Validation of oscillometric pulse wave analysis measurements in children

A SAGE score cutoff that predicts high-pulse wave velocity as measured by oscillometric devices in Brazilian hypertensive patients

We aimed to identify the optimal cutoff SAGE score for Brazilian hypertensive patients who had their pulse wave velocity (PWV) measured with oscillometric devices. A retrospective analysis of patients who underwent central blood pressure measurement using a validated oscillometric device, the Mobil-O-Graph® (IEM, Stolberg, Germany), between 2012 and 2019 was performed. Patients with arterial hypertension and available data on all SAGE parameters were selected. An ROC curve was constructed using the Youden index to define the best score to identify patients at high risk for high PWV. A total of 837 patients met the criteria for SAGE and diagnosis of hypertension. The median age was 59.0 years (interquartile range [IQR]: 47.0-68.0), and 50.7% of the patients were women. The following comorbidities and conditions were present: dyslipidemia (37.4%), diabetes (20.7%), a body mass index score ≥30 kg/m² (36.6%), use of antihypertensive drugs (69.5%), and smoking (18.3%). The median peripheral blood pressure was 128 mmHg (IQR: 117-138 mmHg) for systolic and 81 mmHg (IQR: 73-90 mmHg) for diastolic blood pressure. The median PWV was 8.3 m/s (7.1-9.8 m/s), and the prevalence of high PWV (≥10 m/s) was 22.9% (192 patients). A cutoff SAGE score ≥8 was effective at identifying a high risk of PWV ≥ 10 m/s, achieving 67.19% sensitivity (95% CI: 60.1-73.8) and 93.95% specificity (95% CI: 91.8-95.7). With this cutoff point, 1 out of every 5 treated hypertensive patients would be referred for a PWV measurement. A SAGE score of ≥8 identified Brazilian hypertensive patients with a high risk of future cardiovascular events (PWV ≥ 10 m/s).

Social Jetlag and Cardiometabolic Risk in Preadolescent Children

Objective: Childhood cardiometabolic disease risk (CMD) has been associated with short sleep duration. Its relationship with other aspects of sleep should also be considered, including social jetlag (SJL) which represents the difference between a person's social rhythms and circadian clock. This study investigated whether childhood CMD risk is associated with sleep duration, sleep disturbances, and SJL.

Study Design: The observational study included 332 children aged 8–10 years (48.5% female). The three independent variables were sleep duration, sleep disturbances, and SJL. SJL was calculated as the variation in hours between the midpoint of sleep during free (weekend) days and work/school days. Eleven cardiometabolic biomarkers were measured, including central blood pressure, lipids, glycated hemoglobin, arterial wave reflection, and glucose. Underlying CMD risk factors were identified using factor analysis.

Results: Four underlying CMD risk factors were identified using factor analysis: blood pressure, cholesterol, vascular health, and carbohydrate metabolism. Neither sleep disturbances nor sleep duration were significantly associated with any of the four CMD factors following adjustments to potential confounders. However, SJL was significantly linked to vascular health (p = 0.027) and cholesterol (p = 0.025).

Conclusion: These findings suggest that SJL may be a significant and measurable public health target for offsetting negative CMD trajectories in children. Further studies are required to determine biological plausibility.

Risk Assessment and Clinical Management of Children and Adolescents with Heterozygous Familial Hypercholesterolaemia. A Position Paper of the Associations of Preventive Pediatrics of Serbia, Mighty Medic and International Lipid Expert Panel

Heterozygous familial hypercholesterolaemia (FH) is among the most common genetic metabolic lipid disorders characterised by elevated low-density lipoprotein cholesterol (LDL-C) levels from birth and a significantly higher risk of developing premature atherosclerotic cardiovascular disease. The majority of the current pediatric guidelines for clinical management of children and adolescents with FH does not consider the impact of genetic variations as well as characteristics of vascular phenotype as assessed by recently developed non-invasive imaging techniques. We propose a combined integrated approach of cardiovascular (CV) risk assessment and clinical management of children with FH incorporating current risk assessment profile (LDL-C levels, traditional CV risk factors and familial history) with genetic and non-invasive vascular phenotyping. Based on the existing data on vascular phenotype status, this panel recommends that all children with FH and cIMT ≥0.5 mm should receive lipid lowering therapy irrespective of the presence of CV risk factors, family history and/or LDL-C levels Those children with FH and cIMT ≥0.4 mm should be carefully monitored to initiate lipid lowering management in the most suitable time. Likewise, all genetically confirmed children with FH and LDL-C levels ≥4.1 mmol/L (160 mg/dL), should be treated with lifestyle changes and LLT irrespective of the cIMT, presence of additional RF or family history of CHD.

Earlier antiretroviral initiation is independently associated with better arterial stiffness in children living with perinatally acquired HIV with sustained viral suppression in Mozambique

BACKGROUND

Cardiovascular disease is a major driver of morbidity and mortality in adults living with HIV. The drivers of cardiovascular disease in children living with perinatally acquired HIV (PHIV) with sustained HIV viral suppression are unclear.

