Renal sonography with Doppler for detecting suspected pediatric renin-mediated hypertension - is it adequate?

Pediatric Hypertension: A Condition That Matters

Systemic hypertension has been considered mainly as an adult health issue for a long time, but it is now being increasingly acknowledged as a significant problem also among pediatric patients. The frequency of pediatric hypertension has grown mostly because of increases in childhood obesity and sedentary lifestyles, but secondary forms of hypertension play a role as well. Considering that unaddressed hypertension during childhood can result in enduring cardiovascular complications, timely identification and intervention are essential. Strategies for addressing this disease encompass not only lifestyle adjustments, but also the use of medications when needed. Lifestyle modifications entail encouraging a nutritious diet, consistent physical activity, and the maintenance of a healthy weight. Moreover, educating both children and their caregivers about monitoring blood pressure at home can aid in long-term management. Thus, the aim of this review is to discuss the etiologies, classification, and principles of the treatment of hypertension in pediatric patients.

Nonatherosclerotic Renovascular Hypertension

Renovascular hypertension (RVH) is a secondary form of high blood pressure resulting from impaired blood flow to the kidneys with subsequent activation of the renin-angiotensin-aldosterone system. Often, this occurs due to abnormally small, narrowed, or blocked blood vessels supplying one or both kidneys (ie: renal artery occlusive disease) and is correctable. Juxtaglomerular cells release renin in response to decreased pressure, which in turn catalyzes the cleavage of circulating angiotensinogen synthesized by the liver to the decapeptide angiotensin I. Angiotensin-converting enzyme then cleaves angiotensin I to form the octapeptide angiotensin II, a potent vasopressor and the primary effector of renin-induced hypertension. The effects of angiotensin II are mediated by signaling downstream of its receptors. Angiotensin receptor type 1 is a G-protein-coupled receptor that activates vasoconstrictor and mitogenic signaling pathways resulting in peripheral arteriolar vasoconstriction and increased renal tubular reabsorption of sodium and water which promotes intravascular volume expansion. Angiotensin II stimulates the adrenal cortical release of aldosterone, which promotes renal tubular sodium reabsorption, resulting in volume expansion. Angiotensin II acts on glial cells and regions of the brain responsible for blood pressure regulation increasing renal sympathetic activation. Angiotensin II simulates the release of vasopressin from the pituitary which stimulates thirst and water reabsorption from the kidney to expand the intravascular volume and cause peripheral vasoconstriction (increased sympathetic tone). All of these mechanisms coalesce to increase arterial pressure by way of arteriolar constriction, enhanced cardiac output, and the retention of sodium and water.

Imaging of urinary tract in children in different clinical scenarios: a guide for general radiologists

Background

Children are frequently referred to the pediatric radiology department due to complaints related to the urinary tract.

Main body

We aimed to describe common clinical scenarios in paediatric urology practice and their recommended imaging diagnostic algorithms. Practical imaging approach to following common clinical scenarios and the common radiological findings are discussed: (A) perinatal urinary tract dilatation and other congenital anomalies; (B) recurrent urinary tract infection; (C) enuresis and daytime urinary incontinence; (D) abdominal masses; (E) flank pain; (F) hematuria; (G) trauma; (H) nonpalpable testis, ambiguous genitalia and common urogenital sinus anomalies; and I) renovascular hypertension

Conclusions

Imaging investigations should be tailored according to the clinical presentation in a stepwise approach aiming for optimum patients’ care.

Renovascular hypertension in pediatric patients: update on diagnosis and management

Renovascular hypertension (RVH) is defined as an elevated blood pressure caused by kidney hypoperfusion, generally as a result of anatomic stenosis of the renal artery with consequent activation of the Renin Angiotensin-Aldosterone System. The main causes include genetic and inflammatory disorders, extrinsic compression, and idiopathic alterations. RVH is often asymptomatic and should be suspected in any child with refractory hypertension, especially if other suggestive findings are present, including those with severe hypertension, abdominal bruit, and abrupt fall of glomerular filtration rate after administration of angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. There is a consensus that digital subtraction angiography is the gold standard method for the diagnosis of RVH. Nevertheless, the role of non-invasive imaging studies such as Doppler ultrasound, magnetic resonance angiography, or computed tomographic angiography remains controversial, especially due to limited pediatric evidence. The therapeutic approach should be individualized, and management options include non-surgical pharmacological therapy and revascularization with percutaneous transluminal renal angioplasty (PTRA) or surgery. The prognosis is related to the procedure performed, and PTRA has a higher restenosis rate compared to surgery, although a decreased risk of complications. This review summarizes the causes, physiopathology, diagnosis, treatment, and prognosis of RVH in pediatric patients. Further studies are required to define the best approach for RVH in children.

