Measurement Of Arterial Compliance Research Articles

Enteral protease inhibition mitigates impaired Windkessel function in experimental trauma/hemorrhagic shock

Introduction: Trauma/hemorrhagic shock (T/HS) is characterized by systemic hypotension and poor organ perfusion, but despite efforts to improve hemodynamic stability via blood product/fluid therapy and vasopressor interventions, diastolic blood pressure (DBP) and thus, mean arterial pressure (MAP) is often recalcitrant to interventions. Large artery compliance is an important determinant of the Windkessel model of vascular hemodynamics, but its functional status remains unresolved in T/HS. We have previously demonstrated that enteral protease inhibition restores blood pressure (BP) and improves autonomic function and vascular resistance after T/HS. Here, we were interested in determining the impact of enteral protease inhibition on arterial compliance in T/HS. Methods: Male Wistar rats (~400g) were randomly assigned to three groups, corresponding to administered resuscitation: shed whole blood (WB), lactated Ringer’s (LR), and LR with enteral gabexate mesilate treatment (LR+GM). Under anesthesia, animals were subjected to experimental T/HS, established by midline laparotomy and controlled hemorrhage to maintain MAP at 35-40 mmHg for 90 min. Animals were then fluid resuscitated with WB or LR over 120 min to achieve a goal MAP of 65 mmHg. Carotid-femoral pulse wave velocities (PWV) and diastolic decay time constants (τ) were estimated from BP waveforms as measures of arterial compliance. Pressure myography was conducted on excised femoral arteries from T/HS animals and healthy donors to assess passive biomechanical properties, i.e., tissue energy loss. Results: PWV increased by ~15% in all T/HS animals at the end of shock compared to baseline. During and at the end of reperfusion, the untreated LR group continued to display elevated PWV, while the PWV of LR+GM and WB animals decreased significantly and returned closer to baseline values (LR: 12.4% vs LR+GM: 6.43%, p<0.05; vs WB: 5.03%, p<0.01). Diastolic τ was reduced by ~34% by the end of shock in all groups but was improved in WB and LR+GM groups by 2 hours after reperfusion. In contrast, this decrease in τ was exacerbated in the LR-only group (p<0.01 vs LR+GM & WB) through the end of the experiment. Biomechanical biaxial testing revealed pronounced leftward shifts in circumferential tension-strain curves in all T/HS groups, especially in the untreated LR group, as compared to healthy animals. Untreated LR vessels demonstrated significantly greater energy loss compared to those of healthy control vessels (31.5% vs 19.7%, p<0.05). Conclusions: Enteral GM infusion attenuated both the marked increases in PWV and vascular energy loss seen after T/HS, suggesting that impairment in arterial compliance after T/HS may be mediated, in part, by serine proteases. By targeting the modulators of large artery Windkessel function, organ perfusion during diastole can be maintained to improve hemodynamic stability and clinical outcomes in T/HS. Department of Defense Award W81XWH-17-2-0047 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Diastolic Oscillation Amplitude Used as an Arterial Aging Indicator.

The compliance of the distal arteries depends on their vasoconstrictor tone and distensibility and is sensitive to endothelial function and aging.C2, a component of the Windkessel model,is a measure of distal arterial compliance,and establishes the magnitude of the pressure rise during early diastole. It is calculated from the diastolic portion of theradial pulse wave usingsophisticatedanalyses.C2 is used as a cardiovascular risk indicator since it decreases with aging, high blood pressure, and diabetes. Here, we propose an alternative method to assess the distal arteries distensibility by measuring the amplitude of the oscillation that occurs at the beginning of diastole. Peripheral pulse wave was evaluated noninvasively by applanationtonometry in 511 individuals (264 women) aged between 13 and 70 years. Diastolic amplitude (DA) was measured as the peak-to-peak amplitude of the diastolic oscillation. Radial augmentation index (RAIx) and pulse wave velocity (PWV) were also calculated. DA decreased approximately 2% per decade of life between 16 and 70 years from 19% to 7%, and was higher in men than in women (p<0.0001). Linear regression analysis identified RAIx as the strongest predictor of AD (p<0.0001), followed by age and height. Sex modified the age-related decrease in DA (p< 0.001). By applying the method to measure DA frompreviously published data, we found a strong linear correlation with C2. DA decreased linearly with age in a reciprocal manner to the increase in radial augmentation index, was greater in men than women, and was independent of blood pressure and heart rate, as previously reported for C2.We propose that measuring DAcould provide an alternative index to evaluate distal arterial compliance and aging.

