scholarly journals Does arterial shear explain the magnitude of flow-mediated dilation?: a comparison between young and older humans

2009 ◽  
Vol 296 (1) ◽  
pp. H57-H64 ◽  
Author(s):  
Dick H. J. Thijssen ◽  
Lauren M. Bullens ◽  
Marieke M. van Bemmel ◽  
Ellen A. Dawson ◽  
Nicola Hopkins ◽  
...  
Keyword(s):  
Brachial Artery ◽  
Vascular Function ◽  
Ultrasound Images ◽  
Flow Mediated Dilation ◽  
Healthy Children ◽  
Time To Peak ◽  
Flow Mediated Dilatation ◽  
Young Subjects ◽  
S Peak ◽  
The Relationship

Flow-mediated dilatation (FMD) has become a commonly applied approach for the assessment of vascular function and health in humans. Recent studies emphasize the importance of normalizing the magnitude of FMD to its apparent eliciting stimulus, the postdeflation arterial shear. However, the relationship between shear stress and the magnitude of FMD may differ between groups. The aim of this study was to examine the relationship between the brachial FMD and four different indexes of postdeflation shear rate (SR) in healthy children ( n = 51, 10 ± 1 yr) and young ( n = 57, 27 ± 6 yr) and older ( n = 27, 58 ± 4 yr) adults. SR was calculated from deflation ( time 0) until 9 s (peak), 30 s (0–30), 60 s (0–60), or until the time-to-peak diameter in each individual (0-ttp). Edge detection and wall tracking of high resolution B-mode arterial ultrasound images were used to calculate the conduit artery diameter. In young adults, the brachial artery FMD demonstrated a significant correlation with the area under the SR curve (SRAUC) 0–30 s ( r2 = 0.12, P = 0.009), 0–60 s ( r2 = 0.14, P = 0.005), and 0-ttp ( r2 = 0.14, P = 0.005) but not for the peak SRAUC 0–9 s ( r2 = 0.04, P = 0.12). In children and older adults, the magnitude of the brachial artery FMD did not correlate with any of the four SRAUC stimuli. These findings suggest that in young subjects, postdeflation SRAUC correlates moderately with the magnitude of the FMD response. However, the relationship between FMD and postdeflation shear appears to be age dependent, with less evidence for an association in younger and older subjects. Therefore, we support presenting SRAUC stimuli but not normalizing FMD responses for the SRAUC when using this technique.

scholarly journals Age and sex relationship with flow-mediated dilation in healthy children and adolescents

2015 ◽  
Vol 119 (8) ◽  
pp. 926-933 ◽  
Author(s):  
Nicola D. Hopkins ◽  
Donald R. Dengel ◽  
Gareth Stratton ◽  
Aaron S. Kelly ◽  
Julia Steinberger ◽  
...  
Keyword(s):  
Sex Differences ◽  
Children And Adolescents ◽  
Brachial Artery ◽  
Vascular Function ◽  
Growth Patterns ◽  
Childhood And Adolescence ◽  
Flow Mediated Dilation ◽  
Healthy Children ◽  
Asymptomatic Children ◽  
Age And Sex

Flow-mediated dilation (FMD) is a noninvasive technique used to measure conduit artery vascular function. Limited information is available on normative FMD values in healthy children and adolescents. The objective of this study was to assess relationships between age and sex with FMD across childhood and adolescence. Nine hundred and seventy-eight asymptomatic children (12 ± 3 yr, range 6–18 yr, 530 male) underwent ultrasonic brachial artery assessment before and after 5 min of forearm ischemia. Sex differences in FMD and baseline artery diameter were assessed using mixed linear models. Baseline artery diameter was smaller in females than males [2.96 mm (95% CI: 2.92–3.00) vs. 3.24 mm (3.19–3.28), P < 0.001] and increased with age across the cohort ( P < 0.001). Diameter increased between ages 6 and 17 yr in males [from 2.81 mm (2.63, 3.00) to 3.91 mm (3.68, 4.14)] but plateaued at age 12 yr in females. Males had a lower FMD [7.62% (7.33–7.91) vs. 8.31% (7.95–8.66), P = 0.024], specifically at ages 17 and 18 yr. There was a significant effect of age on FMD ( P = 0.023), with a reduction in FMD apparent postpuberty in males. In conclusion, the brachial artery increases structurally with age in both sexes; however, there are sex differences in the timing and rate of growth, in line with typical sex-specific adolescent growth patterns. Males have a lower FMD than females, and FMD appears to decline with age; however, these findings are driven by reductions in FMD as males near maturity. The use of age- and sex-specific FMD data may therefore not be pertinent in childhood and adolescence.

