Magnetic resonance imaging reveals elevated aortic pulse wave velocity in obese and overweight adolescents

Is There a Role for Imaging Youth at Risk of Atherosclerosis?

PURPOSE OF REVIEW

Cardiovascular (CV) risk factors such as dyslipidemia, hypertension, diabetes, and obesity are associated with an increased risk for CV events in adults. Noninvasive measures of vascular health are associated with these CV events and can potentially help risk stratify children with CV risk factors. The purpose of this review is to summarize recent literature regarding vascular health in children with cardiovascular risk factors.

RECENT FINDINGS

Adverse changes in pulse wave velocity, pulse wave analysis, arterial distensibility, and carotid intima-media thickness are seen in children with CV risk factors supporting potential utility in risk stratification. Assessing vascular health in children can be challenging due to growth-related changes in vasculature, multiple assessment modalities, and differences in normative data. Vascular health assessment in children with cardiovascular risk factors can be a valuable tool for risk stratification and help identify opportunities for early intervention. Future areas of research include increasing normative data, improving conversion of data between different modalities, and increasing longitudinal studies in children linking childhood risk factors to adult CV outcomes.

Pulse Wave Velocity Measurements by Magnetic Resonance Imaging in Neonates and Adolescents: Methodological Aspects and Their Clinical Implications

Pulse wave velocity (PWV) by cardiovascular magnetic resonance (CMR) lacks standardization. The aim of this study was to investigate methodological aspects of PWV measurements by CMR in neonates and adolescents. A computer phantom was created to validate the temporal resolution required for accurate PWV. Fifteen neonates and 71 adolescents underwent CMR with reference standard 3D angiography and phase-contrast flow acquisitions, and in a subset coronal overview images. Velocity and flow curves, transit time methods (time-to-foot (TTF), maximum upslope, and time-to-peak (TTP)), and baseline correction methods (no correction, automatic and manual) were investigated. In neonates, required timeframes per cardiac cycle for accurate PWV was 42 for the aortic arch and 41 for the thoracic aorta. In adolescents, corresponding values were 39 and 32. Aortic length differences by overview images and 3D angiography in adolescents were - 16-18 mm (aortic arch) and - 25-30 mm (thoracic aorta). Agreement in PWV between automatic and manual baseline correction was - 0.2 ± 0.3 m/s in neonates and 0.0 ± 0.1 m/s in adolescents. Velocity and flow-derived PWV measurements did not differ in either group (all p > 0.08). In neonates, transit time methods did not differ (all p > 0.19) but in adolescents PWV was higher for TTF (3.8 ± 0.5 m/s) and maximum upslope (3.7 ± 0.6 m/s) compared to TTP (2.7 ± 1.0 m/s; p < 0.0001). This study is a step toward standardization of PWV in neonates and adolescents using CMR. It provides required temporal resolution for phase-contrast flow acquisitions for typical heartrates in neonates and adolescents, and supports 3D angiography and time-to-foot with automatic baseline correction for accurate PWV measurements.

A Systematic Review of the Associations of Adiposity and Cardiorespiratory Fitness With Arterial Structure and Function in Nonclinical Children and Adolescents

PURPOSE

To summarize the evidence on associations of adiposity and cardiorespiratory fitness (CRF) with arterial structure and function in nonclinical children and adolescents.

METHODS

Two researchers conducted a search in 5 electronic databases in April 2022 to find studies in nonclinical youth (age 5-17.9 y) reporting multivariable associations. Studies were eligible if adiposity and/or CRF were used as the predictor and arterial structure and/or function was the outcome. The Quality Assessment Tool for Quantitative Studies was used to assess methodological quality for experimental studies, and a modified version was used for observational studies.

RESULTS

Ninety-nine studies (72.7% cross-sectional) were included. Ninety-four assessed associations between adiposity and arterial outcomes, most using overall body proportion (n = 71), abdominal (n = 52), or whole-body adiposity (n = 40). Most evidence was inconsistent or nonsignificant, but 59 studies suggested higher abdominal adiposity and worse body proportion were associated with adverse arterial outcomes. Twenty-one assessed associations between CRF and arterial outcomes, with findings inconsistent. Most evidence was rated weak in quality.

CONCLUSION

While high adiposity may contribute to poor arterial outcomes, evidence is limited regarding CRF. Future studies should disentangle these associations by studying youth with healthy adiposity but poor CRF, or vice versa, using longitudinal or experimental study designs.

