Impaired Muscle Oxygenation and Elevated Exercise Blood Pressure in Hypertensive Patients: Links With Vascular Stiffness

Understanding endothelial dysfunction in kidney transplantation: assessment techniques, existing evidence and research needs

INTRODUCTION

KTRs have substantially lower risk for cardiovascular events compared to dialysis, but it remains significantly higher than that in general population, due to the synergistic action of traditional and nontraditional factors. Among them, endothelial dysfunction is suggested to be involved pathogenetically in cardiovascular and renal disease progression, with its improvement being another potential benefit of transplantation.

AREAS COVERED

VOP was the first technique to be used, followed by several functional methods, most commonly FMD. Over the years, several biomarkers of endothelial dysfunction have been used to assess microvascular function. The totality of evidence in KTRs suggests the improvement of endothelial dysfunction after transplantation, but with several gaps in knowledge, including rarity of studies using novel, more accurate techniques. This review presents the current functional methods and biomarkers used to evaluate microvascular and endothelial function in KTRs, discussing the existing evidence on their changes after transplantation and their associations with comorbidities and outcomes in this population. A comprehensive literature search was conducted in PubMed and Scopus for articles published until December 2024.

EXPERT OPINION

Novel methods assessing endothelial function offer a comprehensive, real-time evaluation of microvascular function and should be more widely used to enhance our understanding in this area.

Tissue oxygenation in response to low-load and high-load back squats with continuous blood flow restriction in athletes

To determine muscle oxygenation with continuous blood flow restriction (BFR) training in high load (HL), 80% one-repetition maximum (1RM) and low load (LL), 30% 1RM squat exercises. In week-2 of a 4-week resistance training programme as part of their 3-set training routine, two groups of athletes (n = 4 each), one performing HL training with low cuff pressure (20% arterial occlusion pressure (AOP)), the other LL training with high cuff pressure (60% AOP) had muscle oxygenation assessed with near-infrared spectrophotometry (NIRS), arterial oxygen saturation (SPO2), heart rate (HR), barbell velocity and ratings of perceived exertion (RPE) during barbell back squats (BBS). Changes in the vastus lateralis oximetry were compared to pre- and post-training squat (1RM). Across athletes, there were significant associations between two pre-set-3 exercise variables and post-training 1RM, Tissue Saturation Index (TSI) (R2 = 0.92, p < 0.0002) and HHb concentration (R2 = 0.79, p < 0.003). Generalised regression models indicated that TSI % and HHb concentrations before and after set 3 timepoints were significant predictors of post-training 1RM in the LL group (R2 = 0.99, BIC = -24.9). Well-tolerated continuous LL-BFR training provided greater increases in strength than HL-BFR in athletes.

Impact of ischemic preconditioning combined with aerobic exercise on 24-h ambulatory blood pressure in men with prehypertension and stage 1 hypertension

Introduction

A single bout of aerobic exercise is known to induce a temporary reduction in post-exercise blood pressure termed post-exercise hypotension (PEH). Meanwhile, an ischemic preconditioning (IPC), a series of short ischemia-reperfusion intervention, has also shown antihypertensive effects showing a potential nonpharmacologic intervention for hypertension. While the acute BP reduction effects of aerobic exercise and IPC are individually well-investigated, it remains unclear if combining both interventions has an additive effect on PEH.

Methods

A total of twelve pre- or hypertensive men (six prehypertension, six stage 1 hypertension) underwent either 30 min of aerobic exercise at 50% VO2peak (CON) or IPC before exercise, in a counterbalanced order. IPC involved inflating cuffs on both thighs to 200 mmHg for 5 min, alternating between right and left thighs for three cycles, totaling 30 min. Brachial BP was measured during exercise and 1-h post-exercise recovery whereas muscle oxygen saturation (SmO2) from the rectus femoris was monitored using NIRs during exercise and recovery. Heart rate variability (HRV) and baroreflex sensitivity (BRS) together with a head-up tilt test (at 0 and 50°) were measured at the pre-test, post-test, and 24-h post-test. After the completion of each experiment, 24-h ambulatory blood pressure (ABP) was monitored to assess post-exercise hypotension within a 24-h window.

Results

BP and heart rate responses during exercise and 1-h recovery did not differ between conditions while SmO2 was significantly elevated during exercise in IPC (p = 0.004). There was no difference in HRV and supine BRS. However, significantly reduced titled BRS after exercise was found in CON while IPC preserved BRS similar to pre-exercise value, extending to 24-h post period (p = 0.047). ABP monitoring revealed a significant reduction in systolic BP during sleep in IPC compared to CON (p = 0.046).

Conclusion

The present findings suggest that IPC with a single session of aerobic exercise results in a notable decrease in systolic ABP, particularly during sleep, compared to aerobic exercise alone. This supplementary antihypertensive effect was associated with a sustained BRS, persisting up to 24 h in contrast to the significant decrease observed in CON. Future studies are warranted to investigate long-term adaptations to IPC.

Muscle Oxygen Saturation Dynamics During Upper-Body Resistance Exercise

Research examining the changes in muscle oxygen saturation across multiple sets of resistance exercise is limited. The purpose of this study was to describe the physiological response of muscle oxygenation parameters during upper-body resistance exercise and examine the differential effects of relevant participant characteristics on resistance training performance and muscle oxygen saturation dynamics. Sixty-one recreationally trained men (n = 44; 21.8 ± 2.6 years) and women (n = 17; 20.2 ± 1.8 years) completed five-repetition maximum sets of barbell bench presses at a load equal to 75% 1-RM with a 2 min rest interval. Muscle oxygen saturation (SmO2) dynamics within the anterior deltoid were monitored using a portable near-infrared spectroscopy sensor. The percent change in SmO2 (∆%SmO2), the muscle oxygen re-saturation rate (SmO2RecSlope), and the highest measured SmO2 value during recovery periods (SmO2Peak) were measured. Two-way (sex [men, women] x time [sets 1-5]) repeated measures analyses of variance (ANOVA) were performed on muscle saturation variables. To examine the effect of relevant controlling variables, separate analyses of covariance (ANCOVA) with repeated measures were also performed. No differences were seen with ∆%SmO2 across sets. The main effects for sets occurred for SmO2RecSlope, whereby a decline was noted on sets 4 and 5 (p = 0.001) compared to set 1. Additionally, SmO2Peak was the lowest on set 5 (p < 0.001) compared to all other sets. Moreover, body mass (p = 0.013), diastolic blood pressure (p = 0.044), and mean arterial pressure (p = 0.033) for ∆%SmO2 were the only significant covariates noted amongst the muscle oxygenation variables. In conclusion, no sex differences and only a few set differences in muscle oxygen saturation dynamics were seen without employing any covariates. Body mass, diastolic blood pressure, and mean arterial pressure were identified as factors that could influence observed responses.

Microvascular Reactivity Is Greater Following Blood Flow Restriction Resistance Exercise Compared with Traditional Resistance Exercise

ABSTRACT

Perlet, MR, Hosick, PA, Licameli, N, and Matthews, EL. Microvascular reactivity is greater following blood flow restriction resistance exercise compared with traditional resistance exercise. J Strength Cond Res 38(10): e553-e562, 2024-Chronic blood flow restriction (BFR) resistance exercise can improve muscular strength, hypertrophy, and microvasculature function, but the acute microvascular effects are unknown. We aimed to test the effects of acute BFR resistance exercise on postexercise microvascular reactivity in an exercising muscle and nonexercising muscle compared with traditional resistance exercise (TRE). Twenty-five adults (men = 14, women = 11, age: 22 ± 3 years, body mass: 71.69 ± 14.49 kg, height: 170 ± 10 cm) completed barbell back squat 1-repetition maximum (1RM) testing followed by 2 randomized and counterbalanced resistance exercise visits separated by ≥48 hours. The 2 visits involved either BFR (4 sets of 30-15-15-15 repetitions at 30% 1RM, with 60-second rest intervals) or TRE (4 sets of 10 repetitions at 70% 1RM, 60-second rest intervals). During each exercise visit, a pre- and postbarbell back squat vascular occlusion test was performed using near-infrared spectroscopy to measure skeletal muscle oxygen (SmO 2 ) in the vastus lateralis (VL) and flexor carpi radialis (FCR). Two-way repeated-measures ANOVA found an interaction effect ( p = 0.020) for SmO 2 reactivity in the VL. Post hoc analysis found greater reactive hyperemia postexercise in the VL for the BFR condition ( p < 0.001) but not the TRE condition ( p ≥ 0.05). There were no time, condition, or interaction effects (all p > 0.05) for the same analysis in the FCR. This analysis suggests that BFR, but not TRE, lead to acutely improved microvasculature function. Moreover, it suggests that the effects of BFR resistance exercise are local to the exercised or occluded limb and not systemic.

Effect of Curcumin Intake on Skeletal Muscle Oxygen Saturation Parameters in Older Participants

INTRODUCTION

Aging is associated with increased reactive oxygen species (ROS) and reduced bioavailability of nitric oxide (NO). Curcumin has been shown to increase NO bioavailability due to its ability to neutralize ROS, preventing oxidative stress. The present study aimed to investigate the effect of curcumin intake on skeletal muscle oxygen parameters and exercise tolerance in response to exercise in older people. Changes in circulating levels of NO metabolites were also investigated.

METHODS

Older subjects consumed 10 g of turmeric root extract from Curcuma longa L. (containing 95.33% of the total curcuminoids) or placebo in a randomized, double-blind, crossover study. A time of 2 h after ingestion, the participants performed one set of rhythmic handgrip exercise until the limit of tolerance, followed by 5 min of recovery. During exercise and exercise recovery, skeletal muscle oxygen saturation parameters were recorded.

