Societies for Pediatric Urology Societies for Pediatric Urology
Dialogue Archives: Pediatric Renovascular Hypertension
(Volume 8, Number 12, December 1985)


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Guest Editor: David T. Mininberg, M.D.
Participants: Maria I. New, M.D. Elizabeth Stoner, M.D. Ernest Sosa, M.D.
Editor
Richard M. Ehrlich, M.D. Professor of Surgery/Urology; Co-Chief of Renal Transplantation, School of Medicine, University of California, Los Angeles
Editorial Board
A. Barry Belman, M.D. Chairman, Department of Pediatric Urology Children's Hospital National Medical Center, Washington, DC; Professor of Urology George Washington Medical School
Donald B. Halverstadt, M.D. Clinical Professor of Urology & Pediatrics University of Oklahoma College of Medicine Chief, Pediatric Urology Service, Children's Memorial Hospital, Executive Chief of Staff, State of Oklahoma Teaching Hospitals, Oklahoma City
W. Hardy Hendren, III. M.D. Professor of Surgery Harvard Medical School; Chief of Surgery, Children's Hospital Medical Center, Boston
Panayotis Kelalis, M.D.
Professor and Chairman, Department
of Urology, Mayo Clinic, Rochester, Minn.
Selwyn Levitt, M.D
Adjunct Professor of Urology
New York Medical College;
Clinical Professor of Pediatrics
Albert Einstein College of Medicine;
Co-Director, Section of Pediatric Urology
Westchester Medical Center
Thomas A. Sos, M.D. Souheil Saddekni, M.D.
Publisher
William J. Miller
Lester Persky, M.D
Professor of Urology
Case Western Reserve University
School of Medicine, Cleveland
Victor A. Politano, M.D Professor and Chairman. Dept of Urology University of Miami School of Medicine Miami, Florida
Edward Tank. M.D
Associate Professor of Surgery & Pediatrics University of Oregon School of Medicine Portland, Oregon
Robert M. Weiss, M.D. Professor, Section of Urology Yale University School of Medicine New Haven, Conn.
Robert H. Whitaker, F.R.C.S. Consultant Urologist Addenbrooke's Hospital Cambridge, England Associate Lecturer University of Cambridge
SUBJECT OF CONTROVERSY PEDIATRIC RENOVASCULAR HYPERTENSION
EDITOR'S COMMENTS:
In the last year, 3 asymptomatic children were seen whose hypertension was diagnosed by "spot-checking" of blood pressures at banks and supermarkets. This clearly illustrates that there are a large number of undiagnosed children with hypertension and it should be our mission, and that of the pediatrician, to screen more often in regular office visits.
My own experience, mirrored by most articles in the literature, is not sanguine in treating hypertensive-refluxing children with antireflux surgery and, although it is a relatively rare phenomenon, I have never witnessed amelioration from the surgery. In the hypertensive pool, fascinating cases crop up occasionally. We have seen 2 pediatric patients with Takayasu disease who, unfortunately, have not been amenable to other than drug therapy. We saw 1 reninoma diagnosed by an expert radiologist who sampled upper and lower poles venous renins and multiple Wilms tumors with hypertension. Joe Kaufman had another fascinating case of pheochromocytoma associated with renal artery stenosis. We witnessed 2 cases of postradiation therapy for Wilms tumor with hypertension, whose problems were difficult to sort out as to causation. For a more complete review of the subject, I suggest you read an article entitled "Diagnosis and Therapy of Hypertension in Children" by Menster (Pediatric Clinics of North America 29:933, 1982). Another good article is "The Role of Renal Venous Renin" by Thind {Journal of Urology 134:2, 1985). Multiple references in relation to Takayasu arteritis can be found in JAMA 254:232, 1985 . Our thanks to Dave Mininberg and his coauthors for an interesting update on this important subject. And to all our readers, best wishes from all of us for a happy holiday season. Richard M. Ehrlich, M.D.
reconstructive or extirpative surgery or instrumental manipulation needs to be made. The contributors to this issue have addressed the diverse aspects of the problems of childhood hypertension. Drs. Stoner and New have focused on the endocrinopathies in which hypertension is a prominent and often presenting factor. Dr. Sosa has organized the types of problems associated with hypertension most often thought of as being urologic in nature. Drs. Sos and Saddekni share their data on percutaneous angioplasty for hypertension in children. They raise a standard that any other technique should be able to duplicate if it is to remain a viable choice.
