scholarly journals Limited Effect of 60-Days Strict Head Down Tilt Bed Rest on Vascular Aging

2021 ◽  
Vol 12 ◽  
Author(s):  
Stefan Möstl ◽  
Stefan Orter ◽  
Fabian Hoffmann ◽  
Martin Bachler ◽  
Bernhard Hametner ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Stroke Volume ◽  
Pulse Wave ◽  
Bed Rest ◽  
Aortic Distensibility ◽  
Artificial Gravity ◽  
Vascular Aging ◽  
Aortic Compliance ◽  
Arrival Times ◽  
Vascular Stiffening

BackgroundCardiovascular risk may be increased in astronauts after long term space flights based on biomarkers indicating premature vascular aging. We tested the hypothesis that 60 days of strict 6° head down tilt bed rest (HDTBR), an established space analog, promotes vascular stiffening and that artificial gravity training ameliorates the response.MethodsWe studied 24 healthy participants (8 women, 24–55 years, BMI = 24.3 ± 2.1 kg/m2) before and at the end of 60 days HDTBR. 16 subjects were assigned to daily artificial gravity. We applied echocardiography to measure stroke volume and isovolumetric contraction time (ICT), calculated aortic compliance (stroke volume/aortic pulse pressure), and assessed aortic distensibility by MRI. Furthermore, we measured brachial-femoral pulse wave velocity (bfPWV) and pulse wave arrival times (PAT) in different vascular beds by blood pressure cuffs and photoplethysmography. We corrected PAT for ICT (cPAT).ResultsIn the pooled sample, diastolic blood pressure (+8 ± 7 mmHg, p < 0.001), heart rate (+7 ± 9 bpm, p = 0.002) and ICT (+8 ± 13 ms, p = 0.036) increased during HDTBR. Stroke volume decreased by 14 ± 15 ml (p = 0.001). bfPWV, aortic compliance, aortic distensibility and all cPAT remained unchanged. Aortic area tended to increase (p = 0.05). None of the parameters showed significant interaction between HDTBR and artificial gravity training.Conclusion60 days HDTBR, while producing cardiovascular deconditioning and cephalad fluid shifts akin to weightlessness, did not worsen vascular stiffness. Artificial gravity training did not modulate the response.

Aortic Distensibility in Patients with Cerebrovascular Disease

1995 ◽  
Vol 89 (3) ◽  
pp. 247-253 ◽  
Author(s):  
E. D. Lehmann ◽  
K. D. Hopkins ◽  
R. L. Jones ◽  
A. G. Rudd ◽  
R. G. Gosling
Keyword(s):  
Blood Pressure ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Wave ◽  
Aortic Distensibility ◽  
Control Group ◽  
Aortic Compliance ◽  
Stroke Patients ◽  
Non Invasive ◽  
Control Subjects

1. Non-invasive aortic compliance measurements have been used previously to assess the distensibility of the aorta in several pathological conditions associated with increased cardiovascular risk. We set out to establish whether aortic compliance is abnormal in patients with stroke. 2. Pulse wave velocity measurements of thoracoabdominal aortic compliance were made in 20 stroke patients and 25 age- and sex-matched hospitalized, non-stroke control subjects putatively free of cardiovascular disease. Since compliance varies with non-chronic changes in blood pressure, a blood pressure corrected index of aortic distensibility, Cp, was calculated. 3. Aortic compliance was significantly reduced in patients with stroke compared with non-stroke control subjects (0.46 ± 0.27 versus 0.86 ± 0.34%/10 mmHg, P < 0.0002), corresponding with higher values for pulse wave velocity. Stroke patients also had significantly higher systolic and diastolic blood pressures (P < 0.02 and P < 0.002 respectively) and total cholesterol levels (P < 0.004) than the control subjects. Calculation of Cp did not alter the observation of stiffer aortas in the stroke cohort (P < 0.0007). 4. In both stroke patient and control cohorts, as expected, inverse trends were observed between aortic compliance and blood pressure. Also as expected, in the control group Cp values did not show a relationship with blood pressure (r = 0.02, P = 0.092, not significant). However, in the stroke cohort a marked dependence of Cp on blood pressure was observed (r = −0.48, P = 0.03). 5. Transoesophageal echocardiographic studies have recently identified advanced atherosclerosis in the ascending aorta as a possible source of cerebral emboli and an independent risk factor for ischaemic stroke. Our observations of significantly stiffer thoracoabdominal aortas in patients with stroke lead us to hypothesize that a totally non-invasive assessment of aortic compliance may potentially prove a useful surrogate marker of such atherosclerotic risk. 6. Blood pressure-corrected indices of arterial elastic properties based on normotensive models are widely applied in the literature. Our observation that these indices exhibit a considerable blood pressure dependence leads us to urge caution in the use of such corrections, especially in hypertensive patients.

