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

Functional near-infrared spectroscopy based blood pressure variations and hemodynamic activity of brain monitoring following postural changes: A systematic review

Postural change from supine or sitting to standing up leads to displacement of 300 to 1000 mL of blood from the central parts of the body to the lower limb, which causes a decrease in venous return to the heart, hence decrease in cardiac output, causing a drop in blood pressure. This may lead to falling down, syncope, and in general reducing the quality of daily activities, especially in the elderly and anyone suffering from nervous system disorders such as Parkinson's or orthostatic hypotension (OH). Among different modalities to study brain function, functional near-infrared spectroscopy (fNIRS) is a neuroimaging method that optically measures the hemodynamic response in brain tissue. Concentration changes in oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (HHb) are associated with brain neural activity. fNIRS is significantly more tolerant to motion artifacts compared to fMRI, PET, and EEG. At the same time, it is portable, has a simple structure and usage, is safer, and much more economical. In this article, we systematically reviewed the literature to examine the history of using fNIRS in monitoring brain oxygenation changes caused by sudden changes in body position and its relationship with the blood pressure changes. First, the theory behind brain hemodynamics monitoring using fNIRS and its advantages and disadvantages are presented. Then, a study of blood pressure variations as a result of postural changes using fNIRS is described. It is observed that only 58 % of the references concluded a positive correlation between brain oxygenation changes and blood pressure changes. At the same time, 3 % showed a negative correlation, and 39 % did not show any correlation between them.

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.

Detrimental effects of physical inactivity on peripheral and brain vasculature in humans: Insights into mechanisms, long-term health consequences and protective strategies

The growing prevalence of physical inactivity in the population highlights the urgent need for a more comprehensive understanding of how sedentary behaviour affects health, the mechanisms involved and what strategies are effective in counteracting its negative effects. Physical inactivity is an independent risk factor for different pathologies including atherosclerosis, hypertension and cardiovascular disease. It is known to progressively lead to reduced life expectancy and quality of life, and it is the fourth leading risk factor for mortality worldwide. Recent evidence indicates that uninterrupted prolonged sitting and short-term inactivity periods impair endothelial function (measured by flow-mediated dilation) and induce arterial structural alterations, predominantly in the lower body vasculature. Similar effects may occur in the cerebral vasculature, with recent evidence showing impairments in cerebral blood flow following prolonged sitting. The precise molecular and physiological mechanisms underlying inactivity-induced vascular dysfunction in humans are yet to be fully established, although evidence to date indicates that it may involve modulation of shear stress, inflammatory and vascular biomarkers. Despite the steady increase in sedentarism in our societies, only a few intervention strategies have been investigated for their efficacy in counteracting the associated vascular impairments. The current review provides a comprehensive overview of the evidence linking acute and short-term physical inactivity to detrimental effects on peripheral, central and cerebral vascular health in humans. We further examine the underlying molecular and physiological mechanisms and attempt to link these to long-term consequences for cardiovascular health. Finally, we summarize and discuss the efficacy of lifestyle interventions in offsetting the negative consequences of physical inactivity.

Defining the relationship between arm and leg blood pressure readings: a systematic review and meta-analysis

OBJECTIVES

To define the relationship between arm and leg blood pressure (BP) to inform the interpretation of leg BP readings in routine clinical practice where arm readings are not available.

METHODS

Systematic review of all existing studies comparing arm and leg BP measurements. A search strategy was designed in MEDLINE and adapted to be run across six further databases. Articles were deemed eligible for inclusion if they measured and reported arm and leg BP taken in the supine position and/or the difference between the two. Mean values for arm-leg BP difference and measures of precision [95% confidence intervals (CIs) or SD] were extracted and entered into a random-effects meta-analysis.

RESULTS

A total of 887 articles were screened and 44 were included in the descriptive analyses, including 9771 patients. In the general population, ankle SBP was 17.0 mmHg (95% CI 15.4-21.3 mmHg) higher than arm BP in the supine position. For DBP, there was no difference between arm and ankle BP (-0.3 mmHg, 95% CI -1.5-1.0 mmHg). In patients with vascular disease, SBP was -33.3 mmHg (95% CI -59.1 to -7.6 mmHg) lower in the ankle compared with the arm.

CONCLUSION

This is the first review to provide empirical data defining the difference between BP in the arm and leg in the general population. Findings suggest a diagnostic threshold of 155/90 mmHg could be used for diagnosing hypertension when only ankle measurements are available in routine practice.

