Captopril Renography Research Articles

Prospective study on the prevalence of secondary hypertension among hypertensive patients visiting a general outpatient clinic in Japan.

Secondary hypertension (SH) including endocrine hypertension has been reported to be uncommon. We estimated the prevalence of SH among hypertensive patients. We prospectively studied 1,020 hypertensive patients. As an initial screening, we measured plasma aldosterone concentration, plasma renin activity, serum cortisol concentration and plasma catecholamine concentration and conducted abdominal ultrasonography (US). As a secondary screening, we performed furosemide plus upright test, captopril renography, dexamethasone suppression test, 24-h urine catecholamine measurement and abdominal CT. Finally, primary aldosteronism with the exception of idiopathic hyperaldosteronism, pheochromocytoma, and Cushing's syndrome were diagnosed by histopathological examination of surgical specimens. Idiopathic hyperaldosteronism was clinically diagnosed by adrenocorticotrophic hormone (ACTH)-stimulated adrenal venous sampling and renovascular hypertension by renal arteriography. There were 61 patients with primary aldosteronism, 5 with renovascular hypertension, 11 with Cushing's syndrome, 10 with preclinical Cushing's syndrome and 6 with pheochromocytoma, and the prevalence of SH was 9.1% among 1,020 hypertensive patients. In 76 (82%) of 93 patients with SH, hypertension was cured or improved after unilateral adrenalectomy, transsphenoidal pituitary adenectomy or percutaneous transluminal angioplasty. With the exception of US and CT, all initial and secondary screening tests were found to be sensitive and specific for differentiating SH from essential hypertension (EH). In conclusion, the measurement of various hormone concentrations was very sensitive for ruling out SH--a condition for which, in the present study, there were few specific signs or symptoms--while CT and US examinations were not always useful for differentiating SH from EH. The prevalence of curable SH among hypertensive subjects was higher in this study, which was conducted by our simple method of screening tests, than in previous reports. Hypertensive patients should be screened for SH and the underlying disease treated appropriately to avoid long-term use of antihypertensive drugs and risks of atherosclerotic complications.

Calcium channel blockers: a potential cause of false-positive captopril renography.

The purpose of the study was to review the causes of false-positive and false-negative captopril Tc-99m MAG3 renograms performed to evaluate renovascular hypertension at the authors' institution. From May 2000 to January 2002, 77 patients were referred for evaluation of possible renovascular hypertension with captopril Tc-99m MAG3 renography. If the findings of the captopril study were abnormal, a baseline study was performed 3 days later. The captopril studies were retrospectively reviewed and correlated with available renal arteriography, magnetic resonance angiography, and duplex Doppler sonography studies and clinical follow-up. Renal artery stenosis greater than 70% on an arteriogram and 60% on Doppler studies or magnetic resonance angiography was considered positive for renovascular hypertension. There were five false-negative and four false-positive studies. The five patients who had the false-negative captopril studies underwent arteriography, which showed renal artery stenosis, and a stent was placed in two of them. The four false-positive captopril studies were proved by negative arteriograms in three and negative magnetic resonance angiography in one. Three patients with false-positive studies had bilateral renal function impairment after captopril and were taking calcium channel blockers at the time of the captopril study. One patient had a left nephrectomy and was also taking calcium channel blockers. Chronic intake of calcium channels blockers is a potential cause of bilateral symmetric false-positive captopril renography.

Prognostic Significance of Captopril Renography for Managing Congenital Unilateral Hydronephrosis

