Does altering brachial artery tone with lower-body negative pressure and flow-mediated dilation affect arterial stiffness?

Although medium sized, muscular vessels normally respond to sympathetic stimulation by reducing compliance, it is unclear whether the large brachial artery is similarly affected by sympathetic stimulation induced via lower-body negative pressure (LBNP). Similarly, the impact of flow-mediated dilation (FMD) on brachial artery compliance and distensibility remains unresolved, hi addition, before such measures can be used as prognostic tools, it is important to investigate the reliability and repeatability of both techniques. Using a randomized order design, the effects of LBNP and FMD on the mechanical properties of the brachial artery were examined in nine healthy male subjects (mean age 24y). Non-invasive Doppler ultrasound and a Finometer were used to measure simultaneously the variation in systolic and diastolic diameter, and brachial blood pressure, respectively. These values were used to calculate compliance and distensibility values at baseline, and during both LBNP and FMD. The within-day and between-day repeatability of arterial diameter, compliance, distensibility, and FMD measures were assessed using the error coefficient and intra-class correlation coefficient (ICC). While heart rate (P<0.01) and peripheral resistance increased during LBNP (P<0.05), forearm blood flow and pulse pressure decreased (P<0.01). hi terms of mechanical properties, vessel diameters decreased (P<0.05), but both compliance and distensibility were not changed. On the other hand, FMD resulted in a significant increase in diameter (P<0.001), with no change in compliance or distensibility. hi summary, LBNP and FMD do not appear to alter brachial artery compliance or distensibility in young, healthy males. Whereas measures ofFMD were not found to be repeatable between days, the ICC indicated that compliance and distensibility were repeatable only within-day.

The association between body composition and arterial stiffness in peri-pubescent children

The objective of this study was to examine the association between body composition and arterial stiffuess in peri-pubescent boys and girls. Differences in arterial distensibility were measured in 68 children (45 normal weight, 12 overweight, and 11 obese) between the ages of9 to 12 years. Weight classification was based on age and gender-specific body mass index cut-offs, while pubertal maturation was self-reported using Tanner staging. Distensibility was determined using two-dimensional, B-Mode echo Doppler ultrasound to measure changes at the right common carotid artery (CCA) diameter changes, while carotid pulse pressure (cPP) was measured at the left CCA by applanation tonometry. One-way ANOV A analysis revealed significant differences (p<0.001) in all anthropometric measures between the normal weight and overweight children, as well as the normal weight and obese children. Body stature was only higher in obese children compared to normal weight children (p<0.01). No significant differences were found between groups regarding age or Tanner stage. Common carotid artery distensibility showed a significant difference (p<0.01) between normal weight children (0.008 ± 0.002 mmHg-1 ) compared to obese children (0.005 ± 0.002 mmHg-1 ), with a borderline significant difference between the normal and overweight subjects (p=0.06). There was no significant effect for gender between males and females across all independent variables. The strongest determinants of distensibility in children were cPP (r= -0.52, p

Exploring the relationship between ethnicity and hypertension in Canada

Background: Previous work examining differences in hypertension across ethnic groups employ race as the principal variable. While differences in hypertension have been identified across racial groups, there is great variation between ethnic groups amongst racial groupings that could mask differences in hypertension and cardiovascular disease (CVD) risk. In light of Canada's ethnic diversity, research aimed at identifying specific groups that are at a health disadvantage is essential for understanding the health of the overall population. In addition, this research would be beneficial for creating programs and policies aimed at reducing or eliminating these disparities. Since CVD is the leading cause of mortality in Canada and hypertension is one of the most significant and modifiable risk factors for CVD, it is important to move past crude classifications based on race and examine ethnic group differences. The purpose of this study is to examine the relationship between ethnicity and hypertension in Canada, while employing more narrow classifications for ethnicity than previous studies. In addition, because ethnicity has been shown to be representative of an individual's social experience, this study also aims to investigate whether this relationship can be explained by one or all of the following variable: socioeconomic status, physical activity, body mass index, smoking status, daily alcohol consumption or acculturation. Methods. This study used the 2004 Canadian Community Health Survey, cycle 2.1 to compare 29 different ethnic groups in Canada on whether they had high blood pressure that had been diagnosed by a health professional. Associations were examined using logistic regression. Subsequent logistic regression analyses included socioeconomic status, physical activity, body mass index, smoking status, daily alcohol consumption and acculturation to test for the effect of each of these variables on the relationship between ethnicity and hypertension. Results. Ukrainians, Chinese, Portuguese, South Asians, Aboriginals, Blacks, Filipinos and South East Asians were found to have significantly higher odds of having high blood pressure than Canadians (OR's = 1.50, 1.56, 2.72, 1.38, 1.36, 1.66, 2.21 & 2.24 respectively, p<.001). In addition, the only significant mediating effects were between SES and Aboriginals as well as obesity and Aboriginals. None of the other independent variables accounted for >10% of the risk experienced by the ethnic groups that were significantly associated with hypertension. Interpretation: The odds of having high blood pressure in Canada varies considerably across ethnic groups within racial groups indicating previous research is not specific enough to inform policy and program development. Because this study was not able to explain this relationship using the sociodemographic and lifestyle factors mentioned above, future research should be done to determine what places certain ethnic groups at a greater risk in order to tailor interventions aimed at reducing high blood pressure that are suited to the specific needs of each cultural group.