Renovascular hypertension in children

Paediatric hypertension, defined as systolic blood pressure > 95th percentile for age, sex and height is often incidentally diagnosed. Renovascular hypertension (RVH) is responsible for 5-25% of hypertension in children. Renal artery stenosis and middle aortic syndrome can both can be associated with various conditions such as fibromuscular dysplasia, Williams syndrome & Neurofibromatosis type 1. This paper discusses the approaches to diagnosis and interventional management and outcomes of renovascular hypertension in children. Angiography is considered the gold standard in establishing the diagnosis of renovascular disease in children. Angioplasty is beneficial in the majority of patients and generally repeated angioplasty is considered more appropriate than stenting. Surgical options should first be considered before placing a stent unless there is an emergent requirement. Given the established safety and success of endovascular intervention, at most institutions it remains the preferred treatment option.

Hypertension in Children and Adolescents: A Position Statement From a Panel of Multidisciplinary Experts Coordinated by the French Society of Hypertension

Hypertension is much less common in children than in adults. The group of experts decided to perform a review of the literature to draw up a position statement that could be used in everyday practice. The group rated recommendations using the GRADE approach. All children over the age of 3 years should have their blood pressure measured annually. Due to the lack of data on cardiovascular morbidity and mortality associated with blood pressure values, the definition of hypertension in children is a statistical value based on the normal distribution of blood pressure in the paediatric population, and children and adolescents are considered as having hypertension when their blood pressure is greater than or equal to the 95th percentile. Nevertheless, it is recommended to use normative blood pressure tables developed according to age, height and gender, to define hypertension. Measuring blood pressure in children can be technically challenging and several measurement methods are listed here. Regardless of the age of the child, it is recommended to carefully check for a secondary cause of hypertension as in 2/3 of cases it has a renal or cardiac origin. The care pathway and principles of the therapeutic strategy are described here.

Pediatric hypertension: an updated review

Globally hypertension in adults is among the leading preventable cause of premature death, where a graded association from the childhood hypertension is well recognised. With the concurrent rise in obesity and pediatric hypertension (HTN) during the past decade in developed countries, a parallel trend is emerging in developing countries that has a potential for exponential rise in cardiovascular, cerebrovascular and renal tragedies. A cumulative incidence of pediatric HTN in China and India is 50–70 and 23% respectively, is quite disturbing. New guidelines for the detection, evaluation and management of hypertension in children and adolescents published in 2017, where a jump in prevalence of pediatric HTN is observed, rings a call to address this under-attended burning problem; for which a review in pediatric hypertension and its management is warranted.

Does treatment-resistant hypertension exist in children? A review of the evidence

Treatment-resistant hypertension (TRH) is a well-described condition in adult patients that is associated with poor clinical outcomes. While case reports of hypertension resistant to therapy in children have been published, it is unclear if TRH truly exists in childhood. This educational review will briefly summarize recent evidence and recommendations for TRH in adults, as well as will review the literature regarding medically resistant hypertension in children and adolescents. Finally, we propose a clinical approach for evaluation hypertensive children and adolescents with apparent treatment resistance.

Normative and pathological values of hemodynamic and Doppler ultrasound arterial findings in children

Doppler ultrasound is an effective, useful and remarkably powerful tool in pediatric imaging. If possible, its use is always favored to avoid exposure to radiation or sedatives. By waveform spectrum analysis, Doppler ultrasound reveals information on blood flow and details on normal physiology and pathological processes undiscernible from gray-scale imaging alone. However, Doppler ultrasound remains underused, largely due to the difficult interpretation of changes in Doppler waveforms during childhood. This article provides a narrative review of the literature regarding the normative values and the physiological arterial changes through childhood according to age, weight or height, as well as frequent pathological arterial findings in children, classified by arterial territory.

