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

The relation between blood pressure level and reactivity to mental arithmetic and isometric exercise was investigated in 169 men and 120 women (average age, 32.3 years) from the village of Tecumseh, Mich. In the entire population, the correlation between baseline blood pressure and blood pressure response to both stressors was not significant. Blood pressure reactivity to both stressors was not increased in participants with borderline hypertension (one clinic reading of more than 140 mm Hg systolic and/or 90 mm Hg diastolic). When subjects were classified according to blood pressure response (below and above the 80th percentile), the hyperreactors to mental and physical stress had normal baseline blood pressure values. The hyperreactors also had clinic-to-home blood pressure differences similar to those of the rest of the population. Participants who had borderline hypertension at age 32 years had significantly elevated blood pressures at ages 5, 8, 12, 21, and 22 years. Those who were hyperreactors at age 32 years had normal blood pressures as children and young adults. Results of the present study lend no support to an association between higher blood pressures and blood pressure hyperreactivity. Study participants in Tecumseh will be recalled for future examinations. The independence of blood pressure levels from blood pressure reactivity offers a unique opportunity to prospectively evaluate their separate effects on cardiovascular morbidity.
Hypertension 1991 Apr
PMID:Independence of pressure reactivity from pressure levels in Tecumseh, Michigan. 201 88

Compared with blood pressure measurements in the office setting, ambulatory blood pressure monitoring offers a more accurate and reliable method of diagnosing and managing hypertension. Indications for ambulatory blood pressure monitoring include borderline hypertension, a discrepancy between home and office blood pressure measurements, persistent blood pressure elevation in the office with no end-organ damage, episodic elevations of blood pressure or suggestive symptoms, hypertension resistant to treatment, episodic angina not related to exercise, end-organ damage but normal office blood pressure readings, and evaluation of the efficacy of antihypertensive agents. Several cases are presented for review.
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PMID:Ambulatory blood pressure monitoring in hypertension. 202 Oct 99

An increased sympathetic drive combined with decreased parasympathetic inhibition is found in patients with borderline hypertension, who characteristically have rapid heart rates, high cardiac output and relatively normal vascular resistance (hyperkinetic state). In established hypertension, cardiac output is normal, vascular resistance is elevated and signs of increased sympathetic drive are absent. Apparently hemodynamics and sympathetic drive change during hypertension. The mechanism of the hemodynamic transition in the course of hypertension is well understood. Cardiac output returns from elevated to normal values as beta-adrenergic receptors down-regulate and stroke volume decreases (due to decreased cardiac compliance). The high blood pressure induces vascular hypertrophy, which in turn leads to increased vascular resistance. The mechanism of the change of sympathetic tone from elevated in borderline hypertension to apparently normal in established hypertension can best be explained within the conceptual framework of the "blood-pressure-seeking" properties of the brain. In hypertension, the central nervous system seeks to maintain systemic blood pressure at the higher level. As hypertension advances and vascular hypertrophy develops, arterioles become hyperresponsive to vasoconstriction. At this point, less sympathetic drive is needed to maintain pressure-elevating vasoconstriction, and the central sympathetic drive is down-regulated. The etiology of increased sympathetic drive in hypertension remains unresolved. Subjects with increased sympathetic drive are also usually overweight and have elevated levels of insulin, cholesterol and triglycerides, as well as decreased high-density lipoproteins. Future research must focus on the link between coronary risk factors and sympathetic overactivity in hypertension.
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PMID:Autonomic nervous system dysregulation in human hypertension. 202 Nov 14

The relationship of left ventricular (LV) filling to the clinical and echocardiographic characteristics of 51 patients with untreated hypertension (borderline hypertension n = 17, essential hypertension n = 34) was investigated using two-dimensional echocardiography and Doppler ultrasound. Twenty-five patients had evidence of abnormal LV filling. Linear regression analysis revealed weak but significant correlations of LV filling with age (r = -0.53; P less than 0.0001), systolic blood pressure (r = -0.38; P less than 0.006), LV septal wall thickness (r = -0.44; P less than 0.0001) and LV mass index (r = -0.33; P less than 0.02). There was no association between LV filling and sex, race, heart rate or LV posterior wall thickness or cavity dimension. After stepwise regression analysis, age was found to be the only independent variable associated with LV filling, indicating that the other variables were dependent on age. This study suggests that a) abnormal LV filling is a frequent observation in hypertension b) LV filling is more dependent on age than blood pressure or LV size and c) other pathophysiological factors, so far undetermined, must contribute to the development of these abnormalities.
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PMID:Determinants of left ventricular filling in hypertension. 204 Oct 33

Twenty-eight men with borderline hypertension according to the World Health Organization criteria underwent maximal exercise testing, and then were followed for a two year period. The prevalence of abnormal blood pressure behavior during exercise was 53.58% (n = 15). During follow-up established hypertension developed in 63.33% (n = 10) of subjects with an abnormal blood pressure response to exercise, and only in 15% (n = 2) of subjects with normal blood pressure behavior. In predicting established hypertension development in a two year follow-up, maximal exercise testing has the following statistical values: sensitivity = 83.33%, specificity = 68.75%, accuracy = 75%, positive predictive value = 66.66%, negative predictive value = 84.61%.
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PMID:Abnormal blood pressure response to exercise in borderline hypertension. A two year follow-up study. 204 6