OBJECTIVES

We explored the contribution of HIV-specific risk factors to arterial stiffness independently of traditional risk factors (metabolic syndrome [MetS]) in prepubertal children with PHIV with sustained viral suppression in a low-income country in Africa.

METHOD

For this cross-sectional analysis, arterial stiffness was assessed by pulse wave velocity z-score (PWVz), measured using a Vicorder device. Metabolic syndrome components were measured. We retrospectively collected the antiretroviral therapy (ART) exposures, HIV stage, CD4 count and HIV viral load. A multivariate linear regression model was constructed for MetS components, retaining age and gender as obligatory variables. We then added HIV-related metrics to assess whether these had an independent or additive effect.

RESULTS

We studied 77 virally suppressed children with PHIV without evidence of cardiovascular disease (from medical history and physical examination). In the initial model, the PWVz was independently associated with each MetS component. The PWVz was higher in participants with proportionally greater visceral fat (waist/height ratio), elevated lipids (triglyceride/high-density lipoprotein ratio) and insulin resistance (log homeostatic model assessment [HOMA]). The addition of age at ART initiation increased the model R 2 value from 0.36 to 0.43. In the resulting model, younger age at ART initiation was independently associated with a better PWVz (P < 0.001).

CONCLUSION

Earlier ART initiation was independently associated with lower large artery stiffness. This effect was independent of the effect of elevated lipids, visceral fat and insulin resistance.

Arterial Stiffness and Left Ventricular Myocardial Function in Children with a Well-Functioning Bicuspid Aortic Valve

Fundamento:

A rigidez arterial é um importante preditor de aortopatia e remodelamento miocárdico em pacientes com válvula aórtica bicúspide, podendo estar aumentada na infância.

Objetivo:

Avaliar a rigidez arterial e a função miocárdica do ventrículo esquerdo em crianças com válvula aórtica bicúspide funcional.

Métodos:

Quarenta e quatro crianças com válvula aórtica bicúspide e 41 pares saudáveis com válvula aórtica tricúspide foram incluídos neste estudo caso-controle. Foram obtidos os diâmetros e os escores-z relacionados da raiz aórtica e da aorta ascendente. Quanto à função miocárdica do ventrículo esquerdo, juntamente com as velocidades de fluxo mitral e parâmetros do Modo M, as velocidades miocárdicas e os intervalos de tempo foram avaliados com Doppler tecidual. A análise da onda de pulso foi realizada por aparelho oscilométrico (Mobil-o-Graph). Um valor de p<0,05 foi considerado significativo.

Resultados:

O índice da massa ventricular esquerda, a velocidade A do fluxo mitral, o diâmetro e o escore z da aorta ascendente e o índice de desempenho miocárdico estavam significativamente maiores nos pacientes (p = 0,04, p = 0,02, p = 0,04, p <0,001 e p <0,001 respectivamente). O índice de desempenho miocárdico correlacionou-se positivamente com o diâmetro da aorta ascendente e a velocidade A (r=0,272; p=0,01, r=356; p=0,001, respectivamente). A análise multivariada revelou que o índice de desempenho miocárdico estava relacionado ao diâmetro da aorta ascendente (p = 0,01). O índice de aumento e a velocidade da onda de pulso foram semelhantes entre os grupos (p> 0,05).

Conclusão:

De acordo com a análise da onda de pulso oscilométrico, as crianças com válvula aórtica bicúspide funcional apresentam rigidez arterial semelhante a seus pares saudáveis. O diâmetro da aorta ascendente foi estabelecido como preditor independente da função miocárdica do ventrículo esquerdo. A rigidez arterial pode não ser um fator de risco grave em pacientes pediátricos sem dilatação acentuada da aorta ascendente.

Effects of aerobic, resistance and concurrent exercise on pulse wave reflection and autonomic modulation in men with elevated blood pressure

The acute effects of exercise modes on pulse wave reflection (PWR) and their relationship with autonomic control remain undefined, particularly in individuals with elevated blood pressure (BP). We compared PWR and autonomic modulation after acute aerobic (AE), resistance (RE), and concurrent exercise (CE) in 15 men with stage-1 hypertension (mean ± SE: 34.7 ± 2.5 years, 28.4 ± 0.6 kg/m², 133 ± 1/82 ± 2 mmHg). Participants underwent AE, RE, and CE on different days in counterbalanced order. Applanation tonometry and heart rate variability assessments were performed before and 30-min postexercise. Aortic pressure decreased after AE (− 2.4 ± 0.7 mmHg; P = 0.01), RE (− 2.2 ± 0.6 mmHg; P = 0.03), and CE (− 3.1 ± 0.5 mmHg; P = 0.003). Augmentation index remained stable after RE, but lowered after AE (− 5.1 ± 1.7%; P = 0.03) and CE (− 7.6 ± 2.4% P = 0.002). Systolic BP reduction occurred after CE (− 5.3 ± 1.9 mmHg). RR-intervals and parasympathetic modulation lowered after all conditions (~ 30–40%; P < 0.05), while the sympathovagal balance increased after RE (1.2 ± 0.3–1.3 ± 0.3 n.u., P < 0.05). Changes in PWR correlated inversely with sympathetic and directly with vagal modulation in CE. In conclusion, AE, RE, and CE lowered central aortic pressure, but only AE and CE reduced PWR. Overall, those reductions related to decreased parasympathetic and increased sympathetic outflows. Autonomic fluctuations seemed to represent more a consequence than a cause of reduced PWR.

