Pathophysiology and consequences of arterial stiffness in children with chronic kidney disease

Arterial stiffness is associated with new-onset chronic kidney disease

Background: A potential independent association between arterial stiffness (AS) and the development of new-onset chronic kidney disease (CKD) has not been thoroughly examined. Patients and methods: A total of 6929 participants were collected from the Kailuan study. All participants were free of CKD at the baseline. The participants were divided into four groups based on their brachial-ankle pulse wave velocity (baPWV) values. Cox regression models were used to analyze the relationship between baPWV values and the risk of new-onset CKD. Results: Over the course of a 10.06-year follow-up period, a total of 962 cases of new-onset CKD were documented. Cox proportional hazards analyses showed that a higher baPWV quartile was linked to an increased risk of new-onset CKD. Conclusions: Brachial-ankle pulse wave velocity has a strong correlation with the development of new-onset CKD. Therefore, baPWV can be considered an innovative indicator for predicting the occurrence of new-onset CKD.

Physical activity and its impact on cardiovascular health in pediatric kidney transplant recipients

BACKGROUND

Cardiovascular (CV) morbidity after kidney transplantation (KTx) in childhood is of increasing importance. In light of a high prevalence of CV risk factors, protective measures such as physical activity (PA) come into focus. Our aim was to comprehensively assess PA in pediatric KTx recipients and evaluate its impact on CV health.

METHODS

Forty-eight patients were assessed for frequency, duration, intensity, and setting of PA using the "Motorik-Modul" PA questionnaire. Walking-based activity was measured by accelerometer in a subgroup (n = 23). CV risk factors and subclinical CV organ damage were determined. The impact of PA on CV parameters was analyzed using linear regression models.

RESULTS

Fifty-two percent of pediatric KTx recipients did not reach WHO recommended PA level; 54% did not engage in PA with vigorous intensity (VPA). Twenty-nine percent indicated an extremely inactive lifestyle (< 120 min/week of moderate to vigorous intensity PA, MVPA). Compared to the healthy German KiGGS cohort, KTx recipients specifically lacked engagement in sport activities (KTx: 129 min/week; 95%CI, 97-162 vs. KiGGS, 242 min/week; 95%CI, 230-253). VPA was associated with lower systolic blood pressure (p = 0.024) and resting heart rate (p = 0.005), MVPA with fewer components of the post-transplant metabolic syndrome (p = 0.037), and better left ventricular diastolic function (p = 0.006).

CONCLUSIONS

A considerable lack of PA, especially VPA, exists in young KTx recipients. PA was positively associated with important parameters of CV health. While long-term CV protection through PA seems promising in pediatric KTx recipients, specific educational approaches are most likely needed to increase patients' engagement in sport activities.

Chronic kidney disease mineral bone disorder in childhood and young adulthood: a 'growing' understanding

Chronic kidney disease (CKD) mineral and bone disorder (MBD) comprises a triad of biochemical abnormalities (of calcium, phosphate, parathyroid hormone and vitamin D), bone abnormalities (turnover, mineralization and growth) and extra-skeletal calcification. Mineral dysregulation leads to bone demineralization causing bone pain and an increased fracture risk compared to healthy peers. Vascular calcification, with hydroxyapatite deposition in the vessel wall, is a part of the CKD-MBD spectrum and, in turn, leads to vascular stiffness, left ventricular hypertrophy and a very high cardiovascular mortality risk. While the growing bone requires calcium, excess calcium can deposit in the vessels, such that the intake of calcium, calcium- containing medications and high calcium dialysate need to be carefully regulated. Normal physiological bone mineralization continues into the third decade of life, many years beyond the rapid growth in childhood and adolescence, implying that skeletal calcium requirements are much higher in younger people compared to the elderly. Much of the research into the link between bone (de)mineralization and vascular calcification in CKD has been performed in older adults and these data must not be extrapolated to children or younger adults. In this article, we explore the physiological changes in bone turnover and mineralization in children and young adults, the pathophysiology of mineral bone disease in CKD and a potential link between bone demineralization and vascular calcification.

