Ambulatory blood pressure monitoring: a versatile tool for evaluating and managing hypertension in children

Acute Kidney Injury and Risk of CKD and Hypertension after Pediatric Cardiac Surgery

BACKGROUND AND OBJECTIVES

The association of AKI after pediatric cardiac surgery with long-term CKD and hypertension development is unclear. The study objectives were to determine whether AKI after pediatric cardiac surgery is associated with incident CKD and hypertension.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a prospective cohort study of children of 1 month to 18 years old who were undergoing cardiac surgery at two tertiary care centers (Canada, United States). Participants were recruited before cardiac surgery and were followed during hospitalization and at 3, 12, 24, 36, and 48 months after discharge. Exposures were postoperative AKI, based on the Kidney Disease Improving Global Outcomes (KDIGO) definition, and age <2 years old at surgery. Outcomes and measures were CKD (low eGFR or albuminuria for age) and hypertension (per the 2017 American Academy of Pediatrics guidelines) at follow-up, with the composite outcome of CKD or hypertension.

RESULTS

Among 124 participants, 57 (46%) developed AKI. AKI versus non-AKI participants had a median (interquartile range) age of 8 (4.8-40.8) versus 46 (6.0-158.4) months, respectively, and higher preoperative eGFR. From the 3- to 48-month follow-up, the cohort prevalence of CKD was high (17%-20%); hypertension prevalence was also high (22%-30%). AKI was not significantly associated with the development of CKD throughout follow-up. AKI was associated with hypertension development at 12 months after discharge (adjusted relative risk, 2.16; 95% confidence interval, 1.18 to 3.95), but not at subsequent visits. Children aged <2 years old at surgery had a significantly higher prevalence of hypertension during follow-up than older children (40% versus 21% at 3-month follow-up; 32% versus 13% at 48-month follow-up).

CONCLUSIONS

CKD and hypertension burden in the 4 years after pediatric cardiac surgery is high. Young age at surgery, but not AKI, is associated with their development.

Importance of ambulatory blood pressure monitoring in the diagnosis and prognosis of pediatric hypertension

The prevalence of high blood pressure (BP) at pediatric age has increased progressively, one of the causes of which is obesity. However, the dominant etiology in this age group is renal and/or cardiovascular pathology. Ambulatory blood pressure monitoring (ABPM) is the method of choice for the diagnosis of hypertension, especially in children at high cardiovascular risk. Its use is limited to children from five years of age. Choosing appropriate cuff size is key to obtaining correct blood pressure. The main indication for ABPM is to confirm the diagnosis of hypertension. It also allows the diagnosis of white coat hypertension (which may represent an intermediate stage between the normotensive phase and hypertension), or masked hypertension, associated with progression to sustained hypertension and left ventricular hypertrophy (LVH). Children with isolated nocturnal hypertension should be considered as having masked hypertension. BP load is defined as the percentage of valid measurements above the 95th percentile for age, gender, and height. Values above 25-30% are pathological and those above 50% are predictive of LVH. ABPM correlates with target organ damage, particularly LVH and renal damage. It is useful in the differentiation of secondary hypertension, since these children show higher BP load and less nocturnal dipping, and confirmation of response to therapy. Thus ABPM allows the diagnosis and classification of hypertension, provides cardiovascular prognostic information and identifies patients with intermediate phenotypes of hypertension.

Masked Isolated Nocturnal Hypertension in Children and Young Adults

Isolated nocturnal hypertension (INH) is characterized by normal daytime blood pressure (BP) and elevated nighttime BP diagnosed by ambulatory BP monitoring. Masked isolated nocturnal hypertension (MINH) is a subtype of INH in which office BP is normal. We studied the frequency and characteristics of INH and MINH in children and young adults. One hundred and ninety-eight subjects seen by the pediatric nephrology service were studied retrospectively. Isolated nocturnal hypertension (INH) and MINH were diagnosed according to daytime and nighttime ABP and office BP in the case of the latter. One hundred and eighteen subjects (60%) had normotension, 6 (3%) had isolated daytime hypertension, 32 (16%) had INH, and 42 (21%) had day-night hypertension. Sixteen subjects had MINH (8.1%). The underlying diseases of MINH were as follows: no underlying disease 9 (56%), renal disease 6 (38%), and endocrine disease 1 (6%). There was no significant difference in the underlying disease, gender, age, and BMI between MINH and INH with elevated office BP. In conclusion, MINH is present in children and young adults. Since there were no specific features for MINH, screening with ambulatory or home BP monitoring during sleep may be appropriate.

Evaluating risk factors for chronic kidney disease in pediatric patients with sickle cell anemia

BACKGROUND

Patients with sickle cell anemia (SCA) have an increased prevalence of nephropathy and mortality from chronic kidney disease (CKD).