COMPARISON BETWEEN TWO NONINVASIVE METHODS USED TO ESTIMATE BIOMECHANICAL PROPERTIES OF THE INTERNAL CAROTID ARTERY

Background: Many cardiovascular diseases modified the arterial wall stiffness. Objectives: This work focuses on the quantification of the elastic biomechanical properties of the internal carotid (ICA) wall by applying the cepstral analysis on healthy volunteers aged from 22 to 86 years old. The purpose of this study is to compare two methods of measurement of arterial compliance ([Formula: see text], arterial distensibility ([Formula: see text], arterial elastance (Eh), and Young’s modulus ([Formula: see text]. Material and methods: First, arterial compliance and arterial distensibility were measured in function of wave speed ([Formula: see text], which is measured in our previous works by using two methods. Second, elastance Eh was estimated through the ratio between diastolic radius ([Formula: see text] and [Formula: see text]. Finally, [Formula: see text] was estimated from a statistical study from the literature on h due to the difficulty of measuring wall thickness ([Formula: see text]. Results: The Student test demonstrated that there is a very significant difference between young and old subjects in terms of elastance, compliance, and Young’s modulus ([Formula: see text]). These findings are in agreement with the reference values reported in the literature. They are very satisfying for distinguishing a pathological change in parietal elasticity. Conclusion: The in vivo application of these methods presents their potential for clinical measurement of arterial stiffness.

Towards Characterization of the Complex and Frequency-dependent Arterial Compliance based on Fractional-order Capacitor.

Arterial compliance is a vital determinant of the ventriculo-arterial coupling dynamic. Its variation is detrimental to cardiovascular functions and associated with heart diseases. Accordingly, assessment and measurement of arterial compliance are essential in the diagnosis and treatment of chronic arterial insufficiency. Recently, experimental and theoretical studies have recognized the power of fractional calculus to perceive viscoelastic blood vessel structure and biomechanical properties. This paper presents five fractional-order model representations to describe the dynamic relationship between the aortic blood pressure input and blood volume. Each configuration incorporates a fractional-order capacitor element (FOC) to lump the apparent arterial compliance's complex and frequency dependence properties. FOC combines both resistive and capacitive attributes within a unified component, which can be controlled through the fractional differentiation order factor, α. Besides, the equivalent capacitance of FOC is by its very nature frequency-dependent, compassing the complex properties using only a few numbers of parameters. The proposed representations have been compared with generalized integer-order models of arterial compliance. Both models have been applied and validated using different aortic pressure and flow rate data acquired from various species such as humans, pigs, and dogs. The results have shown that the fractional-order framework is able to accurately reconstruct the dynamic of the complex and frequency-dependent apparent compliance dynamic and reduce the complexity. It seems that this new paradigm confers a prominent potential to be adopted in clinical practice and basic cardiovascular mechanics research.

Associations of Meat and Fish Consumption With Conventional and Radiomics Cardiovascular Magnetic Resonance Phenotypes in the UK Biobank.

Background: Greater red and processed meat consumption has been linked to adverse cardiovascular outcomes. However, the impact of these exposures on cardiovascular magnetic resonance (CMR) phenotypes has not been adequately studied.Objective: We describe novel associations of meat intake with cardiovascular phenotypes and investigate underlying mechanisms through consideration of a range of covariates.Design: We studied 19,408 UK Biobank participants with CMR data available. Average daily red and processed meat consumption was determined through food frequency questionnaires and expressed as a continuous variable. Oily fish was studied as a comparator, previously associated with favourable cardiac outcomes. We considered associations with conventional CMR indices (ventricular volumes, ejection fraction, stroke volume, left ventricular mass), novel CMR radiomics features (shape, first-order, texture), and arterial compliance measures (arterial stiffness index, aortic distensibility). We used multivariable linear regression to investigate relationships between meat intake and cardiovascular phenotypes, adjusting for confounders (age, sex, deprivation, educational level, smoking, alcohol intake, exercise) and potential covariates on the causal pathway (hypertension, hypercholesterolaemia, diabetes, body mass index).Results: Greater red and processed meat consumption was associated with an unhealthy pattern of biventricular remodelling, worse cardiac function, and poorer arterial compliance. In contrast, greater oily fish consumption was associated with a healthier cardiovascular phenotype and better arterial compliance. There was partial attenuation of associations between red meat and conventional CMR indices with addition of covariates potentially on the causal pathway, indicating a possible mechanistic role for these cardiometabolic morbidities. However, other associations were not altered with inclusion of these covariates, suggesting importance of alternative biological mechanisms underlying these relationships. Radiomics analysis provided deeper phenotyping, demonstrating association of the different dietary habits with distinct ventricular geometry and left ventricular myocardial texture patterns.Conclusions: Greater red and processed meat consumption is associated with impaired cardiovascular health, both in terms of markers of arterial disease and of cardiac structure and function. Cardiometabolic morbidities appeared to have a mechanistic role in the associations of red meat with ventricular phenotypes, but less so for other associations suggesting importance of alternative mechanism for these relationships.

