Postural changes may influence popliteal atherosclerosis by modifying local circumferential wall tension

Relationship of blood pressure measured in the calf with arm blood pressure and arterial stiffness: a general population study

AIM

Leg blood pressure (BP) measurement is needed when arm BP evaluation is not feasible, and calf BP, especially when measured in standing position, may have greater association with cardiovascular remodeling than arm BP. This study evaluated the relationship between calf and arm BP, and investigated whether calf BP would be superior to arm BP in predicting increased arterial stiffness [pulse wave velocity (PWV) > 10 m/s].

METHODS

We evaluated clinical and laboratory characteristics, BP measurements, and PWV in 1397 individuals resident in Baependi, Brazil, between 2017 and 2019. Arm BP was measured in the seated and supine positions while calf BP was measured in supine and standing positions using digital oscillometric devices. Carotid-femoral PWV was measured using a noninvasive mechanotransducer.

RESULTS

The sample had 62.7% females, age = 48.1 ± 15.4 years and 8.4% with PWV >10 m/s. Results of linear regression analysis showed that BP values of 140/90 mmHg measured in the arm in supine and seated position were equivalent to calf supine BP values of 164/81 mmHg and 166/78 mmHg and calf standing BP values of 217/137 mmHg and 221/137 mmHg, respectively. Calf-arm BP differences were associated with age, glomerular filtration rate, body mass index, smoking, low-density lipoprotein-cholesterol, diabetes and height. Furthermore, stepwise logistic regression analysis revealed that arm supine systolic BP, but not calf BP measurements, was independently associated with increased arterial stiffness.

CONCLUSION

Thresholds of ≈165/80 mmHg and ≈220/135 mmHg could be used for diagnosing hypertension when only calf measurements in supine and standing positions, respectively, are available. Conversely, calf BP was not superior to arm BP in predicting increased arterial stiffness.

Daily Sitting for Long Periods Increases the Odds for Subclinical Atheroma Plaques

Sedentarism is a risk factor for cardiovascular disease (CVD), but currently it is not clear how a sedentary behavior such as long sitting time can affect atherosclerosis development. This study examined the relationship between sitting time and the prevalence of carotid and femoral subclinical atherosclerosis. A cross-sectional analysis based on a subsample of 2082 participants belonging to the Aragon Workers’ Health Study was carried out. Ultrasonography was used to assess the presence of plaques in carotid and femoral territories; the validated Spanish version of the questionnaire on the frequency of engaging in physical activity used in the Nurses’ Health Study and the Health Professionals’ was used to assess physical activity and sitting time; and demographic, anthropometric, and clinical data were obtained by trained personnel during the annual medical examination. Participants were categorized into <9 h/day and ≥9 h/day sitting time groups. After adjusting for several confounders, compared with participants that remain seated <9 h/day, those participants who remain seated ≥9 h/day had, respectively, OR = 1.25 (95%CI: 1.01, 1.55, p < 0.05) and OR = 1.38 (95%CI: 1.09, 1.74, p < 0.05) for carotid and any-territory plaque presence. Remaining seated ≥9 h/day is associated with higher odds for carotid and any-territory plaque presence independently of physical activity levels and other cardiovascular risk factors.

The effects of two different doses of ultraviolet-A light exposure on nitric oxide metabolites and cardiorespiratory outcomes

Purpose

The present study investigated different doses of ultraviolet-A (UV-A) light on plasma nitric oxide metabolites and cardiorespiratory variables.

Methods

Ten healthy male participants completed three experimental conditions, 7 days apart. Participants were exposed to no light (CON); 10 J cm² (15 min) of UV-A light (UVA10) and 20 J cm² (30 min) of UV-A light (UVA20) in a randomized order. Plasma nitrite [NO₂⁻] and nitrate [NO₃⁻] concentrations, blood pressure (BP), and heart rate (HR) were recorded before, immediately after exposure and 30 min post-exposure. Whole body oxygen utilization (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\dot{V}}}{\rm O}_{2}$$\end{document}V˙O2), resting metabolic rate (RMR) and skin temperature were recorded continuously.

