Postocclusive Reactive Hyperemia Research Articles

Does the Endothelium of Competitive Athletes Benefit from Consumption of n-3 Polyunsaturated Fatty Acid-Enriched Hen Eggs?

The present study aimed to determine the effect of n-3 polyunsaturated fatty acid (PUFA)-enriched hen eggs on microvascular vasodilation, microvascular responsiveness to a stress challenge and markers of oxidative stress in competitive athletes. Competitive athletes (n=23) were divided to a control group (n=9), who consumed three regular hens’ eggs daily (249 mg n-3 PUFAs/d), and n-3 PUFAs group (n=14), who consumed three n-3 PUFA-enriched hen eggs daily (1,053 g n-3 PUFAs/d) for 3 weeks. Endothelium-dependent responses [post-occlusive reactive hyperemia (PORH) and acetylcholine-induced dilation (AChID)] and endothelium-independent responses [sodium nitroprusside-induced dilation (SNPID)] of skin microvascular blood flow were assessed by laser Doppler flowmetry in pre- and post-acute exhausting exercise (AEE) sessions. Blood pressure, serum lipid, free fatty acids profiles, and biomarkers of oxidative stress were measured before and after each dietary protocol. Consumption of serum n-3 PUFAs significantly decreased the n-6/n-3 ratio and enhanced PORH and AChID, but did not affect SNPID at rest. Furthermore, serum glutathione peroxidase and superoxide dismutase activities were significantly decreased in the n-3 PUFAs group but remained unchanged in the control group. In both groups, PORH, AChID, and SNP were significantly reduced post-AEE compared with pre-AEE, both before and after consumption of each diet. Only AChID responsiveness to AEE (ΔAChID) significantly increased following consumption of n-3 PUFAs. Overall, n-3 PUFAs supplementation as n-3 PUFA-enriched hen eggs enhanced microvascular endothelial function at rest and may contribute to adaptation to AEE in competitive athletes.

Does aging alter skin vascular function in humans when spatial variation is considered?

Reports evaluating age-related impairments in cutaneous vascular function assessed by either the venoarteriolar reflex (VAR) induced by venous congestion, or post-occlusive reactive hyperemia (PORH) activated by arterial occlusion, have yielded mixed findings. This may be due to region-specific variability that occurs when assessing local cutaneous vascular responses. We evaluated the hypothesis that aging attenuates VAR and PORH responses in forearm skin assessed across four adjacent sites, each separated by ~4cm to account for inter-site variability. In twenty young (24±4years, 10 females) and twenty older (60±7years, 9 females) adults, VAR and PORH were achieved by a 3-min venous occlusion and 5-min arterial occlusion, each induced by inflating a pressure cuff to 45 and 240mmHg, respectively. Cutaneous blood flow at all skin sites was measured by laser-Doppler flowmetry with the average response from all sites used for between-group comparisons. VAR and PORH responses were similar between groups with the exception that the time required to achieve peak PORH was delayed in older adults (mean difference of 5.5±4.4s, p=0.003, Cohen's d=0.812). We showed that aging had a negligible influence on VAR and PORH responses in forearm skin even when controlling for region-specific variability.

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.

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.

Cutaneous iontophoresis of vasoactive medications in patients with scleroderma-associated pulmonary arterial hypertension.

It remains unknown whether the cutaneous microvascular responses are different between patients with scleroderma-associated pulmonary arterial hypertension (SSc-PAH) and SSc without pulmonary hypertension (PH). We included 59 patients with SSc between March 2013 and September 2019. We divided patients into 4groups: (a) no PH by right heart catheterization (RHC) (n=8), (b) no PH by noninvasive screening tests (n=16), (c) treatment naïve PAH (n=16), and (d) PAH under treatment (n=19). Microvascular studies using laser Doppler flowmetry (LDF) were done immediately after RHC or at the time of an outpatient clinic visit (group b). The median (IQR) age was 59 (54-68) years, and 90% were females. The responses to local thermal stimulation and postocclusive reactive hyperemia, acetylcholine, and sodium nitroprusside iontophoresis were similar among groups. The microvascular response to treprostinil was more pronounced in SSc patients without PH by screening tests (% change: 340 (214-781)) compared with SSc-PAH (naïve+treatment) (Perfusion Units (PU) % change: 153 (94-255) % [p=.01]). The response to A-350619 (a soluble guanylate cyclase (sGC) activator) was significantly higher in patients with SSc without PH by screening tests (PU % change: 168 (46-1,296)) than those with SSc-PAH (PU % change: 22 (15-57) % [p=.006]). The % change in PU with A350619 was directly associated with cardiac index and stroke volume index (R: 0.36, p=.03 and 0.39, p=.02, respectively). Patients with SSc-PAH have a lower cutaneous microvascular response to a prostacyclin analog treprostinil and the sGC activator A-350619 when compared with patients with SSc and no evidence of PH on screening tests, presumably due to a peripheral reduction in prostacyclin receptor expression and nitric oxide bioavailability.

