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

Plasma volume is usually lower in patients with essential hypertension than in normal subjects. Normal or expanded plasma volume in some hypertensive patients may respect either a specific hypervolemic subset of the disease or the upper end of a continuum of volume values. Difficulties in defining these groups stem from the small numbers of subjects studied, from the need for a reliable reference index for volume measurements, and from the multiple factors which may affect intravascular volume. Differences in plasma volume cap influence choice of antihypertensive therapy; patients with expanded volume tend also to have slightly exchangeable sodium and greater extracellular fluid (ECF) volume and to respond well to diuretic therapy. There is also some evidence that low plasma renin activity is more frequent among hypervolemic patients. Essential hypertensives as a group have low plasma to interstitial fluid volume ratio (PV/IF), indicating that ECF distribution between the intravascular and interstitial compartments is shifted toward the latter. This is probably related to altered capillary filtration pressure due to increased venous resistance. Hypovolemic essential hypertensives have significantly lower (P less than 0.01) PV/IF ratio than hypervolemic, but whether this is related to differences in neural venous tone is only speculative. Hemodynamic studies revealed no difference in cardiac output between hypertensive patients with contracted blood volume and those with hypervolemia; total peripheral resistance was even higher in the latter, suggesting that "vasoconstriction" is not different between the two groups. It is widely believed that the relationship between ECF expansion and hypertension depends on the development of hypervolemia, increased cardiac output, and subsequent rise in total peripheral resistance reducing volume expansion and normalizing systemic flow while maintaining a high blood pressure. This sequence of events has been demonstrated in some human and experimental forms of hypertension but not in all. Metyrapone-induced hypertension in dogs could be sustained for up to 6 weeks by increased output with no evidence of "autoregulation" developing, and similar observations were reported in some anephric patients. Complementing these findings are observations of elevated cardiac output in some patients with long-standing essential hypertension or primary aldosteronism. It is therefore suggested that the spectrum of hemodynamic changes associated with volume disturbances in hypertension is too wide to be forced under one hypothesis alone and that neurogenic and other factors may play an important role in that complex relationship.
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PMID:Hemodynamic role of extracellular fluid in hypertension. 77 71

Hypervolemia with hypertension often occurs 36-72 hours following massive blood and fluid replacement for hypovolemic shock. This syndrome of "fluid overload" has been attributed to the rapid intravascular flux of previously sequestered fluid in patients with impaired diuresis. This hypothesis was tested in 35 injured patients who received a mean of 9.3 L of blood and 17.4 L of salt during resucitation. The renal parameters measured soon after resuscitation included: 1) renal clearance of inulin (GFR), para-amino hippurate (ERPF), milliosmoles, sodium, and free water; 2) inulin space, renal vascular resistance (RVR), O2 consumption, renin, renal blood flow (RBF), and response to furosemide. Eighteen patients developed hypertension, hypervolemia, and respiratory insufficiency. When compared to the 17 normovolemic, non-hypertensive patients, the 18 hypervolemic patients had significantly increased RVR, with a significant decrease in RBF despite an increase in plasma volume and cardiac output. Furosemide produced less diuresis and natriuresis in the hypertensive patients. The balance between hypovolemia and "fluid overload" seemed percarious in the hypertensive patients. Peripheral renin and catecholamine levels were normal in both groups. Patients with post-traumatic "fluid overload" appear to have a combination of hypervolemia, respiratory insufficiency, hypertension, increased cardiac output, decreased extracellular fluid space, and decreased renal perfusion. These findings suggest that decreased interstitial fluid space compliance rather than "fluid overload" is the underlying factor leading to respiratory insufficiency. The therapeutic aspects of these findings are discussed.
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PMID:The renal factor in the post-traumatic "fluid overload" syndrome. 89 57

An early diastolic murmur thought to indicate functional aortic regurgitation was heard in 7 of 74 consecutive patients with end-stage renal failure assessed for chronic intermittent haemodialysis and transplantation. In all 7 cases the murmur was transient and related to episodes of hypertension and fluid overload and disappeared on correction of these factors. In a further 2 patients aortic regurgitation resulted from a structural abnormality of the aortic valve. Thus, an early diastolic murmur is not uncommon in this situation and does not necessarily indicate organic aortic valve disease which might preclude selection for haemodialysis and transplantation.
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PMID:Early diastolic murmurs in end-stage renal failure. 90 86