METHODS

We evaluated the association of hyperuricemia and nocturnal hypertension with lower estimated glomerular filtration rate (eGFR) using cystatin-C in patients aged 10-21 years with the HbSS or HbSB0 form of the disease during a non-acute clinic visit. eGFR and uric acid measurements were obtained in 83 and 81 participants, respectively, and 24-h ambulatory blood pressure monitoring (ABPM) was performed in 44 participants. Annual testing included vital signs, complete blood count, comprehensive metabolic panel, medications, urine microalbumin/creatinine, and lactate dehydrogenase measurements. Hyperuricemia was defined as a uric acid level of ≥5.5 mg/dL. Nocturnal hypertension was defined as >25% of nocturnal readings at >95th percentile according to norms established by the American Heart Association Statement on ABPM in children and adolescents.

RESULTS

The mean eGFR was statistically significantly lower in patients with hyperuricemia than in those with normal uric acid levels (143 vs. 161 mL/min/1.73 m², respectively). Of the 44 participants for whom ABPM data were available, 14 (32%) had systolic nocturnal hypertension and 12 (27%) had diastolic nocturnal hypertension. The mean eGFR was statistically significantly lower in participants with nocturnal systolic and diastolic hypertension than in those with normal nocturnal blood pressure. In a regression model, nocturnal hypertension and hyperuricemia were associated with a lower eGFR.

CONCLUSIONS

Two risk factors for CKD, i.e., nocturnal hypertension and hyperuricemia, were associated with lower eGFR in older children and adolescent patients with SCA. Long-term studies on their association with progression to CKD in this population are warranted.

KEY POINT

Nocturnal hypertension and hyperuricemia are established risk factors for nephropathy in other diseases and may play a role in SCA nephropathy.

Association between waist circumference and childhood-masked hypertension: A community-based study

AIM

The aim of this study is to determine the association between waist circumference (WC) and childhood-masked hypertension.

METHODS

A territory-wide, school-based cohort of 1385 Hong Kong students (672 boys and 713 girls) aged 8-17 years was analysed. The ambulatory blood pressure-monitoring assessment was performed using validated oscillometric recorders (A&D TM-2430 (A&D Inc., Tokyo, Japan)) following American Heart Association's recommendations. Subjects were considered normotensive if their casual blood pressure, 24-h daytime and night-time average systolic blood pressure and diastolic blood pressure (DBP) were <95th percentile. If one or more of the ambulatory blood pressure parameters was ≥95th percentile, subjects would be considered suffering from masked hypertension (MH). Subjects who had three successive casual blood pressure measurements above the 95th percentile were excluded.

RESULTS

By body mass index, 148 (10.7%) subjects were obese, 182 (13.1%) overweight and 359 (25.9%) having larger WC (≥85th percentiles). MH was diagnosed in 217 subjects (15.7%). Subjects with larger WC or obesity were significantly associated with higher 24-h daytime and night-time systolic blood pressure (≥95th percentile) (odds ratios from 1.84 to 2.09 and from 2.07 to 3.54 for larger WC and obese respectively, all P < 0.05) as well as 24-h DBP for larger WC (odds ratio = 2, P = 0.015) than normal subjects adjusted by sex, age and height.

CONCLUSION

Waist circumference and body mass index are independent risk factors of childhood and adolescent MH. WC appears a significant associated factor of elevated 24-h DBP in children aged 8-17 years.

Correlation between the morning hypertension on ambulatory blood pressure monitoring and the left ventricular mass in children

PURPOSE

Although high morning blood pressure (BP) is known to be associated with the onset of cardiovascular events in adults, data on its effects in children with hypertension are limited. Our retrospective study aimed to define the clinical characteristics of children with morning hypertension (MH) and to determine its associated factors.

METHODS

We reviewed 31 consecutive patients with hypertension, confirmed by the ambulatory blood pressure monitoring (ABPM). We divided these patients into 2 groups: the MH group (n=21, 67.7%), morning BP above the 95th percentile for age and height (2 hours on average after waking up) and the normal morning BP group (n=10, 32.3%). We compared the clinical manifestations, laboratory results, and echocardiographic findings including left ventricular hypertrophy (LVH) between the groups.

RESULTS

The early/atrial (E/A) mitral flow velocity ratio in the MH group was significantly lower than that in the normal morning BP group. In addition, LV mass was higher in the MH group than in the normal morning BP group, although the difference was not statistically significant. The age at the time of hypertension diagnosis was significantly higher in the MH group than in the normal morning BP group (P=0.003). The incidence of hyperuricemia was significantly higher in the MH group than in the normal morning BP group.

CONCLUSION

Older patients and those with hyperuricemia are at higher risk for MH. The rise in BP in the morning is an important factor influencing the development of abnormal relaxation, as assessed by echocardiography. Clinical trials with longer follow-up periods and larger sample sizes are needed to clarify the clinical significance of MH.