Association between Brachial-Ankle Pulse Wave Velocity as a Marker of Arterial Stiffness and Body Mass Index in a Chinese Population

Objectives: Arterial stiffness is widely accepted as an important predictor of cardiovascular disease (CVD) development. While obesity is generally associated with increased CVD risk, there is evidence that overweight patients with existing CVD may have better clinical outcomes than their lean counterparts. Our study sought to observe any potential association between brachial−ankle pulse wave velocity (BAPWV), a marker of arterial stiffness related to CVD risk, and Body Mass Index (BMI), a crude and widely used measure of obesity. Methods: Adult individuals (n = 857) assessed for routine CV risk were included and grouped according to their BMI (<25 kg/m2: normal; 25−30 kg/m2: overweight, ≥30 kg/m2: obese). Their anthropometric parameters, brachial cuff pressures, and BAPWV were measured. Results: Brachial pressure was significantly higher as BMI increased. BAPWV showed a positive linear association with systolic (r = 0.66, p < 0.01), mean (r = 0.60, p < 0.01), diastolic (r = 0.51, p < 0.01), and pulse (r = 0.53, p < 0.01) pressures. However, a linear relationship between BMI and BAPWV was only apparent in males aged <50 years (p = 0.01) and in females aged ≥50 years (p < 0.01). In individuals with similar brachial systolic pressure, BAPWV was higher in normal-weight subjects compared to overweight−obese ones. Conclusions: This conflicting finding is attributed to an overestimation of the degree of arterial stiffness as a measure of CVD risk in individuals with a less ‘healthy’ BMI. This suggests that BMI may not the appropriate obesity indicator to assess CV risk. Our finding emphasizes the importance of establishing a non-linear relationship between CVD risk, age, and BMI, taking into account apparent sex differences, to predict future CV events. While this finding may suggest a lower degree of stiffness in large arteries of overweight−obese subjects compared to their normal-weight counterparts, the potential implications for individuals with higher BMI need be explored further.

Association of blood pressure, obesity and physical activity with arterial stiffness in children: a systematic review and meta-analysis

Central pulse wave velocity (cPWV) is a biomarker for cardiovascular (CV) risk and a predictor for CV events in adulthood. Alterations of arterial stiffness have also been associated with CV risk in childhood. The study aimed to systematically review and meta-analyze the association of blood pressure (BP), body mass index (BMI), and cardiorespiratory fitness (CRF) with cPWV in children. Literature search was through the databases PubMed, Web of Science, Embase and the Cochrane Register of Controlled Trials. Twenty-two articles were included in the systematic review and eight articles in the meta-analysis. Higher systolic and diastolic BP were associated with higher cPWV (pooled estimated effect size (ES) 0.02 (95% CI: 0.012-0.027; P < 0.001), and ES 0.02 (95% CI: 0.011-0.029; P < 0.001); respectively). Higher BMI correlated with higher cPWV (ES 0.025 (95% CI: 0.013-0.038; P < 0.001)). CRF was inversely associated with cPWV (ES -0.033 (95% CI: -0.055 to -0.011; P = 0.002)). In children, higher BP and BMI are already related to increased cPWV, and enhanced CRF may be a preventive strategy to counteract development of CV disease later in life. IMPACT: This meta-analysis suggests that elevated blood pressure and body mass index in childhood correlate with increased central pulse wave velocity. Children with higher cardiorespiratory fitness appear to have favorably lower arterial stiffening. Elevated blood pressure and altered arterial stiffness originate early in life and childhood risk stratification as well as timely initiation of exercise treatment may help counteract development of manifest cardiovascular disease later in life.

Biological Pathways in Adolescent Aortic Stiffness

Background

Aortic stiffening begins in youth and antedates future hypertension. In adults, excess weight, systemic inflammation, dyslipidemia, insulin resistance, neurohormonal activation, and altered adipokines are implicated in the pathogenesis of increased aortic stiffness. In adolescents, we assessed the relations of comprehensive measures of aortic stiffness with body mass index (BMI) and related but distinct circulating biomarkers.

Methods and Results

A convenience sample of 246 adolescents (mean age, 16±2 years; 45% female, 24% Black, and 43% Hispanic) attending primary care or preventive cardiology clinics at 2 tertiary hospitals was grouped as normal weight (N=98) or excess weight (N=148, defined as BMI ≥age‐ and sex‐referenced 85th percentile). After an overnight fast, participants underwent anthropometry, noninvasive arterial tonometry, and assays for serum lipids, CRP (C‐reactive protein), glucose, insulin, renin, aldosterone, and leptin. We used multivariable linear regression to relate arterial stiffness markers (including carotid‐femoral pulse wave velocity) to BMI z score and a biomarker panel. Carotid‐femoral pulse wave velocity was higher in excess weight compared with normal weight group (5.0±0.7 versus 4.6±0.6 m/s; P<0.01). After multivariable adjustment, carotid‐femoral pulse wave velocity was associated with BMI z score (0.09 [95% CI, 0.01–0.18]; P=0.04) and with low‐density lipoprotein cholesterol (0.26 [95% CI, 0.03–0.50]; P=0.03).

Conclusions

Higher BMI and low‐density lipoprotein cholesterol were associated with greater aortic stiffness in adolescents. Maintaining optimal BMI and lipid levels may mitigate aortic stiffness.

Four-second dynamic exercise testing (T4S) for the assessment of cardiac vagal modulation in obese adolescents

BACKGROUND

Reduced vagal activity is often present in obese adolescents. Simple and practical strategies for the assessment of isolate parasympathetic outflow in this population are therefore useful.

