Renovascular hypertension in blacks

To define the clinical characteristics of renovascular hypertension (RVH) and determine the clinical usefulness of captopril stimulated peripheral renin and postcaptopril renography in blacks at risk for RVH, 79 clinically selected hypertensive blacks were evaluated. Unstimulated (U-PRA), captopril stimulated (S-PRA) peripheral renin, and postcaptopril renography (PC-RENO) were obtained. All subjects underwent conventional renal arteriography. Renal artery stenosis (RAS) was present in 14 of 79 (18%) patients. Renovascular hypertension (RVH) was found in 7 of 79 (9%) patients. S-PRA had a sensitivity and specificity of 38% and 86% respectively to detect RAS; and a sensitivity and a specificity of 17% and 85% respectively to detect RVH. PC-RENO had a sensitivity and a specificity of 64% and 58% respectively to detect RAS; and a sensitivity and a specificity of 67% and 58% respectively to detect RVH. This study suggests that RAS occurs in 18% of clinically selected hypertensive blacks. RVH was present in 9% of this population. Captopril stimulated peripheral renin and postcaptopril renography are not useful as screening tools for the diagnosis of renovascular disease in blacks. Blacks at high risk should be evaluated with angiography.     

The value of the captopril test and the effect of captopril on renal function

We have investigated the use of captopril as a screening test for renovascular hypertension and compared the effects of captopril on renal function in patients with renovascular hypertension and those without renovascular hypertension. The captopril test and kidney gamma scintigraphy were carried out in 50 hypertensive patients, 13 with renovascular hypertension and 37 without. Blood samples were drawn for the determination of plasma renin activity and kidney gamma scintigraphy was done before and 60 minutes after 50 mg oral captopril administration. Results suggesting the diagnosis of renovascular hypertension are the following: a basal and stimulated plasma renin activity of 4 ng ml/hr or more and an absolute increase in plasma renin activity of 3 ng/ml/hr or more if basal plasma renin activity was less than 4 ng/ml/hr. Data from kidney gamma scintigraphy showed that captopril causes a decrease in clearance rate at 20 minutes in patients with renovascular hypertension but not in patients without renovascular hypertension. We conclude that the captopril test can be used to screen for renovascular hypertension, but catopril may impair the renovascular hypertensive patient's renal function.     

The captopril test for identifying renovascular disease in hypertensive patients

To develop a screening test for identifying renovascular hypertension, the blood pressure and plasma renin activity responses to an oral test dose of captopril were studied in 246 quietly seated hypertensive patients. The following criteria were developed that exploit the hyperresponsiveness of renin secretion in renovascular hypertensive patients: a 60-minute post-captopril plasma renin activity of 12 ng/ml per hour or more and an absolute plasma renin activity increase of 10 ng/ml per hour or more, along with a 150 percent increase in plasma renin activity (or a 400 percent increase if the baseline plasma renin activity was below 3 ng/ml per hour). Retrospectively, the test identified, among 200 hypertensive patients without evidence of renal dysfunction, all 56 patients with proved renovascular disease. In this group, false-positive results occurred only in two of 112 patients with essential hypertension and in six with secondary hypertension. Nine untreated patients had blood pressure levels of less than 160/100 mm Hg. The test was neither as sensitive nor specific in the 46 patients with renal insufficiency. This study demonstrates that the renin response to oral captopril is a useful screening test for identifying patients with unilateral or bilateral renovascular disease. Since the test also characterizes the renin dependency of the hypertension, it may have other diagnostic and therapeutic uses.     

Captopril Test and Renal Duplex Scanning for the Primary Screening of Renovascular Disease