Ambulatory and home blood pressure monitoring in children and adolescents: diagnosis of hypertension and assessment of target-organ damage

The prevalence of elevated blood pressure in children and adolescents is more common than previously believed and often represents the early onset of essential hypertension, particularly in adolescents. The definition of hypertension in children is based on distribution criteria and normalcy tables that provide blood pressure percentiles for each measurement method (office, ambulatory and home) according to the individual's age, gender and body size. Owing to the white coat and masked hypertension phenomena, ambulatory blood pressure monitoring is indispensable for the diagnosis of hypertension in children. Home blood pressure monitoring in children has been less well studied, and at present, treatment decisions should not be based solely on such measurements. Hypertension-induced preclinical target-organ damage (mainly echocardiographic left ventricular hypertrophy) is not uncommon in children and should be evaluated in all hypertensive children. Other indices of target-organ damage, such as carotid intima-media thickness, pulse wave velocity and microalbuminuria, remain under investigation in pediatric hypertension.

Arterial hypertension and progression of chronic kidney disease in children during 10-year ambulatory observation

The aim of this study was the long-term retrospective analysis of chronic kidney disease (CKD) progression in children, especially with regard to the presence of hypertension (HTN). The average rate of progression of CKD was higher in patients with HTN than without HTN. Hypertension treatment requires multidrug schemes which need to be intensified with extended time of CKD duration.

Blood pressure variability, prehypertension, and hypertension in adolescents

Medical conditions diagnosed during adolescence may have long term impacts on the health of an individual. As a result, identifying cardiovascular risk factors earlier in life such as prehypertension (pre-HTN) and hypertension (HTN) can have significant benefits across an individual’s lifespan. Diagnosing elevated blood pressure (BP) during adolescence can be difficult, partially due to the natural variability that occurs during this period of life. Levels of BP that define adolescent prehypertension/hypertension are provided as well as an abridged review of BP variability across research groups. Strategies for BP management of adolescents are considered, with the primary focus on nonpharmacologic interventions.

Control of hypertension in treated children and its association with target organ damage

BACKGROUND

The aim of our study was to investigate the control of hypertension (HT) in treated children using ambulatory blood pressure (BP) monitoring (ABPM).

METHODS

We retrospectively reviewed all ABPM studies in our center. Controlled HT was defined as systolic and diastolic BP index (patients' BP divided by the 95th percentile) at daytime and nighttime <1.0 or alternatively as BP load (percentage of BP readings above the 95th percentile) <25% in children on antihypertensive therapy.

RESULTS

A total of 195 ABPM studies were included. The mean age was 13.6 ± 4.0 years. One hundred and thirty two children had renoparenchymal HT, 10 renovascular (RVH), 10 endocrine, 4 cardiovascular, 29 primary (PH) and 5 children other forms of HT. 53% of all children had controlled HT. There was no difference in the prevalence of controlled HT between primary and secondary HT (52% and 53%) using the BP index criterion. Children with renoparenchymal HT had significantly better control of HT than children with RVH (58% vs. 20% P = 0.02). The use of angiotensin-converting enzyme inhibitors (ACEI) monotherapy was significantly more effective in controlling HT than the use of calcium-channel blockers (CCB, P = 0.02). The prevalence of left ventricular hypertrophy in children with uncontrolled HT (assessed in 58 patients) was significantly higher than in children with controlled HT (46% vs. 13%, P < 0.01).

CONCLUSIONS

This is the first pediatric study, to our knowledge, on BP control in hypertensive children using ABPM. It indicates that control of HT is inadequate in ~50% of treated children. Inadequate control of HT is associated with target organ damage in this population.

Office, ambulatory and home blood pressure measurement in children and adolescents

There is an increasing interest in pediatric hypertension, the prevalence of which is rising in parallel with the obesity epidemic. Traditionally the assessment of hypertension in children has relied on office blood pressure (BP) measurements by the physician. However, as in adults, office BP might be misleading in children mainly due to the white coat and masked hypertension phenomena. Thus, out-of-office BP assessment, using ambulatory or home monitoring, has gained ground for the accurate diagnosis of hypertension and decision-making. Ambulatory monitoring is regarded as indispensable for the evaluation of pediatric hypertension. Preliminary data support the usefulness of home monitoring, yet more evidence is needed. Office, ambulatory and home BP normalcy tables providing thresholds for diagnosis have been published and should be used for the assessment of elevated BP in children.

Elevated ambulatory blood pressure in a multi-ethnic population of obese children and adolescents

OBJECTIVES

To evaluate the relationship among ambulatory blood pressure (ABP), body mass index (BMI), and homeostasis model assessment (HOMA) in a multi-ethnic population of obese children with clinic blood pressure in the reference range.