Poor Bone Quality is Associated With Greater Arterial Stiffness: Insights From the UK Biobank.

Osteoporosis and ischemic heart disease (IHD) represent important public health problems. Existing research suggests an association between the two conditions beyond that attributable to shared risk factors, with a potentially causal relationship. In this study, we tested the association of bone speed of sound (SOS) from quantitative heel ultrasound with (i) measures of arterial compliance from cardiovascular magnetic resonance (aortic distensibility [AD]); (ii) finger photoplethysmography (arterial stiffness index [ASI]); and (iii) incident myocardial infarction and IHD mortality in the UK Biobank cohort. We considered the potential mediating effect of a range of blood biomarkers and cardiometabolic morbidities and evaluated differential relationships by sex, menopause status, smoking, diabetes, and obesity. Furthermore, we considered whether associations with arterial compliance explained association of SOS with ischemic cardiovascular outcomes. Higher SOS was associated with lower arterial compliance by both ASI and AD for both men and women. The relationship was most consistent with ASI, likely relating to larger sample size available for this variable (n = 159,542 versus n = 18,229). There was no clear evidence of differential relationship by menopause, smoking, diabetes, or body mass index (BMI). Blood biomarkers appeared important in mediating the association for both men and women, but with different directions of effect and did not fully explain the observed effects. In fully adjusted models, higher SOS was associated with significantly lower IHD mortality in men, but less robustly in women. The association of SOS with ASI did not explain this observation. In conclusion, our findings support a positive association between bone and vascular health with consistent patterns of association in men and women. The underlying mechanisms are complex and appear to vary by sex.

Associations Of Fitness, Physical Activity, And Fatness With A New Index Of Endothelial Function

Current methods for assessing endothelial function, an early marker of cardiovascular disease (CVD), are either invasive or use noninvasive methods that are highly operator dependent or require nonreusable expensive probes, thereby limiting their use for CVD risk prediction. PURPOSE: To assess the relationship of fitness, physical activity (PA), and fatness, each a CVD risk factor, with a novel measure of endothelial function. METHODS: This was a cross-sectional data analysis in adults recruited for a study examining the clinical utility of a new device that measures endothelial vasodilator function using a standard BP cuff. The resulting EnDys score is derived from direct calibrated measurements of brachial arterial compliance throughout the entire transmural pressure curve during a staged cuff release after 5 minutes of upper arm occlusion. A higher score means better endothelial function. Fitness was assessed by a 6-minute walk test (6MWT). Self-report of PA was assessed by the Rapid Assessment of Physical Activity tool. Body mass index (BMI) was used as a marker of general fatness and waist circumference (WC) as a marker of abdominal fatness. RESULTS: In all 153 subjects, 51% were female, 7% were smokers, 7% had CVD, and 10% had type 2 diabetes. The mean ± SD for age was 49.3 ± 17.2, EnDys was 80.8 ± 30.4, BMI was 29.3 ± 6.9 kg/m2, WC was 37.5 ± 6.7 inches, and 6MWT was 495.4 ± 113.5 meters. EnDys was higher in females, 87.6 ± 30.5, vs males, 73.8 ± 28.9, p<0.01. EnDys did not differ by being sedentary, 80.8 ± 27.6, or active, 81.0 ± 33.0, p=0.97. Using bivariate analysis, a lower EnDys was associated with higher BMI, r=-0.23, higher WC, r=-0.33, lower 6MWT, r=0.32, and older age, r=-0.20, all p<0.02 or less. In a multivariate model, 6MWT (β=-0.06, p<0.01), WC (β=-1.02, p<.02), and sex (female, β=6.9, p<0.01) were each independently associated with EnDys. There were no interactions for sex with 6MWT and WC. CONCLUSION: Among measures of fitness, PA, and fatness, and in both sexes, a lower walking distance and a higher waist circumference were each independently associated with a lower EnDys, indicating worse endothelial function. A next logical step is to assess if EnDys improves with interventions like exercise and weight loss, thereby providing a novel and relatively simple way to track progress towards CVD risk reduction.