Hypertension in children is most often treatable and potentially curable, in contradistinction to the adult population. We are therefore obligated to effectively screen, expeditiously diagnose and specifically and effectively treat all those children with hypertension. David T. Mininberg, M.D.
Professor of Clinical Urology/Surgery; Director. Pediatric Urology The New York Hospital-Cornell Medical Center
MARIA I. NEW, M.D.
Chairman, Department of Pediatrics; Chief, Pediatric Endocrinology; Acting Associate Program Director, Pediatric Clinical Research Center; Harold and Percy Uris Professor of Pediatric Endocrinology and Metabolism, The New York Hospital-Cornell Medical Center
ELIZABETH STONER, M.D.
Assistant Professor of Pediatrics; Clinical Associate Physician, The New York Hospital-Cornell Medical Center
Hypertensive Disorders of Childhood
Adrenocortical and renal disorders play an important role in various forms of juvenile hypertension Understanding the underlying mechanisms of childhood hypertension is of utmost importance for its proper diagnosis and management. The pediatrician must be alert to elevated blood pressure in the child and a careful metabolic evaluation must be performed in children with hypertension. Important diagnostic tools include the measurement of plasma renin activity (PRA) and aldosterone levels. These diagnostic studies make it possible to make a specific diagnosis and to target treatment that will reverse or control the hypertensive process. Since the long-term risk of antihypertensive medication in children is unknown, the best approach is to target therapy toward a specific lesion. Juvenile hypertension is associated with several disorders of adrenal steroidogenesis in which the excess formation of a mineralocorticoid hormone by the adrenal cortex results in plasma volume expansion and hyporeninemia. Other disorders associated with childhood hypertension include primary hyperaldosteronism, apparent mineralocorticoid excess, renovascular abnormalities,
GUEST EDITOR'S NOTES:
The problem of childhood hypertension is of diagnostic and therapeutic interest to the pediatric urologist, although the incidence and prevalence of this condition is not precisely known. The work of Homer Smith has functioned as a lightning rod in this regard. He demonstrated that, in a significant number of patients, nephrectomy willcure or ameliorate the hypertension. This finding makes it obligatory upon the pediatric urologist to assist in identifying those patients whose hypertension is amenable to surgical or manipulative therapy. Once this subset has been segregated from the overall group, a decision for
and bilateral endocrine dysfunction of the kidney. All of these disorders must be considered in the diagnosis of childhood hypertension Two forms of congenital adrenal hyperplasia (CAH), transmitted by an autosomal recessive gene, may result in hypertension: 11/3-OHase and 17o-0Hase deficiency. These enzymatic deficiencies result in decreased cortisol synthesis. The decreased cortisol synthesis induces increased pituitary ACTH secretion, with resultant overproduction of adrenal steroid precursor hormones, including the potent mineralocorticoid deoxycorticosterone (DOC). The most prominent clinical feature of 11B-OHase deficiency is virilization. Many patients with this form of CAH also exhibit hypertension. The hypertension has been attributed to the excessive DOC secretion, but a direct causal relationship has not been clearly established. In the untreated state, renin and aldosterone are suppressed by the excessive DOC secretion, with resultant sodium retention and plasma volume expansion. Glucocorticoid treatment suppresses ACTH, causing DOC to decrease, with consequent natriuresis, rise in plasma renin activity, stimulation of the adrenal zona glomerulosa, and increased aldosterone secretion A defect in 17o-OHase results in diminished secretion of glucocorticoid and sex steroids, with increased secretion of DOC. The mechanism for the development of hypertension is similar to that for 11/3-OHase deficiency. In the untreated state, excess DOC secretion from the zona fasciculata results in sodium retention, hyporeninemia, and hypertension. The hypoaldosteronism is the result of suppressed glomerulosa function and may be explained by considering the adrenal fasciculata and glomerulosa as 2 separate glands. According to this model, the fasciculata suffers from the 17a-0Hase defect, producing excessive DOC. Upon administration of dexamethasone, endogenous ACTH stimulation of the fasciculata decreases and, consequently, excessive DOC secretion from the zona fasciculata diminishes. The result is a rise in plasma renin activity and stimulation of the glomerulosa to secrete aldosterone.
