Renal artery stenosis in infants: long-term medical treatment before surgery

Neonatal Hypertension

Neonatal hypertension is uncommon but is becoming increasingly recognized. Normative blood pressure data are limited, as is research regarding the risks, treatment, and long-term outcomes. Therefore, there are no clinical practice guidelines and management is based on clinical judgment and expert opinion. Recognition of neonatal hypertension requires proper blood pressure measurement technique. When hypertension is present there should be a thorough clinical, laboratory, and imaging evaluation to promptly diagnose causes needing medical or surgical management. This review provides a practical overview for the practicing clinician regarding the identification, evaluation, and management of neonatal hypertension.

The hypertensive neonate

Hypertension in neonates is increasingly recognized because of improvements in neonatal intensive care that have led to improved survival of premature infants. Although normative data on neonatal blood pressure remain limited, several factors appear to be important in determining blood pressure levels in neonates, especially gestational age, birth weight and maternal factors. Incidence is around 1% in most studies and identification depends on careful blood pressure measurement. Common causes of neonatal hypertension include umbilical catheter associated thrombosis, renal parenchymal disease, and chronic lung disease, and can usually be identified with careful diagnostic evaluation. Given limited data on long-term outcomes and use of antihypertensive medications in these infants, clinical expertise may need to be relied upon to decide the best approach to treatment. This review will discuss these concepts and identify evidence gaps that should be addressed.

Efficacy of Antihypertensive Therapy in a Child with Unilateral Focal Fibromuscular Dysplasia of the Renal Artery: A Case Study and Review of Literature

Background: Fibromuscular dysplasia (FMD) is one of the important etiologies of renovascular hypertension in children. It is usually resistant to multiple antihypertensive agents and can cause extreme elevation in blood pressures, which can lead to end organ damage if not promptly diagnosed and treated. Treatment options include medical management with antihypertensive agents, balloon or stent angioplasties, surgical revascularization, and nephrectomy. The aim of the study was to review the efficacy of antihypertensive therapy only in the management of FMD in a very young child. Methods: This is a retrospective chart study with review of literature. Results: Here, we report a 22-month-old toddler who presented with severe resistant hypertension and cardiomyopathy who was found to have focal FMD of the right renal artery. She also presented with proteinuria, hyponatremia that was probably secondary to pressure natriuresis, hypokalemia, hyperaldosteronism, and elevated plasma renin activity. The stabilization of blood pressures was done medically with the usage of antihypertensive medications only, without the need for angioplasty or surgical revascularization. Conclusions: We demonstrate that surgical intervention may not always be necessary in the treatment of all cases of FMD, especially in a small child where such intervention may be technically challenging and lead to potential complications. Hence, medical management alone may be sufficient, at least for the short-term, in small children with controlled hypertension and normal renal function, with surgical intervention reserved for FMD with medication-refractory hypertension and/or compromised renal function.

Neonatal hypertension: cases, causes, and clinical approach

Neonatal hypertension is increasingly recognized as dramatic improvements in neonatal intensive care, advancements in our understanding of neonatal physiology, and implementation of new therapies have led to improved survival of premature infants. A variety of factors appear to be important in determining blood pressure in neonates, including gestational age, birth weight, and postmenstrual age. Normative data on neonatal blood pressure values remain limited. The cause of hypertension in an affected neonate is often identified with careful diagnostic evaluation, with the most common causes being umbilical catheter-associated thrombosis, renal parenchymal disease, and chronic lung disease. Clinical expertise may need to be relied upon to decide the best approach to treatment in such patients, as data on the use of antihypertensive medications in this age group are extremely limited. Available data suggest that long-term outcomes are usually good, with resolution of hypertension in most infants. In this review, we will take a case-based approach to illustrate these concepts and to point out important evidence gaps that need to be addressed so that management of neonatal hypertension may be improved.