Sex Differences In Arterial Stiffness Following Acute Resistance Exercise

During resistance exercise there is an increase in blood pressure, with systolic pressure rising up to 400 mmHg. This transient elevation in pressure has been shown to result in acutely stiffer vessels in young males, however, this has not been well studied in young females. It is possible that the sex hormones of young females may be protective against this pressure load, resulting in differential responses following resistance exercise. PURPOSE: The purpose of this study was to determine if there are sex differences in arterial stiffness following an acute resistance exercise bout in young, healthy males and females who are not currently resistance training. METHODS: Carotid beta stiffness (β), arterial compliance (AC), and elastic modulus (Ep) measurements were taken in 23 young participants (10 males, 13 females; 26 ± 1 years) before, immediately after, and 30 minutes following full body resistance exercise. Exercise consisted of 2 sets of 10-12 repetitions performed on 8 resistance machines completed at 40% 1RM for the upper body and 60% 1RM for the lower body. Females were tested during the early follicular phase of their menstrual cycle to control for sex hormones. Exercise values (pre, post, post30) were compared between sexes using a repeated measures ANOVA, with significance set at p < 0.05. When the interaction was significant, the responses were evaluated with paired samples t-tests within each sex and independent t-tests between sexes. RESULTS: There were no sex differences in stiffness values prior to exercise, but males displayed significantly higher β and Ep and lower AC post and post30 compared to females. Males demonstrated significant increases in β (4.2 ± 0.4 to 6.6 ± 0.5 to 5.8 ± 0.5 AU) and Ep (48 ± 5 to 73 ± 6 to 65 ± 6 kPa) and decreases in AC (1.5 ± 0.2 to 0.9 ± 0.1 to 1.1 ± 0.1 mm2/kPa) both immediately and 30 min post resistance exercise compared to baseline values, while females had no change in AC (1.4 ± 0.1 to 1.2 ± 0.1 to 1.5 ± 0.1 mm2/kPa) or Ep (46 ± 4 to 52 ± 5 to 44 ± 5 kPa) with exercise and an immediate increase in β that returned to baseline at 30 min post (4.2 ± 0.3 to 5.1 ± 0.5 to 4.3 ± 0.4 AU). CONCLUSION: Acute resistance exercise in females does not result in the elevation of stiffness as seen in males. It appears females may be protected from this increased pressure load, which may be due to the vasodilatory effects of estrogen.

Method for measurement of arterial compliance by fusion of oscillometry and pulse wave velocity.

Up until now estimation of arterial compliance has been performed either by analysis of arterial pressure changes with respect to volume changes or by inference based on pulse wave velocity (PWV). In this study we demonstrate the possibility of an approach to assess arterial compliance by fusing the two information sources namely the pressure/volume relationship obtained from oscillography and PWV data. The goal is to assess arterial properties easily and robustly, enhancing current hemodynamic monitoring. The approach requires as input signals: an electrocardiogram (ECG), a photo- plethysmogram (PPG) and the arterial oscillation as measured during non-invasive blood pressure measurements based on oscillometry with a cuff. These signals are fused by an algorithm using Bayesian principles underpinned by a physiological model. In our simulations, we demonstrate the feasibility to infer arterial compliance by our proposed strategy. A very first measurement on a healthy volunteer supports our findings from the simulation.Clinical Relevance- Arterial compliance/stiffness is recognized as a key hemodynamic parameter, which is not easily accessible and not a standard parameter currently. The presented method and obtained results are encouraging for future research in this area.