The changes of intracranial and arterial pulse shape under functional loads (hypervolemia and intracranial hypertension) were compared. The logarithmic amplitude-frequency characteristics were found and used for the synthesis of equivalent electrical circuit of arterial pressure pulses transmission on cerebrospinal fluid (CSF) in the cranial cavity. The model obtained points to the necessity of taking into account the induction which was not performed in the earlier models of the CSF-system. It is found that the attenuation factor permitted to estimate the stability of the intracranial circulation system to input influences under different functional conditions.
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PMID:[Frequency analysis of arterial pulse transmission in the cranial cavity]. 113 63

Numerous deviations from normal physiology formerly ascribed to artificial heart pumping actually resulted from experimental artifacts. Recent results indicate that infection, thromboembolism, pulmonary pathology, and renal deterioration could be considered mostly nonspecific artifacts of mechanical heart implantation. Nonetheless, damage to the blood constituents and hepatic congestion seemed to be specific effects of artificial heart pumping. Hemolysis correlated to pumping sac collapse, low cardiac output, and hematocrit value (r = .912, p is less than .001). Hepatic congestion, caused by pulsatile venous hypertension and hypervolemia, was postulated to result from functional atrial volume restriction (small atrium syndrome).
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PMID:Physiology of the artificial heart. 118 49

Studies were undertaken in 33 uremic patients with or without hypertension, 11 normal subjects, and 15 essential hypertensive patients to assess cardiac hemodynamics, plasma volume, extracellular fluid volume, and peripheral renin levels. Cardiac output and intraarterial blood pressure were measured and peripheral vascular resistance index calculated. These studies suggest that uremic hypertension with normal renin values and hypervolemia is hemodynamically sustained by an increase in peripheral resistance rather than by an increased cardiac output. The renin angiotensin system plays a secondary role as compared to overexpansion in the genesis of hypertension in normoreninemic uremic hypertension.
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PMID:Normal renin uremic hypertension. Study of cardiac hemodynamics, plasma volume, extracellular fluid volume, and the renin angiotensin system. 124 34

Five children (four boys and one girl) with chronic renal failure (CRF) developed congestive heart failure 0.5 to 11 years after the onset of the disease. Their ages were from 4 to 13 years old. They noticed tachypnea, tachycardia, cough, chest anxiety, general fatigue and their chest X-rays showed cardiomegaly with cardio-thoracic ratio (CTR) of from 55 to 63% and pulmonary congestion. Their echocardiograms showed no cardiomuscular hypertrophy, but the dilatation of left ventricular diastolic diameter (LVDd), and the decreased ejection fraction (EF) were observed. They were treated with water restriction, antihypertensive agents, cardiotonics and dialysis. Their clinical symptoms improved promptly, but their cardiomegary and echocardiographic findings improved gradually. The causes of heart failure in these patients seemed to be due to uremia, fluid overload and hypertension. The echocardiographic examination was useful for the management of the children with CRF in heart failure.
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PMID:[Echocardiographic assessment of cardiac function in the children of chronic renal failure with cardiomegary]. 129 69

Primarily hypervolaemic, high output forms of hypertension, with features indicating or strongly suggesting fluid overload as the cause of elevated cardiac output, resulting from renal disease with reduced glomerular filtration rate causing sodium retention, renal tubular causes of sodium retention, greatly excessive sodium intake and low renin hypertension, can be treated by reduction of sodium intake and potentiation of its excretion by diuretic therapy, removal of the cause (e.g. aldosteronoma), and calcium antagonists. Excessive vasoconstriction resulting from noradrenaline (norepinephrine) in neurogenic hypertension, phaeochromocytoma, orthostatic hypertension and alpha-adrenergic drug administration; angiotensin excess due to renal ischaemia brought about by aortic coarctation, renal arterial and arteriolar stenosis, intraluminal obstruction, external renal compression, renin-producing tumours, intrinsic kidney diseases and excessive renin substrate; and vascular structural disorders such as atherosclerosis, arteriolitides and fibrosis with or without calcification of major arteries may also induce hypertension. Secondary hypertension of uncertain mechanism may occur in hyperparathyroidism, hyper-or hypothyroidism, or acromegaly. All are best treated by appropriate correction of the endocrine excess or deficiency. It may also occur in pregnancy, where the mechanism may involve prostaglandin-thromboxane imbalance or calcium deficiency; calcium deficiency with some evidence of benefit from calcium supplements; and the recumbent hypertension paradoxically associated with autonomic failure. Excellent responses to specific correction of the underlying cause or pathogenetic mechanism is usual in young individuals but less frequent in older patients.
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PMID:Secondary hypertension. An overview of its causes and management. 137 54

