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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypertension constitutes a major health problem and the challenge is to identify patients having 'surgically' curable renal vascular disease among the majority with so-called essential hypertension. The best of unsatisfactory diagnostic tests are renography and plasma renin activity both before and during angiotensin II blockade. The necessity of better screening tests has increased because of the recent advances in surgical techniques and especially percutaneous transluminal renal angioplasty. The latter has definitely become the method of choice for correction of suspected hemodynamically significant artery stenoses whenever technically feasible. With improved angioplasty techniques the risk of treating renal artery stenosis without hemodynamic and clinical importance (so-called cosmetic repair) has increased. Unfortunately randomized trials including surgery versus angioplasty are not available. It should be kept in mind that only after correction of the stenosis is achieved and the blood pressure has become normal, can the diagnosis of renovascular hypertension be made with certainty.
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PMID:Renovascular hypertension. Diagnosis and intervention. 252 9

Compelling arguments can be made for a local, intrarenal role as angiotensin's first action in phylogeny, with additional cardiovascular and endocrine responses arising later. Perhaps for that reason the vascular bed of the kidney is especially responsive to angiotensin II. Conversely, when the renin-angiotensin system is activated, as it is when sodium intake is restricted or diuretics are administered, the renal blood supply shows the most striking and consistent vasodilatation among vascular beds assessed after converting enzyme inhibition. When renal vascular tone is increased in patients with essential hypertension, converting enzyme inhibitors induce a potentiated acute renal vascular response: renal blood flow increases more than it does in normal subjects, with an associated consistent early increase in sodium excretion and an occasional increase in glomerular filtration rate. Reduced aldosterone release consequent on the block of angiotensin II formation also contributes to the natriuresis and results in positive potassium balance. With long-term therapy renal function tends to be well maintained. The response to converting enzyme inhibition in renal artery stenosis is more complex: as perfusion pressure distal to the stenosis falls there is typical afferent arteriolar dilatation and glomerular capillary pressure tends to be maintained by a rise in postglomerular resistance. To the extent that this is angiotensin mediated, suppression of angiotensin formation can reduce glomerular capillary pressure and thus filtration rate. This is well tolerated in the patient with unilateral stenosis and a healthy contralateral kidney, but can provoke renal failure where the stenosis is bilateral or involves a solitary kidney.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Angiotensin-converting enzyme inhibition: renal aspect. 258 Jan 75

We studied 11 hypertensive patients by a radionuclide technique using Gates' method with [99mTc]DTPA to investigate the acute effects of captopril on glomerular filtration rate (GFR). Five patients had hypertension with unilateral renal artery stenosis (RAS) angiographically documented and six patients had essential hypertension (EH). Total and split GFR were determined under control conditions and after oral administration of captopril (50 mg). In the patients with RAS, captopril induced a significant decrease of GFR in the stenotic kidneys (from 42.4 +/- 4 to 29.6 +/- 3 ml/min, p less than 0.01), while no changes were observed in the nonstenotic kidneys (from 61.2 +/- 3 to 61.6 +/- 5 ml/min, NS). Total GFR was 103.6 +/- 5 ml/min under control conditions and decreased to 91.8 +/- 6 ml/min after captopril (p less than 0.05). No significant changes of GFR were detected after captopril administration in patients with EH. In a separate group of ten patients with EH, good correlation between 24-hr creatinine clearance and fractional uptake of [99mTc]DTPA was obtained. Good reproducibility of this radionuclide technique was also shown. This study demonstrates that the computed radionuclide GFR determination coupled with the captopril test allows one to unmask angiotensin II-dependent renal function and hemodynamic changes. This technique can be useful in clinical practice for identifying patients with renovascular hypertension.
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PMID:Renal artery stenosis detection by combined Gates' technique and captopril test in hypertensive patients. 266 99

Identification of patients with renovascular hypertension (RVH) among the larger group of patients with essential hypertension has been aided by a wide variety of in vitro and in vivo nuclear medicine procedures. The most valuable in vitro procedure remains the radioimmunoassay (RIA) for renin activity obtained from individual renal vein catheterization studies. Lateralizing renin activity provides valuable prognostic information about the likelihood for surgical cure of RVH. Older in vivo procedures for the diagnosis of RVH included rectilinear scanning and probe renography, which suffered from poor resolution and specificity, respectively. These tests have been replaced by computer-interfaced gamma camera scintirenography using 131I- or 123I-labeled orthoiodohippurate (OIH), or scintiangiography using 99mTc-DTPA. False-positive (FP) results for RVH persist due to a wide variety of relatively common conditions that can cause asymmetric renal size and function, including outflow obstruction and parenchymal renal disease. Newer approaches promise to improve the specificity of nuclear medicine procedures for identification of RVH. In particular, the number of FP exams appears to improve when scintirenography is performed before and after the administration of oral angiotensin converting enzyme (ACE) inhibitors, using either 99mTc-DTPA or OIH. The incentive for improved diagnostic testing has increased with the availability of percutaneous transluminal angioplasty (PCTA) for treatment of renal artery stenosis (RAS). Follow up of PCTA with scintirenography is of great value in assessing its effect on renal function and in evaluating the subsequent clinical course of the patient.
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PMID:Differential diagnosis and management of renovascular hypertension through nuclear medicine techniques. 265 10

