Clinical value of ambulatory blood pressure in pediatric patients after renal transplantation

Longitudinal follow-up on vascular morphology and function in children with kidney transplants

AIM

Our aim was to evaluate cardiovascular risk profile in 42 children with kidney transplants (KT) at the Queen Silvia Children's Hospital, Gothenburg Sweden.

METHODS

Forty-two children (7.1-18 years) with KT, time from transplantation 3.5 (0.9-13) years, were examined at inclusion and annually for three consecutive years. Eighteen matched controls were examined once. Cardiovascular phenotyping included ultra-high-frequency ultrasound (UHFUS), pulse wave velocity (PWV), and endothelial function.

RESULTS

Children with KT had higher body mass index (BMI) z-score and blood pressure (BP) z-score than healthy controls (BMI z-score: 0.4 ± 1.0 and - 0.2 ± 0.9, respectively, p = 0.02; SBP z-score: 0.5 ± 0.9 and - 0.8 ± 0.7; DBP z-score: 0.7 ± 0.7 and - 0.3 ± 0.5, respectively, p < 0.001). BP z-score decreased significantly over 3 years; other vascular markers remained unchanged. PWV and carotid intima thickness (IT) were higher in children with KT compared to healthy controls. Children with pre-emptive KT had lower radial IT and dorsal pedal media thickness (MT) compared to children with preceding dialysis.

CONCLUSION

Children with KT show increased cardiovascular risk parameters, not increasing over time. Children on dialysis before KT have more pronounced vascular changes than those with pre-emptive KT, suggesting pre-emptive transplantation more beneficial for cardiovascular health.

Pediatric kidney transplant and cardiometabolic risk: a cohort study

INTRODUCTION

Patients with chronic kidney disease (CKD) are known to have increased cardiovascular risk but there are few data on the risk of pediatric kidney transplant recipients. We aimed to assess the impact of pre- and post-transplant overweight on allograft function and to characterize the evolution of several cardiovascular risk variables over time and their impact.

METHODS

A retrospective analysis of the records of 23 children/adolescents followed at a tertiary center after kidney transplant was conducted. Data on anthropometry and cardiometabolic variables were analyzed before transplant, six and 12 months after the transplant, and at the last follow-up visit. The impact of the variables on allograft function (glomerular filtration rate (GFR)) was estimated by creatinine-based revised Schwartz formula (Cr-eGFR) and was evaluated using nonparametric tests. Results: The 23 patients included in the study had a median age of 6.3 (4.4-10.1) years. Both systolic and diastolic BP z-score values significantly decreased between BMI groups [1.2 (-0.2 - 2.3) vs. 0.3 (-0.4 - 0.6), p=0.027 and 0.8 (-0.4 - 1.3) vs. 0.1 (-0.6 - 0.7), p=0.028, pre-transplant and at the final evaluation, respectively]. During follow-up, GFR values decreased (Cr-GFR: 68.9 (57.7-76.8) vs. 58.6 (48.9-72.9), p=0.033 at 6-months and at the end, respectively). Significant negative correlations between triglycerides and cystatin C-based eGFR (ρ=-0.47, p=0.028) and Cr-Cys-eGFR (ρ=-0.45, p=0.043) at the end of the study were found.

CONCLUSION

Our study showed a high number of overweight children undergoing kidney transplant. A negative correlation between triglycerides and GFR was found, which highlights the importance of managing nutritional status and regular blood lipids evaluation after kidney transplant.

Glomerular filtration and shrunken pore syndrome in children and adults

A major function of the kidney is to, by glomerular filtration, maintain the overall steady-state of 5-30 kDa proteins, many of which are signalling molecules. This function of the kidney has been overlooked, since predominantly low-molecular-mass substances <1 kDa have been used to measure or estimate glomerular filtration rate (GFR). The use of cystatin C (13 kDa) as a marker of GFR has allowed the discovery that the filtration of 5-30 kDa molecules can be selectively impaired defining the shrunken pore syndrome. The discovery, pathophysiology, morbidity (mainly cardiovascular manifestations) and mortality of this syndrome are described.

Cardiovascular Risk Factors are Inversely Associated With Omega-3 Polyunsaturated Fatty Acid Plasma Levels in Pediatric Kidney Transplant Recipients

OBJECTIVES

High plasma levels of the omega-3 fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid, and docosapentaenoic acid associates with positive outcomes in adult renal transplant recipients. However, data from pediatric populations are scarce. The aim of the study was to assess the fatty acid profile in a pediatric renal transplantation cohort and to examine the associations between plasma omega-3 fatty acids and cardiovascular disease (CVD) risk factors.

METHODS

In this cross-sectional study comprising 53 children (median age, 12.2 years; 32 boys) with a renal transplant, we assessed the prevalence of CVD risk factors as well as markers of end organ damage: carotid intima-media thickness (cIMT) and left ventricular mass index. The associations between plasma omega-3 fatty acids and CVD risk factors were assessed.

RESULTS

Twenty-five (47%) patients were preemptively transplanted. Seventy-six percent had dyslipidemia and 51% had hypertension. The mean left ventricular mass index was 40.4 ± 14.3 g/m^2.7, and 14% had left ventricular hypertrophy. The mean cIMT was 0.41 ± 0.04 mm. In a multivariate linear regression, EPA levels were inversely associated to blood pressure (β coeff. = -0.37, P = .007), triglycerides (β coeff. = -0.44, P = .01), and high-density lipoprotein cholesterol (β coeff. = -0.41, P = .01).

CONCLUSION

EPA levels are inversely associated with components of the metabolic syndrome, which may provide support for specific dietary advice or supplementation in this patient population. cIMT is less pronounced in our cohort than in comparable cohorts with lower rate of preemptive transplantations. Our results need replication in prospective cohorts.