Borderline hypertension, a condition in which the blood pressure oscillates between normal and high values, is a predictor of future more severe hypertension. Pathophysiologically, borderline hypertension is different from established hypertension. A large proportion of such patients have elevated cardiac output and a normal vascular resistance. In established hypertension, the output is normal and resistance is elevated. The elevation of cardiac output in borderline hypertension is neurogenic; it can be abolished by an autonomic blockade of the heart. In addition to an increased cardiac sympathetic drive, increased sympathetic tone to the kidney, arterioles, and veins has also been found. In parallel with the hypersympathetic state, patients with borderline hypertension also show decreased parasympathetic tone. The enhanced sympathetic tone leads to a decreased cardiac responsiveness, and eventually, the cardiac output returns to the normal range. High blood pressure causes vascular hypertrophy, and hypertrophic vessels are hyperresponsive to vasoconstriction. These secondary changes in the responsiveness of the heart and blood vessels are the basis of transition from a high cardiac output to high-resistance hypertension. These hemodynamic changes are associated with a downregulation of the sympathetic tone. A picture of an apparently nonneurogenic high-resistance hypertension emerges. Nevertheless, when assessed in regard to the enhanced pressor responsiveness, the sympathetic drive in such patients is still excessive. Despite the apparently normal tone, the sympathetic nervous system continues to play an important pathophysiological role in established hypertension. Borderline hypertension is associated with numerous metabolic abnormalities including obesity and insulin resistance. It is tempting to view all these abnormalities as a common expression of the increased sympathetic drive in hypertension. Explanation of the basis of the association of hypertension and metabolic abnormalities promises to bring new insights into the pathophysiology of two common diseases of civilization: hypertension and diabetes mellitus.
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PMID:Autonomic nervous dysfunction in essential hypertension. 204 40

Cardiac arrhythmias were studied in patients with essential hypertension in relation to their myocardial function. It was found that the arrhythmias occurring in the early period of the disease (borderline hypertension, Stage I hypertension) were primarily functional and affected the course of the disease and hemodynamics to a small degree. The life-threatening arrhythmias recorded in early hypertension were more commonly caused by mitral prolapse. The duration and severity of hypertension, development of left ventricular myocardial hypertrophy, myocardial fiber distension in relative heart failure play a decisive role in the development of cardiac arrhythmias in patients with Stage II hypertensive disease. It is essential to make comprehensive clinical and instrumental studies to clarify the genesis of the arrhythmic syndrome and to correctly choose the management policy in these patients.
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PMID:[Clinical significance of arrhythmia in patients with hypertension]. 206 87

Authors assessed correlation between venous blood catecholamines and prostaglandins concentrations before and after inhibition of sympathetic activity by clonidine in patients with primary hypertension or pheochromocytoma. 30 patients with essential uncomplicated hypertension and 11 with pheochromocytoma underwent the study. The control group consisted of 6 healthy volunteers. Serum norepinephrine (NA), epinephrine (A), prostaglandins: PGE2 PGF2 alpha and prostacyclin metabolite -6-keto-PGF1 alpha were determined before and 3 hours after oral administration of 0.3 mg clonidine. Negative correlation was stated between basic serum norepinephrine and 6-keto-PGF1 alpha concentrations in patients with pheochromocytoma, which could indicate prostacyclin metabolism disorders during persistent hypercatecholaminemia . There was no correlation between catecholamines and prostaglandins during the inhibition of sympathetic activity in patients with pheochromocytoma as well as essential hypertension. The positive correlation was observed between changes in serum NA and PGF2 alpha levels in patients with borderline hypertension. Thus, one may suppose, that correlation between na excretion and vasoconstrictive PGF2 proved in acute experiments, becomes evident within the early stage of hypertension also during sympathetic activity inhibition.
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PMID:[Correlations between catecholamines and prostaglandins in patients with primary arterial hypertension and pheochromocytoma in basic conditions and after administration of clonidine]. 208 2

Using a pulsed Doppler velocimeter with spectral analysis, it is possible to measure instantaneous ascending aortic blood velocity by the suprasternal approach. Cardiac output, stroke volume and maximal acceleration are evaluated from the aortic velocity curve. Maximal aortic acceleration is increased in patients with borderline hypertension by comparison with normal subjects and patients with sustained essential hypertension of the same age. Stroke distance is calculated as the ratio between stroke volume and the cross-sectional area of aortic valve measured by echocardiography. Stroke distance is significantly decreased in patients with sustained hypertension, suggesting that the distance covered by a column of blood passing through the aortic root during one cardiac cycle is smaller in patients with hypertension than in normal subjects.
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PMID:Non-invasive study of cardiac performance using Doppler ultrasound in patients with hypertension. 209 92

Pathophysiological effects of the autonomic nervous system are clearly seen in young patients with a high cardiac output and borderline hypertension. As the hypertension progresses, there is a change from the hyperkinetic circulation in borderline hypertension to the increased vascular resistance seen in established hypertension. This hemodynamic transition is caused by decreased beta-adrenergic responsiveness and decreased end-diastolic distension of the heart combined with an increased alpha-adrenergic responsiveness of the resistance vessels. In parallel, the sympathetic tone decreases in the course of hypertension. This transition in sympathetic tone can be explained by the hypothesis of the 'blood pressure seeking properties of the brain'. The central nervous system 'seeks' to maintain a higher pressure. When vascular overresponsiveness sets in, less sympathetic drive is needed to maintain a neurogenic hypertension. Sympathetic overactivity in borderline hypertension is associated with overweight subjects, insulin resistance and dyslipidemia. This suggests a new area of research to investigate the basis of metabolic abnormalities in hypertension.
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PMID:Changing role of the autonomic nervous system in human hypertension. 209 97


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