Long-term follow-up of neonatal renovascular hypertension

Twelve neonates with hypertension have been followed for a mean of 5.75 years. At onset of hypertension, mean peak blood pressure was 159/99 mmHg. Ten infants had umbilical artery catheters, 9 placed above the origin of the renal arteries. Radionuclide renal scan, and/or angiography demonstrated renovascular disease, primarily renal artery thrombosis, in 11 infants. Onethird of infants were asymptomatic, one-third had normal urinalyses and two-thirds had elevated peripheral plasma renin activities. Blood pressure normalized with medical therapy in all infants and remained normal when therapy was discontinued. Ten infants have normal creatinine clearances on follow-up but 5/11 have unilateral renal atrophy. Radionuclide scans have remained abnormal, even in infants without renal atrophy. In summary, neonatal renovascular hypertension is frequently secondary to renal artery thrombosis, associated with umbilical artery catheterization. Blood pressure usually normalizes with conservative medical management and remains normal off medications. Persistent abnormalities in renal size and function are common.     

Surgical treatment of renovascular hypertension

The evaluation of patients with inadequate control of diastolic blood pressure for surgically correctable forms of hypertension led to the detection and surgical treatment of 56 patients. Detection was facilitated by the use of hypertensive intravenous pyelography and Hippuran renal Scanning. Aortography proved the presence of renal artery disease and renal vein renin assay established its significance in the etiology of the patients' hypertension. Renal artery reconstruction was performed in 50 patients, including 5 who also had reconstruction of major aortoiliac lesions. The extent of renal artery disease precluded arterial reconstruction in six patients, who required nephrectomy. Two postoperative deaths occurred, for a mortality rate of 3.6 per cent. Improvement in mean diastolic blood pressure for the total group of patients from 118 mm Hg preoperatively to 86 mm Hg postoperatively was achieved. Forty-six patients (85 per cent) have a diastolic blood pressure of 90 mm Hg or less; in 5 patients the diastolic blood pressure is 91 to 100 mm Hg but is at least 20 mm Hg lower than the preorative level.     

Management of aortic thrombosis secondary to umbilical artery catheters in neonates

During the past ten years, we have surgically managed seven neonates who developed total occlusion of the distal aorta due to umbilical artery catheters. All patients experienced symptoms of congestive heart failure. Five patients presented with severe hypertension, and all of these had aortorenal involvement: three infants had aortorenal thrombosis and two infants had infrarenal aortoiliac thrombosis with suprarenal extension of thrombus. Two infants had aortoiliac thrombosis with clot confined to the infrarenal aorta. Aortic thrombosis imposes an additional severe hemodynamic insult in these already seriously ill infants. Survival in this group of patients depends upon prompt recognition of this problem, effective surgical correction, and careful perioperative management. Our experience suggests that this diagnosis should be entertained in the infant presenting suddenly with congestive heart failure, hypertension, or lower limb ischemia after umbilical artery catheterization. The diagnosis is preferably confirmed by real-time ultrasound and/or radionuclide flow scan, although aortography may sometimes be necessary. Surgical management includes early transabdominal aortotomy with thrombectomy. Prompt thrombectomy resulted in the survival of six patients. One infant died in acute renal failure. Renal function and leg perfusion is satisfactory in the remaining patients, although one child required later operative correction of renovascular hypertension. Two additional patients needed prolonged postoperative antihypertensive therapy for 14 to 34 months before this problem resolved. Long-term follow-up is necessary for managing renovascular hypertension and monitoring lower extremity perfusion.     

Utility of computed tomographic renal angiogram in the management of childhood hypertension