Hypertension secondary to glucocorticoid-suppressible hyperaldosteronism has been reported by investigators from several continents. The unique feature of this familial, autosomal dominant disorder is complete and rapid suppression of aldosterone secretion within 48 hours of dexamethasone administration. This form of hypertension may be amenable to treatment only in the young. The blood pressure response to dexamethasone treatment in adults is variable and emphasizes the need for early diagnosis of hypertension. Due to the autosomal dominant genetic transmission, the prevalence of dexamethasone-suppressible hyperaldosteronism
may be much higher than has been ascertained to date.
In primary hyperaldosteronism, aldosterone is autonomously produced by the adrenal gland. In children, bilateral adrenal hyperplasia is the predominant adrenal pathology, although adrenal adenomas occur as well. Surgery is the treatment of choice for adrenal adenomas, whereas long-term spironolactone administration may be the preferred treatment for patients with bilateral adrenal hyperplasia because in many of these patients the hypertension recurs after surgery. The syndrome of apparent mineralocorticoid excess or hyporeninemic hypoaldosteronism results from a deficiency of 11 -oxoreductase. This enzyme deficiency results in decreased cortisol metabolism. It is hypothesized that cortisol itself then acts as the mineralocorticoid. Patients with this disorder present with marked hypertension and hypokalemia. The metabolic abnormalities are responsive to treatment with mineralcorticoid receptor antagonists. Cushing's syndrome is another disorder of adrenocortical hyperfunctioning associated with hypertension in childhood. The hypertension may be controlled by restricting salt in the diet and, if necessary, administering mineralocorticoid antagonists. Hypertension remits when the underlying disorder has been treated. It is of interest that hypertension occurs less frequently in patients treated with exogenous glucocorticoids than in patients with spontaneous Cushing's disease. This clinical observation suggests that other factors may play a role in the development of hypertension in patients with endogenous glucocorticoid excess. High renin hypertension results in secondary hyperaldosteronism. Hypertension develops in the presence of renovascular abnormalities of the main renal artery or a segmental renal artery resulting in unilateral renal ischemia. High renin hypertension also may be associated with renal transplantation, genitourinary tract obstruction, fibrous encapsulation of the kidney, and autonomous renin-producing juxtaglomerular cell tumors. Lateralization of renin secretion by renal vein renin measurements is essential for the diagnosis of renal artery stenosis. Surgical correction of renovascular lesions is the most common mode of intervention. Percutaneous transluminal renal angioplasty recently has been used as an effective alternative approach to surgery. The procedure involves transluminal dilation of stenotic vessels with a balloon catheter during renal arteriography. Experience with this procedure in children is limited and should be performed by an experienced team. Other pediatric disorders associated with hyperreninemia include pheochromocytoma, hyperthyroidism, estrogen therapy, and coarctation of the aorta.
SUBJECT OF CONTROVERSY PEOIATRlC RENOVASCULAR HYPERTENSION
Bilateral endocrine dysfunction of the kidney is associated with severe hypertension, marked hyperreninemia, and hyperaldosteronism. Hypersecretion of renin occurs equally by both kidneys and, frequently, there is associated hypertensive encephalopathy and weight loss. The etiology of the disorder is unclear. However, the presence of bilateral juxtaglomerular tumors has been ruled out by pathologic and arteriographic studies. Treatment should be directed at lowering the blood pressure with antihypertensive agents (eg, angiotensin-coverting enzyme inhibitors) until remission occurs.
Captopril, an orally-active inhibitor of the angiotensin l-converting enzyme, is a valuable tool in the diagnosis and treatment of hypertension. Experience with this drug in children, however, is limited. The acute response of blood pressure and PRA to the administration of 1 dose of captopril has been utilized as a predictive test for renovascular hypertension. In patients with renal artery stenosis there is a dramatic decline in blood pressure and a hyperresponsive PRA within 90 minutes of drug ingestion. For those patients whose lesions cannot be corrected surgically and who require medical therapy, captopril is an effective therapeutic modality. Patients on captopril must be followed closely for evidence of renal and hematopoietic toxicity.