Abstract 13944: Young, Non-Hispanic Black Males and Females Exhibit Divergent Peripheral and Cerebral Vascular Reactivity

Introduction: In the U.S., cardiovascular and cerebrovascular diseases (CVD) remain more prominent in non-Hispanic black individuals than in other populations. Across most racial/ethnic groups, total CVD prevalence is ~10% lower in females; however, total CVD prevalence in black females (BF) is similar to that of black males (BM). Conversely, BM have ~23% higher age-adjusted stroke mortality compared to BF, a pattern not seen in other groups. While the mechanisms behind these race-by-sex differences are multifactorial, vascular dysfunction likely contributes. Our group and others have demonstrated reduced brachial artery and cerebrovascular vasodilation in black versus white individuals, though much of this work did not specifically address sex differences. To this end, we have recently investigated and reported divergent mechanisms of reduced cutaneous microvascular function in BM and BF; however, more work is needed to better understand whether such findings extend to other vascular regions. Hypothesis: We tested the hypothesis that BF and BM would have divergent degrees of reduced peripheral and cerebral vasodilator responsiveness. Methods: Eleven BF and 15 BM (22 ± 4 vs. 23 ± 3 yrs) underwent testing for brachial artery flow-mediated dilation (FMD; conduit artery function) and post-occlusive reactive hyperemia (PORH; microvascular function), along with cerebrovascular reactivity (CVR) to rebreathing-induced hypercapnia. Results: FMD was greater in BF versus BM (9.10 ± 3.49 vs. 5.84 ± 2.78%; P = 0.02), even when normalized to baseline diameter or shear rate ( P &lt; 0.05 for both). BF had similar PORH when assessed as peak blood velocity (77.1 ± 19.9 vs. 79.4 ± 19.6 cm • s -1 ; P &gt; 0.05) but lower peak blood flow (343.6 ± 169.8 vs. 495.4 ± 196.9 mL/min; P &lt; 0.05) and blood flow AUC (133.6 ± 61.1 vs. 220.3 ± 130.7 mL; P = 0.04) relative to BM. CVR was greater in BF versus BM (0.024 ± 0.010 vs. 0.012 ± 0.006 cm • s -1 • mmHg -1 • mmHg -1 ; P &lt; 0.01). Conclusion: These data suggest that young, BM have lower vascular reactivity than BF during some, but not all, tests of vascular function. More work in this area is needed to better understand the potential biological and social mechanisms influencing sex differences in vascular function and CVD risk in black individuals.

Oral Glucose Load and Human Cutaneous Microcirculation: An Insight into Flowmotion Assessed by Wavelet Transform.

Simple SummaryThere is increasing evidence to suggest that microcirculation becomes dysfunctional earlier than large blood vessels or the heart in several diseases. In diabetes mellitus, a disease characterized by chronic hyperglycemia, microvascular impairment is well-established; on the contrary, the effect of acute hyperglycemia in microcirculation remains unclarified. Our aim was to investigate the microvascular effect of an oral glucose load (OGL) using laser Doppler flowmetry (LDF) as a perfusion quantification technique, coupled with wavelet transform (WT) to perform a spectral decomposition of the LDF signal. On two distinct occasions (pre-load and post-load), sixteen healthy subjects drank either a standard glucose solution or water. Perfusion was assessed by LDF and WT while resting and during post-occlusive reactive hyperemia (PORH), evoked by a transient three-min occlusion of the brachial artery, in the forearm and the finger pulp. The OGL affected microcirculation in both sites compared to water, significantly blunting the PORH response in the forearm. The WT revealed significant differences in the cardiac and sympathetic components after OGL between the pre-load and post-load periods. These results suggest that an OGL induces a short-term subtle microvascular impairment, probably involving a modulation of the sympathetic nervous system.Microcirculation in vivo has been assessed using non-invasive technologies such as laser Doppler flowmetry (LDF). In contrast to chronic hyperglycemia, known to induce microvascular dysfunction, the effects of short-term elevations in blood glucose on microcirculation are controversial. We aimed to assess the impact of an oral glucose load (OGL) on the cutaneous microcirculation of healthy subjects, quantified by LDF and coupled with wavelet transform (WT) as an interpretation tool. On two separate occasions, sixteen subjects drank either a glucose solution (75 g in 250 mL water) or water (equal volume). LDF signals were obtained in two anatomical sites (forearm and finger pulp) before and after each load (pre-load and post-load, respectively), in resting conditions and during post-occlusive reactive hyperemia (PORH). The WT allowed decomposition of the LDF signals into their spectral components (cardiac, respiratory, myogenic, sympathetic, endothelial NO-dependent). The OGL blunted the PORH response in the forearm, which was not observed with the water load. Significant differences were found for the cardiac and sympathetic components in the glucose and water groups between the pre-load and post-load periods. These results suggest that an OGL induces a short-term subtle microvascular impairment, probably involving a modulation of the sympathetic nervous system.