Measurement, Analysis and Interpretation of Pressure/Flow Waves in Blood Vessels

The optimal performance of the cardiovascular system, as well as the break-down of this performance with disease, both involve complex biomechanical interactions between the heart, conduit vascular networks and microvascular beds. ‘Wave analysis’ refers to a group of techniques that provide valuable insight into these interactions by scrutinizing the shape of blood pressure and flow/velocity waveforms. The aim of this review paper is to provide a comprehensive introduction to wave analysis, with a focus on key concepts and practical application rather than mathematical derivations. We begin with an overview of invasive and non-invasive measurement techniques that can be used to obtain the signals required for wave analysis. We then review the most widely used wave analysis techniques—pulse wave analysis, wave separation and wave intensity analysis—and associated methods for estimating local wave speed or characteristic impedance that are required for decomposing waveforms into forward and backward wave components. This is followed by a discussion of the biomechanical phenomena that generate waves and the processes that modulate wave amplitude, both of which are critical for interpreting measured wave patterns. Finally, we provide a brief update on several emerging techniques/concepts in the wave analysis field, namely wave potential and the reservoir-excess pressure approach.

Inter-operator Reliability for Measuring Pulse Wave Velocity and Augmentation Index

Background: Arterial stiffness is a reversible precursor to hypertension. However, research is needed to determine the minimum amount of training required before acceptable arterial stiffness measurements are collected by novice operators. Objective: To compare novice vs. experienced operator measurements over a 2-week training period to assess when expert-like measures are achieved by the novice operator. Method: Forty-one participants (18 males, 23 females, age: 46.6 ± 14.9 years; BMI: 25.2 ± 3.8; systolic blood pressure: 122.8 ± 14.7 mmHg) received alternating novice and experienced operator arterial stiffness assessments. Measurements included: pulse wave velocity (PWV; using the automatic-capture time-periods of 5-, 10-, and 20-s) and augmentation index (AIx75) measurements using the SphygmoCor XCEL System v1 (AtCor Medical Pty Ltd., Sydney, Australia). Data were chronologically arranged into quintiles. Results: The intraclass correlation coefficient for PWV substantially improved from quintile 1 (r < 0.8) to quintile 2 and beyond (typically r > 0.8) while AIx75 improved consistently (r = 0.7 in quintile 1 and r = 0.97 in quintile 5). The coefficient of variation was lowest in quintile 4 (PWV: 4.7-6% across the three measurement time-periods; and 15% for AIx75) but increased in quintile 5 (PWV: 6.2-10.5%; and 25% for AIx75). All measurements demonstrated acceptable to excellent reliability after quintile 2. Conclusion: To achieve expert-like PWV measurements in this study, the novice operator underwent a familiarization session including guided practice measurements on 5 different people, for 10-15 min per person on two occasions (~2.5 h). The novice operator then required ≥14 practice measurements, with accuracy continuing to improve up to 30 participants. At least 30 training measurements are recommended for novices to take acceptable AIx75 measurements after a familiarization training.

Active Children Through Individual Vouchers Evaluation: A Mixed-Method RCT

INTRODUCTION

Physical activity declines in adolescence, especially among those in deprived areas. Research suggests this may result from accessibility barriers (e.g., cost and locality). The Active Children Through Individual Vouchers Evaluation RCT aimed to improve the fitness and heart health of teenagers in Wales with the help of teenagers who co-produced the study.

STUDY DESIGN

This study was a mixed-method RCT.

SETTING/PARTICIPANTS

Before data collection, which took place at baseline, 6 months, and 12 months for both arms, 7 schools were randomized by an external statistician (4 intervention schools, n=524; 3 control schools, n=385).

INTERVENTION

The Active Children Through Individual Vouchers Evaluation intervention included provision of activity vouchers (£20 per month), a peer mentoring scheme, and support worker engagement for 12 months between January and December 2017. Data analysis occurred February-April 2018.

MAIN OUTCOME MEASURES

Data included measures of cardiovascular fitness, cardiovascular health (blood pressure and pulse wave analysis), motivation, and focus groups.

RESULTS

The intervention showed a trend to improve the distance ran (primary outcome) and was significant in improving the likelihood of intervention teenagers being fit (OR=1.21, 95% CI=1.07, 1.38, p=0.002). There was a reduction in teenagers classified as having high blood pressure (secondary outcome) in the intervention group (baseline, 5.3% [28/524]; 12 months, 2.7% [14/524]). Data on where teenagers used vouchers and evidence from focus groups showed that teenagers wanted to access more unstructured, informal, and social activities in their local areas.