RESULTS

During exercise, the amplitude of deoxyhemoglobin was greater after curcumin intake compared to placebo (CUR: 13.11 ± 9.52 vs. PLA: 10.22 ± 8.39 μM, p = 0.030). Furthermore, a faster skeletal muscle oxygen resaturation during exercise recovery was observed after curcumin compared to placebo (CUR: 1.01 ± 0.65 vs. PLA: 0.32 ± 0.20%.s-1, p = 0.004). These results were associated with significant changes in plasma nitrite (CUR: 6.82 ± 11.68 vs. PLA: -4.94 ± 17.28%, p = 0.028). There was no statistical difference in the total hemoglobin, exercise time until fatigue, and plasma nitrate between groups.

CONCLUSIONS

The present study suggests that curcumin improves muscle oxygenation status at the capillary level in older adults by possibly improving muscle oxygen extraction and/or delivery, with no effect on exercise tolerance.

Reproducibility and sex differences in muscle oxygenation during brachial artery occlusion in healthy participants

SIGNIFICANCE

Near-infrared spectroscopy (NIRS) measurement is a widely used technique to measure muscle oxygenation. A knowledge of the reproducibility of NIRS measurements is essential for the correct interpretation of data.

AIM

Our aim was to test the reproducibility and sex differences of NIRS measurements during brachial artery occlusion in healthy participants.

APPROACH

An NIRS device was used to measure muscle oxygenation and microvascular function during a 5 min brachial occlusion. Muscle oxygen consumption (mVO2) and tissue saturation index (TSI%) were used. The occlusion test was performed three times on separate days for males (n = 13, 28 ± 8 years) and females (n = 13, 29 ± 7 years).

RESULTS

During the occlusion phase, the reproducibility of mVO2 was excellent (intraclass correlation; ICC = 0.90). During the reperfusion phase, the maximal change in TSI% revealed the best reproducibility (ICC = 0.77). There were no sex differences in reproducibility. Male participants had higher muscle oxygenation during occlusion (mVO2, 0.054 ± 0.010 vs. 0.038 ± 0.012 mLO2/min/100 g, p = 0.001, male and female, respectively). There were no sex differences during the reperfusion phase.

CONCLUSION

The reproducibility of NIRS to measure muscle oxygenation and microvascular function during circulation occlusion and reperfusion is good to excellent. Muscle oxygen capacity measured during occlusion is higher in males compared to females, and there are no sex differences in microvascular function during the reperfusion phase.

L-Citrulline Supplementation Improves Arterial Blood Flow and Muscle Oxygenation during Handgrip Exercise in Hypertensive Postmenopausal Women

Endothelial dysfunction decreases exercise limb blood flow (BF) and muscle oxygenation. Acute L-Citrulline supplementation (CIT) improves muscle tissue oxygen saturation index (TSI) and deoxygenated hemoglobin (HHb) during exercise. Although CIT improves endothelial function (flow-mediated dilation [FMD]) in hypertensive women, the impact of CIT on exercise BF and muscle oxygenation (TSI) and extraction (HHb) are unknown. We examined the effects of CIT (10 g/day) and a placebo for 4 weeks on blood pressure (BP), arterial vasodilation (FMD, BF, and vascular conductance [VC]), and forearm muscle oxygenation (TSI and HHb) at rest and during exercise in 22 hypertensive postmenopausal women. Compared to the placebo, CIT significantly (p < 0.05) increased FMD (Δ-0.7 ± 0.6% vs. Δ1.6 ± 0.7%) and reduced aortic systolic BP (Δ3 ± 5 vs. Δ-4 ± 6 mmHg) at rest and improved exercise BF (Δ17 ± 12 vs. Δ48 ± 16 mL/min), VC (Δ-21 ± 9 vs. Δ41 ± 14 mL/mmHg/min), TSI (Δ-0.84 ± 0.58% vs. Δ1.61 ± 0.46%), and HHb (Δ1.03 ± 0.69 vs. Δ-2.76 ± 0.77 μM). Exercise BF and VC were positively correlated with improved FMD and TSI during exercise (all p < 0.05). CIT improved exercise artery vasodilation and muscle oxygenation via increased endothelial function in hypertensive postmenopausal women.

Accumulation of Microvascular Target Organ Damage in Systemic Lupus Erythematosus Patients Is Associated with Increased Cardiovascular Risk

Background: Systemic lupus erythematosus (SLE) is a prototype autoimmune disease associated with increased cardiovascular (CV) burden. Besides increased arterial stiffness and subclinical atherosclerosis, microvascular dysfunction is considered an important component in the pathophysiology of CV disease. However, there is a lack of data regarding the effect of multiple target organ damage (TOD) on CV health. Objectives: This study aimed to evaluate (i) the presence of microvascular changes in SLE in various vascular beds, (ii) the possible associations between the accumulation of microvascular TOD and CV risk and (iii) whether Galectin-3 represents a predictor of combined microvascular TOD. Methods: Participants underwent (i) evaluation of skin microvascular perfusion (laser speckle contrast analysis), (ii) fundoscopy (non-mydriatic fundus camera), (iii) indirect assessment of myocardial perfusion (subendocardial viability ratio) and (iv) determination of urine albumin-to-creatinine ratio (UACR). CV risk was calculated using the QResearch Risk Estimator version 3 (QRISK3). Serum Galectin-3 levels were determined. Results: Forty-seven SLE patients and fifty controls were studied. SLE patients demonstrated impaired skin microvascular reactivity (160.2 ± 41.0 vs. 203.6 ± 40.1%), retinal arteriolar narrowing (88.1 ± 11.1 vs. 94.6 ± 13.5 μm) and higher UACR levels compared to controls. Furthermore, SLE individuals had significantly higher Galectin-3 levels [21.5(6.1) vs. 6.6(6.6) ng/dL], QRISK3 scores [7.0(8.6) vs. 1.3(3.6)%] and a greater chance for microvascular dysfunction. In the SLE group, patients with multiple TOD exhibited higher QRISK3. In the multivariate analysis, the accumulation of TOD correlated with disease activity and Galectin-3 (p < 0.05). Conclusions: Our study showed for the first time that SLE patients exhibit a greater number of cases of TOD. The accumulation of TOD was associated with increased CV risk. Clinicians dealing with SLE should be aware and seek microvascular alterations.

NIRS-Derived Muscle-Deoxygenation and Microvascular Reactivity During Occlusion-Reperfusion at Rest Are Associated With Whole-Body Aerobic Fitness

Purpose: Near-infrared spectroscopy (NIRS) indices during arterial occlusion-reperfusion maneuver have been used to examine the muscle's oxidative metabolism and microvascular function-important determinants of whole-body aerobic-fitness. The association of NIRS-derived parameters with whole-body VO2max was previously examined using a method requiring exercise (or electrical stimulation) followed by multiple arterial occlusions. We examined whether NIRS-derived indices of muscle deoxygenation and microvascular reactivity assessed during a single occlusion-reperfusion at rest are (a) associated with maximal/submaximal indices of whole-body aerobic-fitness and (b) could discriminate individuals with different VO2max. We, also, investigated which NIRS-parameter during occlusion-reperfusion correlates best with whole-body aerobic-fitness. Methods: Twenty-five young individuals performed an arterial occlusion-reperfusion at rest. Changes in oxygenated- and deoxygenated-hemoglobin (O2Hb and HHb, respectively) in vastus-lateralis were monitored; adipose tissue thickness (ATT) at NIRS-application was assessed. Participants also underwent a maximal incremental exercise test for VO2max, maximal aerobic velocity (MAV), and ventilatory-thresholds (VTs) assessments. Results: The HHbslope and HHbmagnitude of increase (occlusion-phase) and O2Hbmagnitude of increase (reperfusion-phase) were strongly correlated with VO2max (r = .695-.763, p < .001) and moderately with MAV (r = .468-.530; p < .05). O2Hbmagnitude was moderately correlated with VTs (r = .399-.414; p < .05). After controlling for ATT, the correlations remained significant for VO2max (r = .672-.704; p < .001) and MAV (r = .407; p < .05). Individuals in the high percentiles after median and tritile splits for HHbslope and O2Hbmagnitude had significantly greater VO2max vs. those in low percentiles (p < .01-.05). The HHbslope during occlusion was the best predictor of VO2max. Conclusion: NIRS-derived muscle deoxygenation/reoxygenation indices during a single arterial occlusion-reperfusion maneuver are strongly associated with whole-body maximal indices of aerobic-fitness (VO2max, MAV) and may discriminate individuals with different VO2max.

Determination of Peak Oxygen Uptake in Patients with Acute Myocardial Infarction: The Role of Arterial Stiffness in Cardio-Vascular-Skeletal Muscle Coupling

The relationship between arterial stiffness and oxygen uptake (VO2) in patients with acute myocardial infarction (AMI) remains unclear. We aimed to investigate this relationship and factors contributing to VO2 in patients with AMI. The role of arterial stiffness in cardio-skeletal muscle coupling during exercise was then elucidated. Upon discharge, we measured exercise capacity using cardiopulmonary exercise testing (CPX), assessed arterial stiffness with the cardio-ankle vascular index (CAVI), and determined body composition to assess the skeletal muscle mass of 101 patients with AMI. Patients were categorized based on their CAVI scores into three groups: (i) normal (CAVI: ≤7.9), (ii) borderline (CAVI: 8.0-8.9), and (iii) abnormal (CAVI: ≥9.0). Subsequently, VO2 was compared among these groups. The relationship between the CAVI and VO2 Peak during CPX and factors contributing to VO2 Peak were investigated. The abnormal CAVI group had a significantly lower VO2 Peak than the normal and borderline groups. The CAVI was associated with VO2 Peak. Furthermore, the CAVI was found to be a factor contributing to VO2 Peak. These findings suggest that arterial stiffness in tissue blood distribution and blood supply causes systemic exercise limits in patients with AMI. This suggests that arterial stiffness plays a significant role in cardio-vascular-skeletal muscle coupling.