In this prospective study we evaluated the results of captopril enhanced diuretic renography in patients with congenital unilateral ureteropelvic junction type hydronephrosis. Captopril renography helps to distinguish patients who have renin-angiotensin system activation from those in whom it is not yet activated. Renin-angiotensin system activation heralds the beginning of compensatory vasoactive response in the kidney. Identifying grades of such activation may help in determine the end points of nonoperative management. We prospectively studied 25 patients with suspected unilateral ureteropelvic junction obstruction treated at our department. A prenatal diagnosis was made in 60% of cases. Patient age was 1 to 144 months (mean 40) and the male-to-female ratio was 4:1. Followup was 6 to 72 months (mean 30). Patient evaluation and analysis included sonography, standard diuretic and captopril renography, glomerular filtration rate, serum creatinine and blood pressure. The indications for surgery were symptoms, differential function below 35%, or a documented decrease of 10% or more during followup. Activation of the renin-angiotensin system was considered positive when split renal function decreased significantly by 5% or more in an obstructed system on a post-captopril study. The results of captopril renography were examined retrospectively in patients who required surgery according to preexisting criteria. Society for Fetal Urology hydronephrosis grade was II to IV in 8, 10 and 7 renal units, respectively. The renin-angiotensin system was activated in 8 of the 25 cases (32%) of unilateral ureteropelvic junction obstruction. In 15 patients there was no change on pre-captopril and post-captopril studies and in 2 split renal function on the obstructed side marginally increased on the post-captopril study. Surgical correction was required in only 6 of the 8 patients with renin-angiotensin system activation. Of those who required surgery hydronephrosis was grades II to IV in 3, 1 and in 2 patients, respectively. In the current study renin-angiotensin system activation correlated with the need for surgery in 75% of the cases of congenital unilateral ureteropelvic type hydronephrosis. Since captopril serves to identify patients who have renin-angiotensin system activation, it may also be possible to grade this activation. Our preliminary results show that there may be a role for captopril renography for identifying the risk group for surgical intervention.

Prognostic Significance of Captopril Renography for Managing Congenital Unilateral Hydronephrosis

Prognostic Significance of Captopril Renography for Managing Congenital Unilateral Hydronephrosis

Captopril renography in Bartter's syndrome

We describe a 19-year-old man who developed muscle weakness due to hypokalemia. His blood pressure on admission was considered to be relatively high, and we performed captopril renography. His baseline renogram was normal, while the results of captopril renography showed delayed patterns similar to those of renovascular hypertension. However, his blood pressure level decreased and returned to the normal range without medication 2 weeks after admission. Our final diagnosis in this patient was Barter's syndrome. We speculate that the delayed pattern of captopril renography was due to an imbalance between the prostaglandin and the renin-angiotensin systems. The blockade of the renin-angiotensin system by captopril may cause dominant prostaglandins, produce systemic vasodilatory effects, and lead to hypoperfusion of the kidneys in patients with Bartter's syndrome.

Usefulness of captopril renography to predict the benefits of renal artery revascularization or captopril treatment in hypertensive patients with diabetic nephropathy

This retrospective study aimed to use captopril renography (CR) for predicting the benefits of captopril treatment in hypertensive patients with diabetic nephropathy. CR was utilized in 60 hypertensive patients with diabetic nephropathy for detecting the probability of renovascular hypertension (RVH) and predicting the benefits of renal artery revascularization or captopril treatment. Ten of the 60 patients showed a high probability of RVH with marked changes of the renogram curve after an oral intake of 50-mg captopril compared to baseline findings. All of the 10 patients confirmed significant main renal artery stenosis in all of them, bilaterally in four patients and unilaterally in the remaining six patients by renal angiographic findings. After successful revascularization, blood pressure was well controlled and renal function was preserved in all of the 10 patients. The other 50 patients showed a low or intermediate probability of RVH with normal findings or unchanged on CR after 50-mg captopril. Then, captopril alone or combination treatment started and continued on 50 patients. After monitoring for at least 6 months, blood pressure was well controlled and renal function was preserved in all the 50 patients on captopril treatment. We conclude that CR should be considered as the standard diagnostic criteria of RVH and may be helpful in predicting the beneficial impact of captopril treatment in hypertensive patients with diabetic nephropathy.

Arteriosklerotische Nierenarterienstenose

Renal artery stenosis (RAS) can cause arterial hypertension and can lead to renal insufficiency. In 1999 16% of patients starting dialysis in Germany suffered from ischemic nephropathy. Cost-effective screening for RAS should be done by Doppler sonography or captopril renography. Doppler sonographic findings can be predictive in respect to progression of stenosis, renal atrophy and postinterventional course of hypertension and kidney survival. The results of recent studies are helpful to select patients for preferential drug treatment or for interventional treatment.