To evaluate the utility of renal duplex scanning and the captopril test in the detection and functional assessment of renovascular disease, by comparing their results with those of angiography and captopril isotopic renography (CIR).Sixty hypertensive patients with aortoiliac disease and 16 with clinically suspected renovascular hypertension (RVH) were included. All the patients underwent renal duplex scanning prior to angiography. In addition, isotopic renograms and a determination of peripheral plasma renin activity (PRA) at baseline and 60 min after oral intake of 50 mg of captopril were both performed. A postcaptopril PRA > 5.7 ng/mL/h was considered as diagnostic of a positive captopril test. On the basis of the results of the angiography and isotopic renograms, all the patients were classified into three groups: group I (n = 33), essential hypertension (EHT); group II (n = 20), hypertension and angiographic RAS > 60% but negative CIR; and group III (n = 24), RAS > 60% and positive CIR. This last condition was considered as highly suspicious for RVH.Renal duplex scanning showed greater accuracy than captopril PRA or CIR for detecting RAS > 60% (groups II and III) with 87.3% versus 52.4% and 45.3% sensitivity (S), and 91.5% versus 84.4% and 92.8% specificity (Sp), respectively. The captopril test correctly identified 44 of 51 EHT patients (groups I and II) and 20 of 23 highly suspected of RVH (group III) with 87% S, 86.5% Sp, 74.1% PPV, and 93.6% NPV. Accuracy was further increased when a combined approach (renal duplex scanning and captopril test) was followed (82.6% S, 93.7% Sp, 86.4 PPV, and 91.8 NPV).In our study, renal duplex scanning was a useful screening method for detecting anatomical RAS. A combination of both renal duplex scanning and captopril test may be an appropriate approach to the primary screening for RVH, thereby permitting the selection of those patients indicated for angiography.     

Re-evaluation of the captopril test for the diagnosis of primary hyperaldosteronism

OBJECTIVE: We aimed to re-evaluate the captopril test in the diagnosis of primary hyperaldosteronism. DESIGN: Serum aldosterone and plasma renin activity were measured supine prior to and 60, 90, 120 minutes after oral captopril, 25 mg. PATIENTS: We have performed this test in ten patients with primary hyperaldosteronism, two with hypertension and secondary hyperaldosteronism and in ten normokalaemic patients with essential hypertension. MEASUREMENTS: Validity was assessed by mathematical prediction methods. RESULTS: Using a ratio of aldosterone to plasma renin activity greater than or equal to 1400 pmol/l per microgram/ml/h as a predictor of primary hyperaldosteronism, the captopril test had a sensitivity of 100%, a specificity of 83% and a predictive value of 82% with a 60-minute post captopril evaluation being sufficient. Nevertheless, this test was only marginally superior to a careful analysis of the supine values where a similar ratio in the presence of a normal or suppressed plasma renin activity predicted primary hyperaldosteronism with a sensitivity also of 100% but a slightly lower specificity of 75% and predictive value of 77%. CONCLUSION: Application of the captopril test to patients identified as abnormal by screening confirms all cases of primary hyperaldosteronism but false positive or equivocal results, necessitating further investigation, may occur in some patients with essential hypertension.     

Diagnostic value of the captopril test in patients with arterial hypertension

In 30 patients with renovascular hypertension, 50 with hypertension in a course of arteries, 71 hypertensive subjects with coexisting parenchymal nephropathy and in 63 with primary hypertension the captopril test was performed after 8 hours night rest and within high sodium diet. Positive test result was stated in 76.67% of patients with renovascular hypertension, in 70.59% of patients with arteritis, in 53.52% of patients with hypertension and coexisting parenchymal nephropathy and in 63.49% of patients with primary hypertension. Significant correlation between increase of plasma renin activity and blood pressure decrease after captopril administration was only stated in patients with renovascular hypertension and in those with arteritis. Results of performed studies impaired the captopril test value in diagnostics of renin-dependent hypertension.     

The captopril test for identification of renovascular hypertension: value and immediate adverse effects

Abstract. To develop a screening test for identification of renovascular hypertension, the blood pressure and plasma renin concentration responses to an oral test dose of captopril (6.25 mg) were studied in 47 hypertensive patients of mean age 61 years (range 34-85 years). Blood pressure was measured at 15-min intervals for 90 min after administration of captopril. Blood samples for plasma renin determination were drawn immediately before and 90 min after drug administration. Eleven patients had renal artery stenosis. The fall in diastolic blood pressure in these patients was greater, on average, than in patients with other forms of hypertension (30 mmHg vs. 14 mmHg, P < 0.01), as was the increase in plasma renin concentration (188 mU l^?1 vs. 2 mU l^?1, P < 0.01). This study demonstrates that the short-term captopril test is useful for distinguishing patients with renovascular disease from those with other forms of hypertension. During the test, 7 patients (15%) exhibited reversible cerebral symptoms. In two of these subjects digital subtraction angiography was performed, which revealed stenosis of the carotid artery. Consequently, it is suggested that captopril should not be used in patients with arteriosclerotic stenoses of the carotids.     

