Renal Vein Renin Studies Research Articles

Cure With Cryoablation of Arterial Hypertension Due to a Renin-Producing Tumor

We herein report on a 20 years old woman with stage I hypertension, who was found to carry a renin-producing tumor (RPT). Due to her young age, the patient underwent screening measurement of plasma renin and aldosterone, abdominal computed tomography (CT) angiography, and selective renal vein renin assessment to identify secondary hypertension. The patient was screened for secondary causes of hypertension and was diagnosed with secondary aldosteronism. Therefore, she underwent an abdominal computed tomography (CT) angiography that was reported as unremarkable. Selective renal vein renin studies showed overproduction of renin in the right kidney and a re-evaluation of her CT allowed detection of an 8-mm mass in her right kidney, suggesting the presence of a RPT. Considering the technical difficulty of renal sparing surgery a CT-guided cryoablation was undertaken, which provided long-term cure of arterial hypertension and normalization of plasma active renin concentration. RPTs usually present with a clinical phenotype featuring stage III and/or malignant hypertension and are held to be exceptionally rare. This case is unique in that it presented with stage I hypertension and a mild clinical phenotype. Moreover, to our knowledge this is the first case of RPTs shown to be safely treated with CT-guided cryoablation and found to be cured at long-term.

The usefulness of renal vein renin studies in hypertensive children: a 25-year experience.

Lateralised renin secretion predicts improvement following surgery/angioplasty of the affected kidney in paediatric hypertension. We retrospectively analysed all our renal vein renin (RVR) studies undertaken in hypertensive children and their subsequent clinical outcomes over a 25-year period. The outcomes were categorised as cure, improvement or no change in hypertension. The proportions that benefited by 'following' or 'ignoring' the RVR results in relation to the aetiology of hypertension and subsequent therapy were compared. A ratio between the RVR value of the dominant kidney and that of the contralateral kidney (R/Rc ratio) above 1.5 was considered to show significant lateralisation. A ratio between RVR value of the contralateral kidney and that of the caudal inferior vena cava (Rc/P ratio) of less than 1.3 was considered to indicate contralateral renin suppression. Of 233 RVR records, 137 were suitable for analysis. Of these, 39 had reflux nephropathy (RN), 73 renovascular disease (RVD) and the others miscellaneous conditions. Of the 39 hypertensive children with RN, the R/Rc ratio was over 1.5 in 20 subjects, of whom 11 underwent surgery. Amongst the 19 with an R/Rc less than 1.5, 4 also had surgery. Of the 73 hypertensive children with RVD, the R/Rc ratio was over 1.5 in 38 subjects, of whom 20 underwent surgery/angioplasty. Amongst the 35 with an R/Rc less than 1.5, 7 also underwent surgery/angioplasty. In RN there was no significant difference in the proportion that improved with allocated treatment, as suggested by the 'test' when compared with those who were 'misallocated'. In RVD, however, the proportion improved (35.0%) by 'following the test' (i.e. R/Rc ratio) was significantly greater than the proportion improved (12.5%) in the group in whom the test was 'ignored'. This was true for both R/Rc and Rc/P ratios. Thus, RVR measurements are useful for identifying hypertensive children with RVD that may have a favourable outcome after surgery, but this does not apply to children with RN. Measurements, however, may have diagnostic value even if surgery or angioplasty is not anticipated.

Renal secretion and hepatic clearance of human multiple renin forms.

Human active renin can be separated into at least five forms by isoelectric focusing. The present study assessed the preferential renal secretion and hepatic degradation of renin forms in humans. The renin form profile of secreted renal renin was determined before transplant in an ex vivo kidney donor perfusion system and compared with the peripheral plasma multiple renin form profile of normal subjects. The effect of hepatic degradation on renin forms was assessed in hepatic vein plasma in comparison with infrarenal vena cava plasma in hypertensive patients during renal vein renin studies. The results revealed a significantly greater proportion of the more basic forms in the perfusate of donor kidneys compared with normal plasma. In hypertensive patients the proportion of the more basic renin forms in the hepatic vein was significantly decreased in comparison with the infrarenal vena cava. Thus, the human kidney may preferentially secrete the more basic renin forms. In contrast, the liver preferentially degrades the more basic forms, giving these forms a shorter plasma half-life. The preferential secretion and clearance of the more basic forms of renin may contribute to short-term control of human renin-angiotensin system activity.

Small kidney and hypertension: selection of patients for surgery.