The Role of Cutaneous Microcirculatory Responses in Tissue Injury, Inflammation and Repair at the Foot in Diabetes.

Diabetic foot syndrome is one of the most costly complications of diabetes. Damage to the soft tissue structure is one of the primary causes of diabetic foot ulcers and most of the current literature focuses on factors such as neuropathy and excessive load. Although the role of blood supply has been reported in the context of macro-circulation, soft tissue damage and its healing in the context of skin microcirculation have not been adequately investigated. Previous research suggested that certain microcirculatory responses protect the skin and their impairment may contribute to increased risk for occlusive and ischemic injuries to the foot. The purpose of this narrative review was to explore and establish the possible link between impairment in skin perfusion and the chain of events that leads to ulceration, considering the interaction with other more established ulceration factors. This review highlights some of the key skin microcirculatory functions in response to various stimuli. The microcirculatory responses observed in the form of altered skin blood flow are divided into three categories based on the type of stimuli including occlusion, pressure and temperature. Studies on the three categories were reviewed including: the microcirculatory response to occlusive ischemia or Post-Occlusive Reactive Hyperaemia (PORH); the microcirculatory response to locally applied pressure such as Pressure-Induced Vasodilation (PIV); and the interplay between microcirculation and skin temperature and the microcirculatory responses to thermal stimuli such as reduced/increased blood flow due to cooling/heating. This review highlights how microcirculatory responses protect the skin and the plantar soft tissues and their plausible dysfunction in people with diabetes. Whilst discussing the link between impairment in skin perfusion as a result of altered microcirculatory response, the review describes the chain of events that leads to ulceration. A thorough understanding of the microcirculatory function and its impaired reactive mechanisms is provided, which allows an understanding of the interaction between functional disturbances of microcirculation and other more established factors for foot ulceration.

Microvascular Reactivity of Peri-implant Mucosa in Humans: Effect of Abutment Material.

The morphology and histology of the soft tissue around the implant are different from the periodontal tissue, but the difference in the regulation of blood flow is not known. The aim of the study was to compare the resting blood flow and the vasodilatation capacity of the gingiva between implants and teeth. Twenty-six healthy volunteers with single-tooth implants were involved. The implant-borne crown was retained on either a zirconia or titanium abutment. The vasodilatation capacity of the gingiva was assessed by a postocclusive reactive hyperemia test. Blood flow was measured by a laser speckle contrast imager at the buccal gingiva of the implant-borne crown and an analog natural tooth. No significant differences in baseline gingival blood flow were observed between the different abutments and the teeth in either region. The hyperemia after compression was significantly attenuated at the zirconia abutments in all regions during the entire investigation period (20 minutes) compared to the titanium abutments and the teeth. No differences were observed between titanium abutments and the teeth. The resting microcirculation seems to be the same at implants and teeth. However, the vascular reactivity might be disturbed at the zirconia, but not at the titanium, abutment.