Captopril-stimulated renin in the diagnosis of restenosis after percutaneous transluminal renal angioplasty

Recurrence of hypertension is reported in a considerable percentage of renovascular hypertensive patients treated by percutaneous transluminal angioplasty (PTRA); among the possible mechanisms for these failures, restenosis of the renal artery is the only correctable one. Since captopril stimulates renin secretion to a greater extent in renovascular than in essential hypertensive patients, we determined if it could be used to unmask significant restenosis in the patients with hypertension recurring after PTRA. Follow-up study was performed in 28 patients treated with PTRA. We found that captopril caused a greater increase in peripheral plasma renin activity in 8 of 8 cases who had recurrence of hypertension and restenosis than in 13 of 15 of the patients who did not. We suggest that the determination of captopril-stimulated renin may provide a useful, simple and economical tool for the detection of restenosis after PTRA.     

Stimulation of Plasma Renin Activity by Captopril in Renovascular Hypertensive Conscious Dogs

The increase in plasma renin activity induced by captopril is used in the clinical evaluation of renovascular hypertensive patients. This increase in plasma renin activity could result from either the concomitant fall in systemic pressure or other effects of captopril, such as the removal of an angiotensin II inhibitory effect on renin release, the increased production of bradykinin or prostaglandins, etc. To examine the effect captopril has on plasma renin activity, independent of changes in systemic pressure, captopril (5, 10 and 50 μg/kg iv) was administered to conscious dogs before and following the development of 1 clip-2 kidney Goldblatt hypertension. Plasma renin activity, under normal conditions remained unchanged, while during hypertension It increased 2.0, 2.8 and 3.5 fold respectively in response to the three doses of captopril. These results suggest that the development of renovascular hypertension sensitized the kidney to release renin when challenged by captopril and that the effect is independent of changes in systemic pressure.     

Dynamic evaluation of the renin-angiotensin system with captopril in screening for renovascular hypertension

In 69 hypertensive with suspected renovascular hypertension the response of plasma renin and angiotensin I to a single oral dose of Captopril (Captopril test) was determined. In 15 of the 16 patients found to have renal artery stenosis at angiography and cured by either revascularization or nephrectomy, Captopril stimulated both plasma renin activity and plasma angiotensin I to a far greater extent than in the majority of the 53 classified as essential hypertensives. False positives were limited to 8. Sensitivity and specificity were 94% and 85%, respectively. In the same series sequential renal angiophotoscan showed 100% sensitivity but a lower specificity (75%). In comparison, both the sensitivity and the specificity of rapid-sequence intravenous pielography, isotopic renogram and recumbent plasma renin activity were far less satisfactory. It is concluded that this simple, safe and economical test should be preferred to the other diagnostic procedures in the screening of renovascular hypertension. Its use in combination with renal angiophotoscan improves diagnostic reliability.     

The captopril test in the detection of renovascular disease in hypertensive patients

A number of reports share the conclusion that the captopril test is an adequate screening procedure for the detection of renovascular disease among hypertensive patients. Therefore, we prospectively studied the value of this test in 149 consecutive hypertensive patients. The test was considered positive if plasma renin activity, after an oral dose of 25 mg of captopril, rose by more then 4.44 ng.L-1.s-1 (16.0 ng/mL per hour). The sensitivity of the test was 39%, the specificity was 96%, the positive predictive value was 81%, and the negative predictive value was 79%. No clinically important cutoff point identifying patients with renal artery stenosis could be detected in the values of baseline and stimulated plasma renin activity nor in baseline blood pressure or changes after captopril testing. The low sensitivity makes the captopril test unfit to be used as a screening procedure in an unselected hypertensive population.     

Captopril test: time over?