Hypertensive Crisis in Pediatric Patients: An Overview

Hypertensive crisis can be a source of morbidity and mortality in the pediatric population. While the epidemiology has been difficult to pinpoint, it is well-known that secondary causes of pediatric hypertension contribute to a greater incidence of hypertensive crisis in pediatrics. Hypertensive crisis may manifest with non-specific symptoms as well as distinct and acute symptoms in the presence of end-organ damage. Hypertensive emergency, the form of hypertensive crisis with end-organ damage, may present with more severe symptoms and lead to permanent organ damage. Thus, it is crucial to evaluate any pediatric patient suspected of hypertensive emergency with a thorough workup while acutely treating the elevated blood pressure in a gradual manner. Management of hypertensive crisis is chosen based on the presence of end-organ damage and can range from fast-acting intravenous medication to oral medication for less severe cases. Treatment of such demands a careful balance between decreasing blood pressure in a gradual manner while preventing damage end-organ damage. In special situations, protocols have been established for treatment of hypertensive crisis, such as in the presence of endocrinologic neoplasms, monogenic causes of hypertension, renal diseases, and cardiac disease. With the advent of telehealth, clinicians are further able to extend their reach of care to emergency settings and aid emergency medical service (EMS) providers in real time. In addition, further updates on the evolving topic of hypertension in the pediatric population and novel drug development continues to improve outcomes and efficiency in diagnosis and management of hypertension and consequent hypertensive crisis.

Diagnostic Role of Renal Doppler Ultrasound and Plasma Renin Activity as Screening Tools for Renovascular Hypertension in Children

OBJECTIVES

The diagnostic role of an ultrasound (US) and plasma renin activity (PRA) combination is unknown, despite the usefulness of Doppler US as a screening tool for renovascular hypertension (RVHT). The purpose of this study was to evaluate the diagnostic usefulness of US for RVHT in children stratified according to PRA.

METHODS

We identified 336 children who underwent renal Doppler US examinations for hypertension and divided them into a high-renin group (n = 177) and a normal-renin group (n = 159) based on PRA and stratified them by age. The Doppler US findings were retrospectively reviewed, and computed tomographic angiography (CTA) for the same children was used as the reference standard.

RESULTS

In the high-renin group, 36 patients had positive Doppler US findings that were confirmed by CTA in 32 cases. The sensitivity and specificity values for Doppler US in the high-renin group were 84.2% and 93.6%, respectively. In the normal-renin group, 10 patients had positive Doppler US findings; these positive findings were confirmed by CTA in 9 cases. The sensitivity and specificity values for US in the normal-renin group were 100.0% and 100.0%. There were anatomic variations (n = 3) and segmental artery stenosis (n = 2) among the cases with false-negative US findings, which were confirmed by CTA.

CONCLUSIONS

If patients have high PRA, a Doppler US examination should be performed with caution to avoid false-negative detection. If patients have normal PRA, renal Doppler US might be adequate for diagnosis of RVHT to avoid unnecessary CTA.

Doppler ultrasonographic and clinical features of middle aortic syndrome

OBJECTIVES

To discuss Doppler ultrasonographic and clinical features of middle aortic syndrome (MAS).

MATERIALS AND METHODS

Doppler ultrasonographic images and clinical dates of 11 patients with MAS confirmed by angiography were retrospectively analyzed from January 2004 to September 2016.

RESULTS

The median age of 11 patients was 10 years (1-39 years). Ten patients presented with hypertension, only 2 cases presented with symptomatic intermittent claudication, and 1 case presented with abdominal pain. The ultrasonographic features of 11 patients with MAS included: (a) Gray-scale image showed significant segmental narrowing of the aorta in 9 cases. (b) Color Doppler demonstrated aliasing in the suspicious narrowed vessels of all cases. (c) On Spectral Doppler image, peak systolic velocity in the location of aorta coarctation was significantly elevated (range, 2.3~4.8 m/s). When infrarenal aorta was involved, a tardus-parvus waveform was only seen in the distal aorta. When suprarenal or inter-renal aorta was involved, a tardus-parvus pattern was seen in the distal aorta as well as renal artery.