The relationship between physical activity level and balance parameters, muscle strength, fear of falling in patients with hypertension

The number of studies investigating the role of physical activity and exercise in hypertension (HT) patients is insufficient in the literature, and reports evaluating the relationship between HT, physical activity, and balance are lacking. This study aims to examine the relationship between physical activity levels and balance parameters, muscle strength, and fear of falling in patients with HT. 78 subjects with HT participated in this study. Demographic and clinical characteristics of all participants were recorded. Blood pressure was evaluated using a sphygmomanometer, physical activity level was assessed using a SenseWear Armband, fear of falling was assessed using the Fall Efficacy Scale, balance was assessed using the Fullerton Advanced Balance Scale, and muscle strength was evaluated using a digital handheld dynamometer. All 78 subjects completed the study as planned. The average age of participants was 57.75 ± 5.82, the mean systolic blood pressure was 133 ± 5.73, and the diastolic blood pressure was 84 ± 6.78. 34.2% of participants used angiotensin-converting enzyme inhibitors, 38% used beta blockers, and 26% used diuretic drugs. A positive correlation between physical activity and balance scores of individuals with HT was found (P < .005). It was also found that low muscle strength was associated with balance and risk of falling (P < .005). There is a positive correlation between decreased physical activity levels and balance in participants with HT. The results suggest that people with HT who have poor balance also have decreased muscle strength against gravity, such as in the quadriceps femoris and gluteus maximus. Overall, we recommend that patients with HT should improve their physical activity levels.

Training the Vessels: Molecular and Clinical Effects of Exercise on Vascular Health-A Narrative Review

Accelerated biological vascular ageing is still a major driver of the increasing burden of cardiovascular disease and mortality. Exercise training delays this process, known as early vascular ageing, but often lacks effectiveness due to a lack of understanding of molecular and clinical adaptations to specific stimuli. This narrative review summarizes the current knowledge about the molecular and clinical vascular adaptations to acute and chronic exercise. It further addresses how training characteristics (frequency, intensity, volume, and type) may influence these processes. Finally, practical recommendations are given for exercise training to maintain and improve vascular health. Exercise increases shear stress on the vascular wall and stimulates the endothelial release of circulating growth factors and of exerkines from the skeletal muscle and other organs. As a result, remodeling within the vascular walls leads to a better vasodilator and -constrictor responsiveness, reduced arterial stiffness, arterio- and angiogenesis, higher antioxidative capacities, and reduced oxidative stress. Although current evidence about specific aspects of exercise training, such as F-I-T-T, is limited, and exact training recommendations cannot be given, some practical implications can be extracted. As such, repeated stimuli 5-7 days per week might be necessary to use the full potential of these favorable physiological alterations, and the cumulative volume of mechanical shear stress seems more important than peak shear stress. Because of distinct short- and long-term effects of resistance and aerobic exercise, including higher and moderate intensities, both types of exercise should be implemented in a comprehensive training regimen. As vascular adaptability towards exercise remains high at any age in both healthy individuals and patients with cardiovascular diseases, individualized exercise-based vascular health prevention should be implemented in any age group from children to centenarians.

The importance of microvascular inflammation in ageing and age-related diseases: a position paper from the ESH working group on small arteries, section of microvascular inflammation

Microcirculation is pervasive and orchestrates a profound regulatory cross-talk with the surrounding tissue and organs. Similarly, it is one of the earliest biological systems targeted by environmental stressors and consequently involved in the development and progression of ageing and age-related disease. Microvascular dysfunction, if not targeted, leads to a steady derangement of the phenotype, which cumulates comorbidities and eventually results in a nonrescuable, very high-cardiovascular risk. Along the broad spectrum of pathologies, both shared and distinct molecular pathways and pathophysiological alteration are involved in the disruption of microvascular homeostasis, all pointing to microvascular inflammation as the putative primary culprit. This position paper explores the presence and the detrimental contribution of microvascular inflammation across the whole spectrum of chronic age-related diseases, which characterise the 21st-century healthcare landscape. The manuscript aims to strongly affirm the centrality of microvascular inflammation by recapitulating the current evidence and providing a clear synoptic view of the whole cardiometabolic derangement. Indeed, there is an urgent need for further mechanistic exploration to identify clear, very early or disease-specific molecular targets to provide an effective therapeutic strategy against the otherwise unstoppable rising prevalence of age-related diseases.

Cerebral oxygenation during exercise deteriorates with advancing chronic kidney disease

BACKGROUND

Cognitive impairment and exercise intolerance are common in chronic kidney disease (CKD). Cerebral perfusion and oxygenation play a major role in both cognitive function and exercise execution. This study aimed to examine cerebral oxygenation during a mild physical stress in patients at different CKD stages and controls without CKD.

METHODS

Ninety participants (18 per CKD stage 2, 3a, 3b and 4 and 18 controls) underwent a 3-min intermittent handgrip exercise at 35% of their maximal voluntary contraction. During exercise, cerebral oxygenation [oxyhaemoglobin (O2Hb), deoxyhaemoglobin (HHb) and total haemoglobin (tHb)] was assessed by near-infrared spectroscopy. Indices of microvascular (muscle hyperaemic response) and macrovascular function (carotid intima-media thickness and pulse wave velocity (PWV)) and cognitive and physical activity status were also evaluated.

RESULTS

No differences in age, sex and body mass index were detected among groups. The mini-mental state examination score was significantly reduced with advancing CKD stages (controls: 29.2 ± 1.2, stage 2: 28.7 ± 1.0, stage 3a: 27.8 ± 1.9, stage 3b: 28.0 ± 1.8, stage 4: 27.6 ± 1.5; P = .019). Similar trends were observed for physical activity levels and handgrip strength. The average response in cerebral oxygenation (O2Hb) during exercise was lower with advancing CKD stages (controls: 2.50 ± 1.54, stage 2: 1.30 ± 1.05, stage 3a: 1.24 ± 0.93, stage 3b: 1.11 ± 0.89, stage 4: 0.97 ± 0.80 μmol/l; P < .001). The average tHb response (index of regional blood volume) showed a similar decreasing trend (P = .003); no differences in HHb among groups were detected. In univariate linear analysis, older age, lower estimated glomerular filtration rate (eGFR), Hb, microvascular hyperaemic response and increased PWV were associated with poor O2Hb response during exercise. In the multiple model, eGFR was the only parameter independently associated with the O2Hb response.

CONCLUSIONS

Brain activation during a mild physical task appears to decrease with advancing CKD as suggested by the smaller increase in cerebral oxygenation. This may contribute to impaired cognitive function and reduced exercise tolerance with advancing CKD.

Muscle Oxygenation and Microvascular Reactivity Across Different Stages of CKD: A Near-Infrared Spectroscopy Study

RATIONALE & OBJECTIVE

Previous studies in chronic kidney disease (CKD) showed that vascular dysfunction in different circulatory beds progressively deteriorates with worsening CKD severity. This study evaluated muscle oxygenation and microvascular reactivity at rest, during an occlusion-reperfusion maneuver, and during exercise in patients with different stages of CKD versus controls.

STUDY DESIGN

Observational controlled study.

SETTING & PARTICIPANTS

90 participants (18 per CKD stage 2, 3a, 3b, and 4, as well as 18 controls).

PREDICTOR

CKD stage.

OUTCOME

The primary outcome was muscle oxygenation at rest. Secondary outcomes were muscle oxygenation during occlusion-reperfusion and exercise, and muscle microvascular reactivity (hyperemic response).

ANALYTICAL APPROACH

Continuous measurement of muscle oxygenation [tissue saturation index (TSI)] using near-infrared spectroscopy at rest, during occlusion-reperfusion, and during a 3-minute handgrip exercise (at 35% of maximal voluntary contraction). Aortic pulse wave velocity and carotid intima-media thickness were also recorded.

RESULTS

Resting muscle oxygenation did not differ across the study groups (controls: 64.3% ± 2.9%; CKD stage 2: 63.8% ± 4.2%; CKD stage 3a: 64.1% ± 4.1%; CKD stage 3b: 62.3% ± 3.3%; CKD stage 4: 62.7% ± 4.3%; P=0.6). During occlusion, no significant differences among groups were detected in the TSI occlusion magnitude and TSI occlusion slope. However, during reperfusion the maximum TSI value was significantly lower in groups of patients with more advanced CKD stages compared with controls, as was the hyperemic response (controls: 11.2%±3.7%; CKD stage 2: 8.3%±4.6%; CKD stage 3: 7.8%±5.5%; CKD stage 3b: 7.3%±4.4%; CKD stage 4: 7.2%±3.3%; P=0.04). During the handgrip exercise, the average decline in TSI was marginally lower in patients with CKD than controls, but no significant differences were detected across CKD stages.

LIMITATIONS

Moderate sample size, cross-sectional evaluation.

CONCLUSIONS

Although no differences were observed in muscle oxygenation at rest or during occlusion, the microvascular hyperemic response during reperfusion was significantly impaired in CKD and was most prominent in more advanced CKD stages. This impaired ability of microvasculature to respond to stimuli may be a crucial component of the adverse vascular profile of patients with CKD and may contribute to exercise intolerance.