CONCLUSIONS

Active Children Through Individual Vouchers Evaluation identified methods that may have a positive impact on cardiovascular fitness, cardiovascular health, and perspectives of activity. Consulting with teenagers, empowering them, and providing more local opportunities for them to take part in activities that are fun, unstructured, and social could positively impact teenage physical activity.

TRIAL REGISTRATION

ISRCTN, ISRCTN75594310.

Fitness and Fatness Are Both Associated with Cardiometabolic Risk in Preadolescents

OBJECTIVE

To determine the associations between cardiorespiratory fitness (CRF) and fatness (overweight-obesity) with cardiometabolic disease risk among preadolescent children.

STUDY DESIGN

This cross-sectional study recruited 392 children (50% female, 8-10 years of age). Overweight-obesity was classified according to 2007 World Health Organization criteria for body mass index. High CRF was categorized as a maximum oxygen uptake, determined using a shuttle run test, exceeding 35 mL·kg^-1·minute^-1 in girls and 42 mL·kg^-1·minute^-1 in boys. Eleven traditional and novel cardiometabolic risk factors were measured including lipids, glucose, glycated hemoglobin, peripheral and central blood pressure, and arterial wave reflection. Factor analysis identified underlying cardiometabolic disease risk factors and a cardiometabolic disease risk summary score. Two-way analysis of covariance determined the associations between CRF and fatness with cardiometabolic disease risk factors.

RESULTS

Factor analysis revealed four underlying factors: blood pressure, cholesterol, vascular health, and carbohydrate-metabolism. Only CRF was significantly (P = .001) associated with the blood pressure factor. Only fatness associated with vascular health (P = .010) and carbohydrate metabolism (P = .005) factors. For the cardiometabolic disease risk summary score, there was an interaction effect. High CRF was associated with decreased cardiometabolic disease risk in overweight-obese but not normal weight children (P = .006). Conversely, high fatness was associated with increased cardiometabolic disease risk in low fit but not high fit children (P < .001).

CONCLUSIONS

In preadolescent children, CRF and fatness explain different components of cardiometabolic disease risk. However, high CRF may moderate the relationship between fatness and cardiometabolic disease risk.

TRIAL REGISTRATION

ACTRN 12614000433606.

Predictors of cardiovascular health in teenagers (aged 13-14 years): a cross-sectional study linked with routine data

Objective

To examine the predictors of cardiovascular health in teenagers (aged 13-14 years).

Methods

Measures of arterial stiffness (augmentation index (AIx)), blood pressure and cardiovascular fitness were taken from 234 teenage children (n=152 boys) and subsequently linked to routine data (birth and general practice records, education data and hospital admission data). Deprivation at school and at individual level was measured at birth, at 1 year old, at 13 years old and at secondary school using the Welsh Index of Multiple Deprivation. Multivariate regression analysis determined associations between routinely collected data and cardiovascular measures.

Results

Teenagers had higher AIx (2.41 (95% CI 1.10 to 3.72)), ran fewer metres (-130.08 m (95% CI -234.35 to -25.78)) in the Cooper Run Test if they attended a more deprived school. However, higher individual level deprivation was associated with greater fitness (199.38 m (95% CI 83.90 to 314.84)). Higher systolic blood pressure was observed in first born children (10.23 mm Hg (95% CI 1.58 to 18.88)) and in those who were never breastfed (4.77 mm Hg (95% CI 1.10 to 8.42)).

Conclusions

Improving heart health in deprived areas requires multilevel action across childhood namely, active play and programmes that promote physical activity and fitness and, the promotion of breastfeeding. Recognition of the important early indicators and determinants of cardiovascular health supports further development of the evidence base to encourage policy-makers to implement preventative measures in young people.

Ambulatory blood pressures and central blood pressures are associated with cardiovascular morbidity in adolescent and young adult patients receiving chronic hemodialysis

BACKGROUND

Left ventricular hypertrophy (LVH) and arterial stiffness measured by pulse wave velocity (PWV) are independent predictors of cardiovascular (CV) mortality in adults receiving chronic dialysis. Hypertension strongly associates with elevated left ventricular mass index (LVMI) and PWV, with ambulatory blood pressure monitoring (ABPM), and central blood pressure (CBP) superior to office blood pressures (BP) in predicting CV morbidity. Few studies have described associations of office BP, ABPM, and CBP with LVMI and PWV in adolescent and young adult patients receiving hemodialysis (HD).

METHODS

Cross-sectional study of 22 adolescents and young adults receiving chronic HD. Pre- and post-dialysis office BP and CBP using applanation tonometry were obtained. Twenty-four-hour ABPM was obtained midweek post-dialysis. Pre- and post-dialysis carotid-brachial PWV were obtained same day as BP measurements. Annual echocardiograms for standard care were reviewed for LVH.