Results

None of the measured parameters changed significantly during CON (all P > 0.05). \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\dot{V}}}{\rm O}_{2}$$\end{document}V˙O2 and RMR were significantly reduced immediately after UVA10 (P < 0.05) despite no change in plasma [NO₂⁻] (P > 0.05). Immediately after exposure to UVA20, plasma [NO₂⁻] was higher (P = 0.014) and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\dot{V}}}{\rm O}_{2}$$\end{document}V˙O2 and RMR tended to be lower compared to baseline (P = 0.06). There were no differences in [NO₂⁻] or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\dot{V}}}{\rm O}_{2}$$\end{document}V˙O2 at the 30 min time point in any condition. UV-A exposure did not alter systolic BP, diastolic BP or MAP (all P > 0.05). UV-A light did not alter plasma [NO₃⁻] at any time point (all P > 0.05).

Conclusions

This study demonstrates that a UV-A dose of 20 J cm² is necessary to increase plasma [NO₂⁻] although a smaller dose is capable of reducing \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\dot{V}}}{\rm O}_{2}$$\end{document}V˙O2 and RMR at rest. Exposure to UV-A did not significantly reduce BP in this cohort of healthy adults. These data suggest that exposure to sunlight has a meaningful acute impact on metabolic function.

Acute whole body UVA irradiation combined with nitrate ingestion enhances time trial performance in trained cyclists

Dietary nitrate supplementation has been shown to increase nitric oxide (NO) metabolites, reduce blood pressure (BP) and enhance exercise performance. Acute exposure to ultraviolet (UV)-A light also increases NO bioavailability and reduces BP. We conducted a randomized, counterbalanced placebo-controlled trial to determine the effects of UV-A light alone and in combination with nitrate on the responses to sub-maximal steady-state exercise and time trial (TT) performance. Nine cyclists (VO2max 53.1 ± 4.4 ml/kg/min) completed five performance trials comprising 10 min submaximal steady-state cycling followed by a 16.1 km TT. Following a familiarization the final four trials were preceded, in random order, by either (1) Nitrate gels (NIT) + UV-A, (2) Placebo (PLA) + UV-A, (3) NIT + Sham light (SHAM) and (4) PLA + SHAM (control). The NIT gels (2 × 60 ml gels, ~8.1 mmol nitrate) or a low-nitrate PLA were ingested 2.5 h prior to the trial. The light exposure consisted of 20 J/cm(2) whole body irradiation with either UV-A or SHAM light. Plasma nitrite was measured pre- and post-irradiation and VO2 was measured continuously during steady-state exercise. Plasma nitrite was higher for NIT + SHAM (geometric mean (95% CI), 332 (292-377) nM; P = 0.029) and NIT + UV-A (456 (312-666) nM; P = 0.014) compared to PLA + SHAM (215 (167-277) nM). Differences between PLA + SHAM and PLA + UV-A (282 (248-356) nM) were small and non-significant. During steady-state exercise VO2 was reduced following NIT + UVA (P = 0.034) and tended to be lower in NIT + SHAM (P = 0.086) but not PLA + UV-A (P = 0.381) compared to PLA + SHAM. Performance in the TT was significantly faster following NIT + UV-A (mean ± SD 1447 ± 41 s P = 0.005; d = 0.47), but not PLA + UV-A (1450 ± 40 s; d = 0.41) or NIT + SHAM (1455 ± 47 s; d = 0.28) compared to PLA + SHAM (1469 ± 52 s). These findings demonstrate that exposure to UV-A light alone does not alter the physiological responses to exercise or improve performance in a laboratory setting. A combination of UV-A and NIT, however, does improve cycling TT performance in this environment, which may be due to a larger increase in NO availability.

Low wall stress in the popliteal artery: Other mechanisms responsible for the predilection of aneurysmal dilatation?