The purpose of this study was to evaluate the utility of computed tomography (CT) renal angiogram (CTRA) in the management of childhood hypertension. This is a retrospective study of 24 children with clinical suspicion of renovascular disease who underwent CTRA examinations. CTRA demonstrated surgically correctable etiology of hypertension in 38% of the patients [5 with renal artery stenosis (RAS) and 4 with renal pathology]. In 5 patients, CTRA findings of RAS were confirmed by catheter angiogram. CTRA missed RAS in 1 patient in whom catheter angiogram showed beaded narrowing of the renal artery. All 6 patients with RAS had resolution of hypertension immediately after angioplasty or surgery. One patient with diffuse renal artery stenosis had an ipsilateral multicystic dysplastic kidney. In this patient hypertension resolved spontaneously as the dysplastic kidney shrunk in size. Seven patients had a renal etiology for hypertension. In 3 of these patients hypertension resolved after nephrectomy. Malignant hypertension in the 4th patient with reflux nephropathy was controlled medically after she underwent bilateral ureteral reimplantation. The remaining 3 patients with renal etiology were managed medically. We found that the etiology was central for hypertension in 4 patients with brain abnormalities, obesity in 1 overweight patient, essential hypertension in 4 patients, and thoracic aorta coarctation in 1 patient. Our study showed that in all except 1 instance CTRA could diagnose a surgically correctable cause for hypertension. CTRA provided useful information for the management of pediatric hypertension in all our patients.     

Arterial reconstructive surgery for renovascular hypertension

Many hypertensive patients with renal artery stenosis and abnormal findings on renin angiotensin assay can be cured or markedly improved by renal artery surgery. Because the mortality is low, we think that patients whose blood pressures are resistant to medical management should be examined carefully for renal artery stenosis as the cause of their hypertension. If such a lesion is found, many of these patients can expect to enjoy a good clinical response from renal artery reconstruction. Those patients who do not have satisfactory results from the surgical correction should undergo aggressive reevaluation to detect any correctable anatomic defects.     

Mild Renal Artery Stenosis Can Induce Renovascular Hypertension and is Associated with Elevated Renal Vein Renin Secretion

Renovascular hypertension is a syndrome which encompasses the physiological response of the kidney to changes in renal blood flow and renal perfusion pressure. Such physiological changes can occur with renal artery occlusion irrespective of the severity of the lesion. We have analyzed hypertensive patients with mild renal artery stenosis and compared them to patients with no stenosis. Renal vein renin sampling from catheterization of the renal vein was performed in all these patients. Patients with mild stenosis had higher renal vein renin ratio (3.01 ± 1.5) than the patients with no stenosis (1.10 ± 0.29; p = 0.002). Patients with mild stenosis were also found to have higher diastolic blood pressure and renal artery resistive indices when compared to patients with no stenosis. We therefore conclude that mild stenosis can precipitate renin‐mediated hypertension in renovascular stenosis and also emphasis that parameters pertinent to renal physiology need to be evaluated before considering treatment options in patients with renal artery stenosis and medical management with RAAS blockade is the preferred modality of therapy for patients with renin‐mediated hypertension.     

Mechanisms of posttransplant hypertension

Posttransplant hypertension is an important risk factor for cardiovascular mortality and graft function. We performed metabolic studies in 35 hypertensive patients with well-maintained graft function on maintenance immunosuppressive drugs and in 17 normotensive control transplant recipients. The group of hypertensive recipients were characterized by increased peripheral plasma renin activity, lack of change in blood pressure in response to salt loading and restriction, and by increased peripheral and renal resistance. In contrast, on the same protocol in a group of patients with essential hypertension, blood pressure fell significantly on a low-salt intake. Peripheral resistance in hypertensive transplant recipients fell in response to saline loading, in contrast to the effects in normotensive transplant recipients. Hypertensive patients with retained native kidneys as compared to those who had these removed prior to transplant, but were still hypertensive, differed only with regard to reduced renal plasma flow in the former group. These data are consistent with a predominantly renin-dependent hypertension in these renal transplant recipients. When bilateral nephrectomy or repair of graft renal artery stenosis is being considered, response to captopril may offer a means of selection; acute renal failure on captopril suggests functionally significant renal artery stenosis.     

Mechanisms of posttransplant hypertension

Summary Hypertension is a common problem in renal failure patients both before and after renal transplantation. The stable allograft can maintain salt, volume, and blood pressure homeostasis and is not intrinsically a hypertensive model. The causes of severe posttransplant hypertension are multiple. Renal vascular tone, body salt and volume status, and renin release are all connected and influenced by immunosuppressive medications, allograft function, and native kidney presence and function. The role of each of these in posttransplant hypertension is reviewed. In most cases, severe hypertension in the stable transplant patient without rejection or transplant renal artery stenosis is greatly improved following native bilateral nephrectomy. Transluminal angioplasty is the preferred initial treatment for transplant renal artery stenosis.     