RESULTS

Pre-dialysis CBP index correlated with LVMI (r = 0.3, p = 0.04) and PWV (r = 0.48, p = 0.02). Hypertensive patients identified by ABPM had worse LVMI; daytime ABPM systolic BP index correlated with LVMI (r = 0.5, p = 0.02). Office BP was not associated with LVMI; only office diastolic BP was associated with PWV (r = 0.46, p = 0.02). There was no correlation of LVMI or PWV with bone health parameters, anemia, interdialytic weight gain, or residual renal function.

CONCLUSIONS

Ambulatory blood pressure monitoring is superior to casual office BP obtained at time of dialysis in delineating cardiovascular morbidity in adolescent and young adult HD patients. CBP is easily performed and correlates with LVMI and PWV in adolescent and young adult HD patients; however, large-scale normative data is needed.

Modifiable Clinical Correlates of Vascular Health in Children and Adolescents with Dyslipidemia

Atherosclerosis promoting cardiovascular disease risk factors (CVDrf) are highly prevalent among youth in the U.S. Determining which standard modifiable clinical measures (SMCMs) has the greatest impact on vascular structure and function is valuable for the health care provider to help identify children at highest risk. The aim of this study was to determine modifiable outpatient clinical predictors of vascular health in youth with CVDrf. Children and adolescents with CVDrf (n = 120, 13.1 ± 1.9 years, 49% female) were recruited from a pediatric preventive cardiology clinic. The SMCMs included BMI z-score, waist-to-height ratio (WTHR), lipid panel, hemoglobin A1c, blood pressure (BP), presence of tobacco smoke exposure, and presence of hypertriglyceridemic waist (HTW) phenotype (triglycerides ≥ 110 mg/dL and waist circumference ≥ 90 percentile). Vascular function and structure were measured with pulse wave velocity (PWV), central systolic BP (CSP), augmentation index (AIx), and carotid artery intima-media thickness (cIMT). Sex and height specific z-scores for PWV, CSP, and cIMT were used. Multiple linear regression with backwards selection identified SMCMs which strongly predicted vascular function and structure. Among SMCMs, WTHR and HTW were the most frequent predictors of vascular function (PWV: R² = 0.32; CSP: R² = 0.35; AIx R² = 0.13). Other predictors of vascular function included hemoglobin A1C, BP, and BMI z-score. Systolic BP and LDL cholesterol were predictors of vascular structure (cIMT: R² = 0.14). The strongest predictors of vascular health in youth with CVDrf were related to measures of central obesity. Targeting these SMCM in lieu of vascular testing in outpatient clinic setting may be practical to identify children and adolescents at greatest risk for CVD.

Peripheral maternal haemodynamics across pregnancy in hypertensive disorders of pregnancy

OBJECTIVES

Evaluating maternal haemodynamics across pregnancy in uncomplicated pregnancies and those complicated by hypertensive disorders of pregnancy (HDP).

STUDY DESIGN

Prospective cohort study from 2015 to 2018 of healthy, nulliparous, singleton-bearing women. Maternal haemodynamics assessed by Uscom BP+ at 9-16 and 32-36 weeks' gestation in pregnancies complicated by HDP [preeclampsia with severe (sPE n = 12) and without severe clinical features (nsPE n = 49), gestational hypertension (GH n = 25), transient gestational hypertension (TGH n = 33)] were compared to uncomplicated pregnancies (n = 286) using mixed-effects linear modelling.

MAIN OUTCOME MEASURES

Maternal haemodynamic adaptation in uncomplicated pregnancies and those complicated by HDP.

RESULTS

Between the two measurements, haemodynamic adaptation in women with sPE and nsPE was significantly different compared to those with uncomplicated pregnancies. An additional increase was observed for peripheral systolic blood pressure [SBP; 14.3 mmHg, 8.6-20.1 (sPE)], peripheral diastolic blood pressure [DBP; 7.7 mmHg, 3.3-12.1 (sPE); 2.6 mmHg, 3.3-12.1 (nsPE)] peripheral mean arterial pressure [MAP; 10.6 mmHg, 5.8-15.5 (sPE); 3.4 mmHg, 0.8-6.0 (nsPE)], peripheral pulse pressure [PP; 6.6 mmHg, 2.1-11.1 (sPE)], central SBP [15.8 mmHg, 10.4-21.2 (sPE); 2.9 mmHg, 0.1-5.8 (nsPE)], central DBP [8.3 mmHg, 3.9-12.6 (sPE); 2.5 mmHg, 0.2-4.8 (nsPE), central MAP [10.8 mmHg, 6.4-15.2 (sPE); 2.6 mmHg, 0.3-5.0 (nsPE)] and central PP [7.6 mmHg, 3.9-11.3 (sPE)]. Augmentation index (AIx) decreased less (15.5%, 6.3-24.6 (sPE); 9.0%, 4.2-13.6 (nsPE)] compared to uncomplicated pregnancies. Haemodynamic adaptation across pregnancy in women with GH and TGH was not different from those with uncomplicated pregnancies.