Assessment of skin microcirculation in primary aldosteronism: impaired microvascular responses compared to essential hypertensives and normotensives

Primary aldosteronism (PA) is associated with considerably higher cardiovascular risk and increased prevalence of organ damage compared to essential hypertension (EH). Laser speckle contrast imaging (LSCI) has emerged as a novel non-invasive tool to assess of skin microcirculation. Our aim was to evaluate skin microvascular function (SMF) using LSCI coupled with post-occlusive reactive hyperemia (PORH) in a group of PA patients (PAs) compared to patients with EH (EHs) and normotensive controls (NTs). We enrolled PAs, age- and gender-matched with EHs and NTs. All participants underwent SMF assessment by LSCI with PORH. We enrolled 109 participants including 29 PAs, 47 EHs, and 33 NTs. SMF was significantly impaired in PAs, including peak time (p < 0.001) and base to peak flux (p < 0.001) compared to NTs and EHs. Among PAs, plasma aldosterone showed a positive correlation with occlusion flux (p = 0.005). Our study shows for the first time that PAs present impaired SMF as assessed with LSCI coupled with PORH, not only compared to NTs but also compared to EHs with similar blood pressure profile. Further studies are needed to investigate the clinical impact of such alterations in terms of pathophysiology and cardiovascular risk prediction.

Nonpharmacological Strategies in Heart Failure with Preserved Ejection Fraction

Patients with heart failure with preserved ejection fraction (HFpEF) suffer from a high rate of cardiometabolic comorbidities with limited pharmaceutical therapies proven to improve clinical outcomes and cardiorespiratory fitness (CRF). Nonpharmacologic therapies, such as exercise training and dietary interventions, are promising strategies for this population. The aim of this narrative review is to present a summary of the literature published to date and future directions related to the efficacy of nonpharmacologic, lifestyle-related therapies in HFpEF, with a focus on exercise training and dietary interventions.

The effect of dietary nitrate on macro- and microvascular function: A systematic review

Previous studies have investigated the impact of dietary nitrate on vascular function due to the association between dietary nitrate ingestion and improvement in nitric oxide (NO) bioavailability. Considering that NO can present different effects through vascular beds (macro- vs. microvasculature) due to the specific characteristic (function and morphology) that each vessel exhibits, it is crucial to investigate the effect of dietary nitrate ingestion on the macro- and microvascular function to understand the effect of nitrate on vascular function. For this reason, this review aimed to evaluate the impact of dietary nitrate on macro- and microvascular function in humans. A total of 29 studies were included in the systematic review, of which 19 studies evaluated the effect of nitrate supplementation on macrovascular function, eight studies evaluated the effect on microvascular function, and two studies evaluated the impact on both macro- and microvascular function. The literature suggests that dietary nitrate ingestion seems to improve the vascular function in macrovasculature, whereas microvascular function appears to be modest. Future studies investigating the effect of nitrate ingestion on vascular function should focus on measuring macro- and microvascular function whenever possible so that the impact of nitrate-rich foods on vascular segments could be better understood.

Association of Cerebral Oxygenation During Exercise With Target Organ Damage in Middle-Aged Hypertensive and Normotensive Individuals

BACKGROUND

The brain is one of the main target organs affected by hypertension. Impaired cerebral oxygenation during exercise is an indicator of cerebral dysfunction. We aimed to investigate whether cerebral oxygenation during exercise correlates with subclinical markers of early target organ damage in a population of middle-aged, newly diagnosed hypertensive and healthy individuals.

METHODS

Carotid intima-media thickness (cIMT) was measured using ultrasound, arterial stiffness was estimated measuring the augmentation index and pulse wave velocity, and retinal vessel diameter was assessed via the central retinal-arteriolar and vein equivalent and retinal-arteriovenous ratio. Participants (n = 93) performed a 3-minute isometric handgrip exercise. Cerebral prefrontal oxygenation was measured continuously using near infrared spectroscopy. The average exercise responses in oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and total hemoglobin (tHb) were assessed. Univariate analyses were performed; partial correlation was used to account for traditional cardiovascular risk factors to identify independent associations between cerebral-oxygenation indices and early markers of target organ damage.

RESULTS

Mean cIMT was negatively correlated with the average exercise response in cerebral oxygenation (rhoO2Hb = -0.348, PO2Hb = 0.001; rhotHb = -0.253, Pthb = 0.02). Augmentation index was negatively correlated with cerebral oxygenation during exercise (rhoO2Hb = -0.374, P < 0.001; rhotHb = -0.332, P = 0.02), whereas no significant correlation was observed between pulse wave velocity and cerebral-oxygenation indices. In the adjusted analysis, cerebral oxygenation was correlated with central retinal arteriolar diameter (CRAE r = 0.233, P = 0.043).

CONCLUSIONS

Our novel findings suggest that indices of lower cerebral oxygenation during a submaximal physical task are associated with markers of early, subclinical target organ damage, namely increased cIMT, arterial stiffness, and arteriolar retinal narrowing in newly diagnosed, untreated, hypertensive individuals.

Methods to evaluate vascular function: a crucial approach towards predictive, preventive, and personalised medicine

Endothelium, the gatekeeper of our blood vessels, is highly heterogeneous and a crucial physical barrier with the ability to produce vasoactive and protective mediators under physiological conditions. It regulates vascular tone, haemostasis, vascular inflammation, remodelling, and angiogenesis. Several cardio-, reno-, and cerebrovascular diseases begin with the dysfunction of endothelial cells, and more recently, COVID-19 was also associated with endothelial disease highlighting the need to monitor its function towards prevention and reduction of vascular dysfunction. Endothelial cells are an important therapeutic target in predictive, preventive, and personalised (3P) medicine with upmost importance in vascular diseases. The development of novel non-invasive techniques to access endothelial dysfunction for use in combination with existing clinical imaging modalities provides a feasible opportunity to reduce the burden of vascular disease. This review summarises recent advances in the principles of endothelial function measurements. This article presents an overview of invasive and non-invasive techniques to determine vascular function and their major advantages and disadvantages. In addition, the article describes mechanisms underlying the regulation of vascular function and dysfunction and potential new biomarkers of endothelial damage. Recognising these biomarkers is fundamental towards a shift from reactive to 3P medicine in the vascular field. Identifying vascular dysfunction earlier with non-invasive or minimally invasive techniques adds value to predictive diagnostics and targeted prevention (primary, secondary, tertiary care). In addition, vascular dysfunction is a potential target for treatments tailored to the person.

Improved microvascular reactivity after aged garlic extract intake is not mediated by hydrogen sulfide in older adults at risk for cardiovascular disease: a randomized clinical trial

PURPOSE

This study aimed to investigate the effects of AGE on microvascular reactivity, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in older individuals at high risk for cardiovascular disease (CVD). Urinary thiosulfate was also investigated as an indirect marker of endogenous hydrogen sulfide (H₂S) synthesis. The study was conducted in a randomized, double-blind, crossover, and placebo-controlled way.

METHODS

Twenty-eight participants (14 male), 67 ± 6 years old with CVD risk factors, ingested 2.4 g of AGE or placebo (PLA). Near-infrared spectroscopy evaluated tissue oxygen saturation (StO₂) during a vascular occlusion test (30 s baseline, 5 min occlusion, and 2 min reperfusion). The upslope of StO₂ signal after cuff release was calculated to measure microvascular reactivity. Urinary thiosulfate levels were measured using a high-performance liquid chromatography system.

RESULTS

The upslope of StO₂ was significantly faster after AGE (1.01 ± 0.37% s^-1) intake compared to PLA (0.83 ± 0.35% s^-1; P < 0.001; d = 0.50). Relative changes in Δ% SBP from pre- to post-AGE intake (- 5.17 ± 5.77%) was significantly different compared to Δ% PLA (0.32 ± 5.99%; P = 0.001; d = 0.93). No significant changes in urinary thiosulfate concentrations were observed between interventions. Moreover, no significant gender effect in any parameter assessed was found.

CONCLUSION

This study demonstrated that a single dose of AGE improved microvascular reactivity in older adults at risk of CVD despite such an effect was not linked with urinary thiosulfate levels. This trial was registered at clinicaltrials.gov as NCT04008693 (May 19, 2020).

Skin microvascular function, as assessed with laser speckle contrast imaging, is impaired in untreated essential and masked hypertension

Skin microcirculation has been proposed as a model of generalized microvascular function. Laser speckle contrast imaging (LSCI) is a novel, noninvasive method to assess skin microvascular function (SMF). To date, SMF data in hypertension are conflicting, and no study with LSCI exists. In addition, the application of LSCI in masked hypertension is scarce. We assessed SMF with LSCI coupled with postocclusive reactive hyperemia (PORH) in patients with newly diagnosed untreated essential hypertension (UHT) and masked hypertension (MH) compared to healthy normotensive (NT) individuals. We enrolled consecutive UHT and MH patients and NT individuals matched for age, sex, body mass index, and smoking status. All participants underwent SMF assessment by LSCI coupled with PORH (PeriCam PSI system, Perimed, Sweden). Correlation analyses were performed between SMF and common cardiovascular risk factors and BP parameters. In total, 70 UHT patients, 20 MH patients and 40 NT individuals were enrolled. UHT and MH patients exhibited significantly impaired SMF compared to NT individuals (UHT patients: base-to-peak flux (p < 0.001)), PORH amplitude (p < 0.001); MH patients: base-to-peak flux (p = 0.013), PORH amplitude (p = 0.022). MH patients did not differ compared to UHT patients. SMF was negatively associated with office, ambulatory and central BP. SMF was negatively associated with blood lipids and smoking. Hypertensive status was the single most important predictor of SMF. UHT and MH patients exhibit impaired SMF compared to NT individuals. MH patients did not differ compared to UHT patients. SMF is negatively associated with BP and cardiovascular risk factors. LSCI could be implemented as a useful tool to investigate SMF in hypertension.