scholarly journals Contribution of nitric oxide to brachial artery vasodilation during progressive handgrip exercise in the elderly

2013 ◽  
Vol 305 (8) ◽  
pp. R893-R899 ◽  
Author(s):  
Joel D. Trinity ◽  
D. Walter Wray ◽  
Melissa A. H. Witman ◽  
Gwenael Layec ◽  
Zachary Barrett-O'Keefe ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Shear Rate ◽  
Brachial Artery ◽  
Vascular Function ◽  
The Elderly ◽  
Flow Mediated Dilation ◽  
Handgrip Exercise ◽  
Modest Contribution ◽  
Older Subjects ◽  
The Relationship

The reduction in nitric oxide (NO)-mediated vascular function with age has largely been determined by flow-mediated dilation (FMD). However, in light of recent uncertainty surrounding the NO dependency of FMD and the recognition that brachial artery (BA) vasodilation during handgrip exercise is predominantly NO-mediated in the young, we sought to determine the contribution of NO to BA vasodilation in the elderly using the handgrip paradigm. BA vasodilation during progressive dynamic (1 Hz) handgrip exercise performed at 3, 6, 9, and 12 kg was assessed with and without NO synthase (NOS) inhibition [intra-arterial NG-monomethyl-l-arginine (l-NMMA)] in seven healthy older subjects (69 ± 2 yr). Handgrip exercise in the control condition evoked significant BA vasodilation at 6 (4.7 ± 1.4%), 9 (6.5 ± 2.2%), and 12 kg (9.5 ± 2.7%). NOS inhibition attenuated BA vasodilation, as the first measurable increase in BA diameter did not occur until 9 kg (4.0 ± 1.8%), and the change in BA diameter at 12 kg was reduced by ∼30% (5.1 ± 2.2%), with unaltered shear rate (Control: 407 ± 57, l-NMMA: 427 ± 67 s−1). Although shifted downward, the slope of the relationship between BA diameter and shear rate during handgrip exercise was unchanged (Control: 0.0013 ± 0.0004, l-NMMA: 0.0011 ± 0.007, P = 0.6) as a consequence of NOS inhibition. Thus, progressive handgrip exercise in the elderly evokes a robust BA vasodilation, the magnitude of which was only minimally attenuated following NOS inhibition. This modest contribution of NO to BA vasodilation in the elderly supports the use of the handgrip exercise paradigm to assess NO-dependent vasodilation across the life span.

scholarly journals The impact of baseline diameter on flow-mediated dilation differs in young and older humans

2008 ◽  
Vol 295 (4) ◽  
pp. H1594-H1598 ◽  
Author(s):  
Dick H. J. Thijssen ◽  
Marieke M. van Bemmel ◽  
Lauren M. Bullens ◽  
Ellen A. Dawson ◽  
Nicola D. Hopkins ◽  
...  
Keyword(s):  
Brachial Artery ◽  
Vascular Function ◽  
Flow Mediated Dilation ◽  
Healthy Children ◽  
Cuff Inflation ◽  
Brachial Artery Diameter ◽  
Age Dependent ◽  
Older Subjects ◽  
The Impact ◽  
Baseline Diameter

Flow-mediated dilation (FMD) has become a commonly applied approach for the assessment of vascular function and health, but methods used to calculate FMD differ between studies. For example, the baseline diameter used as a benchmark is sometimes assessed before cuff inflation, whereas others use the diameter during cuff inflation. Therefore, we compared the brachial artery diameter before and during cuff inflation and calculated the resulting FMD in healthy children ( n = 45; 10 ± 1 yr), adults ( n = 31; 28 ± 6 yr), and older subjects ( n = 22; 58 ± 5 yr). Brachial artery FMD was examined after 5 min of distal ischemia. Diameter was determined from either 30 s before cuff inflation or from the last 30 s during cuff inflation. Edge detection and wall tracking of high resolution B-mode arterial ultrasound images was used to calculate conduit artery diameter. Brachial artery diameter during cuff inflation was significantly larger than before inflation in children ( P = 0.02) and adults ( P < 0.001) but not in older subjects ( P = 0.59). Accordingly, FMD values significantly differed in children (11.2 ± 5.1% vs. 9.4 ± 5.2%; P = 0.02) and adults (7.3 ± 3.2% vs. 4.6 ± 3.3%; P < 0.001) but not in older subjects (6.3 ± 3.4% vs. 6.0 ± 4.2%; P = 0.77). When the diameter before cuff inflation was used, an age-dependent decline was evident in FMD, whereas FMD calculated using the diameter during inflation was associated with higher FMD values in older than younger adults. In summary, the inflation of the cuff significantly increases brachial artery diameter, which results in a lower FMD response. This effect was found to be age dependent, which emphasizes the importance of using appropriate methodology to calculate the FMD.