Contemporary approach to diagnosis and evaluation of renovascular hypertension

Recommendations regarding the clinical protocols for radionuclides of choice and diagnostic criteria for renovascular hypertension have been established by the consensus report on captopril renography. A review of the existing data indicates that postcaptopril renography alone is a safe and effective means of noninvasively screening hypertensive patients. A normal radionuclide study after captopril suggests with a reasonable degree of certainty that potentially reversible renovascular hypertension is unlikely. A positive study in an appropriately screened hypertensive patient with preserved renal function suggests renovascular disease is likely with a sensitivity and specificity in excess of 90%. In the comparative studies of Elliott and Miralles and colleagues, captopril renography was a more sensitive and specific screening test than the captopril plasma renin activity test. Although there may be confounding variables, such as renal dysfunction, medications, and types of stenosis, a positive captopril renogram may suggest a cure or improvement in blood pressure control with successful intervention such as PTRA or revascularization. Whether captopril renography can predict stabilization of individual kidney function is speculative and deserving of further study.

Captopril renography and the relevance of abnormal but bilateral identical curves in the diagnosis of renal artery stenosis.

Captopril renography (CR) has been shown to improve the effectiveness of renal scintigraphy in renovascular hypertension, by inhibiting angiotensin-converting enzyme. CR is particularly sensitive and specific in unilateral renal artery stenosis (RAS), but results in patients with bilateral RAS are less favourable. The aim of this study was to investigate the meaning of abnormal but identical renographic curves in the diagnosis of RAS. One hundred and fifty-eight patients clinically suspected for renovascular hypertension underwent CR, using 50 MBq (99)Tc(m)-mercaptoacetyltriglycine ((99)Tc(m)-MAG(3)), prior to performing renal angiography. CR was performed 1 h after captopril administration. Renograms were analysed according to the consensus criteria. All patients underwent angiography, considered as the "gold standard" in the detection of the presence of RAS (stenosis >50% was defined as significant). All kidneys were categorized into three groups, scintigraphically as well as angiographically: no stenosis, unilateral stenosis and bilateral stenosis. Out of 158 patients 100 (63%) showed a RAS on angiography (58 (37%) unilateral, 42 (26%) bilateral). The sensitivity and specificity of CR evaluated by patient was 83% and 75%, respectively. Thirty patients with completely identical curves were identified, 21 patients with normal curves and nine patients with abnormal identical curves. All but one patient showed no RAS on the angiogram. In this single patient a unilateral stenosis was found. Identical curves on the renogram generally suggest no RAS and are probably due to intrinsic parenchymal disease.

DIURETIC RENOGRAPHY AND ANGIOTENSIN CONVERTING ENZYNE INHIBITOR RENOGRAPHY

Renovascular hypertension and renal outlet obstruction are two clinical conditions well evaluated by nuclear medicine techniques. They both require a specific intervention to challenge a specific aspect of renal functional reserve. Diuretic renography is the oldest common example in nuclear medicine where functional change in the kidney is provoked for diagnostic purposes. The kidney's tubular functional reserve, in this instance, is challenged to induce diuresis and increase urine flow. This intervention permits diuretic renography to retain an essential role in the evaluation of hydroureteronephrosis. Captopril renography is a more recent example of a similar principle and depends on a reactive renin-angiotensin system to identify a kidney responsible for RVH. In both renal outlet obstruction and RVH, an anatomic abnormality is also identified (hydronephrosis and RAS, respectively) at some point in the diagnostic workup. The final diagnosis in each instance, however, depends on evidence for a functional disorder, provoked and measured during the radionuclide interventional examination. These serve as excellent examples of the power of functional imaging to identify specific medical disorders.

Tc-99m-DTPA captopril renography in the detection of renovascular hypertension due to renal polar artery stenosis

A 24-year-old man whose clinical features were suggestive of renovascular hypertension was referred for captopril renal scintigraphy. Captopril renal scintigraphy was positive for renovascular hypertension only when the left kidney was analyzed in 2 separate regions. Angiography confirmed severe stenosis (90%) in the upper branch of the left renal artery.

Abstracts of literature

Abstracts of literature

Evaluation of duplex ultrasound and captopril renography for detection of renovascular hypertension