The association between orthostatic blood pressure changes and subclinical target organ damage in subjects over 60 years old

Background

Although recent studies have indicated that both orthostatic hypotension and orthostatic hypertension independently predict cardiovascular events, the underlying mechanisms are still controversial. The aim of the study was to investigate the relationships between orthostatic changes and organ damage in subjects over 60 years old.

Methods

This is a prospective observational cohort study. One thousand nine hundred and ninety-seven subjects over 60 years old were enrolled. Participants were grouped according to whether they had a drop ≥ 20 mmHg in systolic or ≥ 10 mmHg in diastolic BP (orthostatic hypotension), an increase in mean orthostatic systolic blood pressure ≥ 20 mm Hg (orthostatic hypertension), or normal changes within 3 min of orthostatism. Multiple regression modeling was used to investigate the relationship between orthostatic hypotension, orthostatic hypertension and subclinical organ damage with adjustment for confounders.

Results

Orthostatic hypotension and orthostatic hypertension were found in 461 (23.1%) and 189 (9.5%) participants, respectively. Measurement of carotid intima-media thickness (IMT), brachial-ankle pulse wave velocity (baPWV), clearance of creatinine, and microalbuminuria were associated with orthostatic hypotension; measurement of IMT and baPWV were associated with orthostatic hypertension in a cruse model. After adjustment, IMT [odds ratio (OR), 95% confidence interval (CI) per one-SD increment: 1.385, 1.052–1.823; P = 0.02], baPWV (OR = 1.627, 95% CI: 1.041–2.544; P = 0.033) and microalbuminuria (OR = 1.401, 95% CI: 1.002–1.958; P = 0.049) were still associated with orthostatic hypotension, while orthostatic hypertension was only associated with IMT (OR = 1.730, 95% CI: 1.143–2.618; P = 0.009).

Conclusions

Orthostatic hypotension seems to be independently correlated with increased carotid atherosclerosis, arterial stiffness and renal damage in subjects over 60 years old. Orthostatic hypertension correlates with carotid atherosclerosis only.

Four-Limb Blood Pressure Measurement with an Oscillometric Device: a Tool for Diagnosing Peripheral Vascular Disease

PURPOSE OF REVIEW

Traditionally, the term peripheral vascular disease (PAD) is restricted to the occlusive arterial disease in the leg, but now, the connotation of PAD is more widespread as it encompasses all extracoronary and extracerebral vascular disease. The incidence of PAD is increasing worldwide; therefore, it is necessary to diagnose PAD at an early stage.

RECENT FINDINGS

Oscillometric BP device is widely used for four-limb measurement in clinical practice and provides several parameters for evaluating inter-limb BP difference, such as ankle-brachial index (OS-ABI), inter-arm BP differences (IAD), and inter-ankle BP difference (IAND). Using angiographic results as reference, the ABI, IAD, and IAND from an oscillometric BP device have been demonstrated having high accuracy for diagnosis of PAD. Meanwhile, combination of these parameters could further improve the accuracy of PAD, including the occlusive artery disease in the arm, leg, and aorta. For example, some patients with severe PAD in the leg have normal ABI; in this situation, an increased sIAND could confirm the diagnosis of PAD in the leg. Because ABI, IAD, and IAND from inter-limb oscillometric BP measurement can also predict adverse prognosis, we encourage the use of an oscillometric device to measure four-limb BP and to evaluate the inter-limb BP difference.

Orthostatic Blood Pressure Changes and Subclinical Markers of Atherosclerosis

BACKGROUND

Using a simple standing-up test in normotensive subjects, we evaluated orthostatic upright postural blood pressure (BP) changes and autonomic nervous function, as well as the relationship between orthostatic BP changes and subclinical markers of atherosclerosis.

METHODS

A total of 515 normotensive subjects aged 35-75 years (58.4±10.0 years) were enrolled. We measured body mass index (BMI), systolic BP (SBP) and diastolic BP (DBP), serum lipids, hemoglobin A1c (HbA1c), high-sensitivity C-reactive protein (hs-CRP), and urinary albumin-to-creatinine ratio. Brachial to ankle pulse wave velocity (baPWV) and carotid mean intima-media thickness (IMT) were measured. Participants underwent a simple standing-up test involving sitting then standing for 2 minutes each, followed again by sitting. To evaluate autonomic fluctuations, we calculated the coefficient of variation of the R-R interval, the ratio of low to high frequency heart rate variability (LF/HF), and the coefficient of component variance of high frequency.