Increased urinary catecholamines in a hypertensive child with renal artery stenosis

We report a hypertensive child with renal artery stenosis who exhibited increased urinary excretion of norepinephrine (NE) and normetanephrine (NMN), while vanillylmandelic acid (VMA) excretion was within the normal range. The NMN values prompted us to investigate the patient for pheochromocytoma; for this purpose, NE was determined by plasma catecholamine assays in venous samples obtained by catheterization. The moderately increased NE levels could not be localized to any particular sampling site. Arteriography demonstrated right renal artery abnormalities. Following right nephrectomy with preservation of the right adrenal gland, arterial blood pressure returned to normal. The cause of increased NMN excretion without a concomitant rise in VMA during hypertension is discussed. Received May 23, 1995; received in revised form and accepted February 6, 1996     

The simultaneous occurrence of renal artery stenosis and an aldosteronoma in a patient with hypertension

The simultaneous occurrence of renovascular hypertension and an adrenocortical adenoma is a rare entity. The case of a 64-year-old woman who underwent an aortorenal bypass graft for renovascular hypertension requiring a multidrug antihypertensive regimen is presented. Persistently elevated blood pressures in the postoperative period prompted further workup for other causes of hypertension. Laboratory evaluation showed hyperaldosteronism and hyporeninemia despite enalapril administration. Abdominal computerized tomography (CT) revealed a left adrenal mass which, on surgical removal, was found to be a cortical adenoma. Subsequently, her antihypertensive therapy has been reduced to a single agent. Previous authors have described only four patients with malignant hypertension who had the rare clinical combination of renal artery stenosis and an aldosteronoma. This case reemphasizes the critical need for a thorough search for other surgically correctable lesions in those patients who remain severely hypertensive after the "definitive" operation.     

Renovascular hypertension

Renal artery stenosis is one of the most important forms of secondary hypertension. For years, the only causative treatment was nephrectomy. With rapid advances in cardiovascular and transplantation surgery, operative procedures in renovascular hypertension become more and more sophisticated. Revascularization is superior to medical management of renovascular hypertension in terms of preserved renal function. In recent years, surgical result have been excellent, and even patients with rather complex forms of renovascular hypertension have been successfully operated upon. New classes of antihypertensive drugs, particularly beta-blockers and angiotensin I converting enzyme inhibitors, have enabled the control of blood pressure in most patients with renovascular hypertension but do not assure preservation of renal function. Finally, a fascinating technique, the percutaneous transluminal renal angioplasty, has rapidly advanced to become one of the most popular methods in the treatment of hypertension secondary to renal artery stenosis. However, percutaneous transluminal renal angioplasty is the treatment of choice for most nonostial, nonocclusive lesions.     

Renin-producing renal cell carcinomas—clinical and experimental investigations on a special form of renal hypertension

Summary The pathogenetic relationship between tumour and hypertension was investigated in 129 patients with renal cell carcinoma, of whom 41 (31.8%) were hypertensive. Of these 41 patients with renal tumours and hypertension, 6 (14.6%) were found to have primary reninism. In these patients the plasma renin activity in blood from the renal veins showed a tumour kidney to contralateral kidney ratio of between 4 and 7, and 2 patients also had secondary hyperaldosteronism. In the same 6 cases the renin content in the renal tumour tissue was significantly higher than that in tissue from the adjacent tumour-free renal cortex of the ipsilateral kidney. Immunohistochemical demonstration of renin in the tumour was only possible in these 6 cases. In 5 of these patients blood pressure returned to normal following nephrectomy; in the 6th case there was a drop in blood pressure after nephrectomy. In 3 renin-positive tumours examined, autonomous renin production was demonstrated in cell culture. Renin-producing renal cell carcinomas are an uncommon cause of renal hypertension. The differential diagnosis of hypertension should therefore also include renal tumour.     

Conservative management of neonatal renal artery embolism

Renal artery thrombosis or embolism associated with the use of an umbilical arterial catheter can cause renin-dependent hypertension in the neonate. The tip of the catheter should therefore be kept well below the origin of the renal arteries and the infant's blood pressure monitored. Moreover, since the pressor hypertension may be transient and kidney function may return, a period of medical management should be attempted before proceeding to nephrectomy.     