Renovascular hypertension is the most common form of curable secondary hypertension and, if untreated, may lead to end-stage kidney disease. Given that renal function and hypertension may improve after renal angioplasty, it is pertinent to identify patients with renal artery stenosis. The aim of the present study was to evaluate both duplex ultrasound and captopril renography for detection of renal artery stenosis among hypertensive patients. To avoid selection bias, all patients referred to our center for evaluation of renovascular hypertension were asked to participate in the study. Patients were examined by intra-renal duplex ultrasound (N = 121), measuring pulsatility index and acceleration of the blood flow during early systole. In 98 patients, 99mTc-DTPA captopril renography was performed in conjunction with duplex ultrasound. Renal angiography was performed in all patients regardless of the results of the noninvasive tests. The prevalence of renal artery stenosis was 19%. In the 98 patients examined by both duplex ultrasound and captopril renography, sensitivity and positive predictive values for detection of a renal artery stenosis of 50% degree or more were 84 and 76%, respectively, for duplex ultrasound, whereas captopril renography was associated with a sensitivity and positive predictive value of 68% for both (P = NS). Specificity and negative predictive values were 94 and 96%, respectively, for duplex ultrasound, whereas the corresponding values for captopril renography were 92% for both (P = NS). Specificity and negative predictive values were 94 and 96%, respectively, for duplex ultrasound, whereas the corresponding values for captopril renography were 92% for both (P = NS). Both duplex ultrasound and captopril renography are associated with high specificity and negative predictive values for detection of renal artery stenosis. Sensitivity and positive predictive values are at least as good for duplex ultrasound compared with captopril renography. Given that duplex ultrasound is easier to perform and more cost effective, we propose that it should be the method of first choice when screening for renal artery stenosis in a hypertensive population.

Management of Resistant Hypertension in Patients with Carotid Stenosis: High Prevalence of Renovascular Hypertension

Introduction: Patients with carotid stenosis are at high risk of vascular events and therefore require an optimal control of risk factors such as hypertension. As the treatment of hypertension differs according to the cause, we examined the prevalence of resistant hypertension, and the cause of hypertension, among patients with carotid stenosis followed closely in two randomized trials of carotid endarterectomy. Objective: The purpose of this study was to determine the prevalence of resistant hypertension and of secondary hypertension among patients with carotid stenosis. Methods: A chart review was performed of all patients from our center who participated in the North American Symptomatic Carotid Endarterectomy Trial or the Asymptomatic Carotid Artery Study to determine the prevalence of renovascular hypertension. Results: Among 170 patients with carotid stenosis followed in these two trials, 145 (83.5%) were hypertensive (systolic >160 or diastolic >90 mm Hg); at least 24 (14.1% overall, 16.6% of hypertensives) had renovascular hypertension based on either nuclear medicine renography, renal angiography or both; among the 79 patients with resistant hypertension (mean arterial pressure >130 mm Hg despite treatment), 20 (25.3%) had renovascular hypertension. Adrenocortical hyperplasia was the underlying cause of hypertension in 12 (7.1% of cases, 8.3% of hypertensives, 8.8% of resistant hypertensives). Blood pressures were significantly higher for patients with renovascular and adrenocortical hypertension (p < 0.0001 for systolic, p = 0.024 for diastolic pressures). Conclusion: Among patients with carotid stenosis, renovascular hypertension is unusually common. Resistant hypertension among such patients should lead to investigation and management directed at the cause of hypertension. Appropriate investigations might include plasma renin/aldosterone ratio, captopril renography and MRA of the renal arteries or renal angiography.

Captopril renography (CR) determinants in pts with single kidney (SK) with arterial hypertension (AH)

Captopril renography (CR) determinants in pts with single kidney (SK) with arterial hypertension (AH)

Captopril renography (CR) in women with essential hypertension (EH)

Captopril renography (CR) in women with essential hypertension (EH)

Assessment of Renal Artery Stenosis: Comparison of Captopril Renography and Gadolinium-Enhanced Breath-Hold MR Angiography

AIM: To determine the accuracy of captopril renography (CR) and gadolinium-enhanced breath-hold magnetic resonance (MR) angiography in the diagnosis of 50–99% renal artery stenosis (RAS).MATERIALS AND METHODS: Forty-three patients with possible RAS, of whom 53% had renal function impairment (creatinine >130μmol/l), were included.99mTc-mercaptoacetyl triglycine (MAG3) renography was performed after an oral dose of 25mg captopril. Gadolinium-enhanced MR angiography was performed on a standard 1.5 Tesla system: TR 13.5, TE 3.5, flip angle 60°, matrix 195×512. Intra-arterial digital subtraction angiography (DSA) was the standard of reference.RESULTS: Captropril renography accurately categorized 22 of 26 patients who had either uni- or bilateral RAS of 50–99%. The sensitivity and specificity of CR for the detection of 50–99% stenosis were 85 and 71%, respectively. With MR angiography one occluded artery was incorrectly diagnosed as a stenosis. Sensitivity and specificity were 100 and 94%, respectively. The difference between the accuracies of MR angiography and CR was statistically significant (P=0.02). The accuracy of CR was lower in patients with renal impairment (70%) than in those with normal renal function (90%).CONCLUSION: MR angiography showed a high accuracy in diagnosing RAS of between 50 and 99%. CR was less accurate than MR angiography, especially in patients with renal function impairment. In patients with normal renal function, however, CR remains a useful diagnostic test.Bongers, V. (2000). Clinical Radiology55, 346–352.