RESULTS

SBP and DBP decreased when standing, with a reduction of SBP when changing position of -8.0±10.2mm Hg. Orthostatic hypotension (OH) produced a significantly higher SBP than without OH. The baPWV was significantly higher in OH than in without OH. Stepwise regression analysis adjusted for age, sex, BMI, baseline SBP, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting glucose, HbA1c, hs-CRP, IMT, late systolic peak of the pressure wave form (SBP2), and baPWV confirmed that baPWV, SBP2, and triglycerides were independently related to orthostatic BP changes. Multiple regression analyses showed that a decrease in SBP as well as baseline SBP, age, BMI, and fasting glucose were independent determinants of PWV.

CONCLUSIONS

We have shown that increased arterial stiffness was associated with OH during a standing-up test. Arterial stiffness may contribute to greater BP responses to postural changes from standing.

Valuation of Normal Range of Ankle Systolic Blood Pressure in Subjects with Normal Arm Systolic Blood Pressure

Subject

This study aimed to establish a normal range for ankle systolic blood pressure (SBP).

Methods

A total of 948 subjects who had normal brachial SBP (90-139 mmHg) at investigation were enrolled. Supine BP of four limbs was simultaneously measured using four automatic BP measurement devices. The ankle-arm difference (An-a) on SBP of both sides was calculated. Two methods were used for establishing normal range of ankle SBP: the 99% method was decided on the 99% reference range of actual ankle BP, and the An-a method was the sum of An-a and the low or up limits of normal arm SBP (90–139mmHg).

Results

Whether in the right or left side, the ankle SBP was significantly higher than the arm SBP (right: 137.1±16.9 vs 119.7±11.4 mmHg, P<0.05). Based on the 99% method, the normal range of ankle SBP was 94~181 mmHg for the total population, 84~166 mmHg for the young (18–44 y), 107~176 mmHg for the middle-aged(45–59 y) and 113~179 mmHg for the elderly (≥60y) group. As the An-a on SBP was 13mmHg in the young group and 20mmHg in both middle-aged and elderly groups, the normal range of ankle SBP on the An-a method was 103–153 mmHg for young and 110–160 mmHg for middle-elderly subjects.

Conclusion

A primary reference for normal ankle SBP was suggested as 100-165 mmHg in the young and 110-170 mmHg in the middle-elderly subjects.

Impact of body tilt on the central aortic pressure pulse

The present work was undertaken to investigate, in young healthy volunteers, the relationships between the forward propagation times of arterial pressure waves and the timing of reflected waves observable on the aortic pulse, in the course of rapid changes in body position. 20 young healthy subjects, 10 men, and 10 women, were examined on a tilt table at two different tilt angles, −10° (Head-down) and + 45° (Head-up). In each position, carotid-femoral (T_cf) and carotid-tibial forward propagation times (T_ct) were measured with the Complior device. In each position also, the central aortic pressure pulse was recorded with radial tonometry, using the SphygmoCor device and a generalized transfer function, so as to evaluate the timing of reflected waves reaching the aorta in systole (onset of systolic reflected wave, sT1r) and diastole (mean transit time of diastolic reflected wave, dMTT). The position shift from Head-up to Head-down caused a massive increase in both T_ct (women from 130 ± 10 to 185 ± 18 msec P < 0.001, men from 136 ± 9 to 204 ± 18 msec P < 0.001) and dMTT (women from 364 ± 35 to 499 ± 33 msec P < 0.001, men from 406 ± 22 to 553 ± 21 msec P < 0.001). Mixed model regression showed that the changes in T_ct and dMTT observed between Head-up and Head-down were tightly coupled (regression coefficient 2.1, 95% confidence interval 1.9–2.3, P < 0.001). These results strongly suggest that the diastolic waves observed on central aortic pulses reconstructed from radial tonometric correspond at least in part to reflections generated in the lower limbs.