OBJECTIVES

To compare the methods derived from heart rate variability (HRV) analysis at rest and 4 s exercise testing (T4S) for the assessment of cardiac parasympathetic modulation in adolescents classified as obese (OB) or with normal weight (NW). Additionally, associations between total and trunk fat versus autonomic modulation determined by the two methods were calculated.

APPROACH

A cross-sectional study was conducted with 50 adolescents (26 OB and 24 NW, 14.7  ±  1.5 years), comparing autonomic indices provided by HRV and T4S. Body fractioning was determined employing dual-energy x-ray absorptiometry (DXA).

MAIN RESULTS

The cardiac vagal index (CVI) obtained from T4S and standard time- and frequency-domain HRV measures were lower in OB versus NW (P  ⩽  0.05). Correlations between CVI and HRV indices of cardiac vagal modulation were as follows: CVI versus RMSSD (r  =  0.44; P  =  0.003); CVI versus pNN50 (r  =  0.32; P  =  0.04); CVI versus HF (r  =  0.35; P  =  0.02). Associations between body fat, android/gynoid ratio, and percent trunk fat versus CVI were of similar magnitude and direction than versus HRV indices.

SIGNIFICANCE

The T4S proved to be adequate to detect cardiac parasympathetic impairment in obese adolescents. Moreover, vagal modulation assessed by HRV and T4S inversely correlated with visceral adipose tissue. These findings along with the simplicity and safety of the T4S should encourage its use in the assessment of cardiac parasympathetic modulation in obese pediatric populations.

Effect of Obstructive Sleep Apnea on Cardiovascular Function in Obese Youth

The increasing prevalence of overweight or obese children and adolescents is a significant global health concern. Although the effect of obesity on cardiovascular function has been investigated, little is known on the impact of associated obstructive sleep apnea (OSA) in obese youth. The aim of the present study was to investigate the influence of OSA on cardiovascular functional parameters in obese youth. This is a prospective single-center observational cross-sectional study. Forty-four obese patients and 44 age- and gender-matched control subjects were included. All patients underwent polysomnography and cardiovascular assessment including functional echocardiography and carotid-femoral pulse wave velocity (PWV). Obese patients had higher left ventricular (LV) mass/height^2.7, preserved LV systolic parameters, differences in LV diastolic parameters, and increased PWV and systolic blood pressure at rest compared with control group. In obese youth, 14 of 44 (32%) had OSA. There was no correlation between obesity and the apnea-hypopnea index (AHI). LV mass/height^2.7 significantly correlated with body mass index z-score (r = 0.648, p <0.001) whereas PWV correlated with AHI (r = 0.352, p = 0.038). In obese patients, body mass index z-score was an independent predictor for LV mass/height^2.7 (r = 0.61, p <0.001) and AHI was an independent predictor for higher PWV (r = 0.352, p = 0.038). In conclusion, both obesity and OSA influence cardiovascular performance in obese youth. Although obesity is associated with increased LV mass and reduced LV diastolic function, OSA is associated with changes in arterial stiffness.

Obesity, Visceral Fat, and Hypertension-Related Complications

Background: Hypertension and obesity are very common and complex cardiovascular (CV) risk factors. Our aim was to provide a comprehensive assessment of associations between visceral fat depots and vascular or cardiac complications of hypertension. Methods: All the consecutive patients (age: 45-80 years old) scheduled for elective coronary angiography in the Department of Cardiology were screened, and 400 patients were included into the study group. All the patients had a comprehensive clinical assessment focused on hypertension and obesity, risk factors, fat depots, and several hypertension-related vascular or cardiac complications. Results: The study group (n = 400; F/M: 140/260; age: 61 ± 7 years) included patients with hypertension (n = 354; 88.5%) and normal blood pressure (n = 46; 11.5%) and individuals with obesity (n = 192; 48%), diabetes (n = 139; 35%), metabolic syndrome (n = 240; 60%), and coronary artery disease (n = 286; 71%). Patients with higher degrees of hypertension (grade 3 vs. 2 vs. 1) showed increased body mass index (BMI) and waist circumference and ultrasound indexes of perivascular, epicardial, and abdominal visceral fat with no differences in age, waist-hip ratio, and subcutaneous fat. Both visceral fat depots: perivascular fat (carotid extra-media thickness) and abdominal visceral fat (intra-abdominal thickness) assessed as single measures and ratios were significantly increased in hypertensive patients with high versus low global CV risk in a hypertension-focused risk model (differences more pronounced in patients ≤60 years old). Visceral fat parameters were not independent, but rather additive to general obesity (BMI), except for visceral abdominal fat depot. Conclusions: Visceral abdominal and perivascular fat depots assessed as ultrasound indexes are associated with complications of hypertension and CV risk indicators, especially in patients with a mild-to-moderate hypertension and in younger patients.