Abstract 16530: Post-exercise Flow-mediated Dilation is augmented in Highly Trained Female Athletes

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Daniela K Andaku ◽  
Bruno Archiza ◽  
Flavia C Caruso ◽  
Katiany T Zangrando ◽  
Humberto Lanzotti ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Brachial Artery ◽  
Vascular Function ◽  
Female Athletes ◽  
Maximal Exercise ◽  
High Volume ◽  
Flow Mediated Dilation ◽  
Brachial Artery Diameter ◽  
Arterial Function ◽  
Training History

Background: Recent evidence has indicated a ceiling to the benefits of exercise training that, if chronically surpassed, may have a negative effect on cardiac function. Conversely, improvements in peripheral arterial function may respond positively to chronic high volume training. Recent studies have shown that flow-mediated dilation (FMD) is decreased immediately after maximal exercise in sedentary subjects and is unaltered in subjects who participate in moderate volume exercise. We investigated the acute effects of maximal exercise on vascular function of elite female athletes with a high-volume training history. Methods: Fifteen elite female soccer players (mean age: 22.1 ± 4.4 years; BMI: 20.76 ± 1.75 kg/m2), with a high volume/intensity training history (4-6 hours per day) were evaluated. Subjects underwent maximal cardiopulmonary exercise testing (CPX) on a treadmill (VO2max 41.1 ± 3.9 mLO2•kg-1•min-1). Brachial artery FMD was determined using high-resolution ultrasound before and immediately after CPX. Flow velocity were measured at baseline (BSL) and during reactive hyperemia (RH) both prior to and following exercise. Results: Brachial artery diameter increased during RH before (3.42 ± 0.38mm vs. 3.03 ± 0.28mm, p<0.001) and after CPX (3.61 ± 0.44mm vs. 3.10 ± 0.37mm, p<0.001). Importantly, FMD was increased following CPX compared to BSL (16.86 ± 9.04% vs. 12.95 ± 7.03%, p=0.027). There was significant increase in peak flow velocity during RH before (135.28 ± 42.19cm/s vs. 79.19 ± 28.14cm/s, p=0.001) and after CPX (139.15 ± 41.07cm/s vs. 87.64 ± 21.23cm/s, p<0.001) (Table). Conclusion: The results of the current study indicate that arterial function is improved following acute aerobic exercise in elite female athletes with a chronic high volume training history. These findings deviate from the emerging literature suggesting chronic high volume training may be detrimental to cardiovascular function in the long term.

scholarly journals Study of endothelial function in pregnant women with gestational diabetes mellitus by flow mediated dilation of brachial artery

2020 ◽  
Vol 9 (6) ◽  
pp. 2377
Author(s):  
Nidhi Pandey ◽  
Poonam Goel ◽  
Anita Malhotra ◽  
Reeti Mehra ◽  
Navjot Kaur
Keyword(s):  
Gestational Diabetes ◽  
Endothelial Function ◽  
Pregnant Women ◽  
Brachial Artery ◽  
Vascular Function ◽  
Post Partum ◽  
Control Group ◽  
Flow Mediated Dilation ◽  
The Mean ◽  
The Difference