STUDY DESIGN

A total of 43 obese normotensive children (7-17 years old) were recruited. ABP monitoring, oral glucose tolerance test, lipid levels, and urine microalbumin levels were obtained.

RESULTS

Fourteen percent of the subjects had elevated 24-hour systolic blood pressure (SBP), 9.3% had elevated daytime SBP, and 32.6 % elevated nighttime SBP. For diastolic blood pressure, 4.7% of the sample had an elevated mean nighttime value. Children with more severe obesity (BMI SD score >2.5) had higher 24-hour and nighttime SBP than children with less severe obesity (BMI SD score < or =2.5). Children with HOMA values in the highest quartile had larger waist circumference and higher clinic blood pressure than children with HOMA values in the lowest quartile, and no difference in the mean ABP values was found in the 2 groups . Multiple linear regression analysis showed that 24-hour and nighttime SBP were significantly correlated with BMI SD score.

CONCLUSION

Obese children with normal clinic blood pressure often exhibit elevated ABP. The risk for ambulatory hypertension appears to be correlated with the degree of obesity.

Hypertension in adolescents

In adults, hypertension has long been perceived as a public health problem. By contrast, its impact in childhood is far less appreciated. In fact, quite often, high blood pressure in children is not even diagnosed. Blood pressure is a vital sign that is routinely obtained during a physical examination of adults, but only very seldom in children. The diagnosis of hypertension in children is complicated because 'normal' blood pressure values vary with age, sex and height. As a consequence, almost 75% of the cases of arterial hypertension and 90% of the cases of prehypertension in children and adolescents are currently undiagnosed. Furthermore, adolescence hypertension is increasing in prevalence as the prevalence of pediatric obesity has increased. Ambulatory blood pressure monitoring is a useful method for risk evaluation in adolescents. In addition to being viewed as an important cardiovascular risk factor in adolescents, elevated blood pressure should prompt a thorough search for other modifiable risk factors that, if treated, might reduce teenagers' risk of developing cardiovascular disease in adulthood. Thus, assessing blood pressure values in children represents one of the most important measurable markers of cardiovascular risk later in life and a major step in preventive medicine.

Arterial HTN in children with T1DM--frequent and not easy to diagnose

INTRODUCTION

To evaluate the diagnostic efficacy of the office blood pressure (OBP) and ambulatory blood pressure monitoring (ABPM) in the assessment of hypertension (HTN) in children with diabetes mellitus type 1 (T1DM).

METHODS

We analyzed OBP and ABPM measurements in 84 diabetic children (43 boys) obtained at a median age of 14.9 yr and 6.3 +/- 3.5 yr after diagnosis of T1DM. OBP and ABPM results were converted into standard deviation scores (SDS). In addition, we analyzed blood pressure loads and nighttime dipping. The comparison between OBP and ABPM was performed using kappa coefficient and receiver operator curve (ROC).

RESULTS

HTN was diagnosed in 43/84 (51%) patients using OBP (>95th percentile), and in 24/84 (29%) patients using ABPM ( > or = 95th percentile during 24 h, day or night). Both methods were in agreement in 33 ABPM normotensive and 16 ABPM hypertensive patients (most had nighttime HTN); 32% patients had white-coat HTN and 9.5% patients had masked HTN. The kappa coefficient was 0.175 (95% CI from -0.034 to 0.384) suggesting poor agreement between OBP and ABPM. Diastolic OBP was a better predictor of ABPM HTN (ROC area under the curve (AUC) = 0.71 +/- 0.06) than systolic OBP (AUC = 0.58 +/- 0.07). The percentage of non-dippers ranged from 7 to 23% in ABPM normotensive patients, and 21-42% in ABPM hypertensive patients who also had significantly higher BP loads (p < 0.0001).

CONCLUSION

Children with T1DM often suffer from nocturnal, white coat- and masked HTN, which can not be assessed and predicted by the OBP.

Treatment of systemic hypertension in children and adolescents

PURPOSE OF REVIEW

This review aims to update the practitioner in recent developments in the treatment of hypertension in children and adolescents.

RECENT FINDINGS

In the last years, the treatment of hypertension in children and adolescents has been characterized by an improvement in the definition of hypertension and the more widespread use of the 24-h blood pressure monitor to define the hypertension pattern and assess efficacy of the therapy. A few studies on the use of converting enzyme inhibitors and angiotensin II receptor blocker emphasizing doses, efficacy, and side effects have been published. Of special interest is the tantalizing hypothesis on the role of uric acid in essential hypertension and the practical application of the use of allopurinol as monotherapy for this condition.

SUMMARY

The authors aim to convey the need to define the blood pressure pattern in these patients before any type of therapy is started and the titration of medications according to the pathophysiologic mechanisms involved.