Effects of n-3 Polyunsaturated Fatty Acid-Enriched Hen Egg Consumption on the Inflammatory Biomarkers and Microvascular Function in Patients with Acute and Chronic Coronary Syndrome—A Randomized Study

Simple SummaryThere is a strong potential of n-3 polyunsaturated fatty acid (n-3 PUFA) consumption to reduce cardiovascular risk and prevent adverse outcomes in existing cardiovascular diseases. This study aimed to test the effect of n-3 PUFA supplementation in the form of enriched hen eggs on serum lipid and free fatty acid profiles, inflammatory and oxidative stress biomarkers, and microvascular reactivity in patients with acute and chronic coronary artery disease. Consumption of three n-3 PUFA-enriched hen eggs for three weeks had a favorable effect on serum free fatty acid profile (a lower n-6/n-3 PUFA ratio) and mild anti-inflammatory effects but did not significantly affect microvascular reactivity in patients with coronary artery disease. Because consumption of both regular and n-3 PUFA eggs had no negative effects on any of the measured biological and functional vascular parameters, the results of the present study indicate that eggs can be safely consumed in the daily diet of patients with coronary artery disease.This study aimed to test the effect of n-3 polyunsaturated fatty acid (PUFA)-enriched hen egg consumption on serum lipid and free fatty acid profiles, inflammatory and oxidative stress biomarkers, and microvascular reactivity in patients with coronary artery disease (CAD). Forty CAD patients participated in this study. Of those, 20 patients had acute CAD (Ac-CAD), and 20 patients had chronic CAD (Ch-CAD). The control group (N = 20) consumed three regular hen eggs/daily (249 mg n-3 PUFAs/day), and the n-3 PUFAs group (N = 20) consumed three n-3 PUFA-enriched hen eggs/daily (1053 g n-3 PUFAs/day) for 3 weeks. Serum n-3 PUFA concentration significantly increased (in all CAD patients), while LDL cholesterol and IL-6 (in Ac-CAD patients), and hsCRP and IL-1a (in all CAD patients) significantly decreased in the n-3 PUFAs group. Glutathione peroxidase (GPx) activity significantly decreased, and forearm skin microvascular reactivity in response to vascular occlusion (postocclusive reactive hyperemia (PORH)) remained unchanged in both the n-3 PUFAs and control groups in total CAD, Ac-CAD, and Ch-CAD patients. Potentially, n-3 PUFA-enriched hen eggs can change the free fatty acid profile to a more favorable lower n6/n3 ratio, and to exhibit mild anti-inflammatory effects but not to affect microvascular reactivity in CAD patients.

Type 2 diabetes impairs vascular responsiveness to nitric oxide, but not the venoarteriolar reflex or post-occlusive reactive hyperaemia in forearm skin.

The venoarteriolar reflex (VAR) is a local mechanism by which vasoconstriction is mediated in response to venous congestion. This response may minimize tissue overperfusion, preventing capillary damage and oedema. Post-occlusive reactive hyperaemia (PORH) is used to assess microvascular function by performing a brief local arterial occlusion resulting in a subsequent rapid transient vasodilation. In the current study, we hypothesized that type 2 diabetes (T2D) attenuates VAR and PORH responses in forearm skin in vivo. In 11 healthy older adults (Control, 58±8years) and 13 older adults with controlled T2D (62±10years), cutaneous blood flow measured by laser-Doppler flowmetry was monitored following a 3-min venous occlusion of 45mmHg that elicited the VAR, followed by a 3-min recovery period and then a 5-min arterial occlusion of 240mmHg that induced PORH. Finally, sodium nitroprusside, a nitric oxide donor, was administered to induce maximum vasodilation. VAR and PORH variables were similar between groups. By contrast, maximal cutaneous blood flow induced by sodium nitroprusside was lower in the T2D group. Taken together, our observations indicate that T2D impairs vascular smooth muscle responsiveness to nitric oxide, but not VAR and PORH in forearm skin.

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.

A systematic evaluation of cutaneous microcirculation in the foot using post-occlusive reactive hyperemia.

Cutaneous microcirculatory impairments are associated with skin injury to the foot. Post-Occlusive reactive hyperemia (PORH) is one of the quick and easy methods to assess microcirculatory function. However, there are variations in the protocols currently used. Hence, this study aimed to systematically investigate the reproducibility of PORH protocols with minimal occlusion time in the foot. Post-Occlusive reactive hyperemia was measured using 12 different protocols (three occlusion times, two occlusion sites and with or without temperature control) in 25 healthy adults. Each of the 12 different protocols was repeated three times, and the intraclass correlation coefficient (ICC) was calculated. Intraclass correlation coefficient showed that that ankle level occlusion produced moderate to excellent reproducibility for most PORH measures. In the right foot, 30- and 60-s ankle level occlusion without temperature control showed ICC of >0.40 for all parameters except the area of hyperemia (ICC=-0.36) and biological zero to peak flow percent change (ICC=-0.46). In the left foot, 30-s ankle level occlusion without temperature control showed ICC of >0.40 for all parameters except time to latency (ICC=0.29), after hyperemia (ICC=0.37), and max (ICC=-0.01), and area of hyperemia (ICC=-0.36). But the 60-s protocol showed ICC>0.40 for all except time to max (ICC=0.38). In the hallux protocols, all three 10-, 30-, and 60-s protocols without temperature control showed moderate to excellent reproducibility (ICC>0.40). In most cases, the temporal and area under the perfusion-time curve parameters showed poor reproducibility. Post-Occlusive reactive hyperemia can be tested efficiently with a minimal occlusion time of 10s with hallux occlusion and 30s with ankle occlusion in the foot. This can suggest that microcirculatory assessment is feasible in routine practice and can potentially be included for routine assessment of foot in people with diabetes.