Applications and challenges of using 3D printed implants for the treatment of birth defects

Pediatric implants are a special subclass of a vast number of clinically used medical implants, uniquely designed to address the needs of young patients who are at the onset of their developmental growth stage. Given the vulnerability of the implant receiver, it is crucial that the implants manufactured for small children with birth-associated defects be given careful considerations and great attention to design detail to avoid postoperative complications. In this review, we focus on the most common types of medical implants manufactured for the treatment of birth defects originating from both genetic and environmental causes. Particular emphasis is devoted toward identifying the implant material of choice and manufacturing approaches for the fabrication of pediatric prostheses. Along this line, the emerging role of 3D printing to enable customized implants for infants with congenital disorders is presented, as well as the possible complications associated with prosthetic-related infections that is prevalent in using artificial implants for the treatment of birth malformations.

Hypertension in the neonatal period

PURPOSE OF REVIEW

Continued interest in neonatal hypertension has led to generation of new data on normal blood pressure (BP) values in neonates, identification of new causes of hypertension in the neonatal period, and improved insights into therapy.

RECENT FINDINGS

Normal BP in neonates depends on a variety of factors, including gestational age, postnatal age, and birth weight, and may be influenced by other antenatal conditions. The incidence of neonatal hypertension is low, and it is most often seen in infants with concurrent conditions such as chronic lung disease (CLD) or renal disease, or in those that have undergone umbilical arterial catheterization. Although few data exist on efficacy and safety of antihypertensive medications in neonates, a wide variety of medications have been utilized in those who do require treatment. Hypertension resolves over time in most infants, although robust long-term outcome data are lacking.

SUMMARY

Our understanding of neonatal hypertension continues to evolve. Although better data are available on normal BP and the incidence of hypertension, we still need studies focused on appropriate treatment and long-term prognosis.

Hypertension in infancy: diagnosis, management and outcome

Advances in the ability to identify, evaluate, and care for infants with hypertension, coupled with advances in the practice of Neonatology, have led to an increased awareness of hypertension in modern neonatal intensive care units. This review will present updated data on blood pressure values in neonates, with a focus on the changes that occur over the first days and weeks of life in both term and preterm infants. Optimal blood pressure measurement techniques as well as the differential diagnosis of hypertension in the neonate and older infants will be discussed. Recommendations for the optimal immediate and long-term evaluation and treatment, including potential treatment parameters, will be presented. We will also review additional information on outcome that has become available over the past decade.

Malignant hypertension secondary to renovascular disease during infancy--an unusual cause of failure to thrive

An 11-month-old girl presented with a history of failure to thrive, vomiting, polydipsia, polyuria and visual inattention. She was found to have malignant hypertension due to unilateral renal artery stenosis. This was successfully treated with percutaneous transluminal balloon angioplasty. Nearly 10 years following this initial presentation, she remains normotensive on no anti-hypertensive medications.

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.

Prophylactic calcium and vitamin D treatments in steroid-treated children with nephrotic syndrome

Steroid treatment has several side effects, including the deterioration of the bone and mineral metabolism in children with nephrotic syndrome. This randomized prospective study was conducted to determine the effects and prophylactic role of calcium plus vitamin D treatment on bone and mineral metabolism in children receiving prednisolone treatment. 40 children (27 boys and 13 girls) with NS (18 new onset and 22 relapsing) were included in the study. Their mean age was 4.6+/-1.8 years. All patients received prednisolone treatment (2 mg/kg/day for 4 weeks followed by alternate days at the same dose for 4 weeks). The patients were randomized into treatment (vitamin D 400 IU plus calcium 1 g daily) and non-treatment groups. Bone mineral density, serum Ca, P, alkaline phosphatase and urinary Ca and P excretions were analyzed at the beginning and 2 months after the treatment. The XR36 Norland device was used for bone mineral density analysis. Bone mineral density was significantly decreased in both the treatment (0.54+/-0.15 to 0.51+/-0.1 g/cm(2), P =0.001) and non-treatment (0.52+/-0.18 to 0.45+/-0.16 g/cm(2), P <0.001) group. But the percentage of bone mineral density decrease was found to be significantly lower in the treatment group than in the non-treatment group (4.6+/-2.1% vs. 13.0+/-4.0%, respectively; P <0.001). Serum calcium and urinary calcium excretion increased in the treatment group (8.0+/-1.0 to 10.0+/-0.5 mg/dl and 1.1+/-0.5 to 3.2+/-1.0 mg/kg/day) and non-treatment group (8.1+/-0.8 to 10.0+/-0.6 mg/dl and 1.4+/-0.9 to 3.8+/-3.3 mg/kg/day) after prednisolone treatment (P <0.001). Steroid treatment decreases bone mineral density in children with nephrotic syndrome. Vitamin D plus calcium therapy at the current doses reduces but does not completely prevent bone loss, with no additional adverse effects.