The variability of ankle-arm blood pressure difference and ankle-brachial index in treated hypertensive patients

The purpose of this study was to investigate whether ankle-arm blood pressure (BP) difference (An-a) and ankle-brachial index (ABI) are consistent in treated hypertensive patients with obvious BP variation. This study enrolled 414 hypertensive patients (200 males; mean age, 61.3 ± 13.3 years) admitted to our hospital. BP of four limbs was simultaneously measured using four automatic BP measurement devices on the day of admission, and three and six day after admission. The An-a differences on systolic BP (SBP), diastolic BP (DBP), mean artery pressure (MAP), and pulse pressure (PP) in both sides were calculated, respectively. The relative decrease amplitude (RDA) of BP was calculated using the formula: RDA = (BP1 - BPn)/BP1. The ABI of the right side was calculated. From the first to the third measurement, arm SBP and DBP levels of both arms significantly decreased (right arm: SBP: 163.7 ± 18.4, 147.7 ± 15.3 vs. 135.4 ± 11.7 mm Hg; P < .05; DBP: 86.6 ± 13.4, 79.9 ± 11.6 vs. 74.5 ± 9.6 mm Hg; P < .05); at the same time, the ankle SBP (right ankle: 182.1 ± 22.1, 147.7 ± 15.3 vs. 153.4 ± 16.6 mm Hg; P < .05) and DBP (84.8 ± 13.4, 79.9 ± 11.6 vs. 75.8 ± 9.8 mm Hg; P < .05) of both sides also significantly decreased. The mean An-a of three measurements of both sides was consistent at the levels of about 20 mm Hg on SBP and PP, 7 mm Hg on MAP, and 0 mm Hg on DBP. However, sABI gradually increased from the first to the third measurement.In treated hypertensive patients, the An-a differences on SBP, DBP, PP, and MAP are generally consistent, but sABI is associated with underlying SBP levels.

Myocardial remodeling in hypertension

Left ventricular (LV) hypertrophy and remodeling are frequently seen in hypertensive subjects and result from a complex interaction of several hemodynamic and non-hemodynamic variables. Although increased blood pressure is considered the major determinant of LV structural alterations, ethnicity, gender, environmental factors, such as salt intake, obesity and diabetes mellitus, as well as neurohumoral and genetic factors might influence LV mass and geometry. The conventional concept of hypertensive LV remodeling has been that hypertension leads to concentric hypertrophy, as an adaptive response to normalize wall stress, which is then followed by chamber dilation and heart failure. However, several lines of evidence have challenged this dogma. Concentric hypertrophy is not the most frequent geometric pattern and is less usually seen than eccentric hypertrophy in hypertensive subjects. In addition, data from recent studies suggested that transition from LV concentric hypertrophy to dilation and systolic dysfunction is not a common finding, especially in the absence of coronary heart disease. LV hypertrophy is also consistently associated with increased cardiovascular morbidity and mortality, raising doubts whether this phenotype is an adaptive response. Experimental evidence exists that a blunting of load-induced cardiomyocyte hypertrophy does not necessarily result in LV dysfunction or failure. Furthermore, the hypertrophic myocardium shows fibrosis, alterations in the coronary circulation and cardiomyocyte apoptosis, which may result in heart failure, myocardial ischemia and arrhythmias. Overall, this body of evidence suggests that LV hypertrophy is a complex phenotype that predicts adverse cardiovascular outcomes and may not be necessarily considered as an adaptive response to systemic hypertension.

The prevalence and influence factors of inter-ankle systolic blood pressure difference in community population

Aim

The aim of this study was to investigate the prevalence of interankle systolic blood pressure difference (sIAND) and its influencing factors in community population.

Methods

This study included 2849 (65.1±9.4 y) subjects. Blood pressure (BPs) of four limbs was simultaneously measured with 4 electronic sphygmomanometers after 10 min rest in supine position. The difference of systolic BP (SBP) between two ankles was calculated as DETASBP. The criterion for abnormal sIAND was ≥10 mmHg of absolute DeltaSBP, in which the criterion for 1o sIAND was 10–19 mmHg and for 2o sIAND was ≥20 mmHg. Age, gender, smoking, hypertension, family histories of hypertension and diabetes were recorded. Fasting blood glucose and lipids, circumference of hip and waist, and body mass index (BMI) were measured.

Results

The SBP was higher in the right ankle than in the left ankle (158.9±21.8 vs 157.3±21.6 mmHg, P<0.05) and mean DeltaSBP was 6.08±6.26 mmHg. Similar difference was found in both genders. The prevalence of abnormal was 18.5%, in which, the prevalence 1o sIAND was 15.3% and that of 2o sIAND was 3.1%. Multivariate regression analysis showed that age, waist circumference and blood glucose level were the positive factors for DeltaSBP. The normal upper limit for DeltaSBP was 16.7 mmHg in this population, the prevalence of sIAND by≥16 mmHg was 5.8%.

Conclusion

Aging, hypertension, obesity and abnormal glucose metabolism are positive factors for inter-ankle SBP difference.