OBJECTIVE: The role of non-invasive tests for the detection of renovascular hypertension is still a matter of controversy. The 'captopril test' is widely used; its clinical usefulness, however, remains questionable. The aim of the current study was therefore to report our own experience and to review the published data on the diagnostic significance of the test. PATIENTS AND METHODS: Data from 485 hypertensive patients who underwent a captopril test in consecutive order at our institution were analysed retrospectively. After a 30-min resting period in the supine position 50 mg of captopril was given orally. Blood was collected before and 90 min after dosage for the determination of plasma renin concentration (normal range 3.5-8.0 ng/ml/h). An increase by 100% or more of the baseline value was considered a positive response. Blood pressure was recorded at baseline and at 90 min. RESULTS: A positive response was present in 62 patients; further diagnostic work-up revealed significant renal artery stenosis in 11 of these patients. In the 423 patients with a negative response renal artery stenosis was found in three cases. With some limitations of retrospective analyses in mind, sensitivity and specificity of the test were calculated as 79% and 89%, respectively. No severe complication occurred during the test. CONCLUSION: Our data on the diagnostic indices and the safety of the captopril test are in good agreement with most published series. Altogether, available data suggest that the captopril test has a limited diagnostic accuracy as a screening test for the detection of renovascular hypertension. New radiologic non-invasive techniques with greater diagnostic value are therefore likely to challenge the clinical role of the test in the future.     

Detection of renovascular hypertension. State of the art: 1992.

PURPOSE: To review recent advances in detecting renovascular hypertension. DATA SOURCES: Original English-language reports obtained through a MEDLINE search for the years 1987 to 1991. Also, a manual search through Index Medicus as well as bibliographies of original reports and selected review articles. STUDY SELECTION AND DATA EXTRACTION: Cited studies were critically reviewed with emphasis on study size, patient sample, methods, diagnostic criteria, and reproducibility of results. Where applicable, reviews that combined the results of smaller studies are cited. RESULTS: A sensitivity of 74% and a specificity of 89% have been reported for the captopril test and of 93% and 95%, respectively, for captopril scintigraphy with diethylenetriaminepentaacetic acid (DTPA). The sensitivity and specificity of renal vein renin determination are 80% and 62%, respectively and may increase with the use of stricter technical criteria and maneuvers to stimulate renin secretion. These tests differentiate renovascular hypertension from essential hypertension more reliably than from asymmetric renal parenchymal disease; however, they do not reliably distinguish unilateral from bilateral stenosis. Other tests are less widely used. Intravenous pyelography (sensitivity, 74.5%; specificity, 86.2%) has the disadvantages of radiation and dye load exposure. Intravenous angiography is expensive and invasive and does not always enable visualization of the origin of the renal artery. The roles of duplex ultrasound and magnetic resonance angiography remain to be clarified. CONCLUSIONS: Noninvasive tests are cost effective and have a high predictive value in patients with clinical clues suggestive of renovascular hypertension. These tests are not recommended for use in patients with a low likelihood of disease.     

Use of Captopril in the Diagnosis of Renal Hypertension

Abstract: 1 . The effects of a single 25 mg oral dose of captopril on blood pressure, heart rate and circulating renin, angiotensin I, angiotensin II, bradykinin and catecholamine levels were examined in untreated patients with essential (n = 10, Group I), accelerated (n = 6, Group II) and renal hypertension (n = 8, Group III) studied on a normal sodium diet .
2 . Mean blood pressure fell only slightly in Group I patients, (113 ± 3 to 109 ± 3 mmHg at 60 minutes) but a greater fall was observed in Group II (153 ± 8 to 135 ± 11 mmHg) and a marked fall in Group III, (136 ± 3 to 114 ± 5 mmHg). There were no significant changes in heart rate in any group .
3 . Plasma angiotensin II levels were significantly reduced 30 minutes after captopril in all three groups and returned toward resting values after four hours. The falls in plasma angiotensin II levels were accompanied by reciprocal increases in blood angiotensin I and plasma renin, but blood bradykinin and plasma catecholamine concentrations remained unchanged .
4 . Resting plasma renin levels showed considerable overlap in the three groups and the mean renin values were not significantly different in the three groups. After captopril a marked rise in plasma renin concentration (>2.5 ng/ml/hr) was observed in seven patients in Group III, including all six patients with renovascular disease. In contrast, none of the patients with essential hypertension and only one patient with accelerated hypertension had such an increase. Determination of the acute renin and blood pressure responses to converting enzyme inhibition with a single oral dose of captopril appears to be useful in identifying patients with renovascular hypertension .     