We studied 37 patients with various degrees of hypertension and a small unilateral kidney. Renal vein renin studies were shown to be positive on 19 occasions and negative on 18. Of those positive, 10 had severe and 1 moderate hypertension. Surgery cured 63.3%. In 27% blood pressure improved and 1 patient failed to respond. Eight patients had mild hypertension with a positive renal vein renin ratio (RVRR), but on observation their home blood pressures were normal without medication and they were not considered for surgery. Eighteen patients with mild hypertension and negative RVRR were also not operated. We believe that RVRR is important for a surgical decision, but only in severe and moderate hypertensives. In mild hypertension, measurement of blood pressure at home is normal on most occasions. These are hyperreactive patients and should not have surgery, regardless of the results of their RVRRs.

Renal vein renin measurement and arteriography in the investigation and management of severe childhood hypertension

Forty-two children aged one to sixteen years with persistent and severe hypertension were investigated by renal vein renin measurements. There were no serious complications in the 49 procedures performed and technical failure occurred on three occasions. Arteriography was performed in 35. Asymmetrical renin release was found in 22 patients and of these 15 underwent surgery. This was successful in 12 patients (80%) who became normotensive. Ten had unilateral disease (100% cure rate) but only 2 (40%) with bilateral disease became normotensive. Renal vein renin studies combined with arteriography have a useful role in the investigation and management of childhood hypertension.

Renal vein renin studies in renovascular hypertension--do they really help?

Measurement of the renal vein renin ratio (RVRR) is commonly used to predict the response of blood pressure to surgery in hypertensive patients with unilateral renovascular disease. We have reviewed our experience in 37 such patients in whom renal vein renin levels were measured basally and after stimulation of renin secretion with intravenous diazoxide or tilting. Twenty-four patients were cured or improved. When a basal ratio of greater than or equal to 1.5 (diseased: normal kidney) was taken as a positive test the false positive rate was 39% and the false negative rate 71%, there being little difference in outcome between those with ratios above or below 1.5. No other threshold value of RVRR identified those responding to surgery, and acute stimulation of renin secretion did not increase the value of the test. We conclude that the RVRR is of no prognostic value in the surgical treatment of hypertension due to unilateral renovascular disease.

Renal artery digital‐subtraction angiography: An outpatient investigation for renovascular hypertension

The adequacy and convenience of the digital-subtraction angiographic procedure by means of a Diasonics DF100 as an investigation in renovascular disease were assessed over a nine-month period in 82 sequential renal artery studies, of which 76 were carried out in patients referred for the investigation of hypertension. Contrast medium was injected as a bolus by way of a centrally placed venous catheter, or a small (5 French size or smaller) arterial catheter. Patients tolerated the procedure well, and were fully mobile within 10 minutes to one hour (venous injection) and within two hours (arterial injection) after the procedure. Of the 82 studies, nine were judged as inadequate. All technical failures occurred with the venous injection technique. Of the 76 patients with hypertension, the main renal artery was judged as normal in 61. Renal artery lesions were demonstrated in 15 studies (13 patients). Renal vein renin studies, and the clinical or postoperative course supported the diagnosis of renovascular hypertension in 11 of these. Digital-subtraction angiography of the renal artery is a useful investigation in suspected renovascular hypertension. Its major advantage over conventional angiography is that it can be performed on an outpatient basis.

Early Surgery in the Management of Pediatric Blunt Renal Trauma

Of 40 children with major blunt renal injuries managed surgically 30 (75 per cent) could be followed up to 13 years postoperatively (mean 4.5 years). Measurements of renal size on sequential excretory urograms demonstrated normal growth of the traumatized kidney in all but 1 child. No hypertrophy of the contralateral kidney was noted in any child. Kidney length correlated with renal plasma flow calculated by sequential scintiscans (r equals 0.77). Hypertension was noted in 3 patients. Split renal vein renin studies and angiography showed that hypertension was caused by renal artery stenosis in 1 patient. Although we cannot draw any firm conclusions with regard to the optimal management of major blunt renal injuries, we present precise data that are valuable in comparison to other series of patients managed conservatively or surgically.