Blood pressure (BP), plasma renin concentration (PRC), and 99mTc-labeled diethylenetriaminepenta acetate (DTPA) renography with determination of single kidney 99mTc-DTPA clearance and parenchymal mean transit time (MTT) were measured in exactly the same way on two consecutive days in 14 patients with renovascular hypertension (RVH), unilateral renal artery stenosis in nine and bilateral stenosis in five, and ten patients with essential hypertension (EH). The examination on day 1 served as a control for day 2 during which captopril (25 mg) was given orally one hour before measurements of PRC and DTPA clearance. Blood pressure was reduced by captopril in both groups, but the maximum decrease in systolic BP was slightly more pronounced (P less than .01) in RVH (22%, median) than EH (13%). Plasma renin concentration increased to a much greater extent (P less than .01) after captopril in RVH (366%) than in EH (46%), Single kidney 99mTc-DTPA clearance was significantly (P less than .01) reduced (-39.5%) and MTT considerably prolonged (170%) on the affected/most affected side in RVH, but both parameters were only slightly changed or unchanged on the unaffected/least affected side (-6.5%, -2% respectively) and were not significantly changed in any of the sides in EH. The degree of renal artery stenosis was significantly correlated to the increase in PRC (rho = -0.786, n = 14 patients, P less than .01), to the reduction in single kidney 99mTc-DTPA clearance (rho = 0.729, n = 19 kidneys, P less than .01) and to the prolongation in MTT (rho = -0.785, n = 16 kidneys, P less than .01). By analysis of the captopril-induced changes in 99mTc-DTPA clearance and MTT, it was possible to predict the existence of a moderate to several renal artery stenosis in arterial hypertension with a very high degree of probability, and the use of changes in 99mTc-DTPA clearance and MTT after angiotensin-converting enzyme (ACE) inhibition may become a valuable tool in differentiation between RVH and EH.
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PMID:Differentiation between renovascular and essential hypertension by means of changes in single kidney 99mTc-DTPA clearance induced by angiotensin-converting enzyme inhibition. 265 58

Hypertension is a common problem encountered after renal transplantation. Many different mechanisms may be responsible for hypertension in this setting, and therapy will depend upon the mechanism(s) affecting the individual patient. Factors that may cause or aggravate post-transplantation hypertension include renal dysfunction secondary to rejection or other diseases of the transplanted kidney, renin production from the diseased native kidneys if these kidneys have not been surgically removed, extracellular fluid volume expansion, toxic effects of medications used after transplantation, especially cyclosporine and intravenous prednisolone, or primary hypertension in the donor or recipient. Renal artery stenosis may predispose to acute renal failure in the presence of treatment with angiotensin-converting enzyme inhibitors. Severe renal artery stenosis may also lead to refractory salt and water retention and fluid overload with congestive heart failure and hypertension, mediated primarily due to extracellular fluid volume excess. Therapy with percutaneous transluminal renal angioplasty or, as a last resort, surgery, can be successful in controlling these problems.
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PMID:Refractory hypertension after renal transplantation. 266 26

Non invasive 24 hours ambulatory blood pressure monitoring was performed in 81 patients with secondary hypertension (renoparenchymatous nephropathy n = 15, diabetic nephropathy n = 10, Conn's disease n = 4, renal artery stenosis n = 15, pheochromocytoma n = 2, hemodialysis patients n = 15 and patients after kidney transplantation n = 20). The results were compared to 201 patients with essential hypertension. The results showed that 98.5% of patients with essential hypertension have a nightly decline in blood pressure of at least 15 mmHg (systolic + diastolic), whereas 69% of patients with secondary hypertension showed either an attenuated circadian rhythm or no circadian rhythm. Patients with pheochromocytoma who had a night time increase in blood pressure demonstrated the greatest difference to the essential hypertension collective followed by patients with diabetic nephropathy, Conn's disease and the group of patients after kidney transplantation. After successful treatment of the condition leading to hypertension circadian periodicity returned in some patients. In summary these results suggest that the absence of a night time decline in blood pressure during 24-hour-ambulatory monitoring is an indication of secondary hypertension.
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PMID:[Absence of nocturnal decrease in blood pressure in 24-hour blood pressure monitoring: an indication of secondary hypertension]. 266 27