ASSESSMENT OF MICROVASCULAR REACTIVITY IN RANDOMLY SELECTED ADULT POPULATION EHUH STUDY CROATIAN SCIENTIFIC FOUNDATION

Objective: To assess the forearm skin microvascular reactivity and anthropometric parameters in randomly selected population and seek the differences between a group of people who had elevated blood pressure at the time of measurement and those who were normotensive. Design and method: Total of 148 randomly selected individuals (50 men/98 women) participated in this study. The exclusion criteria were less than 1l of urine collected at 24 h, and creatinine values below the reference values. Forthy eight individuals included in this study had arterial hypertension (HT) and 44 had normal arterial blood pressure values (NT). Post-occlusive reactive hyperemia (PORH) in skin microcirculation following 1 minute of vascular occlusion period was assessed using laser Doppler flowmetry. Anthropometric parameters, blood pressure, heart rate were measured, and 24-hour urine was collected to sodium excretion and creatinine measurement. P &lt; 0,05 was considered statistically significant. Results: Sistolic (SBP), diastolic (DBP) and mean (MAP) arterial blood pressure were significantly higher, while PORH was significantly lower in HT group compared to NT individuals. HT had higher body mass index (BMI) and waist circumference, while there were no differences in heart rate between HT and NT group. In HT individuals, PORH was negatively associated with waist circumference (r = -0,438), and positively associated with heart rate (r = 0,316). Sodium excretion was positively associated with DBP (r = 0,361). In NT group, PORH was negatively associated with SBP (r = -0,362) and MAP (r = -0,37). SBP and MAP were positively associated with BMI (r = 0,484,r = 0,312) and waist circumference (r = 0,421,r = 0,319). Sodium excretion was positively associated with BMI (r = 0,546) and waist circumference (r = 0,523). Analyzes of all individuals together showed that PORH was negatively associated with BMI (r = -0,253), SBP (r = -0,274) and MAP (r = -0,24), while BMI was positively associated with SBP (r = 0,359), DBP (r = 0,219) and MAP (r = 0,312). Conclusions: High blood pressure attenuated microvascular function. Arterial blood pressure is related to obesity (BMI, waist circumference).

MASKED HYPERTENSIVES AS ASSESSED WITH LASER SPECKLE CONTRAST IMAGING EXHIBIT IMPAIRED SKIN MICROVASCULAR REACTIVITY SIMILAR TO ESSENTIAL HYPERTENSIVE INDIVIDUALS

Objective: Laser Speckle Contrast Imaging (LSCI) is a novel method to dynamically assess skin microcirculation with very high resolution and reproducibility compared to other laser methods. Skin microcirculation has been proposed as a model of generalized microvascular function and a potential biomarker in cardiovascular prognosis. Masked hypertension is considered a hypertension phenotype of substantial cardiovascular risk similar to essential hypertension (EH). In this study we evaluated skin microvascular reactivity in masked hypertensives as compared to hypertensives and healthy, normotensive individuals using LSCI coupled with post-occlusive reactive hyperemia (PORH) test. Design and method: We included 20 newly diagnosed masked hypertensives aged 50.0 ± 9.0 and compared them to 70 never treated, newly diagnosed patients with EH aged 49.5 ± 8.7 and 40 healthy, normotensive individuals aged 48.5 ± 8.5 years. Hypertension phenotypes were defined according to standard office and ambulatory blood pressure monitoring (ABPM) criteria. The Mobil-O-Graph-NG (IEM, Stolberg, Germany) device was used for ABPM. All subjects underwent forearm skin perfusion recording under standardized conditions using a LSCI device (PeriCam PSI NR System, Perimed, Järfälla, Sweden) coupled with PORH. Data were analyzed by manufacturer's software (PIMSoft, Perimed). Results were expressed as i) the percentage increase of perfusion from baseline to peak condition (%), and ii) the amplitude of PORH response expressed as the peak cutaneous vascular conductance (CVC) minus baseline CVC. The CVC was calculated as the flux of each time interval divided by mean arterial pressure (perfusion units [PU]/mmHg). Results: Masked hypertensives showed significantly lower percentage increase of perfusion from baseline to peak condition as compared to controls (155.4 ± 48.11 vs 190.54 ± 45.88, p = 0.013) but not compared to hypertensives (155.4 ± 48.11 vs 150.6 ± 41.93, p = NS), respectively. In addition, PORH amplitude was significantly lower in masked hypertensives as compared to controls (0.62 ± 0.2 vs 0.76 ± 0.2, p = 0.02) but no difference was found compared to hypertensives (0.62 ± 0.2 vs 0.52 ± 0.1, p = NS), respectively. Conclusions: Masked hypertensives, when assessed with LSCI coupled with PORH, present impaired skin microvascular reactivity as compared to healthy controls. However, their skin microvascular responses were similar to those of hypertensives, highlighting a state of increased microvascular damage in this hypertension phenotype.

