin-aldosterone-system. First of all, there is a 2,5- to 4fold increase of renin substrate synthesis in the liver. As a consequence, more angiotensin I and angiotensin II are released. Angiotensin II stimulates the secretion of aldosterone in the adrenals, thus producing a higher aldosterone concentration in plasma. The urinary excretion of aldosterone is elevated to a lesser degree, probably because of the simultaneously increased binding of aldosterone to plasma proteins. The release of renin is suppressed to 50% by negative feedback mechanisms. Some possible factors in the etiology of hypertension induced by oral contraceptives are discussed.

Adult↗
PubMed1988

Hypertension induced by pregnancy, oral contraceptives, and postmenopausal replacement therapy.

Hypertension may develop during pregnancy or with the use of OC pills. Although the precise manner by which this rise in blood pressure occurs is unknown, appropriate management of the problem can protect against the consequences. The use of hormonal replacement therapy after menopause is not associated with a rise in blood pressure, and appears to provide significant protection against CHD.

Adolescent↗
PubMed1978

Studies on the prevalence of renal disease and hypertension in relation to schistosomiasis. IV. Systemic blood pressure hypertension and related features.

Two comparable rural communities but with varying endemicity of urinary schistosomiasis in environs of Ibadan, Nigeria, have been studied by a total cross-sectional population survey. It has been found that:- (i) schistosomiasis does not predispose to raised blood pressure (ii) both diastolic and systolic blood pressure increase with age. (iii) prevalence of systemic hypertension is higher in females than males (iv) body weight and height are related to hypertension in both males and females (v) parity would seem to be related to hypertension in the females (vi) except in the younger female group (1--19 years) where polyuria, frontal headache, palpitations appear related to systolic hypertension, raised blood pressure would appear to have no symptoms. In particular headache in any part of the head bears no clear relationship. (vii) The majority of hypertensives would appear to belong to the primary variety but proteinuria among females has been found to be significantly related to hypertension.

Adolescent↗
PubMed1976

[Clinical aspects of hypertension under contraceptive steroids].

In Europe, about 1 per cent of women using oral contraceptives develop hypertension. The frequency seems to increase with age and in women who had earlier shown hypertensive disorders of pregnancy. A failure in the feedback mechanisms of the renin-angiotensin-aldosterone system is suggested to be an important factor in the etiology of hypertension induced by oral contraceptives. Usually, blood pressure returns to normal after cessation of treatment with contraceptive steroids; on the other hand, some cases of irreversible hypertension and kidney failure have been described. Besides the measurement of blood pressure before any treatment with hormonal contraceptives is started, blood pressure should be controlled after three months. In the differential diagnosis of hypertension induced by oral contraceptives, primary aldosteronism and renal artery stenosis have to be excluded; these hypertensive disorders show similar biochemical changes, but should be treated by surgical intervention. The choice of other contraceptives by women with this type of hypertensive disease is discussed.

Adult↗