Blood Pressure Variability and the Progression of Chronic Kidney Disease: a Systematic Review and Meta-Analysis

BACKGROUND

Blood pressure variability (BPV) is a risk factor for poor prognosis including cardiovascular events, chronic kidney disease, and mortality, independent of elevated BP.

METHODS

We searched PubMed/Medline, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to November 23, 2022. Cohort studies reporting the association between BPV and chronic kidney disease (CKD) progression were selected. Hazard ratios were pooled using a random-effects model. Meta-regression, subgroup analyses, and sensitivity analyses were conducted.

RESULTS

A total of 23 studies were included in this systematic review and meta-analysis. Increased BPV was associated with progression of CKD (HR: 1.21, 95% CI: 1.09-1.33) and incidence of ESRD (HR: 1.08, 95% CI: 1.08-1.30). Among the different BPV metrics, high variation independent of mean (VIM), coefficient of variation (CV), standard deviation (SD), and average real variability (ARV) were indicated as predictors of CKD progression.

DISCUSSION

Increased BPV was associated with CKD progression.

Cardiovascular Risks of Hypertension: Lessons from Children with Chronic Kidney Disease

Hypertension is the most common complication of chronic kidney disease (CKD) in children, having a strong association with subsequential cardiovascular disease (CVD). In pediatric CKD, a considerable percentage of children with hypertension are undiagnosed or undertreated. Prior research has evaluated structural and functional markers of subclinical CVD and biomarkers in adults with CKD, while ideal biomarkers in pediatrics are still insufficiently studied. The ultimate goal of this review is to summarize what is currently known about state of hypertension, cardiovascular risk factors, and potential CVD markers/biomarkers in children with pre-dialysis CKD. We discuss omics-related biomarkers and the pathophysiologic processes of endothelial dysfunction, kidney injury, oxidative stress and inflammation that are classified by specific biomarkers. Moreover, we illustrate the existing challenges and highlight the paucity of pediatric CKD research to evaluate these CVD biomarkers for future clinical pediatric practice. Thus, achieving clinical utility of CVD biomarkers for use in pediatric CKD remains a significant challenge requiring additional efforts.

Arterial Stiffness and Chronic Kidney Disease Progression in Children

BACKGROUND AND OBJECTIVES

CKD has been linked to increased arterial stiffness in adults, but data in children with CKD remain conflicting. We aimed to investigate the longitudinal dynamics and determinants of pulse wave velocity in children with CKD and its association with CKD progression.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed an analysis of the Cardiovascular Comorbidity in Children with Chronic Kidney Disease (4C) study, which prospectively followed children aged 6-17 years with CKD stages 3-5. Follow-up was censored at the time of KRT initiation. Two separate analyses were performed: with absolute pulse wave velocity (primary outcome) and with pulse wave velocity standardized to height (z score; restricted to participants ≤17 years) as a sensitivity analysis.

RESULTS

In total, 667 patients with a mean baseline eGFR of 27 ml/min per 1.73 m2 were included. Pulse wave velocity above the 95th percentile was observed in 124 (20%) patients at baseline. Absolute pulse wave velocity increased gradually over the median follow-up of 2.7 (interquartile range, 0.7-4.4) years, whereas pulse wave velocity z score remained relatively stable. Absolute pulse wave velocity over time associated with time; older age; higher mean arterial pressure, LDL cholesterol, and albuminuria; and lower ferritin. Pulse wave velocity z score (n=628) was associated with the same variables and additionally, with higher diastolic BP z score, lower height z score, younger age, and girls. Of 628 patients, 369 reached the composite end point of CKD progression (50% eGFR loss, eGFR <10 ml/min per 1.73 m2, or the start of KRT) during a median follow-up of 2.4 (interquartile range, 0.9-4.6) years. Pulse wave velocity z score did not associate with CKD progression by univariable or multivariable proportional hazard analysis correcting for the established predictors eGFR, proteinuria, and BP.