Evaluation of PRA and plasma aldosterone levels is critical to making a specific diagnosis of juvenile hypertension. Under normal conditions, when sodium intake is high, plasma volume is expanded and PRA is suppressed. Similarly, when sodium intake is low, PRA is increased. Therefore, in order to accurately interpret PRA and aldosterone values these parameters must be adjusted for the level of dietary sodium. Quantitation of urinary sodium provides a reasonable estimate of dietary salt. In addition, nomograms have been developed to account for the normal aldosterone-sodium relationship so that PRA and aldosterone levels may be plotted and properly evaluated (Am J Cardiol 37:658, 1976). Children with hypertension often are asymptomatic. Therefore, careful measurement of blood pressure in all children is essential. If hypertension is found, a thorough evaluation must be undertaken in order to define the pathogenesis and to make possible specific targeting of treatment. □
ERNEST SOSA, M.D.
Assistant Professor of Surgery/Urology, The New York Hospital-Cornell Medical Center
Renal Hypertension in Children
It is difficult to determine the incidence of hypertension in a pediatric population; in part, because hypertension is difficult to define, but also because pressure elevations are not sustained in most children. As a working guideline, the task force for Hypertension Control in Children has suggested that hypertension be defined as a blood pressure greater than the 95 percentile for age, determined on 3 separate occasions. These guidelines are a good reference point but they do not completely reflect the wide variation of growth and maturation at different ages.
It is known that blood pressure increases with age until adolescence when it approaches adult values. The blood pressure is lower in girls compared with age-matched boys during childhood. Blood pressures are equal in age-matched black and white populations until adolescence when it increases more rapidly in blacks.
All forms of adult hypertension will occur in children and adolescents. Transient hypertension is more common in children than adults. Between 50% and 80% of patients less than 10 years old will have secondary hypertension which contrasts to the adult population where 90% of hypertension is without known cause. It is, therefore, imperative to evaluate all hypertensive children, seeking potentially curable causes for their hypertension. A secondary form of blood pressure elevation is more often found in young patients presenting with severe hypertension of recent onset. The pressure elevation in these patients is often symptomatic, frequently found to be associated with headaches, weight loss and, possibly, even seizure disorder. Renal disease is the most common secondary cause of hypertension in children. Renal parenchymal disease accounts for 75% of cases. Renovascular disease, discussed elsewhere in this issue, is the etiology in another 25% of cases of secondary hypertension. Renovascular disease is important to recognize because it is usually progressive and is often amenable to correction. Hypertension due to renal parenchymal disease is generally more difficult to correct but equally important to recognize so as to provide appropriate and adequate treatment in hopes of maximally preserving renal function. My discussion will focus on describing urologic diseases that result in renal parenchymal damage and hypertension. Reflux Nephropathy. Reflux nephropathy is defined as renal parenchymal scarring associated with vesicoureteral reflux, often with an onset during the first 5 years of life. It has been reported by Savage in 1975 and Wallace in 1978 that 10% to 12% of
children with reflux nephropathy will become hypertensive by late adolescence or early adult life. Studies in the association of hypertension and reflux nephropathy were carried out by Wallace who followed 141 patients with RN for a minimum of 10 years after their ureterovesical reimplantation. He eliminated from the study patients who developed end-stage renal disease. At follow-up, 18 patients were found to be hypertensive who had not been hypertensive previously. The mean age at onset of hypertension was 19 years. By retrospective analysis of their prereimplant radiographs, Wallace noted that 19% of patients with bilateral renal scarring and 11% of patients with unilateral renal scarring at the time of surgery became hypertensive. None of the 33 patients who lacked radiographic evidence of renal scarring in the perioperative period became hypertensive in this period.