[Renovascular hypertension in a child with type 1 neurofibromatosis]

Arterial hypertension in pediatric patients with neurofibromatosis type 1 (NF 1) is usually due to renal artery stenosis (RAS) mainly involving the proximal part of the vessel. The treatment modalities are highly individualized. In severe and/or bilateral RAS, antihypertensive drugs are either ineffective or have the potential risk for acute renal failure, while percutaneous transluminal angioplasty (PTA) has limited success due to the ostial localization of RAS and the tough fibrotic tissue involved that is refractory to dilatation Renal autotransplantation has potential advantages when medical control and PTA/or bypass techniques failed. Here we report 5 year-old girl with NF 1 and hyponatremic hypertensive syndrome due to severe bilateral disease, occluded proximal part of the right artery and ostial stenosis (80%) of the left one. Only left kidney was identified on 99 m Tc DTPA, but the right one was visualized on the renal ultrasonography and in the late phase of arterial renography due to well developed collateral circulation. Multiple antihypertensive drugs (nifedipine, labetolol and minoxidil) in maximal doses and PTA failed to normalize BP while short term therapy with ACEI with NF1 and hyponatremic hypertensive syndrome due to severe bilateral renovascular disease; occluded proximal part of the right renal artery and ostial stenosis (80%) of the left one. Only left kidney was identified on 99 m Tc DTPA, but the right one was visualized on the renal ultrasonography and in the late phase of arterial renography due to well developed collateral circulation. Multiple antiphypertensive drugs (nifedipine, labetolol and minoxidil) in maximal doses and PTA failed to normalize BP while. short term therapy with ACEI, captopril induced transient acute renal failure. Autotransplantation of right kidney saved its function and improved BP control. Our current case Autotransplantation of right kidney saved its function and improved BP control. Our current case is illustrative for a difficult management of renovascular hypertension in children with NF1. This is the first and up to now the only case of autotransplantation performed in Yugoslavia.

Midaortic syndrome in the fetus and premature newborn: a new etiology of nonimmune hydrops fetalis and reversible fetal cardiomyopathy

Nonimmune hydrops fetalis is the final common pathway of many conditions that ultimately result in fetal anasarca. Even after extensive evaluation, the etiology of a small percentage of cases of hydrops remains unknown. We present a case of midaortic syndrome, also known as abdominal coarctation syndrome, in a fetus with hydrops and a severe cardiomyopathy. The clinical manifestations of midaortic syndrome in this fetus and premature newborn, including malignant hypertension and reversible cardiomyopathy, are detailed. The fetal pathophysiology of midaortic syndrome remains speculative, but likely includes fetal hypertension as the cause of cardiac dysfunction. To our knowledge, this is the first report of midaortic syndrome as an etiology for nonimmune hydrops fetalis.

Renal artery stenosis and nephrotic syndrome: a rare combination in an infant

We describe an uncommon pediatric finding of unilateral renal artery stenosis, which presented as nephrotic syndrome, hypertension, failure to thrive, and hyponatremia. The child was a previously well 8-month-old male who looked well but had mild periorbital edema with severe hypertension. After 3 days of captopril therapy, the nephrotic-range proteinuria significantly improved. However, the hypertension persisted. Renal imaging revealed a small left kidney with reduced parenchymal uptake and no significant excretion. A renal angiogram demonstrated left renal artery stenosis with increased left renal vein renin activity. The hypertension resolved within 24 h of a left nephrectomy, but non-nephrotic-range proteinuria persisted for 8 months post operatively. Pathology of the left kidney was consistent with fibromuscular dysplasia. Although a few glomeruli (1%) had changes consistent with focal segmental glomerulosclerosis, such a few abnormal glomeruli were unlikely to account for the nephrotic syndrome. Hypertension-induced changes in the unaffected right kidney probably caused the nephrotic-range proteinuria.