The popliteal artery (PA) is, after aorta, the most common site for aneurysm formation. Why the PA is more susceptible than other peripheral muscular arteries is unknown. We hypothesized that the wall composition, which in turn affects wall properties, as well as the circumferential wall stress (WS) imposed on the arterial wall, might differ compared to other muscular arteries. The aim was to study the WS of the PA in healthy subjects with the adjacent, muscular, common femoral artery (CFA) as a comparison. Ninety-four healthy subjects were included in this study (45 males, aged 10-78 years and 49 females, aged 10-83 years). The diameter and intima-media thickness (IMT) in the PA and CFA were investigated with ultrasound. Together with blood pressure the WS was defined according to the law of Laplace adjusted for IMT. The diameter increased with age in both PA and CFA (p<0.001), with males having a larger diameter than females (p<0.001). IMT increased with age in both PA and CFA (p<0.001), with higher IMT values in males only in PA (p<0.001). The calculated WS was unchanged with age in both arteries, but lower in PA than in CFA in both sexes (p<0.001). In conclusion, this study shows that the PA and CFA WS is maintained during aging, probably due to a compensatory remodelling response with an increase in arterial wall thickness. However, the stress imposed on the PA wall is quite low, indicating that mechanisms other than WS contribute to the process of pathological arterial dilatation in the PA.

Leg blood pressure measured in orthostatic posture is associated with left ventricular mass in normotensive subjects

BACKGROUND

Changing from a supine to an orthostatic posture is associated with substantial increments in leg blood pressure (BP) levels, which could ultimately influence the hemodynamic burden imposed on the heart. This study investigated the relationship between brachial and leg BP measurements and the left cardiac chamber's structure and assessed the role of body posture changes in this regard.

METHODS

One hundred and thirty normotensive, nondiabetic, nonsmoking, normolipemic subjects were evaluated by a clinical history, anthropometry, the analysis of metabolic parameters, echocardiography, and the measurement of BP in the arm and the calf in both supine and orthostatic positions.

RESULTS

Significant correlation coefficients between the leg BP measurements and the cardiac structure were detected, especially between the orthostatic pulse pressure (PP) and the left ventricular (LV) wall thickness (r = 0.38; P < 0.001), the orthostatic PP and the LV mass (r = 0.37; P < 0.001), and the orthostatic systolic BP (SBP) and the left atrial size (r = 0.35; P < 0.001). Stepwise and standard regression analysis adjusted for brachial BP and anthropometric and metabolic variables confirmed that the leg orthostatic PP was independently related to the LV wall thickness and mass. Moreover, the leg orthostatic SBP was associated with the left atrial dimension even after adding the LV mass to the statistical models. Finally, triglyceride levels and body surface area showed significant relationship with leg orthostatic PP and SBP, whereas brachial orthostatic PP and SBP were only associated with age and anthropometric variables.

CONCLUSIONS

Orthostatic leg BP is independently associated with the cardiac structure in normotensive subjects.

Relationship between serum uric acid and internal carotid resistive index in hypertensive women: a cross-sectional study

Background

The impact of serum uric acid (SUA) on arteries of hypertensive subjects remains to be fully established. This study investigated the relationship between SUA and carotid structural and hemodynamic parameters in hypertensive men and women.

Methods

Three hundred and thirty eight patients (207 women and 131 men) were cross-sectionally evaluated by clinical, laboratory, hemodynamic and carotid ultrasound analysis. Common carotid diameters, circumferential wall tensions, Young’s Elastic Modulus, Stiffness Index, Arterial Compliance and intima-media thickness (IMT) were determined. Internal carotid artery resistive index (ICRI), a hemodynamic measure that reflects local vascular impedance and microangiopathy, was also assessed.