NAIL CAPILLARY DENSITY DURING POSTOCCLUSIVE REACTIVE HYPEREMIA AND VENOUS CONGESTION IS MORE IMPAIRED IN DIABETIC COMPARED TO NON-DIABETIC CKD PATIENTS

Objective: Alterations in endothelial function and capillary circulation have been associated with increased cardiovascular events and overall mortality. Both diabetes mellitus (DM) and chronic kidney disease (CKD) have been associated with microcirculatory damage. Nailfold video-capillaroscory can provide a thorough assessment of capillary density and microcirculation changes. This is the first study examining in comparison microcirculatory function parameters in diabetic and non-diabetic patients with CKD. Design and method: We included 48 diabetic and 48 non-diabetic adult patients (&gt;18 years) with CKD (eGFR: &lt; 90 and &gt; 15 mL/min/1.73m2), matched in a 1:1 ratio for age, sex and eGFR within each CKD stage (2, 3a, 3b and 4). All participants underwent nailfold video-capillaroscopy, during which capillary density was measured at normal conditions (baseline), after a 4-minute arterial occlusion (postocclusive reactive hyperemia) and at the end of a 2-minute venous occlusion (congestion phase). Results: Baseline demographic, anthropometric and laboratory characteristics were similar between patients with and without diabetes in total and in CKD stages. Overall, no significant differences at baseline capillary density were observed between groups; however diabetic patients presented significantly lower capillary density during reactive hyperemia (36.3 ± 3.8 vs 38.3 ± 4.3 capillaries/mm2, p = 0.022) and at venous congestion (37.8 ± 4.0 vs 39.8 ± 4.2 capillaries/mm2, p = 0.015). When stratified according to CKD stages, the between-group differences in parameters of interest were not significant in stages 2, 3a and 4. In stage 3b, capillary density was significantly lower in diabetic compared to non-diabetic subjects at baseline (31.1 ± 2.8 vs 33.4 ± 3.4 capillaries/mm2, p = 0.044), during postocclusive hyperemia (36.8 ± 2.7 vs 40.0 ± 4.3 capillaries/mm2, p = 0.037) and venous congestion (38.3 ± 2.8 vs 41.5 ± 3.5 capillaries/mm2, p = 0.022). Conclusions: Capillary density during postocclusive reactive hyperemia and after venous congestion is lower in diabetic compared to non-diabetic CKD patients, a finding indicative that diabetes is an additional factor contributing to microcirculatory functional impairment in CKD. These differences are more prominent in CKD stage 3b, and less prominent in earlier and later stages.

N-3 POLYUNSATURATED FATTY ACIDS ENRICHED HEN EGGS CONSUMPTION ENHANCES MICROVASCULAR ENDOTHELIAL FUNCTION IN PROFESSIONAL ATHLETES