Experience in the Management of Hypertension with Unilateral Chronic Pylkonephritis: Results of Nephrectomy in Selected Patients

We report the experience of a regional centre serving a population of 3 millions in the management of patients with hypertension and unilateral scarred kidneys between 1972 and 1981. Thirty one patients were studied, fifteen have been subjected to nephrectomy and sixteen managed conservatively. The medically and surgically treated patients differed only in that the diseased kidney was smaller, 7.7 +/- 1.9 vs 9.9 +/- 1.7 cm, (p less than 0.01), and systolic blood pressure higher, 224 +/- 34 vs 198 +/- 30 mmHg, (p = 0.05), in the surgically treated group. Following nephrectomy blood pressure was normal without drugs in four patients, control was made easier in 10 patients and only one patient, who had bilateral disease, failed to benefit. In the non-surgical group drugs could be withdrawn in only one patient and control became easier in only five. Serum creatinine did not increase following nephrectomy, but had increased significantly at the time of the most recent follow up in the medically treated patients (89 +/- 20 to 102 +/- 32 mumol 1(-1), p less than 0.05). We conclude that nephrectomy is of value in the management of some patients with unilateral chronic pyelonephritis and need not result in loss of renal function. Renal vein renin studies may be helpful in selecting patients for surgery but examination of the effect of nephrectomy in patients without differences in renal vein renin is necessary to establish this.

Renovascular hypertension with unilateral atherosclerotic renal artery occlusion: diagnostic use of renal vein renins.

Selective renal vein renin studies were performed in seven male patients with severe hypertension and atherosclerotic occlusion of a main renal artery. In five patients, peripheral plasma renin activity was increased, and there was evidence for hypersecretion of renin from the affected kidney and suppression of renin release from the opposite kidney. In one patient, who had occlusion of one renal artery and a high-degree stenosis of the contralateral renal artery, the two kidneys appeared to contribute equally to the high circulating plasma renin activity. Removal of the atrophic, ischemic kidney from these patients, plus bypass of the contralateral renal artery in one patient, resulted in cure or improvement of their hypertension. In one patient, despite hypersecretion of renin from the atrophic kidney, surgery was not recommended because his systemic blood plasma renin activity was not elevated. Histologic examination of the excised kidneys revealed moderate glomerular scarring and tubular atrophy. The findings indicate that the same criteria, derived from renal vein renin studies, that have been used to predict the outcome of surgical repair of renal artery stenosis in hypertensive patients can be applied to the evaluation of patients with hypertension and complete occlusion of a main renal artery.

Frequent Falsely Negative Renal Vein Renin Tests in Unilateral Renal Parenchymal Disease

A retrospective analysis of 12 hypertensive patients with unilateral renal parenchymal disease was done to evaluate the roles of renal vein renin testing and an operation. The patients were considered to have renal parenchymal disease on the basis of radiographic and/or pathologic findings. Only 2 patients had positive renal vein renin studies. Both of these patients were improved after unilateral nephrectomy but 1 had subsequent progression of disease and renal failure. Of the 10 patients with negative studies 5 had unilateral nephrectomy: 4 of them, nevertheless, experienced substantial improvement in the hypertension.It is concluded that hypertensive patients with unilateral renal parenchymal disease often can benefit from an operation and that renal vein renin testing in such patients can be misleading.

Surgical Correction of Renovascular Hypertension: Dissociation between Post-operative Changes in Plasma Renin and Blood Pressure

Conventionally used criteria for predicting the blood pressure response to surgery in renovascular hypertensive disease rely on the demonstration of renin dependency. To assess the validity of this, we have related post-operative changes in plasma renin to the efficacy of surgical treatment of renovascular hypertension. We report nine hypertensive patients with unilateral renal disease and raised peripheral plasma renin activity (PRA), who were studied before and after either nephrectomy or renal artery stenosis bypass. In four patients blood pressure fell to normal levels, and has remained normal without treatment for periods varing from one to four years. In only one of these patients did renal vein renin studies indicate hypersecretion of renin on the operated side with contralateral suppression. Of the remaining five patients, three showed partial reduction of diastolic blood pressure and in two blood pressure was unchanged, although it was more easily controlled with antihypertensive medication. In all patients studied, peripheral venous plasma renin activity fell significantly after surgery, becoming normal in seven patients: in one of these blood pressure was unchanged, and it remained significantly elevated in two. Thus, correction of renin hypersecretion is not necessarily associated with restoration of blood pressure to normal. Tests for surgical correctability of renal hypertension which attribute a central role to renin hypersecretion may therefore yield misleading results.

Renin Profiling for Diagnosis and Treatment of Hypertension

Recent research shows that the renin-angiotensin-aldosterone axis either maintains or causes some or all of the high blood pressure of most patients and demonstrates anew that renin-sodium profiling defines this involvement. Performed with a serum potassium measurement, this now reliable test is useful for primary screening and then, in conjunction with renal vein renin studies or an aldosterone profile, for diagnosis or exclusion of surgically curable renovascular or adrenocortical hypertensions. For the remaining majority with essential hypertension, renin profiling exposes the relative participation of either vasoconstriction or volume factors, thereby guiding simpler, more specific, and predictably effective antirenin or antivolume treatments. Renin profiling identifies those in whom treatment should begin with a beta-blocker as opposed to a diuretic while not infrequently also providing baseline information about severity and prognosis in individual patients.