The physiological and clinical importance of cardiorespiratory fitness in people with abdominal aortic aneurysm

New Findings

What is the topic of this review?

This review focuses on the physiological impact of abdominal aortic aneurysm (AAA) on cardiorespiratory fitness and the negative consequences of low fitness on clinical outcomes in AAA. We also discuss the efficacy of exercise training for improving cardiorespiratory fitness in AAA.

What advances does it highlight?

We demonstrate the negative impact of low fitness on disease progression and clinical outcomes in AAA. We highlight potential mechanistic determinants of low fitness in AAA and present evidence that exercise training can be an effective treatment strategy for improving cardiorespiratory fitness, postoperative mortality and disease progression.

Abstract

An abdominal aortic aneurysm (AAA) is an abnormal enlargement of the aorta, below the level of the renal arteries, where the aorta diameter increases by >50%. As an aneurysm increases in size, there is a progressive increase in the risk of rupture, which ranges from 25 to 40% for aneurysms >5.5 cm in diameter. People with AAA are also at a heightened risk of cardiovascular events and associated mortality. Cardiorespiratory fitness is impaired in people with AAA and is associated with poor (postoperative) clinical outcomes, including increased length of hospital stay and postoperative mortality after open surgical or endovascular AAA repair. Although cardiorespiratory fitness is a well‐recognized prognostic marker of cardiovascular health and mortality, it is not assessed routinely, nor is it included in current clinical practice guidelines for the management of people with AAA. In this review, we discuss the physiological impact of AAA on cardiorespiratory fitness, in addition to the consequences of low cardiorespiratory fitness on clinical outcomes in people with AAA. Finally, we summarize current evidence for the effect of exercise training interventions on cardiorespiratory fitness in people with AAA, including the associated improvements in postoperative mortality, AAA growth and cardiovascular risk. Based on this review, we propose that cardiorespiratory fitness should be considered as part of the routine risk assessment and monitoring of people with AAA and that targeting improvements in cardiorespiratory fitness with exercise training might represent a viable adjunct treatment strategy for reducing postoperative mortality and disease progression.

Frailty influences the vascular responsiveness of elderly individuals with chronic heart failure

INTRODUCTION

Frailty is highly prevalent in heart failure (HF) patients. HF is associated with oxidative stress and chronic inflammation, which impair oxygen use by skeletal muscles. Little is known about the influence of frailty on vascular responsiveness and tissue oxygenation.

OBJECTIVE

Analyze the influence of frailty on vascular responsiveness and muscle oxygenation in elderly individuals with and without HF.

METHODS

Individuals aged ≥60 years, with or without HF, were evaluated for frailty (phenotype). Near-infrared spectroscopy (NIRS) was used to assess muscle oxygenation at rest (oxygen saturation - StO₂ and deoxyhemoglobin) and during handgrip exercise (minimum StO₂ and maximum deoxyhemoglobin), and oxygenation variables.

STATISTICAL ANALYSIS

Results were grouped according to the frailty phenotype: non-frail, pre-frail, and frail. Shapiro-Wilk test was used to assess normality. Data were compared using a two-way analysis of variance (ANOVA). Bonferroni post hoc test was applied to determine the influence of frailty or HF on NIRS variables. SPSS software was used in the analyses; p < 0.05 was considered significant.

RESULTS

55 elderly participants (61.8% female; 70.4 ± 7.2 years old; 28 HF patients) participated in the study. 32.7% (n = 18) were classified as non-frail, 43.3% (n = 24) as pre-frail, and 23.6% (n = 13) as frail. The analysis of vascular responsiveness (n = 52) identified an influence (p < 0.05) of frailty on the reperfusion rate (slope 2 and ∆StO₂ of nadir-peak) and desaturation during occlusion (area under the curve of StO₂) in HF patients. There was no influence of frailty or HF on muscle oxygenation at rest and during exercise (n = 54; p > 0.05).

CONCLUSION

The coexistence of frailty and HF seems to impair vascular responsiveness, as frail elderly participants with HF presented lower reperfusion rates and higher desaturation levels during the arterial occlusion test. However, the presence of frailty or HF alone had no influence on muscle oxygenation at rest or during exercise.

Blood pressure response during treadmill exercise testing and the risk for future cardiovascular events and new-onset hypertension

OBJECTIVE

The physiologic response to exercise may provide valuable prognostic information. We investigated the association of blood pressure (BP) measurements during exercise stress testing (EST) with long-term risk of myocardial infarction, stroke or death (major adverse cardiovascular event, MACE), as well as the development of new-onset hypertension.

METHODS

A retrospective analysis of treadmill ESTs (years 2005-2019) performed by the Bruce protocol in patients aged 35-75 years without a history of cardiovascular disease (n = 14 792; 48% women). BP was documented at rest, submaximal exercise (Bruce stage-2), peak exercise and recovery (2 min). Association of SBP measures with study outcomes during median follow-up of 6.5 years was investigated.

RESULTS

Highest vs. lowest SBP quartile at rest (≥140 vs. <120 mmHg), submaximal-exercise (≥170 vs. <130 mmHg), peak-exercise (≥180 vs. ≤145 mmHg) and recovery (≥160 vs. <130 mmHg) was associated with an increase in the adjusted hazard ratio and 95% confidence interval (CI) for MACE: 1.53 (1.23-1.88), 1.33 (1.01-1.76), 1.30 (1.05-1.61), 1.35 (1.09-1.68), respectively. The association between SBP at submaximal exercise and recovery with MACE displayed a J-shaped pattern. Among nonhypertensive patients (n = 8529), excessive SBP response to peak exercise (≥190 mmHg in women and ≥210 mmHg in men) was an independent predictor of hypertension [hazard ratio (95% CI)]: 1.87 (1.41-2.48), as were SBPs during submaximal exercise [>160 vs. ≤130 mmHg: 2.44 (1.97-3.03)] and recovery [≥140 vs. ≤120 mmHg: 1.65 (1.37-1.98)].

CONCLUSION

BP measurement during rest, exercise and recovery phases of EST provides incremental prognostic information regarding long-term risk for cardiovascular events and the probability for developing hypertension.

Skeletal muscle and cerebral oxygenation levels during and after submaximal concentric and eccentric isokinetic exercise

The aim was to investigate the potential differences in muscle (vastus lateralis) and cerebral (prefrontal cortex) oxygenation levels as well as in the number of repetitions and total work output between isokinetic eccentric and concentric exercise at a moderate relative intensity until exhaustion. Ten recreationally active young men underwent two isokinetic exercise sessions either concentric or eccentric, one on each randomly selected leg. The protocols were performed at 60°/s and an intensity corresponding to 60% of the maximal voluntary contraction (MVC) of each contraction type. Concentric torque was significantly lower compared to eccentric torque in both peak values and at values corresponding to 60% of MVC [230 ± 18 Nm vs. 276 ± 19 Nm (P = .014) and 137 ± 12 Nm vs. 168 ± 11 Nm, respectively (P = .010)]. The participants performed 40% more contractions during eccentric compared to concentric exercise [122 ± 15 vs. 78 ± 7, respectively]. No differences were found in the levels of oxyhaemoglobin, deoxyhemoglobin, total haemoglobin and tissue saturation index when eccentric and eccentric exercise regimes were compared (all P > .05). Our results demonstrate that eccentric exercise of moderate intensity leads to greater resistance to fatigue and more work output compared to concentric exercise, despite the comparable muscle and cerebral oxygenation levels.

Εndothelial and microvascular function in CKD: Evaluation methods and associations with outcomes

BACKGROUND

Cardiovascular disease is the major cause of morbidity and mortality in patients with chronic kidney disease (CKD). Endothelial dysfunction, the hallmark of atherosclerosis, is suggested to be involved pathogenetically in cardiovascular and renal disease progression in these patients.

METHODS

This is a narrative review presenting the techniques and markers used for assessment of microvascular and endothelial function in patients with CKD and discussing findings of the relevant studies on the associations of endothelial dysfunction with co-morbid conditions and outcomes in this population.

RESULTS

Venous Occlusion Plethysmography was the first method to evaluate microvascular function; subsequently, several relevant techniques have been developed and used in patients with CKD, including brachial Flow-Mediated Dilatation, and more recently, Near-Infrared Spectroscopy and Laser Speckle Contrast Analysis. Furthermore, several circulating biomarkers are commonly used in clinical research. Studies assessing endothelial function using the above techniques and biomarkers suggest that endothelial dysfunction occurs early in CKD and contributes to the target organ damage, cardiovascular events, death and progression towards end-stage kidney disease.

CONCLUSIONS

Older and newer functional methods and several biomarkers have assessed endothelial dysfunction in CKD; accumulated evidence supports an association of endothelial dysfunction with outcomes. Future research with new, non-invasive and easily applicable methods could further delineate the role of endothelial dysfunction on cardiovascular and renal disease progression in patients with CKD.

Skin microvascular dysfunction in systemic lupus erythematosus patients with and without cardiovascular risk factors

OBJECTIVES

Patients with SLE have increased cardiovascular mortality. Alterations in both macro- and micro-circulation have been associated with cardiovascular disease. We sought to assess skin microvascular function by using laser speckle contrast analysis (LASCA) in patients with SLE, with and without cardiovascular disease and risk factors.