The precise mechanisms producing hypertension in reflux nephropathy have eluded researchers but several pathophysiologic alterations have been described. In 1978, Savage, reported that peripheral plasma renin activity (PRA) was increased in 9 out of 15 children with reflux nephropathy and hypertension. All of these patients had previously undergone reimplantations of 1 or both ureters, had normal renal function and were off medications. In addition, he studied another 100 normotensive children with reflux nephropathy who had undergone successful reimplantations and had normal renal function. In 8 out of 100 of these patients, PRA was elevated. Savage found no correlation between the level of the plasma renin activity and the severity of the renal scarring. He theorized that these 8 patients could represent a subgroup that would eventually become hypertensive and proposed to follow these patients prospectively. Eighty-five patients were available for follow-up at 5 years. These ranged in age from 6 to 20 years. Peripheral PRA was measured in all patients and found to be increased in 11. Eight patients had newly elevated PRA, but no patient was hypertensive. Measurement of peripheral PRA did not have any prognostic value for the stated period of follow-up in identifying which patients with reflux nephropathy were at greatest risk to develop hypertension in young adulthood. In 1984, Dillon reported on 77 patients with reflux nephropathy. The group was divided into a subgroup of 26 patients who were normotensive and 51 patients who were hypertensive. Five of the 26 normotensive children had elevated peripheral plasma renin activities in contrast to a PRA elevation in 36 of 51 hypertensive children. In the latter group, renal vein renin ratios exceeded a 1.5 ratio in 33% of patients with either unilateral or bilateral assymmetrical scarring. In 7 patients with bilateral symmetrical scarring there was no evidence of lateralization of renin secretion. Thirteen patients with unilateral
disease and 9 patients with bilateral assym metrical disease underwent nephrectomy of the more diseased kidney. In 14 of these 22 patients, the blood pressure was normal off medication at short-term follow-up. The patients in Dillon's group were older than the patients followed by Savage. This fact could imply that measurement of PRA may gain more prognostic significance at an older age, but further studies to define the role of the renin-angiotensin system in the hypertension associated with reflux nephropathy are needed.
Nephrectomy is not advocated as a treatment for hypertension associated with reflux nephropathy. Renal parenchymal disease tends to be progressive in nature and therefore, an attempt to preserve total renal mass should be made. All too often, removal of a diseased kidney may gain a transient lowering of the blood pressure only to have the parenchymal disease process unmasked on the contralateral Ľnormal" kidney, according to Vaughan in 1974. A nephrectomy is only justified if the expected gain of removing a renin-secreting source is far greater than the potential renal compromise caused by the loss of the sodium-water excreting capacity. Taken together, these studies suggest that the presence of bilateral renal scarring in patients with vesicoureteral reflux identifies a group at higher risk for developing hypertension in late adolescence and young adult life. Patients with bilateral renal scarring at the time of surgery are at greatest risk for becoming hypertensive, while patients without parenchymal scars are the least likely to become hypertensive. Furthermore, these data suggest that increased plasma renin activity in a normotensive child with reflux nephropathy has no prognostic value in identifying those at greatest risk to become hypertensive. In older reflux nephropathy patients, the hypertension is more likely to be associated with asymmetric renal vein renin secretion. The role of the renin-angiotensin system in the initiation and/or maintenance of the hypertension, if any, in this group has not yet been determined. It would appear from Wallace's study that at least some patients will have renin-dependent hypertension. However, a longer follow-up period is necessary to confirm that nephrectomy actually helped these patients. The role of other hormonal systems, (ie, the sympathetic nervous system, vasopressin) has not been elucidated in the hypertension of RN. Careful, long-term follow-up of patients after ureteral reimplantation should include routine determinations of blood pressure, renal function and size, urinalysis and culture of the urine. A number of these patients are expected to suffer progressive deterioration in renal function, a process which can be hastened by uncontrolled hypertension and infection. Ask-Upmark Kidney. Ask-Upmark described a rare
SUBJECT OF CONTROVERSY PEDIATRlC RENOVASCULAR HYPERTENSION
