Associated extrarenal vascular diseases may complicate the treatment and outcome of renovascular hypertension

Hypertension crisis as the first symptom of renovascular hypertension in children

BACKGROUND

Renovascular hypertension (RVH) is one of the main causes of hypertensive crisis (HTN-C). It is characterized by acute onset and severe disease, and early diagnosis and treatment are difficult. The objective was to describe the characteristics of RVH and factors associated with RVH leading to HTN-C in children. At present, there are few clinical studies on RVH in children with large cases in China.

METHODS

This study retrospectively analyzed the clinical data of inpatient children with RVH. Patients were divided into non-hypertensive crisis (non-HTN-C) group, and HTN-C group according to the first symptoms and blood pressure. Further, HTN-C were classified as hypertensive urgency (HTN-U) or hypertensive emergency (HTN-E).

RESULTS

Fifty-four pediatric cases (41 boys and 13 girls) were included. 83.3% of the RVH cases were ≥ 6 years old. Three cases were classified into the non-HTN-C group. Of the 51 HTN-C cases, 18 cases were grouped as HTN-U and 33 as HTN-E. The HTN-U group were mainly asymptomatic (50.0%, 9/18) while the HTN-E group mainly presented with neurological symptoms (72.7%, 24/33). The number of unknown etiology children was 32 (59.2%). The top three known etiologies were Takayasu's arteritis (50.0%, 11/22), congenital renal dysplasia (27.3%, 6/22) and fibromuscular dysplasia (13.6%, 3/22). As for the target organ damage of RVH, patients had a higher prevalence of left ventricular hypertrophy (71.4%, 35/49) and retinopathy (77.8%, 21/27).

CONCLUSIONS

Most RVH patients with HTN-C as the first symptoms, especially for males over 6 years old, should be assessed for RVH even if they were asymptomatic. Most asymptomatic patients with RVH already had target organ damage, and symptomatic patients even developed life-threatening complications. As preventive measures, routine monitoring of BP during children's physical examinations is advised.

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.

Genetics of renovascular hypertension in children

OBJECTIVE

In most cases of renovascular hypertension in children, the cause is unclear. The aim of this study was to investigate genetic variation as a factor in the development of renovascular hypertension in children.

METHODS

In a cohort of 37 unrelated children from a single tertiary referral center, exome sequencing was performed. We assessed variants in recognized and suspected disease genes and searched for novel ones with a gene-based variant-burden analysis.

RESULTS

In the majority of patients, exome sequencing could not identify causative variants. We found a pathogenic variant in a recognized associated disease gene in five patients (three pathogenic variants in NF1, one in ELN and a deletion of chromosome 7q11.23, consistent with Williams syndrome). In two other patients, (likely) pathogenic variants were found in putative renovascular hypertension genes (SMAD6 and GLA), with clinical implications for both. Ten additional patients carried variants of uncertain significance (VUS) in known (n = 4) or putative (n = 6) renovascular hypertension disease genes. Rare variant burden analysis yielded no further candidate genes.

CONCLUSION

Genetic contributors, such as germline mutations in NF1, ELN, 7q11.23del were present in only 5 out of 37 (14%) children with renovascular hypertension. Twelve other children (32%) had potentially causal variants identified, including a pathogenic variant in SMAD6; a vasculopathy gene hitherto unknown to link with renovascular hypertension. Most importantly, our data show that exome sequencing can rarely identify the cause of renovascular hypertension in nonsyndromic children. We suggest that nongenetic factors or somatic genetic variation will play a more important role.