CONCLUSIONS

Pulse wave velocity is increased in children with CKD but does not associate with eGFR or CKD progression.

Hydrogen Sulfide-to-Thiosulfate Ratio Associated with Blood Pressure Abnormalities in Pediatric CKD

Identifying children with chronic kidney disease (CKD) at high risk of cardiovascular disease (CVD) and ensuring they receive appropriate treatment can prevent CVD events and mortality later in life. Hydrogen sulfide (H2S) is a gaseous signaling molecule participating in CVD and CKD. Thiosulfate is not only an oxidation product of H2S but is also a H2S donor. We examined whether H2S, thiosulfate, and their combined ratio have differential associations with CVD risk markers in 56 children and adolescents aged 6-18 years with CKD stages G1-G4. Up to two-thirds of CKD children showed higher BP load on 24 h ambulatory blood pressure monitoring (ABPM), even in the early stage. CKD children with ABPM abnormalities had a higher H2S-to-thiosulfate ratio, while H2S-related parameters were not affected by the severity of CKD. The H2S-to-thiosulfate ratio was positively correlated with 24 h systolic BP (SBP), nighttime SBP, and carotid artery intima-media thickness (cIMT). After adjusting for confounders, H2S was negatively associated with LV mass, thiosulfate was positively associated with 24-DBP, and the H2S-to-thiosulfate ratio was positively correlated with nighttime SBP and cIMT. Our data demonstrate differential associations in circulating H2S, thiosulfate, and their combined ratio with CVD risk in childhood CKD. Further studies are required to determine whether targeting the H2S signaling pathway can develop novel therapeutic strategies against CVD in this high-risk population.

Disparities between determinants of impaired vascular structure and function in young people with primary hypertension: a systematic review

OBJECTIVE

Early effects of primary hypertension on arterial structure and function in children and young people (CYP) and their determinants remain elusive. We aimed to review independent determinants of carotid intima-media thickness (cIMT), carotid wall cross-sectional area (WCSA) and carotid-femoral pulse wave velocity (cfPWV) in CYP with primary hypertension.

METHODS

We performed a systematic review of studies reporting multivariable analysis of cfPWV, cIMT and WCSA in CYP (up to 25 years of age) with primary hypertension. Literature search was performed in PubMed database and 13, 12 and two articles including 3860 (age range 4-25 years, 50% male individuals), 2038 children (5-25 years, 55% male individuals) and 136 children (5-17 years, 85% male individuals) were selected for final analysis of cfPWV, cIMT and WCSA, respectively.

RESULTS

Ninety and 86% of the studies reported higher cfPWV and cIMT in CYP with elevated blood pressure (BP) compared with normotensive controls. Different indices of BP were positively associated with cfPWV in 92% of studies, whereas BMI showed association in 31%. Carotid IMT associated with BP indices in 50% and with BMI in 25% of the studies. WCSA was studied longitudinally and its improvement associated with decrease in measures of central obesity.

CONCLUSION

We found a disparity between the determinants of structural and functional impairment of arterial tree in CYP with primary hypertension. In contrast to cIMT and WCSA, increase of cfPWV is almost exclusively determined by BP.

What Level of Blood Pressure Is Concerning in Childhood?

The 95th percentile of blood pressure (BP) among healthy children is the currently accepted level used to denote a hypertensive BP reading in pediatric patients. Yet, ample data have emerged showing that the detrimental effects of high BP can be demonstrated at BP levels considered normal by current guidelines. Cardiac, vascular, cognitive, and kidney effects have been shown starting at the 90th percentile in cross-sectional studies, and markers of adult cardiovascular disease appear in longitudinal cohorts whose members had modestly elevated or even normal BP as youth. This review summarizes data that support a lower threshold of concern for children and adolescents, and outlines some of the remaining questions to be answered before a lower threshold BP level could be adopted.