Objective: We reported previously that consumption of n-3 polyunsaturated fatty acids (n-3 PUFAs) enriched hen eggs (777 mg of n-3 PUFAs per day for three weeks) enhances forearm skin microvascular reactivity to vascular occlusion (post occlusion reactive hyperemia; PORH), and decreases arterial blood pressure (BP), serum triglycerides and high sensitivity C reactive protein (hsCRP) level in healthy individuals. Present study aimed to determine the effect of n-3 PUFAs enriched hen eggs consumption on microvascular reactivity in professional athletes. Design and method: 23 young healthy professional athletes (3 women and 20 men, age ranged 18–28 years) have consumed three standard hen eggs per day (249 mg of n-3 PUFAs/day) (Control group) or three n-3 PUFAs enriched hen eggs per day (1053 mg of n-3 PUFAs/day) (n-3 PUFA group) for three weeks. Forearm skin microvascular blood flow in response to vascular occlusion (PORH) and iontophoresis of acetylcholine (ACh) (endothelium-dependent vasodilation) and sodium nitroprusside (SNP) (endothelium-independent vasodilation) were assessed using laser Doppler flowmetry before and after diet protocols. Body mass index (BMI), waist-to-hip ratio (WHR), BP, fasting lipid panels, fasting blood glucose (fBG) and hsCRP were measured in all subjects before and after diet protocols. Results: BMI, WHR, BP, fasting lipid panels, fBG and hsCRP were not significantly changed after consumption of either eggs compared to baseline measurements within n-3 PUFAs or Control group. Consumption of n-3 PUFAs eggs significantly improved PORH and ACh-induced dilation (AChID) compared to baseline measurement within n-3 PUFAs group. Contrary, consumption of standard eggs did not induce any significant change in PORH and AChID compared to baseline in Control group. SNP-induced dilation was similar before and after respective diet protocol in both Control and n-3 PUFA groups. Conclusions: This is the first study to demonstrate that consumption of n-3 PUFAs enriched functional food (hen eggs) for three weeks enhances skin endothelium-dependent microvascular reactivity in professional athletes. This result provides foundation for future investigation of potential mechanisms by which n-3 PUFAs could improve endothelial function, and overall vascular adaptation to regular physical activity in professional athletes.

CAPILLARY DENSITY DURING POSTOCCLUSIVE REACTIVE HYPEREMIA AND VENOUS CONGESTION DETERIORATES WITH ADVANCING CKD STAGES

Objective: Cardiovascular disease is the main cause of mortality in CKD patients. Endothelial dysfunction and capillary rarefaction are established cardiovascular risk factors. Nailfold video-capillaroscory provides a thorough assessment of capillary density and microcirculation changes. The aim of this study is to examine structural and functional capillary density in CKD patients of stages 2 to 4. Design and method: A total of 96 CKD patients were included in the study. The population consisted of 4 equal groups according to CKD stage (2, 3a, 3b and 4). All patients underwent nailfold video-capillaroscopy, during which capillary density was measured at baseline, after a 4-minute arterial occlusion (postocclusive reactive hyperemia) and at the end of a 2-minute venous occlusion (congestion phase). Arterial stiffness and arterial wave parameters were measured with applanation tonometry and common carotid intima-media thickness (IMT) with a 2D ultrasound device. Results: Capillary density at baseline showed a progressive reduction with advancing CKD stages (stage 2: 32.63 ± 2.79, stage 3a: 31.23 ± 3.84, stage 3b: 32.48 ± 3.34, stage 4: 28.50 ± 3.09, p &lt; 0.001). Similar reductions were observed in capillary density during postocclusive hyperemia (39.42 ± 3.00, 37.63 ± 4.24, 38.35 ± 3.83, and 33.77 ± 3.34, respectively, p &lt; 0.001) and after venous congestion (41.10 ± 3.09, 39.02 ± 4.41, 39.90 ± 3.51, and 35.21 ± 3.40, p &lt; 0.001). Office pulse wave velocity showed a non-significant increasing trend with advancing CKD, but carotid IMT did not. In multivariate regression analysis, eGFR showed a positive association (per ml/min increase; OR: 0.053, 95%CI: 0.004 to 0.101), whereas diabetes (OR: -1.706, 95%CI: -3.176 to -0.236), and parathormone (PTH) (per pg/ml increase; OR: -0.022, 95%CI: -0.036 to -0.008) negative associations with post-occlusive capillary density. Conclusions: Both structural and functional capillary density progressively decrease with advancing CKD stages. Apart from reduced eGFR, the presence of diabetes and increased PTH levels are independently associated with this reduction. This capillary rarefaction may play a central role in the increased burden of cardiovascular events in CKD patients.