Correction of renal hypertension by ligation of stenotic segmental renal artery

Hypertension secondary to segmental renal ischemia caused by segmental renal artery stenosis has been relieved by nephrectomy, partial nephrectomy, excision of atrophic segments, or repair of the segmental vessels. This is a report of hypertension caused by stenosis of a segmental renal artery and cured by simple ligation of the stenotic artery.     

Severe renovascular hypertension in an infant with congenital solitary pelvic kidney

Renal artery stenosis (RAS) is one of the most common causes of severe arterial hypertension in infants. Its management is very difficult, especially when present in a single kidney. We report a case of severe hypertension caused by RAS of congenital single pelvic kidney in a 4-month-old boy. The patient presented with cardiorespiratory insufficiency that was first treated as acute fulminate myocarditis. Medical treatment of arterial hypertension was disappointing, as it had to be balanced between congestive cardiac failure and acute renal failure. Percutaneous transluminal angioplasty (PTA) done by coronary balloon dilatation catheters through the left axillary access was successful. Following dilatation of the renal artery, blood pressure decreased and its good control was possible by only one drug. With improved medical blood pressure control and normal growth development, the reassessment of clinical therapy options adjusted to a larger vessel size would be possible. Renovascular hypertension due to RAS in infants with a solitary kidney is difficult to control by medical treatment alone. PTA should be considered as a viable option in infants with refractory hypertension due to renal artery stenosis in a solitary kidney, since it has the potential of improving hypertension while preserving renal function.     

Renal Artery Stenosis: To Intervene,or Not to Intervene, “That is the Question”

Renal artery stenosis (RAS) due to atherosclerosis continues to be a major cause of secondary hypertension. It can also lead to renal dysfunction due to ischemic nephropathy. While major clinical trials have emphasized that medical management should be preferred over angioplasty and stenting for the treatment of renal artery stenosis, clinical scenarios continue to raise doubts about the optimal management strategy. Herein, we present two cases that were admitted with hypertensive emergency and renal function deterioration. Medical therapy failed to control the blood pressure and in one patient, renal failure progressed to a point where renal replacement therapy was required. Both patients underwent angioplasty (for >90% stenosis) and stent insertion with successful resolution of stenosis by interventional radiology. Postoperatively, blood pressure gradually decreased with improvement in serum creatinine. Dialysis therapy was discontinued. At 4‐ and 8‐month follow‐up, both patients continue to do well with blood pressure readings in the 132–145/70–90 mmHg range. This article highlights the importance of percutaneous interventions in the management of atherosclerotic RAS and calls for heightened awareness and careful identification of candidates who would benefit from angioplasty and stent insertion.     

Clinical and duplex ultrasound follow-up after balloon angioplasty for atherosclerotic renal artery stenosis.

The purpose of this study was to investigate changes in blood pressure and renal function after percutaneous renal artery balloon angioplasty in hypertensive patients with atherosclerotic renal artery stenosis. Renal artery lesions were assessed by duplex ultrasound before and after renal artery balloon angioplasty. Renal arteries were classified as normal, < 60% stenosis, > or =60% stenosis, and occluded according to previously validated duplex criteria. Data regarding risk factors for atherosclerosis and years of hypertension were collected. Systolic and diastolic blood pressure, creatinine, and number of medications were obtained before and after intervention. The immediate technical outcome of renal artery angioplasty was classified based on the arteriographic result as follows: success (residual stenosis < or =30%), partial success (residual stenosis 31-50%), or unsuccessful (residual stenosis > 50%). For bilateral procedures, success required both renal arteries to be classified as technical successes; a technical success on one side only was classified as partial success. The blood pressure response to intervention was classified as follows: cure (diastolic blood pressure < or =95 mm Hg on no medications), improved (control of blood pressure with a significant reduction in number of medications or control of previously elevated blood pressure without a change in medications), or failed (all other responses). The study group included 28 patients (14 men, 14 women) with a mean age of 65 years. The preintervention and the first postintervention evaluations occurred within 180 days of the procedure. All patients were hypertensive, and all except one were under medical treatment. Mean duration of hypertension was 9.1 +/-8.8 years. There were 38 interventional procedures (28 unilateral, 10 bilateral) involving 41 renal arteries; seven arteries had two procedures done. Before angioplasty, all renal arteries had lesions of > or =60% diameter reduction by duplex scanning. Endovascular stents were deployed following angioplasty in 14 (34%) of the procedures. The technical result was classified as a success in 24 (63%), a partial success in 12 (32%) of the procedures, and two procedures (5%) were classed as technical failures. There were statistically significant reductions in blood pressure following successful and partially successful procedures, but cure of hypertension was achieved in only 11% of cases. There were no significant changes in creatinine in any of the technical result groups. Of the 38 renal arteries evaluated with duplex ultrasound following intervention, 39% were found to have stenosis of > or =0% involving a treated renal artery, including one postintervention occlusion. Cure of hypertension was rare in this patient population with atherosclerotic renal artery stenosis. More than one third of the treated renal arteries showed > or =0% lesions recurring after the procedure. Thirteen percent of those with technical success and 17% of those with partial technical success had creatinine improvement of at least 20% over the baseline value. Significant clinical and anatomic improvement were relatively uncommon following balloon angioplasty in this series of patients.     