Effect of head-down-tilt bed rest and hypovolemia on dynamic regulation of heart rate and blood pressure

2000 ◽  
Vol 279 (6) ◽  
pp. R2189-R2199 ◽  
Author(s):  
Ken-Ichi Iwasaki ◽  
Rong Zhang ◽  
Julie H. Zuckerman ◽  
James A. Pawelczyk ◽  
Benjamin D. Levine
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Transfer Function ◽  
Stroke Volume ◽  
Plasma Volume ◽  
High Frequency ◽  
Function Analysis ◽  
Bed Rest ◽  
Baroreflex Control ◽  
Transfer Function Analysis

Adaptation to head-down-tilt bed rest leads to an apparent abnormality of baroreflex regulation of cardiac period. We hypothesized that this “deconditioning response” could primarily be a result of hypovolemia, rather than a unique adaptation of the autonomic nervous system to bed rest. To test this hypothesis, nine healthy subjects underwent 2 wk of −6° head-down bed rest. One year later, five of these same subjects underwent acute hypovolemia with furosemide to produce the same reductions in plasma volume observed after bed rest. We took advantage of power spectral and transfer function analysis to examine the dynamic relationship between blood pressure (BP) and R-R interval. We found that 1) there were no significant differences between these two interventions with respect to changes in numerous cardiovascular indices, including cardiac filling pressures, arterial pressure, cardiac output, or stroke volume; 2) normalized high-frequency (0.15–0.25 Hz) power of R-R interval variability decreased significantly after both conditions, consistent with similar degrees of vagal withdrawal; 3) transfer function gain (BP to R-R interval), used as an index of arterial-cardiac baroreflex sensitivity, decreased significantly to a similar extent after both conditions in the high-frequency range; the gain also decreased similarly when expressed as BP to heart rate × stroke volume, which provides an index of the ability of the baroreflex to alter BP by modifying systemic flow; and 4) however, the low-frequency (0.05–0.15 Hz) power of systolic BP variability decreased after bed rest (−22%) compared with an increase (+155%) after acute hypovolemia, suggesting a differential response for the regulation of vascular resistance (interaction, P < 0.05). The similarity of changes in the reflex control of the circulation under both conditions is consistent with the hypothesis that reductions in plasma volume may be largely responsible for the observed changes in cardiac baroreflex control after bed rest. However, changes in vasomotor function associated with these two conditions may be different and may suggest a cardiovascular remodeling after bed rest.

scholarly journals Race/Ethnicity, Vascular Aging, and Mortality Risk: Evidence from the Health and Retirement Study

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 873-874
Author(s):  
Kevin Heffernan ◽  
Janet Wilmoth ◽  
Andrew London
Keyword(s):  
Blood Pressure ◽  
Arterial Stiffness ◽  
Pulse Wave Velocity ◽  
Ethnic Groups ◽  
Wave Velocity ◽  
Mortality Risk ◽  
Pulse Wave ◽  
Health And Retirement Study ◽  
Vascular Aging ◽  
Retirement Study