Screening for renal artery stenosis: which patients? Which test?

If a patient has clinical clues suggestive of renovascular hypertension such as persistently high blood pressure despite a multiple-drug regimen, it may be reasonable to screen him or her using captopril renography, duplex ultrasonography, or magnetic resonance angiography.

Predicting the outcome of invasive treatment of renal artery disease.

Analysis of the factors influencing the outcome of performed or attempted invasive treatment for renal artery disease (RAD). University Hospital. Thirty-five hypertensive patients with 31 stenoses and 14 occlusions of renal artery. Angioplasty was performed on 25 patients (attempted for 30), primary stenting on one, nephrectomy on three, and renal resection on one patient. A decrease of diastolic blood pressure (DBP) by >/=15 mmHg after intervention. A DBP response was seen in 24 patients. In 11 patients, invasive treatment did not result in a DBP response or failed technically. Compared with these patients, the responders were younger (55 +/- 11 vs. 66 +/- 8 years, P = 0.001) and tended to have higher DBP (100 +/- 8 vs. 93 +/- 11 mmHg, P = 0.065). The function of the affected kidney, or that of the more affected kidney if RAD was bilateral, was better preserved in responders (relative clearance on captopril renography 23 +/- 15 vs. 8 +/- 4%, P = 0.008). A response was more often seen in unilateral than in bilateral RAD (81% vs. 33%, P = 0.015). A relative clearance of </=10% on captopril renography had sensitivity of 88% and specificity of 81% for renal artery occlusion. Step-wise logistic analysis. (1) When DBP was< 95 mmHg with two antihypertensives, the response rate was 1/6 vs. 24/29 for more severe hypertension (P = 0.004). (2) Elderly patients had a response rate of 2/5 vs. 22/24 in younger patients (P = 0.024). (3) Response rates in bilateral and unilateral disease were not different, nor did the function of the affected kidney impact the DBP response. However, three of the four responders with </=10% relative clearance had an occluded renal artery and underwent nephrectomy. Middle-aged patients with easily controlled hypertension and elderly hypertensives do not usually have a blood pressure response to the performed or attempted invasive treatment of RAD. Therefore, it seems recommendable not to screen such patients for RAD, unless their renal function is deteriorated. If the affected kidney functions poorly on captopril renography, angioplasty is usually not applicable and seldom leads to a blood pressure response.

Quantitative Residual Cortical Activity Measurement: Appropriate Test for Diagnosis of Renal Artery Stenosis?

Objectives: To evaluate the diagnostic validity of quantitative measurement of residual cortical activity (RCA) in renal artery stenosis (RAS). Methods: In 45 patients with a high clinical likelihood of renovascular hypertension (RVH) and unimpaired renal function, dynamic imaging was performed after an intravenous bolus injection of 148 MBq ^99mTc MAG3 for both baseline renoscintigraphy and captopril renography following oral application of 50 mg captopril. RCA was measured according to the Sfakianakis method: RCA = cortical counts at 20 min/counts at peak ×100%. An increase in RCA of ≥5% from baseline was considered indicative of RAS. After renography, all patients underwent selective transfemoral angiography with the digital subtraction technique. A luminal reduction of ≥50% was considered as proof of RAS. Results: The number of kidneys that had a change of ≥5% in RCA values was 12 (27.2%) in normal kidneys, 7 (58.3%) in the patients with bilateral RAS, 14 (82.3%) in the patients with unilateral RAS, and 21 (72.4%) in overall kidneys with RAS. The positive test ratio in pathologic groups was significantly higher than normal (p < 0.05). The sensitivity and specificity of the RCA test were 72.4 and 72.7%, respectively; the positive and negative predictive values were 63.6 and 80%, respectively. Conclusion: Quantitative measurements of RCA can be used as a diagnostic parameter of renal artery stenosis and may contribute of the diagnostic accuracy of visual interpretation and other renographic diagnostic criteria.