The association between blood pressure and vascular characteristics in children

Hypertension is thought to exist in up to five percent of children. A select number of studies have investigated the role elevated blood pressure plays in pediatric atherosclerotic progression. However these studies contain significant methodological flaws and fail to recognize important confounding factors. Therefore, the influence of elevated blood pressure on arterial health in children remains to be clearly understood. The purpose of this study was to investigate the association between blood pressure (BP) and arterial thickness and stiffuess in children. Common carotid artery (CCA) intima-media thickness (IMT) and distensibility (Dist), as well as systemic pulse wave velocity (PWV) were measured in 21 elevated blood pressure (EBP; BP ~ 95th percentile) and 83 normal blood pressure (NBP; BP < 90th percentile) children 11-14 years of age. Both EBP and NBP groups demonstrated BP within the normal clinical range, but EBP showed significantly elevated BP as compared to the NBP group. Independent t-tests failed to show significant differences between the EBP and NBP groups for CCA IMT (0.43 ± 0.05 mm and 0.42 ± 0.06 mm, respectively) and Dist (0.0058 ± 0.0024 mmHg-1 and 0.0064 ± 0.0019 mmHil respectively). In contrast, a significantly elevated PWV (parterial structure and function as measured through CCA Dist and IMT, but do possess significantly altered systemic arterial stiffuess as measured through PWV. This may be the result of sympathetic predominance and its significant influence on the peripheral vasculature. More studies are needed to clearly illustrate the temporal sequence of pediatric atherosclerotic progression in response to elevated BP.

The Effects of a Psychosocial Behavioural Intervention on Arterial Health in Children

This study evaluated the effects of a Leisure and Well-Being Model (LWM) psychosocial intervention on arterial health, measured by arterial stiffness and thickness, in 82 children aged 10-13 (n=41; intervention, n=41; control) over one year. The intervention was to provide children with the awareness, skill development, and application of positive emotion, personal strengths, coping, and free-time vitality. Results showed no change in arterial health for children exposed to the intervention compared to controls. However, a significant systolic blood pressure decrease was found in children exposed to the intervention and increased in those of the control group (F (1, 73) = 4.085, p = 0.047). This is the first study to show that a psychosocial intervention has a positive effect on childhood cardiovascular health within one year. Hence, if exposed for-or followed for- a longer period of time, it may be possible to see further improvements in arterial health.

ARTERIAL STIFFNESS IN CHILDREN WITH AND WITHOUT DEVELOPMENTAL COORDINATION DISORDER

The purpose of this study was to determine whether children with potential developmental coordination disorder (p-DCD) demonstrate increased arterial stiffness and thickness compared to age and school matched controls (mean age 14.7 yrs). We also assessed whether these measures differed by sex. Compliance, distensibility, and intima-media thickness (IMT) were measured at the common carotid artery for 28 children with p-DCD and 47 controls. ECG-R-wave-toe pulse wave velocity (PWV) was also measured for 29 children with p-DCD and 45 controls. We found that compared to controls males with p-DCD had significantly higher PWV (3.8±0.2 vs. 4.1±0.3, p=0.001) and lower distensibility (0.82± 0.19 vs. 0.70± 0.17, p=0.034) while females showed no significant differences (p=0.523 and p=0.123 respectively). As a result, it is apparent that sex differences exist with respect to arterial health within this population and that children with p-DCD may be more likely to develop cardiovascular disease later in life.

The Influence of Sex on the Relationship Between Arterial Mechanical Properties and Cardiovagal Baroreflex Sensitivity

Cardiovagal baroreflex sensitivity (cvBRS) demonstrates a strong relationship with arterial mechanical properties. Both cvBRS and arterial mechanics differ by sex such that males demonstrate greater cvBRS, yet lower large artery elasticity than females. Whether the relationship between cvBRS and arterial mechanics is similar in males and females remains unexamined. As a result, it is unclear whether arterial mechanics contribute to sex differences in cvBRS. This study investigated the cross-sectional relationship between cvBRS and arterial mechanical properties of the common carotid, carotid sinus and aortic arch (AA) in 36 (18 females) young, healthy normotensives. The cvBRS-arterial mechanics relationship did not reach statistical significance and did not differ by sex. Both cvBRS and AA distensibility were greater in females than males. Sex differences in cvBRS were eliminated after controlling for AA distensibility. These findings suggest that in this sample, AA elasticity may contribute to the greater cvBRS in females than males.