Neonatal hypertension--diagnostic and therapeutic approach

Hypertension in the neonate is a rare disease. Although the definition of hypertension in this age group has not been completely standardized, recent studies have provided new normative data that may be used to facilitate identification of such infants. The most common causes of clinically and treatable hypertension in neonates is renal artery occlusion due to thromboembolic events related to umbilical catheterization. Additionally, congenital problems such as aortic coarctation, structural renal malformations and renovascular disease, as well as acquired renal disease and certain medications must always be considered. History and physical examination will usually identify the probable cause in most cases, and the laboratory or radiologic testing will confirm the diagnosis. Treatment of neonatal hypertension should be tailored to the severity of the blood pressure elevation, and to the underlying cause of hypertension. A wide range of therapeutic agents are now available for management of neonatal hypertension in both the acute and chronic settings, but is important to correct the iatrogenic causes before using them. In most cases hypertension will resolve, but some infants may require prolonged treatment.     

Case of renal artery stenosis in an elderly patient after nephrectomy diagnosed by ultrasound sonography, showing improvement of blood pressure and renal dysfunction after renal artery stenting

Arteriosclerotic renal artery stenosis is one of the increasingly common diseases that affects many aged patients. There are various non-invasive methods to diagnose renal artery stenosis, such as contrast enhanced CT or MRI. However, these methods are not appropriate for patients with renal dysfunction. Ultrasound sonography is becoming one of the promising methods to diagnose artery stenosis because of photographic improvements. In this case, a 72-year-old woman was hospitalized 7 months after nephrectomy because of severe hypertension, heart failure and kidney dysfunction. The heart failure was quite uncontrollable in spite of massive administration of diuretics, and finally, hemodialysis was started to control her volume status. In consideration of her past history and abdominal bruit, we evaluated the renal artery stenosis by ultrasound sonography and confirmed the diagnosis by renal angiography. To improve hypertension control, we performed renal artery stenting, which resulted in an impressive improvement of her blood pressure and renal function. We recognized the importance of careful causal evaluation of renal dysfunction, even though it is difficult to apply invasive therapy to patients after nephrectomy.     

Hyponatremic Hypertensive Syndrome Presenting as Malignant Hypertension in a Four-Year-Old Girl

The prevalence of renal and renovascular hypertension in the general population is not known precisely; in children it probably accounts for the majority of cases of secondary hypertension. The symptoms of renovascular hypertension vary, and sometimes it can be asymptomatic. In rare cases, clinical manifestations can include electrolyte disorders including hyponatremia. An uncommon etiology of true hyponatremia of renal origin is the hyponatremic hypertensive syndrome. It has been reported in adults with malignant hypertension, but was considered as an unusual form of presentation of renovascular disease in children. In this report, a four-year-old girl presented with hypertensive encephalopathy related to the hyponatremic hypertensive syndrome caused by right renal artery stenosis. Treatment with percutaneous angioplasty was successful, with total resolution of symptoms. This case emphasizes the importance of routine blood pressure evaluation as a major contribution to the prevention of morbidity and mortality associated with severe forms of hypertension in children.