Results

Univariate analysis showed no significant correlation of SUA with carotid diameters, elasticity/stiffness indexes, IMT and circumferential wall tensions in both genders. Conversely, SUA correlated with ICRI (r = 0.34; p < 0.001) in women, but not in men, and hyperuricemic women presented higher ICRI than normouricemic ones (0.684 ± 0.007 vs. 0.649 ± 0.004; p < 0.001). Stepwise and logistic regression analyses adjusted for potential confounding factors showed that ICRI was independently associated with SUA and hyperuricemia in women.

Conclusions

This study demonstrated that SUA was associated with ICRI in hypertensive women, suggesting that there might gender-related differences in the relationship between SUA and vascular damage in subjects with systemic hypertension.

Increased popliteal circumferential wall tension induced by orthostatic body posture is associated with local atherosclerotic plaques

OBJECTIVE

Lower limb arteries are exposed to higher hemodynamic burden in erectile posture. This study evaluated the effects of body posture on popliteal, carotid and brachial circumferential wall tension (CWT) and investigated the relationship between local CWT and atherosclerotic plaques in subjects with cardiovascular risk factors.

METHODS

Two hundred and three subjects (118 women and 85 men) with cardiovascular risk factors (smoking, hypertension or diabetes mellitus) underwent clinical and laboratory analysis and had their blood pressure measured in the arm and calf in supine and orthostatic positions. Arteries were evaluated by ultrasound analysis, while CWT was calculated according to Laplace's law.

RESULTS

Among the enrolled participants, 47%, 29% and none presented popliteal, carotid and brachial plaques, respectively. Carotid CWT measurements were not associated with local plaques after adjustment for potential confounders. Conversely, general linear model and logistic regression analyses adjusted for potential confounders demonstrated that peak orthostatic CWT was the only local hemodynamic parameter showing significant relationship with popliteal plaques in the whole sample. In gender-specific analyses, although positively correlated with popliteal plaques in both genders, local peak orthostatic CWT exhibited an independent association with popliteal plaques after adjustment for potential confounders only in women.

CONCLUSION

Popliteal CWT measured in orthostatic posture, rather than in supine position, is associated with popliteal atherosclerotic plaques, particularly in women. These findings suggest that erectile posture might play a role in the atherogenesis of leg arteries by modifying local hemodynamic forces and that there may be gender differences in this regard.

Sodium intake is associated with carotid artery structure alterations and plasma matrix metalloproteinase-9 upregulation in hypertensive adults

The mechanisms by which dietary sodium modulates cardiovascular risk are not fully understood. This study investigated whether sodium intake is related to carotid structure and hemodynamics and to plasma matrix metalloproteinase (MMP) activity in hypertensive adults. One hundred thirty-four participants were cross-sectionally evaluated by clinical history, anthropometry, carotid ultrasound, and analysis of hemodynamic, inflammatory, and metabolic variables. Daily sodium intake (DSI) was estimated by 24-h recall, discretionary sodium, and a FFQ. In 42 patients, plasma MMP-2 and MMP-9 activities were also analyzed. The mean DSI was 5.52 ± 0.29 g/d. Univariate analysis showed that DSI correlated with common carotid artery systolic and diastolic diameter (r = 0.36 and 0.34; both P < 0.001), peak and mean circumferential tension (r = 0.44 and 0.39; both P < 0.001), Young's Elastic Modulus (r = 0.40; P < 0.001), intima-media thickness (r = 0.19; P < 0.05), and internal carotid artery resistive index (r = 0.20; P < 0.05). Multivariate analyses revealed that only artery diameter, circumferential wall tension, and Young's Elastic Modulus were independently associated with DSI. Conversely, plasma MMP-9 activity was associated with DSI (r = 0.53; P < 0.001) as well as with common carotid systolic diameter (r = 0.33; P < 0.05) and Young's Elastic Modulus (r = 0.38; P < 0.01). In conclusion, sodium intake is associated with carotid alterations in hypertensive adults independently of systemic hemodynamic variables. The present findings also suggest that increased MMP-9 activity might play a role in sodium-induced vascular remodeling.