CONCLUSIONS

Significant segmental narrowing and a tardus-parvus waveform are the important ultrasonographic features in patients with MAS, the latter may be more reliable. Doppler ultrasound can be used as a simple screening method, especially for children and adolescents suspected of having a vascular cause of refractory hypertension.

Evaluation and Management of Stage 2 Hypertension in Pediatric Patients

PURPOSE OF REVIEW

To update the definition and clinical practice of stage 2 hypertension (HTN) in pediatrics.

RECENT FINDINGS

The 2017 American Academy of Pediatrics Clinical Practice Guideline (AAP CPG) for Screening and Management of High Blood Pressure in Children and Adolescent includes new normative blood pressure tables for children and adolescents ages 1 to 17 years and new definitions for stage 2 HTN. This review will highlight these aspects as well as new recommendations in the guideline specific to stage 2 HTN. It will outline how the new guideline differs from the previous 2004 guideline, the implications of these differences, and suggested changes in evaluation and management of stage 2 HTN. Lastly, the review will address topics relevant to daily clinical practice including competitive athletic participation, investigation for secondary HTN and HTN comorbidities, and blood pressure-lowering therapy. With the publication of the new AAP CPG introducing revised normative tables, the prevalence of stage 2 HTN in pediatrics is expected to rise. Based on the new guidelines, there is less emphasis on investigation for secondary HTN and more attention to lifestyle modifications for primary HTN. Future research should address whether there is BP level within the stage 2 HTN range above which the approach to evaluation and management should be altered in this heterogeneous patient population.

Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents

These pediatric hypertension guidelines are an update to the 2004 "Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents." Significant changes in these guidelines include (1) the replacement of the term "prehypertension" with the term "elevated blood pressure," (2) new normative pediatric blood pressure (BP) tables based on normal-weight children, (3) a simplified screening table for identifying BPs needing further evaluation, (4) a simplified BP classification in adolescents ≥13 years of age that aligns with the forthcoming American Heart Association and American College of Cardiology adult BP guidelines, (5) a more limited recommendation to perform screening BP measurements only at preventive care visits, (6) streamlined recommendations on the initial evaluation and management of abnormal BPs, (7) an expanded role for ambulatory BP monitoring in the diagnosis and management of pediatric hypertension, and (8) revised recommendations on when to perform echocardiography in the evaluation of newly diagnosed hypertensive pediatric patients (generally only before medication initiation), along with a revised definition of left ventricular hypertrophy. These guidelines include 30 Key Action Statements and 27 additional recommendations derived from a comprehensive review of almost 15 000 published articles between January 2004 and July 2016. Each Key Action Statement includes level of evidence, benefit-harm relationship, and strength of recommendation. This clinical practice guideline, endorsed by the American Heart Association, is intended to foster a patient- and family-centered approach to care, reduce unnecessary and costly medical interventions, improve patient diagnoses and outcomes, support implementation, and provide direction for future research.

Ultrasound imaging of renin-mediated hypertension

The incidence of primary (i.e. essential) hypertension in children and adolescents is increasing; however, secondary hypertension, with an identifiable cause, remains relatively common and might be treatable or even curable. Renovascular hypertension is an uncommon but important secondary cause of hypertension in the pediatric population that can be associated with substantial morbidity. In this article we discuss renin-mediated causes of hypertension in children and related complications, review renal Doppler ultrasound techniques for the evaluation of renin-mediated hypertension (including both direct and indirect assessments), and briefly appraise the literature pertaining to renal Doppler ultrasound and the assessment of pediatric hypertension. Finally, we describe a proposed role for renal Doppler ultrasound in the workup of suspected renin-mediated hypertension in children and adolescents.