form of segmental hypoplasia in 1 or both kidneys associated with severe high renin hypertension in the pediatric population. The involved kidneys tend to be small with globular contours. Radiographically, deep grooves on the cortical surfaces may be seen over dilated calyces. The adjacent renal tissue appears well preserved. Histologically, the hypoplastic areas are devoid of glomeruli and manifest thickened, stenosed vessels. There is an increase in the number of juxtaglomerular cells near the damaged vessels and increased renin content in these cells has been demonstrated by immunofluorescence as well as peroxidase and antiperoxidase techniques. Characteristically, there is an absence of inflammatory-cell infiltrates in contrast to the histologic appearance of reflux nephropathy kidneys. Theories attempting to explain the etiology of the Ask-Upmark kidney are controversial. Two schools of thought have provided an explanation. In 1971, Royer described 36 patients with a diagnosis of Ask-Upmark kidney. He found 25 females (69%) and 11 males (31%) in the group. Impairment of growth was found in 60% of the group and proteinuria in 50%. None of the patients were found to have vesicoureteral reflux In T979, Arant described 18 patients with Ask-Upmark kidney, again involving females (61%) more than males (39%). In contrast to Royer's group, vesicoureteral reflux was radiographically demonstrable in 16 of the 18 patients. Ask-Upmark kidneys have been shown to hypersecrete renin, accounting for the hypertension. Caution is advised once again in treating these patients with nephrectomy of the more involved kidney as the disease often turns out to be bilateral. As in the case of patients with reflux nephropathy and hypertension, nephrectomy should only be considered when the gain achieved by removing a renin-producing source far outweighs the loss of the nephrons with their salt and water excreting capacity. Page Kidney. In 1934, Irwin Page produced a model of hypertension that was renin-dependent by wrapping the canine kidney in cellophane. The clinical equivalent of this experimental model of hypertension is that of compression of the renal parenchyma by a subcapsular or a perirenal process, which produces renal ischemia, resulting in excess renin release and hypertension. Sufrin reviewed 29 patients with a mean age of 25 years who were hypertensive and were radiologically or surgically diagnosed as having Page kidney. The etiology for the perinephric process was noted to be trauma in 80% of the patients. Of those patients surgically explored, 85% were found to have a hematoma and 15% a urinoma.
Treatment in this group of patients included the observation of 8 patients with cure or improvement of the hypertension in 7 (88%). In 17 patients, a
nephrectomy was performed and in 15 of these (88%), hypertension was cured or improved. In 50% of patients treated by evacuation of the hematoma or urinoma, the hypertension was cured or improved. The author suggested that conservative treatment, that is observation, is as efficacious as surgery in preventing the onset of hypertension. However, these results must be interpreted cautiously as the patients were not stratified for duration of the lesion, age, or prior history of hypertension. A more recent review by Sterns (1985) contrasted nephrectomy versus evacuation of the perinephric process for the treatment of chronic subcapsular hematoma. Of 26 patients treated by nephrectomy, hypertension was cured in 22 (85%), improved in 2 (7.5%) and unchanged in 2 patients (7.5%). Of patients treated by evacuation of the chronic hematoma, 11 were cured of their hypertension (36%), one was improved (9%) and 6 of 11 remained unchanged (55%). In this subgroup patients, surgical intervention was clearly superior.
These studies suggest that in the acute phase, evacuation or spontaneous reabsorpition of the hematoma results in improvement or cure of the associated hypertensive disorder. However, when a subcapsular hematoma is present chronically, a thick, fibrous pseudocapsule forms which does not resolve by conservative means.
Renin-dependent hypertension can be caused by renal parenchymal compression due to other etiologies, including renal cysts, retroperitoneal or renal tumors or by the enlargement of contiguous organs.
Renal Neoplasms. Sixty percent of children with Wilms tumor present with hypertension often associated with hyperreninemia due to renin secretion by the tumor or by normal parenchyma compressed by the tumor. Treatment of Wilms tumor is of course standardized and includes nephrectomy and chemotherapy and radiation therapy according to stage and grade. The hypertensive state is eliminated by eradication of the tumor. Of interest, it has been found that recurrence of hypertension may herald the recurrence of the tumor.
Another form of renal neoplasma occurring in the pediatric population is the juxtaglomerular cell tumor also know as reninoma. There are approximately 22 reported cases of reninomas in children and young adults ranging in age from 7 to 47 years.^The tumor is cortical, has never been shown to metastasize, and is characterized by a large amount of renin production and secretion. Diagnosis is made by finding the increased peripheral plasma renin activity, lateralization of renal vein renin activity to the side of the tumor with contralateral suppression, secondary hyperaldosteronism with hypokalemia and, of course, hypertension. An angiogram is necessary to identity
the tumor which appears as a renal cortical lucency best seen during the nephrogram phase. Intravenous pyelography has not been reliable diagnostically nor has sonography. The treatment of this condition is nephrectomy or partial nephrectomy when feasible. Radiation Nephritis. Therapeutic doses of radiation produce renal injury that can progress to renal insufficiency and hypertension. Radiation produces lesions of the glomeruli, renal tubules and vessels. Extensive thickening, hylanization and focal fibrinoid changes occur in the media of lobular and intralobular arteries of the kidney. Hypertension takes years to manifest and the pathogenesis is sodium and water retention. Occasionally, increased renin secretion may be documented from ischemic areas of the kidney irrigated by the altered arterioles and intralobular arteries.