The burden of subclinical cardiovascular disease in children and young adults with chronic kidney disease and on dialysis

Background

Cardiovascular disease (CVD) is a common cause of morbidity and mortality even in young people with chronic kidney disease (CKD). We examined structural and functional CV changes in patients ˂30 years of age with CKD Stages 4 and 5 and on dialysis.

Methods

A total of 79 children and 21 young adults underwent cardiac computed tomography for coronary artery calcification (CAC), ultrasound for carotid intima-media thickness (cIMT), carotid–femoral pulse wave velocity (cfPWV) and echocardiography. Differences in structural (CAC, cIMT z-score, left ventricular mass index) and functional (carotid distensibility z-score and cfPWV z-score) measures were examined between CKD Stages 4 and 5 and dialysis patients.

Results

Overall, the cIMT z-score was elevated [median 2.17 (interquartile range 1.14–2.86)] and 10 (10%) had CAC. A total of 16/23 (69.5%) patients with CKD Stages 4 and 5 and 68/77 (88.3%) on dialysis had at least one structural or functional CV abnormality. There was no difference in the prevalence of structural abnormalities in CKD or dialysis cohorts, but functional abnormalities were more prevalent in patients on dialysis (P < 0.05). The presence of more than one structural abnormality was associated with a 4.5-fold increased odds of more than one functional abnormality (95% confidence interval 1.3–16.6; P < 0.05). Patients with structural and functional abnormalities [cIMT z-score >2 standard deviation (SD) or distensibility <−2 SD) had less carotid dilatation (lumen:wall cross-sectional area ratio) compared with those with normal cIMT and distensibility.

Conclusions

There is a high burden of subclinical CVD in young CKD patients, with a greater prevalence of functional abnormalities in dialysis compared with CKD patients. Longitudinal studies are required to test these hypothesis-generating data and define the trajectory of CV changes in CKD.

Pulse Wave Velocity, Central Haemodynamic Parameters, and Markers of Kidney Function in Children

OBJECTIVES

Chronic kidney disease (CKD) is a well-established risk factor for cardiovascular diseases. Studies in adults have demonstrated the association between mildly decreased kidney function or even normal values of markers of kidney function to pulse wave velocity (PWV), a measure of arterial stiffness and a predictor of cardiovascular events. Our study aimed to evaluate associations between markers of CKD, PWV, and central haemodynamic parameters in children and adolescents at risk of subclinical kidney damage.

METHODS

182 children and adolescents with hypertension, obesity, or hypercholesterolaemia (risk factors for subclinical kidney damage) were included in the study. The subjects were subdivided into 4 groups comprising children and adolescents with hypertension (group 1), obesity (group 2), hypercholesterolaemia (group 3), and a group with a combination of risk factors, such as obesity-related hypertension and metabolic syndrome (group 4). The study groups were compared to a group of healthy controls (group 5). PWV was measured by applanation tonometry (SphygmoCor, SCOR-Vx, Sydney, NSW, Australia) and laboratory parameters (serum creatinine, serum cystatin C, and microalbuminuria) were collected.

RESULTS

Pearson's correlation coefficient demonstrated a statistically significant correlation between PWV and serum creatinine in group of all subjects (r = 0.220, p = 0.002). Further subdivision showed the correlation was significant in group 4 (r = 0.370, p = 0.002). In group 2 a correlation between PWV and cystatin C was found (r = -0.535, p = 0.009). In multiple regression analysis of all subjects with PWV as the dependent variable, age and diastolic blood pressure were statistically significant. Correlations between markers of kidney function and central haemodynamic parameters also showed significant correlations between serum creatinine and heart rate (HR) (r = -0.476, p < 0.001) as well as associated parameters (augmentation index, standardized at HR 75/min, ejection duration, and subendocardial viability ratio).

CONCLUSIONS

Our study demonstrated a correlation between serum creatinine and PWV in children with combined risk factors for atherosclerosis and probable subclinical kidney damage. Further prospective research is needed to confirm the findings, and thus the preventive role of PWV determination in paediatric nephrology.