The prevalence of coronary artery disease substantially affects both cardiac and noncardiac surgery. Assuming that biometric data reported from North America are representative for Germany, the following incidences can be estimated: around 1 million out of 8 million patients operated upon each year will suffer from coronary artery disease, and 15,000 of these patients will have a perioperative myocardial infarction. Since a close relationship has been shown between pre-, intra-, and postoperative myocardial ischaemia and postoperative cardiac morbidity and mortality, early diagnosis and therapy of acute perioperative myocardial ischaemia is warranted. The purpose of this review is to weigh critically the various methods for diagnosis of myocardial ischaemia in view of their practicability and cost/benefit relationship in the perioperative setting. The symptoms of angina pectoris are unreliable in the perioperative period, since patients are premedicated preoperatively, without symptoms during anaesthesia, and usually receive analgesics postoperatively. Intraoperative detection of myocardial ischaemia focuses on standard electrocardiography (ECG) with on-line registration of the ST-segment in two leads (usually leads II and V5) and automatic analysis of ST-segment deviation, achieving a sensitivity of 80% in the detection of myocardial ischaemia. Measurement of regional wall motion abnormalities with trans-esophageal echocardiography (TEE) is a more sensitive method of myocardial ischaemia detection compared to ECG. However, several reasons preclude the broader application of this method in the perioperative phase: (1) it lacks validation by an accepted and independent gold standard; (2) there is a wide spectrum of false-positive findings (considerable interindividual variations in left ventricular contraction, bundle branch blocks, hypertension, hypervolemia); (3) changes in the inferior and apical segments of the left ventricle cannot be detected by single-plane TOE. Detection in these segments might be achieved with biplane echocardiography, but few data on this improved technique are presently available; (4) the method is semi-invasive and might be not applicable during periods with a high incidence of myocardial ischaemia, e.g., intubation, the end of anaesthesia, and extubation; (5) anaesthetists seldom fulfil standard guidelines in echocardiography training; and (6) the method is expensive, which also limits its broader application. Cardiokymography, a noninvasive technique, allows analog representation of anterior wall motion.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[Perioperative diagnosis of acute myocardial ischemia]. 141 5

Hypertension-hypervolemia therapy (HHT) is widely employed for treatment against vasospasm after subarachnoid hemorrhage (SAH). A few investigations have been reported to establish the fact that HHT results in a high incidence of congestive heart failure and pulmonary edema as well as deterioration of brain edema. From the point of view that the cerebral circulation is not independent of the systemic circulation, the authors investigated the effect of HHT on the systemic circulation of patients with SAH. In 72 patients, intracranial pressure (ICP), pulmonary catheter wedge pressure (PCWP), pulmonary arterial pressure (PA), central venous pressure (CVP), arterial pressure (AP), cardiac index (CI), arterial blood gas (ABGS), electrocardiogram (ECG), serum and urine electrolytes were monitored postoperatively. Furthermore, among these patients, the flow (Flow), volume (Volume) and velocity (Velocity) of the cortical vessels were monitored by means of a Laser Doppler in 25 patients. A cisternal or spinal drain was placed in all of the patients. Elevation of PCWP and CVP and Flow were observed when 300ml of 10% glycerol was administered within a period of 30 minutes, whereas administration of the same dose of glycerol over a period of 60 or 120 minutes caused no significant changes on these parameters. Elevation of PCWP and CVP and decrease of CI and Flow, occasionally associated with premature ventricular contraction (PVC), were observed in some patients when 100ml of 25% albumin was administered. However, administration of the same dose of albumin over a period of 120 or 240 minutes did not cause deterioration of the cardiac function. These facts could be explained by Guyton's law in which massive transfusion causes cardiac dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Serious pitfalls which can be encountered in a course of hypertension-hypervolemia therapy for vasospasm]. 157 56


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