Background: The objective of the study was to assess vascular function in normal pregnant women and women with gestational diabetes and to study its temporal relationship with gestational age at 24-28-week POG and at 36-38-week POG and changes in FMD in postpartum period.Methods: Assessment of vascular function was done at 24-28-week POG, 36-38-week POG and at 6-12-week postpartum by flow mediated dilation of brachial artery in 37 healthy pregnant women and 37 pregnant women with GDM.Results: In GDM group mean FMD at 24-28 weeks of POG, at 36-38 weeks POG was lower as compared to the control group (11.225±6.20,8.464±6.09 versus 14.49±5.21, 10.898±4.12) although the difference in mean FMD in two groups was not statistically significant. It was found that the decrease in FMD at 36-38-week POG as compared to 24-28 weeks POG was statistically significant in both the groups (p<0.001).Conclusions: This study revealed that when endothelial function as assessed by FMD was compared at different period of gestation, the mean decrease in FMD at 36-38-week POG as compared to 24-28-week POG and 6-week post-partum was statistically significant in patients with GDM and as well as the control group, however this trend of change was same in both the groups and was not statistically significant when compared between the two group (GDM versus control). A negative correlation of FMD was found with BMI, and HBA1c, that was stronger in GDM group.

scholarly journals Heterogeneity in the vasodilatory function of individual extremities

Vascular ◽  
2019 ◽  
Vol 28 (1) ◽  
pp. 87-95
Author(s):  
Tomoyasu Kadoguchi ◽  
Masahiro Horiuchi ◽  
Shintaro Kinugawa ◽  
Koichi Okita
Keyword(s):  
Muscle Strength ◽  
Grip Strength ◽  
Brachial Artery ◽  
Popliteal Artery ◽  
Muscle Activity ◽  
Vascular Function ◽  
Knee Extension ◽  
Flow Mediated Dilation ◽  
Significant Difference ◽  
Vasodilatory Function

Objectives Heterogeneity and homogeneity in the flow-mediated dilation of the human body's individual extremities are not fully understood, and the relationship between flow-mediated dilation and local muscle activity is unclear. We assessed the flow-mediated dilation of four individual extremities and sought to determine the contribution of local muscle activity (evaluated as muscle strength) to the flow-mediated dilation in each extremity. Methods Thirteen healthy young right-handed nonactive males participated. The flow-mediated dilation in the brachial and popliteal arteries at both arms and legs was assessed by ultrasound Doppler. Muscle strength was evaluated as the grip strength and knee extension. Results There was a significant difference in the brachial artery (BA)-FMD values between the subjects' dominant and non-dominant sides (8.0 ± 2.8 vs. 5.5 ± 2.2%, p < 0.05), whereas the two sides showed similar popliteal artery (PA)-FMD values. There was no significant correlation in flow-mediated dilation between the dominant brachial artery and popliteal artery. The BA-FMD was significantly correlated with the grip strength in both upper extremities (dominant: r = 0.562, non-dominant: r = 0.548; p < 0.05, respectively). Conclusion These results demonstrated heterogeneity in the flow-mediated dilation of individual extremities. We observed that local muscle activity can affect the local vascular function. Measurements of vasodilatory function in individual extremities should thus be carefully considered.

Combined aerobic and resistance training and vascular function: effect of aerobic exercise before and after resistance training

2007 ◽  
Vol 103 (5) ◽  
pp. 1655-1661 ◽  
Author(s):  
Takanobu Okamoto ◽  
Mitsuhiko Masuhara ◽  
Komei Ikuta
Keyword(s):  
Resistance Training ◽  
Aerobic Exercise ◽  
Brachial Artery ◽  
Vascular Function ◽  
Pulse Wave ◽  
Aerobic Exercise Training ◽  
Flow Mediated Dilation ◽  
Brachial Artery Diameter ◽  
Combined Training ◽  
Before And After

Aerobic exercise training combined with resistance training (RT) might prevent the deterioration of vascular function. However, how aerobic exercise performed before or after a bout of RT affects vascular function is unknown. The present study investigates the effect of aerobic exercise before and after RT on vascular function. Thirty-three young, healthy subjects were randomly assigned to groups that ran before RT (BRT: 4 male, 7 female), ran after RT (ART: 4 male, 7 female), or remained sedentary (SED: 3 male, 8 female). The BRT and ART groups performed RT at 80% of one repetition maximum and ran at 60% of the targeted heart rate twice each week for 8 wk. Both brachial-ankle pulse wave velocity (baPWV) and flow-mediated dilation (FMD) after combined training in the BRT group did not change from baseline. In contrast, baPWV after combined training in the ART group reduced from baseline (from 1,025 ± 43 to 910 ± 33 cm/s, P < 0.01). Moreover, brachial artery FMD after combined training in the ART group increased from baseline (from 7.3 ± 0.8 to 9.6 ± 0.8%, P < 0.01). Brachial artery diameter, mean blood velocity, and blood flow in the BRT and ART groups after combined training increased from baseline ( P < 0.05, P < 0.01, and P < 0.001, respectively). These values returned to the baseline during the detraining period. These values did not change in the SED group. These results suggest that although vascular function is not improved by aerobic exercise before RT, performing aerobic exercise thereafter can prevent the deteriorating of vascular function.