METHODS

Continuous blood flow was recorded using a LASCA device during baseline, a 5-min arterial occlusion and a 5-min reperfusion period.

RESULTS

Thirty-five patients with SLE (85.7% women) with a median disease duration 12.0 (6.5-17.5) years and a mean age of 46.3 (8.6) years and 31 controls matched for age, sex and BMI were enrolled. During reperfusion, SLE patients exhibited a smaller peak magnitude compared with controls (161.0 (47.1) vs 197.2 (41.4)%, respectively, P =0.002). Results remained unchanged among 24 SLE patients without cardiovascular disease compared with the control group (169.2 (48.1) vs 195.6 (34.0)%, respectively, P =0.002).

CONCLUSION

Our study shows, for the first time, that patients with SLE, even without overt cardiovascular disease or risk factors, exhibit a blunted microvascular reactivity during reperfusion compared with controls. These results show that skin microvascular dysfunction is present in SLE independently of the CV burden that these patients bear and may represent an early sign of vascular damage.

Suitability of the muscle O2 resaturation parameters most used for assessing reactive hyperemia: a near-infrared spectroscopy study

Background

There is a spectrum of possibilities for analyzing muscle O₂ resaturation parameters for measurement of reactive hyperemia in microvasculature. However, there is no consensus with respect to the responsiveness of these O₂ resaturation parameters for assessing reactive hyperemia.

Objectives

This study investigates the responsiveness of the most utilized muscle O₂ resaturation parameters to assess reactive hyperemia in the microvasculature of a clinical group known to exhibit impairments of tissue O₂ saturation (StO₂).

Methods

Twenty-three healthy young adults, twenty-nine healthy older adults, and thirty-five older adults at risk of cardiovascular disease (CVD) were recruited. Near-infrared spectroscopy (NIRS) was used to assess StO₂ after a 5-min arterial occlusion challenge and the following parameters were analyzed: StO_{2slope_10s}, StO_{2slope_30s}, and StO_{2slope_until_baseline} (upslope of StO₂ over 10s and 30s and until StO₂ reaches the baseline value); time to StO_2baseline and time to StO_2max (time taken for StO₂ to reach baseline and peak values, respectively); ∆StO_2reperfusion (the difference between minimum and maximum StO₂ values); total area under the curve (StO_2AUCt); and AUC above the baseline value (StO_{2AUC_above_base}).

Results

Only StO_{2slope_10s} was significantly slower in older adults at risk for CVD compared to healthy young individuals (p < 0.001) and to healthy older adults (p < 0.001). Conversely, time to StO_2max was significantly longer in healthy young individuals than in older adult at CVD risk.

Conclusions

Our findings suggest that StO_{2slope_10s} may be a measure of reactive hyperemia, which provides clinical insight into microvascular function assessment.

Measuring tibial hemodynamics and metabolism at rest and after exercise using near-infrared spectroscopy

The bone vascular system is important, yet evaluation of bone hemodynamics is difficult and expensive. This study evaluated the utility and reliability of near-infrared spectroscopy (NIRS), a portable and relatively inexpensive device, in measuring tibial hemodynamics and metabolic rate. Eleven participants were tested twice using post-occlusive reactive hyperemia technique with the NIRS probes placed on the tibia and the medial gastrocnemius (MG) muscle. Measurements were made at rest and after 2 levels of plantarflexion exercise. The difference between oxygenated and deoxygenated hemoglobin signal could be reliably measured with small coefficients of variation (CV; range 5.7-9.8%) and high intraclass correlation coefficients (ICC; range 0.73-0.91). Deoxygenated hemoglobin rate of change, a potential marker for bone metabolism, also showed good reliability (CV range 7.5-9.8%, ICC range 0.90-0.93). The tibia was characterized with a much slower metabolic rate compared with MG (p < 0.001). While exercise significantly increased MG metabolic rate in a dose-dependent manner (all p < 0.05), no changes were observed for the tibia after exercise compared with rest (all p > 0.05). NIRS is a suitable tool for monitoring hemodynamics and metabolism in the tibia. However, the local muscle exercise protocol utilized in the current study did not influence bone hemodynamics or metabolic rate. Novelty: NIRS can be used to monitor tibial hemodynamics and metabolism with good reliability. Short-duration local muscle exercise increased metabolic rate in muscle but not in bone. High level of loading and exercise volume may be needed to elicit measurable metabolic changes in bone.

The effect of muscle blood flow restriction on hemodynamics, cerebral oxygenation and activation at rest

This study tested the hypothesis that muscle blood flow restriction reduces muscle and cerebral oxygenation, at rest. In 26 healthy males, aged 33±2 yrs, physiological variables were continuously recorded during a 10-min period in two experimental conditions: a) with muscle blood flow restriction through thigh cuffs application inflated at 120 mmHg (With Cuffs, WC) and b) without restriction (No Cuffs, NC). Muscle and cerebral oxygenation were reduced by muscle blood flow restriction as suggested by the increase in both muscle and cerebral deoxygenated hemoglobin (Δ[HHb]; p<0.01) and the decrease of muscle and cerebral oxygenation index (Δ[HbDiff]; p<0.01). Hemodynamic responses were not affected by such muscle blood flow restriction, whereas baroreflex sensitivity was reduced (p=0.009). The perception of leg discomfort was higher (p<0.001) in the WC than in the NC condition. This study suggests that thigh cuffs application inflated at 120 mmHg is an effective method to reduce muscle oxygenation at rest. These changes at the muscular level seem to be sensed by the central nervous system, evoking alterations in cerebral oxygenation and baroreflex sensitivity. Novelty bullets: • Thigh cuffs application inflated at 120 mmHg effectively reduces muscle oxygenation at rest. • Limiting muscle oxygenation appears to reduce cerebral oxygenation, and baroreflex sensitivity, at rest. • Even in healthy subjects, limiting muscle oxygenation, at rest, affects neural integration.

Vascular endothelial damage in COPD: current functional assessment methods and future perspectives

Introduction: Cardiovascular disease is a major cause of death in chronic obstructive pulmonary disease (COPD), but the relationship between these two entities is not fully understood; smoking, inflammation, arterial stiffness and endothelial dysfunction are significant determinants. Endothelial dysfunction is not only associated with cardiovascular disease, but also with COPD severity.Areas covered: Several functional methods have been developed to evaluate endothelial function in healthy and diseased individuals; from the invasive angiography of epicardial coronary arteries and Venous-Occlusion-Plethysmography, to more modern, noninvasive approaches such as Flow-Mediated-Dilatation, Peripheral-Arterial-Tonometry and Near-Infrared-Spectroscopy, all these methods have boosted clinical research in this field. In this context, this narrative review, which included articles published in PubMed and Scopus up to 25-November-2020, summarizes available functional methods for endothelial damage assessment in COPD and discusses existing evidence on their associations with comorbidities and outcomes in this population.Expert opinion: Accumulated evidence suggests that endothelial dysfunction occurs in early stages of CΟPD and worsens with pulmonary obstruction severity and during acute exacerbations. Novel methods evaluating endothelial function offer a detailed, real-time assessment of different parameters related to vascular function and should be increasingly used to shed more light on the role of endothelial damage on cardiovascular and COPD progression.

Exertional Desaturation in Idiopathic Pulmonary Fibrosis: The Role of Oxygen Supplementation in Modifying Cerebral-Skeletal Muscle Oxygenation and Systemic Hemodynamics

BACKGROUND

In patients with idiopathic pulmonary fibrosis (IPF) with isolated exertional desaturation, there are limited data regarding the effectiveness of oxygen supplementation during exercise training; the underlying mechanisms that contribute to these responses are unknown.

OBJECTIVES

To examine in these IPF patients the effects of oxygen supplementation during submaximal exercise (vs. medical air) on cerebral/skeletal muscle oxygenation and systemic hemodynamics.

METHODS

In this randomized, cross-over, placebo-controlled trial, IPF patients (n = 13; 63.4 ± 9.6 years) without resting hypoxemia but a significant desaturation during maximal cardiopulmonary exercise testing underwent 2 steady-state exercise trials (65% peak-work-load), breathing either oxygen-enriched or medical air. Cerebral/skeletal muscle oxygenation (near-infrared spectroscopy) and beat-by-beat hemodynamics (photoplethysmography) were monitored.

RESULTS

In the air protocol, from the initial minutes of submaximal exercise, patients exhibited a marked decline in cerebral oxygenated hemoglobin (O2Hb) and an abrupt rise in deoxygenated hemoglobin (HHb). Oxygen supplementation alleviated desaturation, lessened dyspnea, and prolonged exercise duration (p < 0.01). Oxygen supplementation during exercise (i) attenuated cerebral deoxygenation (cerebral-HHb: 0.7 ± 1.9 vs. 2.5 ± 1.5 μmol/L, O2 and air protocol; p = 0.009) and prevented cerebral-Hbdifference decline (2.1 ± 2.7 vs. -1.7 ± 2.0 μmol/L; p = 0.001), (ii) lessened the decline in muscle O2-saturation index, and (iii) at isotime exercise, it resulted in lower muscle-HHb (p = 0.05) and less leg fatigue (p < 0.05). No differences between protocols were observed in exercise cardiac output and vascular resistance.

CONCLUSIONS

IPF patients with isolated exertional hypoxemia exhibit an inability to increase/maintain cerebral oxygenation during submaximal exercise. Correcting desaturation with O2 supplementation prevented the decline in brain oxygenation, improved muscle oxygenation, and lessened dyspnea, suggesting an efficacy of acute oxygen supplementation during exercise training in protecting brain hypoxia in these IPF patients.