In addition, radiation may produce hypertension by slow progessive injury to large and medium-sized arteries that lie within treatment portals. Small and growing arteries of children are especially sensitive to radiation injury. Larger arteries become stenotic or hypoplastic while smaller vessels are likely to occlude. In addition, atheromatous degeneration of the vessels is accelerated by radiation injury, contributing to the establishment of renovascular hypertension. Unfortunately, the progressive nature of the vascular lesions makes long-term cure by revascularization unlikely.
Summary. In summary, some urological diseases that may be associated with hypertension in children have been described. It is important in treating any of these conditions to be aware of their association with hypertension and in caring for these patients to continually assess renal function and size, blood pressure and sterility of the urine. Except for renal neoplasms, management of renal hypertension is usually best performed by appropriate, conservative means and careful follow-up. Nephrectomy is rarely indicated but may be appropriate if the gain of removing renin-producing tissue far outweighs the loss of water and sodium secreting nephrons. In this regard, it must be kept in mind that many of the renal parenchymal diseases tend to be bilateral and may present asynchronously. Removal of a kidney may produce a transient improvement in the blood pressure only to have the hypertension return when the disease becomes manfest in the contralateral kidney.
YOUR RESPONSE
We'd like to hear from you and would welcome your comments, experiences, criticisms, etc. on the subject of this issue and other issues of this publication. Please send them to Richard M. Ehrlich, M.D., Division of Urology, UCLA Medical Center, Los Angeles, CA 90024.
THOMAS A. SOS, M.D.
Professor of Radiology: Head of Cardiovascular and Intervention Radiology. The New York Hospital-Cornell Medical Center
SOUHEIL SADDEKNI, M.D.
Assistant Professor Radiology. The New York Hospital-Cornell Medical Center
Role of Renal Angioplasty
Until recently, hypertension due to renal artery stenosis in the pediatric age group could only be treated by complicated vascular surgical reconstruction or by medical therapy. Unfortunately, no matter how effective the medical control of hypertension is, it does not deal with the underlining abnormality and, in fact, may cause deterioration of renal function and eventually, a loss of the involved kidney.
A recent application of renal angioplasty to children in our experience has been very promising. We have now performed percutaneous transluminal renal angioplasty on 14 patients who range from the age of 10 months to 20 years. The onset of hypertensron was at 2 weeks to 17 years. The presentation and diagnostic work-up of these patients was also unique. Seven were asymptomatic; however, 2 had had previous strokes and 1 each had had headache, nosebleed, and known congenital genital urinary or heart disease.
The diagnostic work-up in these patients and its results were as follows: Plasma renin activity was obtained in 8 patients and was positive in all 8. Selective renal vein renin sampling was obtained in
11  patients of whom 10 were true positive and 1 was a false negative. Intravenous digital subtraction angiography (IVDSA) was performed in 6 patients where there were 2 true positive, 2 false negative, and 2 indeterminate cases. Aortography was performed in all 14 cases where there were 10 true positive and 4 false negative. The false negatives were due to branch lesions which were missed on aortography. In each of these 4 cases, selective arteriography correctly identified the abnormality. No false positive or false negative selective artertograms were obtained.
The etiology of stenosis was considered to be fibromuscular dysplasia in 12 arteries in 11 patients, fibromuscular dysplasia and postsurgical stenosis in 1 artery of 1 patient, and arteritis in 3 arteries in 2 patients. Of the 16 arteries involved with stenoses, 7 stenoses were in the main renal artery, 4 branch arteries were involved while in 5 additional cases, both the main and branch renal arteries were involved with 10 stenoses. Percutaneous transluminal renal angioplasty was attempted in 14 patients. Technically successful angioplasty was performed in
12 patients, 1 of whom had bilateral disease. Partial success was obtained in 1 additional patient who had bilateral disease, but only 1 side could be dilated
SUBJECT OF CONTROVERSY PEDIATRIC RENOVASCULAR HYPERTENSION
since the other side was totally occluded. In 1 patient, angioplasty failed in attempting to dilate a small hypoplastic stenosed renal artery. In the 12 patients where technical success was achieved, 9 (75%) were cured and 3 (25%) were improved in terms of their blood pressure. One patient, in whom partial success was obtained, had improvement of his hypertension. In our series, there were no major complications in spite of the fact that many branch lesions were involved and that 2 of the patients had only solitary kidneys.