Multiple office blood pressure measurement: a novel approach to overcome the weak cornerstone of blood pressure measurement in children. Data from the SPA project

BACKGROUND

This contribution aims to report and analyze a novel approach for office blood pressure measurement in children.

METHODS

Healthy children 5 to 8 years of age were eligible. After 5 minutes rest, 10 unattended blood pressure readings were taken at 3-minute intervals using a validated automated oscillometric device. After discarding outlier values (< 5th or > 95th percentile of the recorded values), the coefficient of variation and the mean of the 10 readings were calculated. The single readings #1 to #10 were compared with this elaborated average of the 10 measurements.

RESULTS

Two hundred eighty-one healthy, non-obese children (137 females, 49%), median age 5.7 (IQR 5.3-6.1) years, were analyzed. The median coefficients of variation were 7% (IQR 5-9) for systolic and 4% (IQR 3-6) for diastolic blood pressure. The first 3 measurements were significantly different from the average, while the readings #4 to #10 were not. Based on the average, only nine subjects had a systolic or diastolic blood pressure > 90th centile (n = 3 > 95th percentile).

CONCLUSIONS

Although most guidelines advise three blood pressure readings, these findings suggest that in children, office blood pressure measurement might be improved by including ten measurements. In situations of time constraints, the fourth blood pressure reading might be used as a reliable approximation.

Inadequate blood pressure control demonstrated by ambulatory blood pressure monitoring in pediatric renal transplant recipients

BACKGROUND

Adequate BP control in RT recipients should not rely only by normal office BP but also on normal 24-hour BP. This study aims to assess adequacy of BP control by ABPM and to assess ABPM parameters associated with LVMI in pediatric RT recipients.

MATERIALS AND METHODS

Patients aged 5-20 years who have been followed after RT were enrolled. Demographic data and BP assessed by office and ABPM were collected. Echocardiography was performed to detect LVMI.

RESULTS

Thirty RT recipients (18 males) with median age of 15 years (IQR 13-18.5) were included. Among 23 patients who were taking antihypertensive drugs, uncontrolled hypertension was detected in 34.8% and 78.3% by office BP measurement and ABPM, respectively. Thus, the difference in prevalence of uncontrolled hypertension observed by ABPM versus office BP was 43.5%. Those seven patients who were not taking antihypertensive drugs because of normal office BP, four patients (57.1%) had masked hypertension and one patient had elevated BP. Fifteen patients have progression of LVH after RT. Multivariate analysis revealed that age (OR 1.369, 95%CI 0.985-1.904, P-value = 0.062) had a trend to be associated with progression of LVH. Moreover, nighttime systolic BP z-score was significantly correlated with LVMI (r = 0.551, P-value = 0.002).

CONCLUSION

The difference in prevalence of uncontrolled hypertension uncovered by ABPM was 43.5%. Nighttime SBP z-score was significantly correlated with LVMI.

Steroid withdrawal improves blood pressure control and nocturnal dipping in pediatric renal transplant recipients: analysis of a prospective, randomized, controlled trial

BACKGROUND

Variable effects of steroid minimization strategies on blood pressure in pediatric renal transplant recipients have been reported, but data on the effect of steroid withdrawal on ambulatory blood pressure and circadian blood pressure rhythm have not been published so far.

METHODS

In a prospective, randomized, multicenter study on steroid withdrawal in pediatric renal transplant recipients (n = 42) on cyclosporine, mycophenolate mofetil, and methylprednisolone, we performed a substudy in 28 patients, aged 11.2 ± 3.8 years, for whom ambulatory blood pressure monitoring (ABPM) data were available.

RESULTS

In the steroid-withdrawal group, the percentage of patients with arterial hypertension, defined as systolic and/or diastolic blood pressure values recorded by ABPM > 1.64 SDS and/or antihypertensive medication, at month 15 was significantly lower (35.7%, p = 0.002) than in controls (92.9%). The need of antihypertensive medication dropped significantly by 61.2% (p < 0.000 vs. control), while in controls, it even rose by 69.3%. One year after steroid withdrawal, no patient exhibited hypertensive blood pressure values above the 95th percentile, compared to 35.7% at baseline (p = 0.014) and to 14.3% of control (p = 0.142). The beneficial impact of steroid withdrawal was especially pronounced for nocturnal blood pressure, leading to a recovered circadian rhythm in 71.4% of patients vs. 14.3% at baseline (p = 0.002), while the percentage of controls with an abnormal circadian rhythm (35.7%) did not change.

CONCLUSIONS

Steroid withdrawal in pediatric renal transplant recipients with well-preserved allograft function is associated with less arterial hypertension recorded by ABPM and recovery of circadian blood pressure rhythm by restoration of nocturnal blood pressure dipping.

White-coat hypertension from a paediatric perspective

AIM

This mini review explored the prevalence of white-coat hypertension (WCH), which is very common in children. It results in elevated office blood pressure (BP) but normal ambulatory BP monitoring (ABPM) readings.

METHODS

WCH can only be identified by analysing and comparing office BP readings and ABPM, which periodically records BP every 20-30 minutes over 24-hour period. This study provides initially the background for WCH in adults, together with a comprehensive overview of the most relevant paediatric data on WCH.

RESULTS

Accurate measurements of BP are very important for the diagnosis and management of hypertension. It is important to acknowledge the clinical relevance of WCH and follow up children who display this BP phenotype by carrying out ABPM, so that clinicians can build up an accurate picture of their BP. It is also important to identify children who have BP issues and are overweight or obese, so that treatment of this modifiable cardiovascular risk factor can be initiated.

CONCLUSION

Using ABPM provides paediatricians with a more precise evaluation of a child's BP readings than office BP readings. It is the gold standard for diagnosing WCH.