Young healthy adults with a family history of hypertension have increased microvascular reactivity but decreased macrovascular function

OBJECTIVE

To determine whether, like hypertensives, normotensive adults with a family history of hypertension (+FHH) display lower microvascular reactivity and conduit artery function than normotensive adults without a family history of hypertension (-FHH).

METHODS

A forearm vascular occlusion test was performed on healthy normotensive adults while resting in the supine position. A near-infrared spectroscopy sensor placed on the forearm measured skeletal muscle oxygen saturation kinetics to determine microvascular reactivity. Simultaneously, an ultrasound probe placed on the brachial artery above the occlusion cuff was used to assess flow-mediated dilation; a test of macrovascular function.

RESULTS

Twenty-two participants were included in this investigation (-FHH n = 13, +FHH n = 9). Following cuff release, the resaturation slope (1st 10 s median ± SD, -FHH 2.76 ± 2.10, +FHH 5.59 ± 2.47%/s; p = .036) was greater in +FHH when accounting for the magnitude and rate of the decrease in skeletal muscle oxygen saturation during occlusion. Conversely, flow-mediated dilation (median ± SD, -FHH 5.96 ± 5.22, +FHH 4.10 ± 3.17%∆; p = .031) was lower in +FHH when accounting for baseline artery diameter and shear rate.

CONCLUSIONS

Young +FHH adults have altered microvascular and macrovascular reactivity compared with young -FHH adults.

Association of lifetime blood pressure with adulthood exercise blood pressure response: the cardiovascular risk in young Finns study

PURPOSE

Elevated blood pressure (BP) in childhood has been associated with increased adulthood BP. However, BP and its change from childhood to adulthood and the risk of exaggerated adulthood exercise BP response are largely unknown. Therefore, we studied the association of childhood and adulthood BP with adulthood exercise BP response.

MATERIALS AND METHODS

This investigation consisted of 406 individuals participating in the ongoing Cardiovascular Risk in Young Finns Study (baseline in 1980, at age of 6-18 years; follow-up in adulthood in 27-29 years since baseline). In childhood BP was classified as elevated according to the tables from the International Child Blood Pressure References Establishment Consortium, while in adulthood BP was considered elevated if systolic BP was ≥120 mmHg or diastolic BP was ≥80 mmHg or if use of antihypertensive medications was self-reported. A maximal cardiopulmonary exercise test with BP measurements was performed by participants in 2008-2009, and exercise BP was considered exaggerated (EEBP) if peak systolic blood pressure exceeded 210 mmHg in men and 190 mmHg in women.

RESULTS

Participants with consistently high BP from childhood to adulthood and individuals with normal childhood but high adulthood BP had an increased risk of EEBP response in adulthood (relative risk [95% confidence interval], 3.32 [2.05-5.40] and 3.03 [1.77-5.17], respectively) in comparison with individuals with normal BP both in childhood and adulthood. Interestingly, individuals with elevated BP in childhood but not in adulthood also had an increased risk of EEBP [relative risk [95% confidence interval], 2.17 [1.35-3.50]).

CONCLUSIONS

These findings reinforce the importance of achieving and sustaining normal blood pressure from childhood through adulthood.

Assessment of Endothelial and Microvascular Function in CKD: Older and Newer Techniques, Associated Risk Factors, and Relations with Outcomes

BACKGROUND

Endothelium is the inner cellular lining of the vessels that modulates multiple biological processes including vasomotor tone, permeability, inflammatory responses, hemostasis, and angiogenesis. Endothelial dysfunction, the basis of atherosclerosis, is characterized by an imbalance between endothelium-derived relaxing factors and endothelium-derived contracting factors.

SUMMARY

Starting from the semi-invasive venous occlusion plethysmography, several functional techniques have been developed to evaluate microvascular function and subsequently used in patients with CKD. Flow-mediated dilatation of the forearm is considered to be the "gold standard," while in the last years, novel, noninvasive methods such as laser speckle contrast imaging and near-infrared spectroscopy are scarcely used. Moreover, several circulating biomarkers of endothelial function have been used in studies in CKD patients. This review summarizes available functional methods and biochemical markers for the assessment of endothelial and microvascular function in CKD and discusses existing evidence on their associations with comorbid conditions and outcomes in this population. Key Messages: Accumulated evidence suggests that endothelial dysfunction occurs early in CKD and is associated with target organ damage, progression of renal injury, cardiovascular events, and mortality. Novel methods evaluating microvascular function can offer a detailed, real-time assessment of underlying phenomena and should be increasingly used to shed more light on the role of endothelial dysfunction on cardiovascular and renal disease progression in CKD.

Covid-19 Quarantine: Impact of Lifestyle Behaviors Changes on Endothelial Function and Possible Protective Effect of Beetroot Juice

The current recommendation for reducing person-to-person Coronavirus 2019 (COVID-19) transmission is social distancing, including remote work and school, and home confinement. However, confinement may cause negative feelings, such as frustration, anger, boredom, and stress, in quarantined people. Furthermore, unhealthy diet and physical inactivity behaviors are commonly linked to home confinement, leading to weight gain, metabolic disorders, smoking, and exacerbated alcohol consumption. As a result, these unhealthy behaviors are typically linked to vascular endothelium damage (endothelial dysfunction), which is a first step for the development of cardiovascular disease (CVD). Given that CVD is the main cause of morbidity and mortality worldwide, attenuating the progression of endothelial dysfunction is very important for the control of CVD. Consuming vegetable rich in nitrate, such as beetroots, may be an effective way to prevent endothelial dysfunction. Several emerging studies have recommended beetroot juice in order to improve endothelial function in hypertensive, hypercholesterolemic individuals, as well as in those with CVD risk factors. Therefore, nitrate-rich vegetable consumption, such as beetroot, should be encouraged to be included in the diet during confinement from COVID-19 outbreaks in order to alleviate the potential negative effect of home confinement on cardiovascular health.

Measurement and Changes in Cerebral Oxygenation and Blood Flow at Rest and During Exercise in Normotensive and Hypertensive Individuals

PURPOSE OF REVIEW

Summarize the methods used for measurement of cerebral blood flow and oxygenation; describe the effects of hypertension on cerebral blood flow and oxygenation.

RECENT FINDINGS

Information regarding the effects of hypertension on cerebrovascular circulation during exercise is very limited, despite a plethora of methods to help with its assessment. In normotensive individuals performing incremental exercise testing, total blood flow to the brain increases. In contrast, the few studies performed in hypertensive patients suggest a smaller increase in cerebral blood flow, despite higher blood pressure levels. Endothelial dysfunction and increased vasoconstrictor concentration, as well as large vessel atherosclerosis and decreased small vessel number, have been proposed as the underlying mechanisms. Hypertension may adversely impact oxygen and blood delivery to the brain, both at rest and during exercise. Future studies should utilize the newer, noninvasive techniques to better characterize the interplay between the brain and exercise in hypertension.

Exploring the Association between Vascular Dysfunction and Skeletal Muscle Mass, Strength and Function in Healthy Adults: A Systematic Review

Background: The prevalence of vascular dysfunction increases with advancing age, as does the loss of muscle mass, strength and function. This systematic review explores the association between vascular dysfunction and skeletal muscle health in healthy adults. Methods: EMBASE and MEDLINE were searched for cross-sectional and randomized controlled studies between January 2009 and April 2019, with 33 out of 1246 studies included based on predefined criteria. Assessments of muscular health included muscle mass, strength and function. Macrovascular function assessment included arterial stiffness (pulse wave velocity or augmentation index), carotid intima-media thickness, and flow-mediated dilation. Microvascular health assessment included capillary density or microvascular flow (contrast enhanced ultrasound). Results: All 33 studies demonstrated a significant association between vascular function and skeletal muscle health. Significant negative associations were reported between vascular dysfunction and -muscle strength (10 studies); -mass (9 studies); and -function (5 studies). Nine studies reported positive correlations between muscle mass and microvascular health. Conclusions: Multiple studies have revealed an association between vascular status and skeletal muscle health in healthy adults. This review points to the importance of screening for muscle health in adults with vascular dysfunction with a view to initiating early nutrition and exercise interventions to ameliorate functional decline over time.

Is flow-mediated dilatation associated with near-infrared spectroscopy-derived magnitude of muscle O2 desaturation in healthy young and individuals at risk for cardiovascular disease?

Vascular occlusion test (VOT)-induced reactive hyperemia in brachial artery is crucial to flow-mediated dilation (FMD). Emerging studies have suggested that reactive hyperemia depends on the magnitude of the O₂ desaturation (ischemia) in downstream microvessels. Although near-infrared spectroscopy-derived tissue O₂ saturation index (TSI) has been used to assess the magnitude of ischemia, the association between FMD and the magnitude of O₂ desaturation has not been addressed. Therefore, the aim of the present study was to evaluate whether FMD correlates with the magnitude of muscle O₂ desaturation in healthy young individuals and older adults at risk for cardiovascular disease (CVD). Twenty healthy young individuals and 20 others at risk for CVD participated in the study. The magnitude of ischemic stimulus was determined by calculating the area under curve of TSI signal over 5 min of cuff occlusion period. Oxygen resaturation rate was calculated as the upslope of the TSI signal over 10 s following cuff deflation. There was no significant correlation between FMD and the magnitude of ischemic stimulus in both groups assessed (young: R = 0.327; P = 0.159 and older: R = -0.184; P = 0.436). However, a significant correlation between the magnitude of O₂ desaturation and O₂ resaturation rate in young (R = 0.555; P = 0.011) and older individuals at risk for CVD (R = 0.539; P = 0.014). In conclusion, FMD response did not correlate with the magnitude of muscle O₂ desaturation, although it seems to be partially associated with O₂ resaturation rate.