CONCLUSION

Women who develop preeclampsia show an altered, while those who develop GH or TGH demonstrate a comparable haemodynamic adaptation compared to uncomplicated pregnancies. TGH is not a benign condition.

Blood Pressure and Arterial Stiffness in Kenyan Adolescents With the Sickle Cell Trait

The potential association between sickle cell trait (SCT) and increased arterial stiffness/blood pressure (BP) has not been evaluated in detail despite its association with stroke, sudden death, and renal disease. We performed 24-hour ambulatory BP monitoring and arterial stiffness measurements in adolescents raised in a malaria-free environment in Kenya. Between December 2015 and June 2016, 938 randomly selected adolescents (ages 11–17 years) who had been continuous residents of Nairobi from birth were invited to participate in the study. Standard clinic BP measurement was performed, followed by 24-hour ambulatory BP monitoring and arterial stiffness measurement using an Arteriograph24 (TensioMed Ltd., Budapest, Hungary) device. SCT status was determined using DNA genotyping in contemporaneously collected blood samples. Of the 938 adolescents invited to participate, 609 (65%) provided complete data for analysis. SCT was present in 103 (15%). Mean 24-hour systolic and diastolic BPs were 116 (standard deviation (SD), 11.5) mm Hg and 64 (SD, 7) mm Hg, respectively, in children with SCT and 117 (SD, 11.4) mm Hg and 64 (SD, 6.8) mm Hg, respectively, in non-SCT children. Mean pulse wave velocity (PWV) was 7.1 (SD, 0.8) m/second and 7.0 (SD, 0.8) m/second in SCT and non-SCT children, respectively. We observed no differences in PWV or in any clinic or ambulatory BP-derived measures between adolescents with and without SCT. These data suggest that SCT does not independently influence BP or PWV.

Stroke Volume Monitoring: Novel Continuous Wave Doppler Parameters, Algorithms and Advanced Noninvasive Haemodynamic Concepts

PURPOSE OF REVIEW

Adequate oxygen delivery is essential for life, with hypoxia resulting in dysfunction, and ultimately death, of the cells, organs and organism. Blood flow delivers the oxygen bound in the blood, while haemodynamics is the science of blood flow. Stroke volume (SV) is the fundamental unit of blood flow, and reflects the interdependent performance of the heart, the vessels and the autonomic nervous system. However, haemodynamic management remains generally poor and predominantly guided by simple blood pressure observations alone.

RECENT FINDINGS

Doppler ultrasound measures SV with unequalled clinical precision when operated by trained personnel. Combining SV with BP measurements allows calculation of flow-pressure based measures which better reflect cardiovascular performance and allows personalised physiologic and pathophysiologic modelling consistent with Frank's and Starling's observations.

SUMMARY

Doppler SV monitoring and novel flow-pressure parameters may improve our understanding of the cardiovascular system and lead to improved diagnosis and therapy. This review examines the physics and practice of Doppler SV monitoring and its application in advanced haemodynamics.

Cardiometabolic Risk Variables in Preadolescent Children: A Factor Analysis

BACKGROUND

Atherosclerosis begins during preadolescence and is occurring at an accelerated rate. This acceleration has been linked to poor lifestyle behaviors and subsequent cardiometabolic complications. Although the clustering of cardiometabolic risk factors has been recognized for over 2 decades, previous studies in children have predominantly examined the relationships between atherosclerosis and individual cardiometabolic risk factors or have grouped together preadolescent and adolescent children. Further, no known studies have included glycated hemoglobin or central hemodynamic measures such as central systolic blood pressure and augmentation index.

METHODS AND RESULTS

Principal component analysis was performed on a cross-sectional sample of 392 children (aged 9.5 years, 50% girls) from 3 representative sample sites across New Zealand. Four factors explained 60% of the variance in the measured variables. In order of variance explained, the factors were: blood pressure (central systolic blood pressure and peripheral systolic and diastolic blood pressure), adiposity (waist circumference, body mass index, and glycated hemoglobin), lipids (total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol), and vascular (augmentation index, heart rate, and fasting blood glucose).

CONCLUSIONS

In accordance with previous findings in adults and adolescents, one common factor is unlikely to define cardiometabolic health in preadolescent children. Each of the factors, except vascular, which was predominantly explained by augmentation index, are in agreement with previous findings in adolescents. An additional novel finding was that glycated hemoglobin and fasting blood glucose loaded onto different factors, supporting previous work suggesting that fasting blood glucose indicates short-term glycemic control, whereas glycated hemoglobin reflects chronic glycemic control.

CLINICAL TRIAL REGISTRATION

URL: www.anzctr.org.au/. ID: ACTRN12614000433606.

Central blood pressure and pulse wave amplification across the spectrum of peripheral blood pressure in overweight and obese youth

OBJECTIVE

To identify vascular phenotypes across blood pressure (BP) conditions in overweight and obese youths, by assessing office BP (oBP), and central BP (cBP), and pulse pressure (PP) amplification. Whether or not 24-h ambulatory BP monitoring (ABPM) and pulse wave velocity (PWV) add insight to the issue has also been examined.