Renovascular hypertension is a potentially curable form of high blood pressure. However, it is unclear how best to select patients who are likely to have renovascular hypertension, what diagnostic strategy to use in these selected patients, and how to predict the hemodynamic significance of a renal artery stenosis. We determined the prevalence of renovascular hypertension in adults who exhibited suggestive clinical features. In these clinically selected patients, we then determined the test characteristics of various diagnostic and potential screening tests. Renovascular hypertension was diagnosed if correction of renal artery stenosis resulted in decreased blood pressure. Of the 66 hypertensive adults evaluated, 11 (16.7%) had renovascular hypertension. Captopril-stimulated peripheral renin activity detected renovascular hypertension with 73% sensitivity, 72% specificity, 38% positive predictive value, and 92% negative predictive value. Less optimal combinations of sensitivity and specificity were found for differential glomerular filtration rate renography, differential effective renal plasma flow renography, and selective renal vein renin ratios, each performed after a single dose of captopril. Intravenous digital subtraction renal angiography detected all patients with renovascular hypertension and was normal in 71% of patients with essential hypertension. To evaluate potential screening tests for renovascular hypertension, we calculated predictive values applied to a low prevalence population. If the observed sensitivities and specificities apply to a population with 5% prevalence of renovascular hypertension, captopril-stimulated peripheral renin would have a positive predictive value of 12% and a negative predictive value of 98%. In 16 patients with known renal artery stenosis, neither the captopril-stimulated renal vein renin ratio nor captopril-stimulated differential renography accurately predicted blood pressure response to correction of the stenosis. We conclude that clinical criteria can identify a subgroup with 16.7% prevalence of renovascular hypertension. In this high prevalence group, intravenous digital subtraction renal angiography will identify virtually all patients with renovascular hypertension, and a normal study will be sufficient to exclude renovascular hypertension. In unselected hypertensive patients, screening with captopril-stimulated peripheral renin activity may be the most useful and efficient procedure for identification of patients with renovascular hypertension. Functional tests do not accurately predict the hemodynamic significance of a renal artery stenosis.
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PMID:Prospective analysis of strategies for diagnosing renovascular hypertension. 267 Jul 63

To check the reliability of the captopril test and of quantitative radioisotope techniques for the primary diagnosis of renovascular hypertension the data from 41 patients suspected of this disease were retrospectively analysed. In all cases plasma renin activity (PRA) was assayed in peripheral blood and in renal vein blood before and after 25 mg captopril. Double tracer studies with 131I-hippuran and 99mTc-DTPA were also performed, as was renal arteriography. The postoperative blood pressure plots of 23 patients with unilateral renal artery stenosis (who had subsequently been operated upon) were included in the evaluation. Renovascular hypertension was diagnosed in 21 patients and essential hypertension in 20. Twelve of the 20 patients with essential hypertension had renal artery stenosis, but this had not produced renovascular hypertension. The diagnostic significance of the tests as markers of renovascular hypertension was as follows: captopril test P less than 0.001, glomerular filtration fraction P less than 0.02, hippuran clearance P less than 0.001. The captopril test and the quantitative radioisotope techniques were in agreement in identifying patients with renal artery stenosis and renovascular hypertension. False-positive results due to methodological shortcomings can be avoided by applying both methods in succession.
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PMID:[Endocrine and nuclear medicine diagnosis of renovascular hypertension]. 268 83

The mosaic of essential hypertension seems to be gaining new tiles at an accelerating rate. Of the many pathophysiological factors and markers for the factors that can be considered as possible elements of a profiling algorithm, there are relatively few with solid data to support their use. Use of plasma renin activity for prospective profiling does not appear to be valid for individual patients. It remains useful for diagnosis of renal artery stenosis and primary aldosteronism. The black race does have some well-documented pathophysiological differences from the white race regarding hypertension, and there are some useful data bits for selecting specific therapy. The elderly, obese patients, and young patients with hyperdynamic circulation appear to have enough group characteristics to enable selection of drugs more targeted to their needs. Anxious patients who often display symptoms that mimic pheochromocytoma symptoms comprise a unique group. One of the largest groups is patients with hypertension plus one or more concomitant diseases. Finally, drug selection decisions must also consider the effect of drugs on serum lipoproteins, left ventricular hypertrophy and vascular compliance, sexual function and other quality of life issues, and cost.
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PMID:Newer principles of patient profiling for antihypertensive therapy. 268 80


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