Diagnostic work-up of renal vascular hypertension in children is fraught with difficulty. In adults, the majority of lesions involve the main renal artery, especially in artheromatous disease. In children, however, the frequency of branch disease necessitates greater reliance on peripheral and selective renal vein renin sampling and assay with the understanding that intravenous digital subtraction angiography is not an adequate screening test in children for suspected renal vascular hypertension. Indeed, in many cases even the aortogram is inadequate in detecting branch lesions either in vessels too small to be seen without magnification arteriography or where overlapping branches cover the location of the stenosis.
The technical and blood pressure control success of renal angioplasty in children matches that of vascular surgery. The advantages of renal angioplasty are that complicated surgical reconstruction, including complicated bench surgery and autotransplantation. are not necessary, but rather, under direct fluoroscopic radiologic visualization, branch lesions can be dilated and the length of recuperation is reduced from weeks to days with the result that there is a concomitant major financial savings.
Based on our experience, we conclude that renal angioplasty is the procedure of choice for children with renal vascular hypertension caused by vascular stenoses and that surgery should be reserved for those rare cases where the lesions do not adequately respond to dilation when a complication is encountered.
o Ureterocele Management Update
(Guest Editor: Anthony A. Caldamone, M.D.)
□  Postnatal Management of UPJ Obstruction Detected Antenatally (Guest Editor: M. David Gibbons, M.D.)
□  Hematuria in Children
(Guest Editor: William A. Brock, M.D.)
□  Voiding Dysfunction in Neurologically Normal Children (Guest Editor: William E. Kaplan, M.D.)
□  Myelomeningocele Management (Guest Editor: Barry A. Kogan, M.D.)
o Single-Stage Hypospadias Repair (Guest Editor: Jeffrey Wacksman, M.D.)
□  Clitoroplasty (Part 1)
(Guest Editor: Ronald R. Pfister, M.D.) d Clitoroplasty (Part 2)
(Guest Editor: Ronald R. Pfister, M.D.)
□  Bilateral Wilms Tumor
(Guest Editor: Robert Kay, M.D.) o Continent Urinary Reservoir
(Guest Editor: Michael E. Mitchell, M.D.)
□  Renovascular Hypertension In Children (Guest Editor: David T. Mininberg, M.D.)
WHAT'S AHEAD
Here are some of the topics which will be discussed in
the upcoming issues of Dialogues in Pediatric Urology
and the Guest Editors of these issues:
Chordee Without Hypospadias
(Guest Editor: Richard T. Hurwitz, M.D.)
Neonatal Dilations of Urinary Tract
(Guest Editor: Selwyn Levitt, M.D.)
Prenatal Diagnosis of a Congenital Anomaly
(Guest Editor: Arnold H. Colodny, M.D.)
Urography, Ultrasonography, Radio Pharmaceuticals
(Guest Editor: Evan J. Kass, M.D.)
Kidney Stones
(Guest Editor: Terry W. Hensle, M.D.)
Congenital Genital Anomalies
(Guest Editor: Casimir F. Firlit, M.D.,Ph.D.)
Hypospadias Surgery
(Guest Editor: R. Lawrence Kroovand, M.D.)
Volume 8 (1985)
Listed below are the topics and Guest Editors of the 1985 issues in Volume 8. A-complete set of issues for this volume can be purchased for . Individual issues cost .00 each. Send your request along with your check to: Dialogues in Pediatric Urology, 45 Villa Road, Pearl River, N.Y. 10965.
□ Experimental Aspects Of Testicular Torsion (Guest Editor: Ronald Rabinowitz, M.D.)
Opinions expressed in this publication are the sole responsibility of the individuals named and do not necessarily reflect the opinions of the editorial board or the publisher and members of this organization.
Copyright © 1985 by William J. Miller Associates, Inc.
All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying recording or by any information retrieval system, without written permission from the publisher.