A modelling framework for assessment of arterial compliance by fusion of oscillometry and pulse wave velocity information

Background and ObjectivesMeasurement of arterial compliance is recognized as important for clinical use and for enabling better understanding of circulatory system regulation mechanisms. Estimation of arterial compliance involves either a direct measure of the ratio between arterial volume and pressure changes or an inference from the pulse wave velocity (PWV). In this study we demonstrate an approach to assess arterial compliance by fusion of these two information sources. The approach is based on combining oscillometry as used for blood pressure inference and PWV measurements based on ECG/PPG. Enabling reliable arterial compliance measurements will contribute to the understanding of regulation mechanisms of the arterial tree, possibly establishing arterial compliance as a key measure relevant in hemodynamic monitoring. MethodsA measurement strategy, a physiological model, and a framework based on Bayesian principles are developed for measuring changes in arterial compliance based on combining oscillometry and PWV data. A simulation framework is used to study and validate the algorithm and measurement principle in detail, motivated by previous experimental findings. ResultsSimulations demonstrate the possibility of inferring arterial compliance via fusion of simultaneously acquired volume/pressure relationships and PWV data. In addition, the simulation framework demonstrates how Bayesian principles can be used to handle low signal – to – noise ratio and partial information loss. ConclusionsThe developed simulation framework shows the feasibility of the proposed approach for assessment of arterial compliance by combining multiple data sources. This represents a first step towards integration of arterial compliance measurements in hemodynamic monitoring using existing clinical technology. The Bayesian approach is of particular relevance for such patient monitoring settings, where measurements are repeated frequently, context is relevant, and data is affected by artefacts. In addition, the simulation framework is necessary for future clinical-study design, in order to determine device specifications and the extent to which noise affects the inference process.

Aortic stiffness and central systolic pressure are associated with ambulatory orthostatic BP fall in chronic kidney disease.

Orthostatic hypotension (OH) has a significant association with cardiovascular disease. OH becomes more common in older age, as does arterial stiffness, shown to be independently associated with impaired baroreflex sensitivity and OH. Measurement of arterial compliance and central blood pressures are increasingly important, with evidence that central BP more closely correlates to end-organ damage and mortality than peripheral measurements. Patients with chronic kidney disease (CKD) are high risk for cardiovascular events, which can be predicted through measures of arterial compliance. We hypothesised that OH is associated with arterial stiffness and central blood pressure in CKD patients. We tested this hypothesis within the arterial compliance and oxidant stress as predictors of loss of renal function, morbidity and mortality in chronic kidney disease (ACADEMIC) study, a single-centre prospective observational study of the progression of arterial stiffness and renal function. One hundred and forty-six patients with CKD 3 or 4. Twenty-four-hour ambulatory BP monitoring with postural sensing (DIASYS Integra 2, Novacor France); central systolic and diastolic BP (cSBP and cDBP) and aortic Augmentation Index using Sphygmocor® (Atcor, Australia); Carotid-femoral pulse wave velocity (cfPWV) using Complior® (ALAM Medical, France). Twenty-three patients had a postural SBP fall (prevalence 15.8%), with mean drop 7mmHg. Patients with OH had higher cfPWV (15.2m/s vs 12.7m/s in patients without OH, p < 0.001) and central SBP (147.5 vs 135.7, p = 0.012). Regression analysis gave an odds ratio (OR) of orthostatic SBP fall for cfPWV of 1.46 (95% CI 1.16-1.84, p = 0.001) and 1.03 for cSBP (95% CI 1.004-1.06, p = 0.024) after adjustment for cardiovascular risk factors. Aortic stiffness and central SBP are independently associated with orthostatic SBP fall in CKD patients. This suggests that enhanced arterial stiffness may be an underlying mechanism in baroreflex dysfunction, and may partly explain the vascular risk in CKD patients.

MON-116 STUDY OF CALCIUM CARBONATE VERSUS SEVELAMER ON VASCULAR STIFFNESS IN HAEMODIALYSIS PATIENTS.

Patients with chronic kidney disease (CKD) develop accelerated vascular stiffening, contributing to increased mortality and morbidity. Pulse wave velocity (PWV) provides a useful clinical measure of arterial compliance. Studies have shown that the phosphate binder (PB) sevelamer, when compared to calcium-based PB (CBPB), may be associated with attenuation of vascular stiffening and calcification. Currently, there is a paucity of data comparing the effects of sevelamer versus CBPB on PWV. We report an interim analysis of pulse wave velocity in a cross over study of phosphate binders.