METHODS

White youths of both sexes with overweight or obesity and of European origin, ranging from 8 to 18 years of age, were included. oBP, cBP, PWV, and 24-h ABPM were measured. oBP conditions and 'white-coat' hypertension were defined as recommend by European Society Hypertension Guidelines in Children and Adolescents. Patients were divided into subgroups of 'normal' or 'high' according to cBP and PP ratio.

RESULTS

A total of 593 patients (mean age, 12.2 ± 2.3 years; 275 women) were included in the study. The largest differences between office SBP and central SBP correspond to the isolated systolic hypertension (ISH) group, in which only 25% of patients have high cBP, in contrast to 50% of the systo-diastolic hypertension (SDH) group. Two patterns emerged based on cBP and PP ratio - while the highest cBP was among the SDH, the highest PP amplitude was in the ISH group. Ninety percent of the SDH were confirmed with 24-h ABPM, in contrast to 75% of the ISH, who were white-coat hypertensive. PWV showed a progressive increment across the groups from normotension to SDH. Significant differences were observed only when compared with the normotensive, but not among all other groups.

CONCLUSION

In overweight and obese hypertensive patients, ISH is prevalent, posing a challenge for the clinician of whether these may therefore be diagnosed and managed as hypertensive patients. Until prospective studies can give more knowledge, 24-h ABPM can offer information for making clinical decisions.

Reliability of oscillometric central blood pressure and wave reflection readings: effects of posture and fasting

OBJECTIVE

Oscillometric pulse wave analysis devices have recently emerged, presenting suitable options for investigating central hemodynamic properties in clinical practice. This study sought to examine whether the between-day reliability of central SBP (cSBP) and systemic arterial wave reflection (augmentation index, AIx) readings exceed the criterion for acceptable reliability or are affected by posture (supine and seated) and fasting state.

METHODS

Twenty healthy adults (50% female, 27.9 years, 24.2 kg/m) were tested on six different mornings: 3 days fasted and 3 days nonfasted. On each occasion, participants were tested in supine and seated postures. Oscillometric pressure waveforms were recorded on left upper arm.

RESULTS

For cSBP, there was nonsignificant main effect for fasting state (P = 0.819) but there was a main effect for posture (P = 0.002). Conversely, for AIx, there was nonsignificant main effect for posture (P = 0.537) but there was a large main effect for fasting state (P = < 0.001). The criterion intraclass correlation coefficient value of 0.75 was exceeded for both variables when participants were assessed under the combined supine-fasted condition. For cSBP, the reliability coefficient was lowest (best) when supine fasted (6.8 mmHg) and greatest (worst) when seated nonfasted (8.6 mmHg). For AIx, the reliability coefficient was lower for the supine (11.4-11.7%) compared with the seated (14.0-15.2%) posture.

CONCLUSION

Findings from this study suggest that oscillometric assessments of central hemodynamic variables exceed the criterion for acceptable reliability and are most reliable when participants are evaluated while supine and fasted.

Reliability of oscillometric central hemodynamic responses to an orthostatic challenge

BACKGROUND

Monitoring central hemodynamic responses to an orthostatic challenge may provide important insight into autonomic nervous system function. Oscillometric pulse wave analysis devices have recently emerged, presenting clinically viable options for investigating central hemodynamic properties. The purpose of the current study was to determine whether oscillometric pulse wave analysis can be used to reliably (between-day) assess central blood pressure and central pressure augmentation (augmentation index) responses to a 5 min orthostatic challenge (modified tilt-table).

METHODS

Twenty healthy adults (26.4 y (SD 5.2), 55% F, 24.7 kg/m(2) (SD 3.8)) were tested on 3 different mornings in the fasted state, separated by a maximum of 7 days. Central hemodynamic variables were assessed on the left arm using an oscillometric device.

RESULTS

Repeated measures analysis of variance indicated a significant main effect of the modified tilt-table for all central hemodynamic variables (P < 0.001). In response to the tilt, central diastolic pressure increased by 4.5 mmHg (CI: 2.6, 6.4), central systolic blood pressure increased by 2.3 (CI: 4.4, 0.16) mmHg, and augmentation index decreased by an absolute - 5.3%, (CI: -2.7, -7.9%). The intra-class correlation coefficient values for central diastolic pressure (0.83-0.86), central systolic blood pressure (0.80-0.87) and AIx (0.79-0.82) were above the 0.75 criterion in both the supine and tilted positions, indicating excellent between-day reliability.

CONCLUSION

Central hemodynamic responses to an orthostatic challenge can be assessed with acceptable between-day reliability using oscillometric pulse wave analysis.