Association of Arterial Stiffness With Chronic Kidney Disease Progression and Mortality

Chronic kidney disease (CKD) is a major public health concern. Despite many potentially life-threatening conditions that can accompany kidney disease, cardiovascular disease (CVD) remains the leading cause of death in these patients. Adjusted-for-age mortality from CVD in patients with end-stage renal disease is 10-30 times higher than in the general population. A decrease in renal function accelerates the development of cardiac pathology. Simultaneous exposure of CVD and CKD plays an important role in the relationship between arterial stiffness (AS) and estimated glomerular filtration rate. But there is a controversy as to whether the AS causes deterioration in kidney function, if renal dysfunction leads to AS, or the relationship is reciprocal. Hence, several studies that recruited high-risk populations reached a conclusion that comorbidities might lead to both AS and decline in kidney function over time. A number of studies have shown that several markers of AS, such as pulse pressure, central and peripheral pressure are associated with the development of CKD. This review takes into account the theoretical background, current status, and future potential of the techniques that measure AS within context of CKD assessment and management.

The slope of cerebral oxyhemoglobin oscillation is associated with vascular reserve capacity in large artery steno-occlusion

Inadequate cerebral perfusion is a risk factor for cerebral ischemia in patients with large artery steno-occlusion. We investigated whether prefrontal oxyhemoglobin oscillation (ΔHbO₂, 0.6-2 Hz) was associated with decreased vascular reserve in patients with steno-occlusion in the large anterior circulation arteries. Thirty-six patients with steno-occlusion in the anterior circulation arteries (anterior cerebral artery, middle cerebral artery, and internal carotid artery) were included and compared to thirty-six control subjects. Patients were categorized into two groups (deteriorated vascular reserve vs. preserved vascular reserve) based on the results of Diamox single- photon emission computed tomography imaging. HbO₂ data were collected using functional near-infrared spectroscopy. The slope of ΔHbO₂ and the ipsilateral/contralateral slope ratio of ΔHbO₂ were analyzed. Among the included patients (n = 36), 25 (69.4%) had deteriorated vascular reserve. Patients with deteriorated vascular reserve had a significantly higher average slope of ΔHbO₂ on the ipsilateral side (5.01 ± 2.14) and a higher ipsilateral/contralateral ratio (1.44 ± 0.62) compared to those with preserved vascular reserve (3.17 ± 1.36, P = 0.014; 0.93 ± 0.33, P = 0.016, respectively) or the controls (3.82 ± 1.69, P = 0.019; 0.94 ± 0.29, P = 0.001). The ipsilateral/contralateral ΔHbO₂ ratio could be used as a surrogate for vascular reserve in patients with severe steno-occlusion in the anterior circulation arteries.

Cardiovascular disease in children with chronic kidney disease

PURPOSE OF REVIEW

Cardiovascular disease (CVD) is a significant cause of morbidity and mortality in children with chronic kidney disease (CKD). The cause of CVD in children with CKD is multifactorial and there are new and emerging data regarding prevalence and risk factors for CVD in this population.

RECENT FINDINGS

A number of recent publications from longitudinal cohort studies of children with CKD have greatly increased our knowledge about the prevalence and risk factors for CVD including hypertension, obesity and dyslipidaemia. Masked hypertension and isolated nocturnal hypertension both correlate with surrogate markers of CVD in children. Obesity and adiposity are associated with an increased risk of CVD. Markers other than BMI such as waist to height ratio and fat-free tissue to fat tissue ratio better correlate with the presence of CVD in children. Dyslipidaemia is extremely prevalent in the paediatric CKD population, but there is a lack of consensus on treatment. More data on the relationship between bone mineral disease and CVD continue to emerge including an association between hyperparathyroidism and isolated nocturnal hypertension.

SUMMARY

Children with CKD have multiple potentially modifiable risk factors for CVD. Research focused on CVD outcomes in children is needed.