scholarly journals Noninvasive Assessment of Endothelium-Dependent Flow-Mediated Dilation of the Brachial Artery

1997 ◽  
Vol 2 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Akimi Uehata ◽  
Eric H Lieberman ◽  
Marie D Gerhard ◽  
Todd J Anderson ◽  
Peter Ganz ◽  
...  
Keyword(s):  
Blood Flow ◽  
Endothelial Function ◽  
Brachial Artery ◽  
Vascular Function ◽  
Reactive Hyperemia ◽  
Intraobserver Variability ◽  
Flow Mediated Dilation ◽  
Noninvasive Technique ◽  
Brachial Artery Diameter ◽  
Cuff Occlusion

Coronary atherosclerosis is characterized by an early loss of endothelium-dependent vasodilation. However, the methods of assessing coronary endothelial function are invasive and difficult to repeat over time. Recently, a noninvasive ultrasound method has been widely used to measure flow-mediated dilation in the brachial artery as a surrogate test for endothelial function. We seek to further validate this method of measuring vascular function. The brachial artery diameters and blood flow of 20 normal volunteers (10 males and 10 females) were measured using high resolution (7.5 MHz) ultrasound and strain gauge plethysmography. Flow-mediated endothelium-dependent vasodilation was measured in the brachial artery during reactive hyperemia after 5 minutes of cuff occlusion in the upper arm. The brachial artery diameter increased maximally by 9.7 ± 4.3% from baseline at 1 min after cuff release and blood flow increased by 1002 ± 376%. Five min of cuff occlusion was sufficient to achieve 97 ± 6% of maximal brachial artery dilation and degree of dilation was not different whether the cuff was inflated proximally or distally to the image site. The intraobserver variability in measuring brachial diameters was 2.9 % and the variability of the hyperemic response was 1.4%. In young, healthy men and women, the baseline brachial artery diameter was the only factor that was predictive of the flow-mediated vasodilation response. The brachial noninvasive technique has been further validated by the determination of flow-mediated dilation. This method of assessing endothelial function may help to determine the importance of vasodilator dysfunction as a risk factor in the development of atherosclerosis.

Brachial artery flow-mediated dilation is not affected by pregnancy or regular exercise participation

2011 ◽  
Vol 121 (8) ◽  
pp. 355-365 ◽  
Author(s):  
Tracey L. Weissgerber ◽  
Gregory A. L. Davies ◽  
Michael E. Tschakovsky
Keyword(s):  
Shear Stress ◽  
Pregnant Women ◽  
Brachial Artery ◽  
Luteal Phase ◽  
Regular Exercise ◽  
Flow Mediated Dilation ◽  
Brachial Artery Diameter ◽  
Exercise Participation ◽  
Time To Peak ◽  
Late Luteal Phase

Whether brachial artery FMD (flow-mediated dilation) is altered in pregnancy by 28–35 weeks compared with non-pregnant women remains controversial. The controversy may be due to limitations of previous studies that include failing to: (i) test non-pregnant controls in the mid-late luteal phase, (ii) account for effects of pregnancy on the dilatory shear stimulus, (iii) account for physical activity or (iv) control for inter-individual variation in the time to peak FMD. In the present study, brachial artery FMD was measured in 17 active and eight sedentary pregnant women (34.1±1.6 weeks of gestation), and in 19 active and 11 sedentary non-pregnant women (mid-late luteal phase). Decreased vascular tone secondary to increased shear stress contributes minimally to pregnancy-induced increases in baseline brachial artery diameter, as shear stress removal during distal cuff inflation in pregnant women did not reduce diameter to baseline levels observed in non-pregnant controls. Neither the shear stimulus nor the percentage FMD was affected by pregnancy or regular exercise. Continuous diameter measurements are required to control for delayed peak dilation during pregnancy (57±15 compared with 46±15 s; P=0.012), as post-release diameter measured at 60 or 55–65 s post-release underestimated FMD to a greater extent in non-pregnant than in pregnant women.

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