Prolonged Sitting Increases Arterial Stiffness in Healthy Adults

Chronic sedentary behavior increases risk for cardiovascular disease, which is the leading cause of death globally. Sitting impairs leg vascular health. Simple perturbations to increase leg blood flow prevent impairments, however, the effects on central cardiovascular health are unknown. Arterial stiffness (AS) is an indicator of CVD, and Pulse Wave Velocity (PWV) is a non-invasive measure of arterial compliance. Pulse Wave Analysis (PWA) measures augmentation index (AIx) and central pressure provides additional information about AS. PURPOSE: To investigate the effects of prolonged sitting, with and without calf raises on aortic AS (carotid-femoral PWV) central blood pressure (CBP), and AIx. METHODS: After familiarization, sedentary participants (n=20, 21.7 yrs (2.9), BMI 25.7 m/kg2 (5.3), 70% female) sat for 180 minutes with and without performing 10 calf raises every 10 minutes in a random order. Following 20 min of supine rest, baseline vascular measures were collected. Measures of CBP and AIx were recorded at 10, 90, and 170 min of sitting. Near-infrared spectroscopy (NIRS) was used to assess total hemoglobin (tHB) concentration in the gastrocnemius muscle (index of blood pooling). Data were analyzed with a linear mixed model and are presented as mean difference (SE). RESULTS: PWV increased significantly (0.30 m/s (0.46), p <0.001) while AIx significantly decreased (-9.2% (11.0), p<0.001). tHb tended to increase with sitting (0.9 (1.0), p=0.082) and in the control condition (2.1 (1.0), p=0.084). CONCLUSIONS: Sitting increases aortic AS but decreases AIx, an effect which may be mediated by blood pooling in the lower leg. Intermittent calf raises are insufficient to alter AS, as PWV increased by 0.30 m/s acutely. Despite being below the clinical threshold of 1.0 m/s with chronic inactivity, the acute increases in PWV in 3 hours may increase heart burden and become meaningful over time.

OBJECTIVE-SUBJECTIVE DISPARITY IN COGNITIVE IMPAIRMENT: A CROSS-SECTIONAL INVESTIGATION IN POSTMENOPAUSAL WOMEN

Subjective memory complaint (SMC), now recognised as a prodromal phase of dementia, is linked to poor working memory and attention in perimenopausal women; whether this association remains postmenopausally is unknown. We examined the predictive value for subjective complaints of (a) objective indices of cognitive performance; (b) cardio-metabolic status, and (c) perceptions of well-being in a cross-sectional study. The following baseline measures were recorded in 142 postmenopausal women aged 65±1 years who were enrolled in a two-year resveratrol intervention trial: 10 neuropsychological tests that assess cognitive domains of processing speed, attention, language, working, verbal and episodic memory and cognitive flexibility; cardio-metabolic measures of blood pressure, systemic and cerebral arterial compliance, HOMA-IR and fasting lipids; perceptions of well-being including depressive symptoms, mood states, sleep quality, menopausal symptoms, quality-of-life (using SF-36) and osteoarthritic pain. When asked ‘Do you perceive any memory or cognitive difficulties?’, 68 women responded ‘yes’ and were grouped as SMC. Verbal and episodic memory performances were higher in the SMC group (P=0.022 and 0.011 respectively). No significant differences were seen for all other domains or in their cardio-metabolic status or age or education level. However, the SMC group reported 66% more depressive symptoms (P<0.001), twice likely to have mood disturbances (P=0.012), more menopausal symptoms (32% higher, P=0.009), lower quality-of-life (P=0.015) and 54% increase in daytime dysfunction due to sleepiness (P=0.003). Pain did not differ between groups. In our cohort, poor mood states, sleep quality and quality-of-life were associated with SMC. However, SMC did not reflect cardio-metabolic abnormalities or objective cognitive dysfunction. The link between SMC and future cognitive impairment is still unclear.

Aerobic versus isometric handgrip exercise in hypertension: a randomized controlled trial.

Aerobic dynamic exercise reduces blood pressure (BP) and is broadly recommended by current American and European hypertension guidelines. Isometric exercise is currently not recommended, since data from only a few studies are available. We compare for the first time the effects of isometric handgrip training and aerobic exercise in a randomized controlled trial. A total of 75 hypertensive patients were randomized to one of the following 12-week programmes: Isometric handgrip training five times weekly (two contractions of 2 min at 30% of maximal power with each arm); 'Sham-handgrip training' five times weekly (two contractions of 2 min at 5% of maximal power with each arm); Aerobic exercise training of 30 min three to five times per week. All patients underwent office BP measurement, 24-h ambulatory BP measurement and noninvasive assessment of arterial compliance and systemic vascular resistance at baseline and after 12 weeks. Baseline epidemiological and hemodynamic characteristics did not differ between groups. Aerobic exercise led to a significant reduction of systolic 24-h BP (P = 0.025), office SBP (P = 0.03), systemic vascular resistance (P = 0.001) and small artery elasticity index (P = 0.005). There were no statistical significant changes of these parameters in the isometric exercise and the 'sham exercise' groups (P > 0.05 each). Isometric handgrip training, performed according to a typical protocol, did not reduce BP in hypertensive patients. Aerobic exercise, even as an uncontrolled and unsupervised exercise regimen, led to a significant reduction of ambulatory and office BP.