Sonographic evaluation of renovascular hypertension in the pediatric population: State-of-the-art

Hypertension in children affects 2-5% of the pediatric population. Identifying secondary causes of hypertension is crucial, as some of these entities may be treatable. Renovascular hypertension accounts for 5-10% of the secondary causes of hypertension in children and is mainly related to fibromuscular dysplasia and neurofibromatosis type 1. Ultrasonographic evaluation of the kidneys, including Doppler interrogation, is the recommended primary screening tool. A comprehensive study of the upper abdomen and retroperitoneum allows for identification of additional underlying etiologies. The purpose of this review is to emphasize the different causes of renovascular hypertension in children one can diagnose during the initial ultrasonographic evaluation. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:282-292, 2017.

Non-invasive imaging cannot replace formal angiography in the diagnosis of renovascular hypertension

OBJECTIVES

Renovascular disease (RVD) is found in about 10 % of secondary childhood hypertension. Digital subtraction angiography (DSA) is the gold standard to diagnose RVD. Non-invasive imaging methods like Doppler ultrasound (US), magnetic resonance angiography (MRA), and computed tomography angiography (CTA) are increasingly used. Our aim was to evaluate the role and accuracy of US, MRA, and CTA compared to DSA in diagnosing RVD in children.

PATIENTS AND METHODS

A retrospective review of 127 children with suspected renovascular hypertension was performed in children referred to Great Ormond Street Hospital between 2006 and 2014 due to clinical suspicion of renovascular hypertension and/or findings on US and/or MRA or CTA.

RESULTS

Ninety-nine of 127 children (78 %) were diagnosed with renovascular disease and 80 were treated with percutaneous transluminal angioplasty during the same procedure. The median age at presentation was 5.6 (range, 2.5-10.6) years. Thirty-six children had unilateral renal artery stenosis in major extraparenchymal vessels, 47 bilateral stenosis and 16 intrarenal small vessel disease. US had a sensitivity of 63 % and specificity of 95 %. MRA and CTA were performed in 39 and 34 children, respectively. CTA sensitivity was slightly higher than that of MRA, 88 vs. 80 %, and specificity 81 vs. 63 %.

CONCLUSIONS

The sensitivity of MRA and CTA is still too low to reliably rule out renovascular disease in children with a strong suspicion of this diagnosis. DSA remains the gold standard to diagnose renovascular hypertension and is recommended when clinical and laboratory criteria are highly suggestive of renovascular disease even with normal radiological investigations from non-invasive methods.

Functional assessment of the kidneys in a 10 month-old child with renal artery stenosis by intravoxel incoherent motion

Renovascular stenosis is an important cause for arterial hypertension in childhood. We report a 10-month-old girl with arterial hypertension caused by right-sided renal artery stenosis detected by Doppler ultrasound. Magnetic resonance imaging (MRI) was performed before renal artery angioplasty to depict vascular anatomy in detail and to retrieve additional functional information of the kidneys by analysis of intravoxel incoherent motion (IVIM). The value of quantitative diffusion weighted imaging of the kidneys prior to percutaneous transluminal renal angioplasty (PTRA) is discussed.

Duplex ultrasound findings before and after surgery in children and adolescents with renovascular hypertension

We report our experience with duplex ultrasound in young patients with renal artery stenosis (RAS) or middle aortic syndrome (MAS) before and after surgery (1995 and 2009). Of 36 patients (mean age: 13 ± 7 y), 21 had RAS and 15 had MAS. For patients with RAS, the Vmax in the affected artery was 350 ± 111 cm/s before surgery and 145 ± 55 cm/s after surgery. The resistance index was 0.46 ± 0.1 in the post-stenotic kidney and increased to 0.60 ± 0.08 after revascularization. Determination of the flow profile in the iliac artery revealed triphasic flow. In individuals with MAS, Vmax in the aorta was 323 ± 98 and the resistance index in both kidneys was low, even in the absence of RAS. The flow profile in the iliac arteries was monophasic before surgery and became triphasic after surgery. Duplex ultrasound is useful for the evaluation of children and young adults both pre- and post-surgery. Duplex ultrasound criteria for RAS in adults appear to be applicable in children and young adults also. The diagnostic evaluation of suspected renal vascular disease should include assessment of the aorta and the flow profile in the iliac arteries, as this could help differentiate between aortic and isolated renal artery stenosis.