Abstract Vascular aging, which is associated with cardiovascular disease risk and mortality, is characterized by increasing arterial stiffness. The gold standard method for the assessment of arterial stiffness is carotid-femoral Pulse Wave Velocity (cfPWV). An emerging body of research suggests that cfPWV can be reasonably estimated from two commonly measured clinical variables—age and blood pressure. Thus, estimated Pulse Wave Velocity (ePWV) holds promise as a novel and easily obtained measure of arterial stiffness that can be used to study vascular aging, particularly with nationally representative datasets that collect biomarker data on sufficiently large sample sizes to examine race/ethnic differences. This analysis uses data from the 2006-2016 Health and Retirement Study to examine race/ethnic variation in the relationship between ePWV and mortality risk. We estimate logistic regression models predicting mortality over an eight-year period for four racial/ethnic groups: White, Black, Other, and Hispanic. Controls are included for sociodemographic characteristics, health status and behaviors, and blood biomarkers such as C-reactive protein, cystatin-C, hemoglobin A1c, total cholesterol and high-density lipoprotein (HDL) cholesterol. The results indicate ePWV increases the risk of mortality in the total sample and among each race/ethnic group, net the effect of age, systolic blood pressure, and diastolic blood pressure. Mechanisms that mediate this relationship are explored. The findings provide insight into vascular aging processes that influence mortality risk among race/ethnic groups.

scholarly journals Heart rate and blood pressure dependence of aortic distensibility in rats: comparison of measured and calculated pulse wave velocity

2020 ◽  
Vol 39 (1) ◽  
pp. 117-126
Author(s):  
Bart Spronck ◽  
Isabella Tan ◽  
Koen D. Reesink ◽  
Dana Georgevsky ◽  
Tammo Delhaas ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pressure Dependence ◽  
Pulse Wave ◽  
Aortic Distensibility

Two Methods to Assess Aortic Compliance Using Blood Pressure and Pulse-Wave Velocity

2020 ◽  
Author(s):  
Noah Manring ◽  
Mouayed Al-Toki
Keyword(s):  
Blood Pressure ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Wave ◽  
Rubber Tube ◽  
Aortic Compliance ◽  
Cardiovascular Morbidity And Mortality

Abstract Aortic compliance has been well established as an independent predictor of cardiovascular morbidity and mortality. The current "gold standard" for assessing aortic compliance is to use the carotid-femoral pulse-wave velocity (PWV) as a surrogate; however, PWV alone has been discussed in the literature as being inadequate for assessing compliance, especially for elderly patients and others who have a stiff aorta. In this paper an equation for the aortic compliance is developed using two approaches: 1) lumped-parameter modeling based on blood-pressure data and 2) distributed modeling based on the PWV. In-vitro experiments are conducted using a silicone-rubber tube which simulates the aorta, and an actual aorta harvested from a 1-year old, Holstein heifer. For both the rubber aorta and the Holstein aorta, a comparison is made between the blood-pressure model and the PWV model. In conclusion it is shown that good agreement exists between the two models, suggesting that either model may be used depending upon the available data. Furthermore, due to differences in material properties, it is shown that the compliance of the rubber aorta increases with mean arterial-pressure, while the compliance of the Holstein aorta decreases with mean arterial-pressure. Clinical implications of this research are also discussed.

scholarly journals Measuring methods of blood pressure and arterial stiffness. A new approach

2019 ◽  
pp. 23-27
Author(s):  
Christina Antza ◽  
Vasilios Kotsis
Keyword(s):  
Blood Pressure ◽  
Arterial Stiffness ◽  
Pulse Wave ◽  
Vascular Aging ◽  
Everyday Clinical Practice ◽  
New Approach ◽  
Factors Affecting ◽  
Hypertensive Population ◽  
Difficult Time ◽  
The Everyday

Carotid-femoral pulse wave velocity (c-f PWV) is considered to be one of the main factors affecting CV risk in the hypertensive population and has been included to the detailed screening of the hypertensive patients according to the ESH guidelines. Despite the large number of studies proving the correlation of blood pressure (BP) and c-f PWV as well as arterial stiffness, there are only few studies to show which BP measurement method can better predict arterial stiffness. Generally, these studies express the superiority of ABPM in the prediction of c-f PWV and early vascular aging (EVA). Furthermore, while guidelines recommend measuring c-f PWV in the hypertensive population, on the other hand it is difficult, time consuming and expensive to measure arterial stiffness in the everyday clinical practice, limiting its use only for experts. These limitations lead to the creation of a new score, the Early Vascular Aging Ambulatory score (EVAAs), which uses parameters from the ABPM and other cardiovascular risk factors in order to identify the possibility of each patient to have EVA. The score should be further studied for its accuracy in a larger population, as well for predicting hard end points in prospective studies.

Abstract 271: Evidence of Arterial Stiffness in Young Adult Women Born Extremely Preterm (<29 weeks).