Increased arterial stiffness is an independent risk factor for hemorrhagic transformation in ischemic stroke undergoing thrombolysis

BackgroundHemorrhagic transformation (HT) is a multifactorial phenomenon and represents a possible complication of ischemic stroke, especially after thrombolytic treatment. Increased arterial stiffness has been associated with intracranial hemorrhage, but there is no evidence of association with HT after thrombolytic therapy. The aim of our study is to investigate a possible link between arterial stiffness and HT occurrence after thrombolytic therapy in patients with ischemic stroke. MethodsWe enrolled 258 patients (135 males, 123 females; mean age: 73±12years) with acute ischemic stroke undergoing intravenous thrombolysis or/and mechanical thrombectomy. All stroke patients underwent neuroimaging examination, 24-h heart rate and blood pressure monitoring and brain CT-scan after 24–72h to evaluate HT occurrence. The linear regression slope of diastolic on systolic blood pressure was obtained and assumed as a global measure of arterial compliance, and its complement (1 minus the slope), named arterial stiffness index (ASI), has been taken as a measure of arterial stiffness. ResultsOut of 258, HT occurred in 55 patients. ASI was significantly higher in patients with HT than in patients without HT (0.70±0.12 vs 0.62±0.14, p<0.001). Logistic regression model showed ASI as independent predictors of HT (OR: 1.9, 95% CI: 1.09–3.02, for every 0.2 increase of ASI): in particular, OR was 5.2 (CI: 2.22–12.24) when ASI was >0.71, in comparison with ASI lower than 0.57. ConclusionsOur results point to arterial stiffness as a novel independent risk factor for HT after ischemic stroke treated with thrombolysis, suggesting a particularly high bleeding risk when ASI is >0.71.

Relationship between carotid arterial properties and cerebral white matter hyperintensities.

Since arterial stiffness is a functional measure of arterial compliance and may be an important marker of cerebrovascular disease, we examined the association of carotid artery stiffness with white matter hyperintensity volume (WMHV) in a cross-sectional study of 1,166 stroke-free participants. Carotid beta stiffness index (STIFF) was assessed by M-mode ultrasound of the common carotid artery and calculated as the ratio of natural log of the difference between systolic and diastolic blood pressure over STRAIN, a ratio of the difference between carotid systolic and diastolic diameter (DD) divided by DD. WMHV was measured by fluid-attenuated inversion recovery MRI. The associations of STIFF, DD, and STRAIN with WMHV were examined using linear regression after adjusting for sociodemographic, lifestyle, and vascular risk factors. In a fully adjusted model, larger carotid DD was significantly associated with greater log-WMHV (β = 0.09, p = 0.001). STIFF and STRAIN were not significantly associated with WMHV. In adjusted analyses stratified by race-ethnicity, STRAIN (β = -1.78, p = 0.002) and DD (β = 0.11, p = 0.001) were both associated with greater log-WMHV among Hispanic participants, but not among black or white participants. Large carotid artery diameters are associated with greater burden of white matter hyperintensity (WMH) in this multiethnic population. The association between increased diameters, decreased STRAIN, and greater WMH burden is more pronounced among Hispanics. These associations suggest a potential important pathophysiologic role of extracranial large artery remodeling in the burden of WMH.

Pulmonary Arterial Compliance in Acute Respiratory Distress Syndrome: Clinical Determinants and Association With Outcome From the Fluid and Catheter Treatment Trial Cohort.