Central aortic blood pressure from ultrasound wall-tracking of the carotid artery in children: comparison with invasive measurements and radial tonometry

Differences between central aortic root (c) and peripheral (p) systolic blood pressure (SBP) may be particularly marked in children, but noninvasive methods for assessing cSBP in children have not been validated. We compared estimates of cSBP obtained from radiofrequency ultrasound wall tracking of the carotid artery (ART.LAB system) with that measured directly by a catheter in the aortic root at the time of arterial cannulation. Carotid waveforms were calibrated from invasive measurements of mean and diastolic pressures. In 9 children aged 10.5 ± 5.0 years (mean ± SD), cSBP obtained from carotid wall tracking was highly correlated with invasive measures of cSBP (r=0.99) with mean (± SD) difference 3.9 ± 2.5 mm Hg. Second, we compared values of cSBP obtained from the carotid with those obtained using noninvasive applanation tonometry at the radial artery and a radial-to-aortic transfer function (SphygmoCor). Both carotid and radial tonometric measurements were calibrated from the same peripheral mean and diastolic measurements of blood pressure obtained by sphygmomanometry. In 84 children aged 13.2 ± 3.2 years, there was excellent agreement between the 2 methods (r=0.95; P<0.001) with mean difference 0.71 ± 3.7 mm Hg (95% confidence interval =-1.53 to 1.01). This invasive validation study confirms that cSBP as estimated by carotid wall tracking provides an acceptable measurement of true cSBP when calibration is from true mean and diastolic pressures. Close agreement of cSBP obtained by carotid wall tracking and radial tonometry suggests that these provide similar results when calibrated from the same peripheral blood pressure measurements.

Percentiles for central blood pressure and pulse wave velocity in children and adolescents recorded with an oscillometric device

OBJECTIVE

In adults with arterial hypertension, measuring arterial stiffness by pulse wave velocity (PWV) can determine the extent of cardiovascular subclinical organ damage. PWV has independent predictive value for cardiovascular events, but there are currently no recommendations for measuring PWV in children. In addition, central systolic blood pressure (cSBP) strongly reflects vascular changes. The aim of this study was to establish percentiles for cSBP and PWV in children and adolescents to evaluate and classify altered vascular function in youths.

METHODS AND RESULTS

We measured PWV and cSBP with an oscillometric device with inbuilt ARCSolver-algorithm (estimated by using the brachial waveform) and calculated smoothed reference percentiles for 1445 children and young adults (49.5% female; 13.41 ± 2.80 years, range 8-22 years; PWV 4.67 ± 0.34 m/s; cSBP 100.7 ± 8.9 mmHg) using the LMS-method based on age and height. PWV and cSBP increased with age and height, but slightly differently for girls and boys, possibly reflecting different growth patterns. Between 8 and 21 years, PWV increased from 4.29 ± 0.32 to 4.98 ± 0.33 m/s in girls and from 4.27 ± 0.18 to 5.22 ± 0.46 m/s in boys. While girls showed a minor increase in cSBP (91.2 ± 7.5 to 109.1 ± 8.6 mmHg), the cSBP in boys ranged from 90.0 ± 5.8 to 110.5 ± 9.6 mmHg with a more pronounced increase between 14 and 17 years.

CONCLUSION

These percentiles for PWV and cSBP can help define arterial stiffness in youths and contribute to risk stratification for cardiovascular disease. For example, in children with prehypertension or isolated systolic hypertension, PWV and cSBP can provide additional information about the function of the vascular system, thereby strengthening intervention strategies.

Pre-Adolescent Cardio-Metabolic Associations and Correlates: PACMAC methodology and study protocol

INTRODUCTION

Although cardiovascular disease is typically associated with middle or old age, the atherosclerotic process often initiates early in childhood. The process of atherosclerosis appears to be occurring at an increasing rate, even in pre-adolescents, and has been linked to the childhood obesity epidemic. This study will investigate the relationships between obesity, lifestyle behaviours and cardiometabolic health in pre-pubescent children aged 8-10 years, and investigates whether there are differences in the correlates of cardiometabolic health between Māori and Caucasian children. Details of the methodological aspects of recruitment, inclusion/exclusion criteria, assessments, statistical analyses, dissemination of findings and anticipated impact are described.

METHODS AND ANALYSIS

Phase 1: a cross-sectional study design will be used to investigate relationships between obesity, lifestyle behaviours (nutrition, physical activity/fitness, sleep behaviour, psychosocial influences) and cardiometabolic health in a sample of 400 pre-pubescent (8-10 years old) children. Phase 2: in a subgroup (50 Caucasian, 50 Māori children), additional measurements of cardiometabolic health and lifestyle behaviours will be obtained to provide objective and detailed data. General linear models and logistic regression will be used to investigate the strongest correlate of (1) fatness; (2) physical activity; (3) nutritional behaviours and (4) cardiometabolic health.

ETHICS AND DISSEMINATION

Ethical approval will be obtained from the New Zealand Health and Disabilities Ethics Committee. The findings from this study will elucidate targets for decreasing obesity and improving cardiometabolic health among preadolescent children in New Zealand. The aim is to ensure an immediate impact by disseminating these findings in an applicable manner via popular media and traditional academic forums. Most importantly, results from the study will be disseminated to participating schools and relevant Māori health entities.