HEMODIALYSIS AND PERITONEAL DIALYSIS PATIENTS HAVE SEVERELY IMPAIRED ENDOTHELIAL POST-OCCLUSIVE FOREARM VASODILATORY RESPONSE ASSESSED WITH LASER SPECKLE CONTRAST IMAGING

Abstract Objective: Endothelial dysfunction is associated with cardiovascular events and mortality in various disease states, including end-stage-renal-disease (ESRD). Novel technological approaches have emerged for real-time assessment of endothelial reactivity. This study examined forearm skin microcirculation using Laser Speckle Contrast Imaging (LSCI) before and after arterial occlusion in ESRD patients undergoing hemodialysis (HD) or peritoneal dialysis (PD). Design and method: Thirty-eight patients undergoing HD were matched in a 1:1 ratio with 38 PD patients (for age, sex and dialysis vintage) and 38 controls (for age and sex). Skin microvascular reactivity parameters assessed with LSCI included baseline perfusion, occlusion perfusion, and peak perfusion during post-occlusive reactive hyperemia (PORH); time to peak perfusion; proportional change from baseline to peak perfusion; baseline and peak cutaneous vascular conductance (CVC); proportional change from baseline to peak CVC; and the amplitude of the PORH response (calculated as the difference between peak and baseline CVC). Results: Baseline perfusion [HD: 46.97 ± 14.6; PD: 49.32 ± 18.07; controls: 42.02 ± 11.94 Laser-Specle-Perfusion-Units (LSPU), p = 0.097] and peak post-occlusion perfusion (104.77 ± 28.68 vs 109.04 ± 40.77 vs 116.96 ± 30.96 LSPU, p = 0.238) did not differ between groups. However, the post-occlusive vascular response was completely different, since time to peak response (HD: 7.24 ± 6.99; PD: 10.68 ± 9.45; controls: 11.11 ± 5.1 sec, p = 0.003) and the (%) increase from baseline to peak perfusion (HD: 133% ± 66; PD: 149% ± 125; controls: 187% ± 61, p = 0.001) was significantly lower in ESRD patients. ESRD patients had also lower levels of peak CVC, indicating the maximum capillary recruitment (HD: 1.05 ± 0.3; PD: 1.07 ± 0.44; controls: 1.57 ± 0.52 LSPU/mmHg, p &lt; 0.001), lower % increase of CVC at peak (p = 0.001), and lower amplitude of the PORH response (p = 0.001) (a measure of the difference between baseline and maximum capillary recruitment). Conclusions: Using this novel non-invasive technology endothelial post-occlusive skin vasodilatory response was found to be similar between HD and PD patients and significantly impaired compared to controls. Future studies are needed to assess the prognostic implications of this microcirculatory functional defect.

Reduced Endothelial Function in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome-Results From Open-Label Cyclophosphamide Intervention Study.

Introduction: Patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) present with a range of symptoms including post-exertional malaise (PEM), orthostatic intolerance, and autonomic dysfunction. Dysfunction of the blood vessel endothelium could be an underlying biological mechanism, resulting in inability to fine-tune regulation of blood flow according to the metabolic demands of tissues. The objectives of the present study were to investigate endothelial function in ME/CFS patients compared to healthy individuals, and assess possible changes in endothelial function after intervention with IV cyclophosphamide.Methods: This substudy to the open-label phase II trial “Cyclophosphamide in ME/CFS” included 40 patients with mild-moderate to severe ME/CFS according to Canadian consensus criteria, aged 18–65 years. Endothelial function was measured by Flow-mediated dilation (FMD) and Post-occlusive reactive hyperemia (PORH) at baseline and repeated after 12 months. Endothelial function at baseline was compared with two cohorts of healthy controls (N = 66 and N = 30) from previous studies. Changes in endothelial function after 12 months were assessed and correlated with clinical response to cyclophosphamide. Biological markers for endothelial function were measured in serum at baseline and compared with healthy controls (N = 30).Results: Baseline FMD was significantly reduced in patients (median FMD 5.9%, range 0.5–13.1, n = 35) compared to healthy individuals (median FMD 7.7%, range 0.7–21, n = 66) (p = 0.005), as was PORH with patient score median 1,331 p.u. (range 343–4,334) vs. healthy individuals 1,886 p.u. (range 808–8,158) (p = 0.003). No significant associations were found between clinical response to cyclophosphamide intervention (reported in 55% of patients) and changes in FMD/PORH from baseline to 12 months. Serum levels of metabolites associated with endothelial dysfunction showed no significant differences between ME/CFS patients and healthy controls.Conclusions: Patients with ME/CFS had reduced endothelial function affecting both large and small vessels compared to healthy controls. Changes in endothelial function did not follow clinical responses during follow-up after cyclophosphamide IV intervention.