Pulmonary vascular dysfunction is associated with adverse prognosis in patients with the acute respiratory distress syndrome; however, the prognostic impact of pulmonary arterial compliance in acute respiratory distress syndrome is not established. We performed a retrospective analysis of 363 subjects with acute respiratory distress syndrome who had complete baseline right heart catheterization data from the Fluid and Catheter Treatment Trial to test whether pulmonary arterial compliance at baseline and over the course of treatment predicted mortality. Baseline pulmonary arterial compliance (hazard ratio, 1.18 per interquartile range of 1/pulmonary arterial compliance; 95% CI, 1.02-1.37; p = 0.03) and pulmonary vascular resistance (hazard ratio, 1.28 per interquartile range; 95% CI, 1.07-1.53; p = 0.006) both modestly predicted 60-day mortality. Baseline pulmonary arterial compliance remained predictive of mortality when pulmonary vascular resistance was in the normal range (p = 0.02). Between day 0 and day 3, pulmonary arterial compliance increased in acute respiratory distress syndrome survivors and remained unchanged in nonsurvivors, whereas pulmonary vascular resistance did not change in either group. The resistance-compliance product (resistance-compliance time) increased in survivors compared with nonsurvivors, suggesting improvements in right ventricular load. Baseline measures of pulmonary arterial compliance and pulmonary vascular resistance predict mortality in acute respiratory distress syndrome, and pulmonary arterial compliance remains predictive even when pulmonary vascular resistance is normal. Pulmonary arterial compliance and right ventricular load improve over time in acute respiratory distress syndrome survivors. Future studies should assess the impact of right ventricular protective acute respiratory distress syndrome treatment on right ventricular afterload and outcome.

Mapping cerebral pulse pressure and arterial compliance over the adult lifespan with optical imaging.

Cerebrovascular health is important for maintaining a high level of cognitive performance, not only in old age, but also throughout the lifespan. Recently, it was first demonstrated that diffuse optical imaging measures of pulse amplitude and arterial compliance can provide estimates of cerebral arterial health throughout the cortex, and were associated with age, estimated cardiorespiratory fitness (eCRF), neuroanatomy and cognitive function in older adults (aged 55–87). The current study replicates and extends the original findings using a broader age range (a new adult sample aged 18–75), longer recording periods (360 s), and a more extensive optical montage (1536 channels). These methodological improvements represent a 5-fold increase in recording time and a 4-fold increase in coverage compared to the initial study. Results show that reliability for both pulse amplitude and compliance measures across recording blocks was very high (r(45) = .99 and .75, respectively). Pulse amplitude and pulse pressure were shown to correlate with age across the broader age range. We also found correlations between arterial health and both cortical and subcortical gray matter volumes. Additionally, we replicated the correlations between arterial compliance and age, eCRF, global brain atrophy, and cognitive flexibility. New regional analyses revealed that higher performance on the operation span (OSPAN) working memory task was associated with greater localized arterial compliance in frontoparietal cortex, but not with global arterial compliance. Further, greater arterial compliance in frontoparietal regions was associated with younger age and higher eCRF. These associations were not present in the visual cortex. The current study not only replicates the initial one in a sample including a much wider age range, but also provides new evidence showing that frontoparietal regions may be especially vulnerable to vascular degeneration during brain aging, with potential functional consequences in cognition.

Impact of physical activity on cardiovascular status in obesity.

We have recently shown that being physically active (PA) counteracts, but not eliminates the increased risk of future cardiovascular disease in overweight and obese subjects. To investigate this further, we studied the impact of being normal weight, overweight and obese on multiple markers of subclinical cardiovascular disease in relation to physical activity. At age 70, 1016 subjects were investigated in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Being PA was defined as performing regular heavy exercise (self-reported). According to body mass index (BMI)/PA groups, the participants were categorized as PA/normal weight (BMI<25kg/m2 , n=104), non-PA/normal weight (n=234), PA/overweight (BMI 25-29·9kg/m2 , n=133), non-PA/overweight (n=295), PA/obese (BMI≥30kg/m2 , n=54) and non-PA/obese (n=169). Several different measurements of endothelial reactivity and arterial compliance (plethysmography and ultrasound), cartotid artery atherosclerosis and echocardiography were performed, and seven markers of coagulation/fibrinolysis were measured. Physically active subjects with obesity showed impaired vasoreactivity in the forearm resistance vessels, increased left ventricular mass and impaired left ventricular systolic and diastolic functions, together with impaired coagulation/fibrinolysis when compared to PA/normal-weight subjects (P<0·05 to <0·001). The majority of these disturbances were seen also in PA/overweight subjects when compared to PA/normal-weight subjects (P<0·05 to <0·001). Our data provide additional support for the notion that an increased level of self-reported physical activity does not fully eliminate the deleterious cardiovascular consequences associated with overweight and obesity.