Clinical evaluation of the captopril screening test for primary aldosteronism

In order to investigate the validity of angiotensin converting enzyme inhibition with captopril as a screening test for primary aldosteronism (PA), 50 mg of captopril were administered orally to 7 patients with PA, 17 with essential hypertension (EH), 5 with renovascular hypertension (RVH), 2 with renoparenchymal hypertension (RH) and 8 normal volunteers. The plasma aldosterone concentration (PAC) was suppressed to less than 15 ng/dl in all of the EH, RVH and RH patients and normal subjects 90 min after administration of captopril, but not suppressed in 6 of 7 patients with PA. In addition, the plasma renin activity (PRA) was increased to greater than 1 ng/ml/h in 10 of 17 patients with EH and in all with RVH, RH and the normal controls, but to less than that in 6 of 7 PA and the remaining EH patients. The PAC to PRA ratio after captopril was greater than 20 in all patients with PA, while it remained below 20 in EH, RVH and RH patients and normal controls. From these results, we conclude that the PAC to PRA ratio in the captopril administration test is a simple and useful tool to detect PA in hypertensive patients. In addition, the test has a great advantage in that it can be safely applied to outpatients with relatively severe hypertension.     

Conversion of inactive renin to active renin following acute angiotensin converting enzyme inhibition in essential hypertension and renovascular hypertension

The physiological role of inactive renin, especially the question of whether and how a conversion to active renin takes place in vivo, remains controversial. In order to show the dynamic alterations from inactive to active renin following acute ACE-inhibition, both forms of renin were investigated in both renal veins and the peripheral circulation of 20 patients with essential hypertension and 20 patients with renovascular hypertension before and 1 h after 25 mg of captopril. Active and inactive renin were determined indirectly as plasma renin activity (PRA, unit: ng/ml x h). In vitro activation of inactive renin was achieved with trypsin (1 mg/ml plasma), followed by a further determination of PRA (= total renin). Subtraction of the active renin from the total renin yields the amount of inactive renin. In patients with essential hypertension, the mean values of active renin increase equally in both renal veins (1.4 and 1.3 before, 1.9 and 1.8 after captopril) and the peripheral circulation (0.9 and 1.3) (p less than 0.002), whereas the inactive renin decreases correspondingly. Renal veins: 7.6 and 8.2 before, 7.2 and 7.6 after captopril; peripheral circulation: 7.7 before and 7.0 after captopril (p less than 0.05). In all patients with renovascular hypertension, there is basally a marked lateralization of active renin (6.4 vs 3.5; p less than 0.01) and inactive renin (20.5 and 18.9, p less than 0.03) towards the side of the ischemic kidney. After captopril, the values for total renin and active renin increase (p less than 0.001), and the side difference for active renin becomes still more pronounced (33.0 vs 14.2; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Reversible renin-dependent renovascular hypertension successfully treated with percutaneous transluminal renal angioplasty and stenting

A 37-year old woman was suspected of having renovascular hypertension because of recent onset severe hypertension (blood pressure 220/135 mmHg; compared to 132/65 mmHg two years earlier) and an abdominal bruit. A captopril renal scan indicated the presence of right renal artery stenosis. Additionally, a captopril plasma renin activity (PRA) provocation test showed a positive result for renovascular hypertension (baseline PRA = 291 microU/mL; 1 hour post-captopril PRA = 1444 microU/mL). Selective renal angiography demonstrated a severe critical stenotic lesion at the distal portion of the right renal artery. Blood pressure (BP) decreased to 136/80 mmHg one day after successful percutaneous transluminal renal angioplasty and stenting. Repeat renal angiography six months after the procedure revealed no evidence of in-stent restenosis. Blood pressure (BP = 137/76 mmHg) and plasma renin profile (baseline PRA = 23.8 microU/mL; 1 hour post-captopril PRA=22.3 microu/mL) also were normal six months following initial revascularization. Moreover, blood pressure (137/84 mmHg) and renin profile remained normal 2.5 years after the procedure (baseline PRA = 24.3 microU/mL; 1 hour post-captopril = 25.6 microU/mL). The results of this study have thus demonstrated a case of renin-dependent renovascular hypertension in which both the blood pressure and plasma renin activity profile normalized following successful percutaneous transluminal angioplasty and stenting.     