No effect of fitness on brachial or forearm vascular function during acute inflammation in young adults

Acute inflammation is associated with increased risk of cardiovascular events and impaired vasodilatory capacity. Vasodilatory capacity can be measured in different segments of the arterial tree; however, it is unknown if the effects of acute inflammation are vascular segment-specific or if inflammation-induced dysfunction can be attenuated by factors that modulate cardiovascular risk, such as high cardiorespiratory fitness. The purpose of this study was to determine the effect of acute inflammation and fitness on conduit artery, resistance artery, and microvascular function in healthy, young adults. Vascular function was assessed at baseline and 24 h after a typhoid vaccination in 11 low-fit (5 male, 24 yr of age, 34.5 ± 2.9 ml·kg^-1·min^-1 peak O₂ uptake (V̇o_2peak)] and 12 high-fit (7 male, 27 yr of age, 56.4 ± 9.7 ml·kg^-1·min^-1 V̇o_2peak) young adults. Vascular assessments included flow-mediated dilation (FMD) of the brachial artery, forearm reactive hyperemia (RH) via venous occlusion plethysmography, and near-infrared spectroscopy (NIRS) during a 5-min arterial occlusion. Acute inflammation was evident with increases in IL-6 and C-reactive protein (P < 0.01), and mean arterial pressure did not change (P = 0.33). FMD was lower in the high-fit group, yet it was reduced in both groups at 24 h, even after controlling for shear (P < 0.05). No effect of acute inflammation was observed for RH or NIRS (P > 0.05). Acute inflammation had nonuniform effects on vascular function throughout the arterial tree in young adults, and fitness did not alter the vascular response. This suggests that cardiorespiratory fitness may not protect the vasculature during acute inflammation in young adults in the absence of age- or disease-related decline in vascular function.

The effects of the analysis strategy on the correlation between the NIRS reperfusion measures and the FMD response

This study aimed to investigate the correlation between near-infrared spectroscopy (NIRS)-derived measures of microvascular responses using a range of different analysis and flow-mediated dilation (FMD). Additionally, we aimed to investigate whether assessing NIRS and FMD simultaneously or non-simultaneously would affect this association. Thirty-five healthy young individuals (26 ± 13 years old) participated in the study. Twenty were submitted to a simultaneous NIRS/FMD test (NIRS probe placed below the cuff during FMD test) and fifteen to a non-simultaneous FMD and NIRS intervention (NIRS test performed 20 min after FMD). NIRS-derived oxygen saturation signal (StO₂) during reperfusion was analyzed as follow: upslope of a 10 s (slope 10 s) and 30 s (slope 30 s) reperfusion window immediately following cuff deflation, time for the StO₂ to reach the pre-occlusion ₍baseline) values after cuff release (time to baseline) and to reach the peak after cuff release (time to max), difference between the minimum and maximum StO₂ value reached after cuff deflation (Magnitude) and; the total area under the reperfusion curve above the baseline value until the end of the 2 min post cuff release (AUC 2 min). There was a significant positive correlation between slope 10 s and FMD in the simultaneous (r = 0.60; p < 0.05) and non-simultaneous (r = 0.62; p < 0.05) assessments. There was no significant correlation between NIRS-derived slope 30 s, time to baseline, time to max, magnitude, and AUC 2 min and the FMD in both methods. The association between NIRS and FMD is analysis strategy dependent, regardless if assessed simultaneously or non-simultaneously.

The effects of aging and cardiovascular risk factors on microvascular function assessed by near-infrared spectroscopy

This study aimed to evaluate whether NIRS-derived reperfusion rate would detect potential differences in the forearm microvascular responsiveness between young healthy adults, and older adults free from or with cardiovascular disease (CVD) risk factors. Fifteen healthy young (age: 24.8 ± 4.0 years), seventeen older adults free of CVD risk factors (age: 67.0 ± 6.8 years), and twenty-three older adults with CVD risk factors (age: 67.9 ± 8.0 years) participated this study. Individuals underwent a blood draw and vascular occlusion test (30 s of baseline, 5 min of occlusion, and 2 min of reperfusion) and microvascular responsiveness was evaluated by using NIRS-derived tissue oxygen saturation indexes during reperfusion. A significant slower reperfusion rate and lower reperfusion magnitude was observed in older adults with CVD risk factors compared to healthy young and older adults. Although no statistical differences were found between healthy young and older individuals, there was a small (d = 0.4) effect size for reperfusion rate and moderate (d = 0.7) effects size for reperfusion magnitude when comparing these groups. In conclusion, this study demonstrated that even though the effects of aging per se on microvascular function should not be completely neglected, the CVD risk factors seem to be determinant on microvascular responsiveness impairment associated with aging.

Effects of ischaemic conditioning on tissue oxygen saturation and heart rate variability: an observational study

Objective

Ischaemic conditioning (IC) has organ-protective effects, but its clinical results have been inconsistent. Tissue oxygen saturation (StO₂) and heart rate variability (HRV) reflect peripheral microcirculation and autonomic nervous system activity, but their changes during IC have not been well documented. We assessed StO₂ and HRV during IC in patients undergoing cardiac surgery and healthy volunteers.

Methods

Ten patients undergoing cardiac surgery and 10 healthy male volunteers underwent remote IC (four 5-minute cycles of ischaemia/reperfusion) applied to the upper arm. Changes in StO₂ at the thenar eminence and HRV according to the R-R intervals were recorded during IC.

Results

The lowest StO₂ during ischaemia significantly decreased in patients and significantly increased in volunteers. Among the HRV parameters, the low-frequency domain, which corresponds to sympathetic activity, significantly increased after IC in volunteers but not in patients. Other variables were similar between the groups.

Conclusions

These results suggest that the minimum tissue oxygen content is depleted during ischaemia in patients and preserved in healthy volunteers. Sympathetic nervous activity seems to increase after IC in healthy volunteers but remains unaffected in patients. Thus, IC may act differently between patients undergoing cardiac surgery and healthy subjects.

The association between near-infrared spectroscopy assessment of microvascular reactivity and flow-mediated dilation is disrupted in individuals at high risk for cardiovascular disease

OBJECTIVE

This study aimed to evaluate the correlation between the NIRS-derived reperfusion slope and %FMD in the arm of healthy and at high risk for CVD individuals.

METHODS

Twelve healthy (24 ± 4 years) and twelve at high risk for cardiovascular disease (65 ± 11 years) individuals participated in the study. The individuals were submitted to a conduit artery FMD followed by a NIRS-VOT microvascular function test in the arm. Microvascular responsiveness was calculated as the forearm reperfusion slope, and macrovascular function was assessed as the percent of change in FMD (%FMD) of the brachial artery.

RESULTS

There was a significant correlation between reperfusion slope and %FMD (R = 0.61, P < 0.05) in the healthy group; however, no significant correlation between FMD and reperfusion slope (R = -0.21, P > 0.05) was found in individuals at high risk for CVD.

CONCLUSION

The correlation between NIRS-derived reperfusion slope and %FMD was disrupted in the arm of individuals at high risk for cardiovascular disease compared to healthy individuals. The findings of the present study reinforce the importance of examining vascular function at microvasculature and conduit artery level, especially in populations with risk factors for CVD.

A brief submaximal isometric exercise test 'unmasks' systolic and diastolic masked hypertension

OBJECTIVES

An exaggerated blood pressure (BP) response during dynamic exercise testing has been proposed as an additional screening tool to identify systolic masked hypertension (masked-HYP). However, masked-HYP in young people is often characterized by an elevated DBP. Static/isometric exercise elicits augmented sympathetic stimulation causing greater increases in both SBP and DBP than dynamic exercise.

AIMS

To examine whether individuals with masked-HYP exhibit exaggerated BP responses during a submaximal handgrip vs. normotensive individuals and individuals with sustained hypertension (true-HYP), and the possible associations of exercise BP with total peripheral resistance (TPR), central/aortic BP, and 24-h-ambulatory BP (24-h BP).

METHODS

Eighty-six participants [untreated, newly diagnosed, masked-HYP (n = 27), true-HYP (n = 31), and normotensive individuals (n = 28); 46.3 ± 10.7 years], following evaluation of office BP, central/aortic BP, pulse wave velocity, carotid intima-media thickness, echocardiocardiography, and 24-h BP, underwent a 3-min handgrip (30% maximal voluntary contraction) with beat-by-beat BP and hemodynamics assessment (Finapres Medical Systems).

RESULTS

Despite similar baseline-BP in masked-HYP and normotensive individuals, during exercise masked-HYP exhibited a markedly greater (P < 0.01) SBP and DBP vs. normotensive individuals, and similar BP to true-HYP. TPR significantly increased (P < 0.001) during exercise, in masked-HYP and true-HYP. The exaggerated BP responses in masked-HYP were evident from the 1st minute of exercise and correlated (P < 0.05) with central/aortic-BP, aortic stiffness, 24-h BP, day-BP, night-time-BP, and interventricular septum thickness.

CONCLUSION

During handgrip, masked-HYP exhibited exaggerated BP and TPR responses, similar to those of true-HYP. These responses were evident from the 1st minute of exercise and correlated with 24-h BP, suggesting that systolic and diastolic masked-HYP can be 'unmasked' during a brief, submaximal, handgrip test.