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Fanny Huyard ◽  
Laurence Vaujois ◽  
Mariane Bertagnolli ◽  
Anik Cloutier ◽  
Jean-Luc Bigras ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Young Adult ◽  
Arterial Stiffness ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Pulse Wave ◽  
Adult Women ◽  
Vascular Aging ◽  
Young Adult Women ◽  
Extremely Preterm

Background: Epidemiological studies reported that preterm infants have increased arterial systemic blood pressure in adulthood. We have recently shown in an animal model that premature vascular aging could be involved in this process. Aim: To assess biophysical properties (arterial stiffness) of the aorta as early signs of a vascular aging process in young adult women born extremely preterm. Methods: We studied 4 women (aged 24±1 years) born extremely preterm (26.1±0.5 weeks, 803±58 grams) in the absence of any significant medical or psychiatric co-morbidity. Subjects were compared to 6 control women born at term (40.6±0.8 weeks, 32518±139 grams) matched for age. The aortic diameters, the pulse wave transit time around the aortic arch and the ascending aortic peak flow were measured with echo-Doppler and the blood pressure recorded. Pulse wave velocity, aortic input impedance (Zi), characteristic impedance (Zc), arterial pressure-strain elastic modulus (Ep), and arterial wall stiffness index (βSI) were calculated. Results: Preterm women had slightly but not significantly increased arterial systolic blood pressure compared to young women born term (111±6 vs. 104±2 mmHg, p=0.23). Diastolic and mean arterial blood pressure were similar (62±4 vs. 61±3, p=0.84 and 77±4 vs. 75±3 mmHg, p=0.73 respectively). Pulse wave velocity did not differ between groups (3.6±0.6 vs. 3.2±0.2 m/sec, p=0.53). βSI and Ep, direct indices of central arterial rigidity, were not significantly different between preterm women compared to controls (4.9±2.1 vs. 3.7±0.4, p=0.46 and 58±24 vs. 42±4 kPa, p=0.38 respectively). Zc and Zi, indices of the resistance to ejection to blood flow, were increased compared to controls (134±21 vs. 105±9, p=0.18 and 185±8 vs. 152±10, p<0.05 dynes. sec. cm -5 , respectively). Conclusions: This first series of results suggest that women who were born very preterm present indices of arterial rigidity compared to term controls. This alteration of the vascular tree could be a patho-physiological mechanism linking prematurity to adult cardiovascular diseases.

No effect of artificial gravity on lung function with exercise training during head-down bed rest

2015 ◽  
pp. 1-7
Author(s):  
Longxiang Su ◽  
Yinghua Guo ◽  
Yajuan Wang ◽  
Delong Wang ◽  
Changting Liu
Keyword(s):  
Lung Function ◽  
Pulse Rate ◽  
Vital Capacity ◽  
Pulmonary Ventilation ◽  
Bed Rest ◽  
Forced Expiratory Volume ◽  
Observation Time ◽  
Artificial Gravity ◽  
Postural Changes ◽  
Expiratory Flow

AbstractTo explore the effectiveness of microgravity simulated by head-down bed rest (HDBR) and artificial gravity (AG) with exercise on lung function. Twenty-four volunteers were randomly divided into control and exercise countermeasure (CM) groups for 96 h of 6° HDBR. Comparisons of pulse rate, pulse oxygen saturation (SpO2) and lung function were made between these two groups at 0, 24, 48, 72, 96 h. Compared with the sitting position, inspiratory capacity and respiratory reserve volume were significantly higher than before HDBR (0° position) (P&lt; 0.05). Vital capacity, expiratory reserve volume, forced vital capacity, forced expiratory volume in 1 s, forced inspiratory vital capacity, forced inspiratory volume in 1 s, forced expiratory flow at 25, 50 and 75%, maximal mid-expiratory flow and peak expiratory flow were all significantly lower than those before HDBR (P&lt; 0.05). Neither control nor CM groups showed significant differences in the pulse rate, SpO2, pulmonary volume and pulmonary ventilation function over the HDBR observation time. Postural changes can lead to variation in lung volume and ventilation function, but a HDBR model induced no changes in pulmonary function and therefore should not be used to study AG CMs.

Sign in / Sign up

Export Citation Format

Share Document