Effects of a single administration of captopril on hemodynamics and serum angiotensin converting enzyme activity, plasma renin activity and plasma aldosterone concentration in hypertensive patients

Hemodynamic responses and behaviors of the renin-angiotensin-aldosterone system to a single administration of captopril (50 mg) were studied in 16 hypertensive patients (essential hypertension, n = 10; renovascular hypertension, n = 3; primary aldosteronism, n = 2; Cushing's syndrome, n = 1). In 10 essential hypertensive patients, the immediate blood pressure reduction caused by decreased total peripheral resistance after the administration of captopril was observed without changes of cardiac output and heart rate. Serum angiotensin converting enzyme activity and plasma aldosterone concentration significantly decreased, whereas plasma renin activity significantly elevated 2 hours after the administration of captopril. The close relationship between the pretreatment value of plasma renin activity and the maximum decrease in mean blood pressure in 16 hypertensive patients suggests that the depressor response to a single administration of captopril could evaluate the degree of angiotensin II dependency in the maintenance of high blood pressure in various types of hypertension.     

High prevalence of primary aldosteronism using postcaptopril plasma aldosterone to renin ratio as a screening test among Italian hypertensives

The prevalence of primary aldosteronism (PA) was assessed in a specialized hypertension center. Baseline and postcaptopril (50 mg orally) aldosterone to plasma renin activity ratio (A/R) as a screening tool were preliminarily tested in a sample including 22 patients with histories of PA and 53 patients with low-renin essential hypertension (EH). Sensitivity and specificity of A/R ≥35 were 95.4% and 28.3% at baseline, compared with 100% and 67.9% after captopril. Using postcaptopril A/R ≥35 and confirmation by acute saline loading, a PA prevalence of 6.3% was found among 1046 consecutive hypertensive patients with normal renal function. Of those 66 PA patients, 16 (24.2%) had a unilateral adenoma, whereas 50 (75.8%) had idiopathic hyperaldosteronism. At presentation, 45.4% of the PA and 16.3% of EH patients were treated with two or more antihypertensive drugs (χ² = 33.117, P < .0001). However, among untreated patients (n = 553), the prevalence of mild-to-moderate hypertension (ie, <180/110 mm Hg) was not different between patients with PA and those with EH (70.6% v 76.7%, χ² = 0.086, P = .770). Serum potassium ≥3.6 mEq/L was found in 60.6% of PA patients. In conclusion, we observed the following: 1) postcaptopril compared with baseline A/R is a better screening tool for PA; 2) PA is relatively frequent among hypertensive individuals; 3) PA is not necessarily associated with severe hypertension; and 4) hypokalemia is an insensitive screening criterion for PA.     

Reactive hyperreninemia in renovascular hypertension after angiotensin blockage with saralasin or converting enzyme inhibitor.

Baseline plasma renin activity and responses to saralasin and converting enzyme inhibitor SQ 20881 (teprotide) in 47 untreated patients with surgically correctable renovascular hypertension were compared to those in 100 patients with high- and normal-renin essential hypertension. All 32 renovascular patients on normal sodium intake had high renin-sodium profiles and renin values greater than or equal to 5 ng angiotensin I/mL.h, as compared to 20 of 64 with essential hypertension. Diagnostic discrimination was greatly enhanced by infusion of saralasin or SQ 20881, which elicited marked reactive hyperreninemia in 31 of 32 renovascular patients but in only two of 64 with essential hypertension. Reactive hyperreninemia appeared to be more a specific test for renovascular hypertension than depressor responses. Prior dietary sodium depletion abolished this specificity. The results suggest that after initial screening with renin measurements, testing with angiotensin blocking agents may be a useful secondary screening procedure for more invasive and definitive procedures.