Observations on the use and limitations of renal vein renins in hypertensive patients.

From our consecutive series of renal vein renin studies in 170 patients with kidney disorders and hypertension, we present those cured by surgical correction of a unilateral renal artery stenosis during the period 1973--75. The renin secretion patterns of these patients range between no demonstrable abnormality, even with a stimulating procedure using dihydralazine 7.5 i.v., and massive renin secretion already during basal conditions. Thus, the renin secretion may not be increased even after stimulation in some patients with durable unilateral renovascular hypertension. This fact may be explained by the rise of the systemic blood pressure, eventually maintained by sodium and water retention and accompanied by adaptive changes in the contralateral kidney. The perfusion pressure is thereby kept normal in the affected kidney, eliminating a stimulus for renin secretion. It is likely that many cases of renovascular hypertension pass through an early stage where no involvement of the renin-angiotensin system may be discovered. Of course, these patients will also benefit from surgery. The conclusion is that renin studies for diagnostic purposes should be performed when patients are on treatment and kept normotensive for some time, and that an additional challenge of the perfusion pressure, i.e., by use of dihydralazine, intravenously should be performed.

Diazoxide-induced stimulation of renin release in renal vein renin sampling.

1. The acute effect of diazoxide (150-300 mg, intravenously) on renal venous renin has been evaluated in forty-four patients with suspected renal hypertension. 2. In twenty-seven studies which showed no lateralization, diazoxide raised the mean peripheral renin to 175% of control (P less than 0-05) but the renal vein renin ratio showed an insignificant change (1-15 to 1-21). 3. In seventeen studies which showed lateralization the increase in peripheral renin was similar, but mean renal vein renin ratio increased from 1-90 to 3-52 (P less than 0-005), and the mean ratio of contralateral renal vein to peripheral renin showed no change (1-05 to 1-07), indicating persistence of contralateral suppression. 4. Diazoxide accentuates the distinction between lateralizing and non-lateralizing renal vein renin studies.

Role of renin and aldosterone in hypertension due to a renin-secreting tumor

A renin-secreting renal tumor is a rare cause of curable hypertension characterized clinically by hypertension, hypokalemia, hyperaldosteronism and increased plasma renin activity (PRA). Prior subtotal adrenalectomy in such a patient allowed examination of the role of hyperreninemia in the absence of excessive aldosterone secretion. Hypertension was severe, but serum potassium and aldosterone production were normal. PRA was markedly increased under all conditions studied, with a persistent increase noted with changes in posture. Renal vein renin studies were critical in localizing the renal tumor, and unilateral nephrectomy resulted in a prompt fall in PRA to subnormal levels and dramatic cure of the hypertension. Renin content of the renal tumor was more than 500 times higher than in the adjacent kidney, and histologic studies confirmed that the tumor was of juxtaglomerular cell origin. This case demonstrates that severe hypertension can occur in this syndrome despite subtotal adrenalectomy and further illustrates an association of renin overproduction with a specific type of hypertension.

Renal vein renin studies in a patient with renal hilar pheochromocytoma and renal artery stenosis.

PHEOCHROMOCYTOMA and renal arterial stenosis are each important and surgically significant causes of hypertension. The combination of pheochromocytoma with renal arterial stenosis is rare, but it has been observed in a small number of patients. Table 1 lists eight such cases reported by other investigators.6' 7, 8, 16, 17, 19 Measurements of catecholamines and their metabolites are established criteria for diagnosis of pheochromocytoma.14 Recent reports from our laboratory 11 and by others 5 show that measurement of renal venous plasma renin activity is a useful diagnostic test in renovascular hypertension. If the ratio between renin activity in plasma from the side with anatomic stenosis and that from the opposite renal vein is 1.5 or greater, our experience indicates that the patient is likely to be relieved of hypertension or significantly improved by appropriate surgical correction of the lesion. It has further been shown.10,12 that assumption of an upright posture enhances renin plasma activity on the involved side far more than on the uninvolved side, and increases the ratio of the two. Studies of catecholamine and renal venous plasma renin activity were performed and were of assistance in the evaluation of a patient with the combination of left renal hilar pheochromocytoma and left renal arterial stenosis.