Attenuation of microvascular function in those with cardiovascular disease is similar in patients of Indian Asian and European descent

Post-ischemic skin peak oxygen saturation is associated with cardiovascular risk factors: a Swedish cohort study

The objective of this study was to explore the associations between skin microcirculatory function and established cardiovascular risk factors in a large Swedish cohort. As part of the Swedish CArdioPulmonary bioImage Study (SCAPIS), microcirculatory data were acquired at Linköping University hospital, Linköping, Sweden during 2016-2017. The subjects, aged 50-64 years, were randomly selected from the national population register. Microcirculatory reactivity was assessed using a 5-min arterial occlusion-release protocol. Comprehensive skin microcirculatory data were continuously acquired by using a fiberoptic probe placed on the lower right arm. After exclusion of missing data (208), 1557 subjects were remaining. Among the parameters, skin microcirculatory peak oxygen saturation after occlusion release, had the strongest relationship to the cardiovascular risk factors. The linear associations between peak oxygen saturation and cardiovascular risk factors were analyzed adjusted for age and sex. We found a negative association with peak oxygen saturation (standardized regression coefficient) for blood pressure (systolic -0.05 (95% CI: -0.10;-0.003) and diastolic -0.05 (-0.10; -0.003)), BMI -0.18 (-0.23; -0.13), waist circumference (males -0.20 (-0.32; -0.16), females -0.18 (-0.25; -0.11)), prevalent diabetes -0.31 (-0.49; -0.12), hypertension -0.30 (-0.42; -0.18), dyslipidemia -0.24 (-0.40; -0.09), fasting glucose level -0.06 (-0.12; -0.01), HbA1c -0.07 (-0.12; -0.02), triglyceride level -0.09 (-0.14; -0.04), hsCRP -0.12 (-0.17; -0.07), and current smoker versus never smoked -0.50 (-0.67; -0.34). A positive association with peak oxygen saturation was found for cholesterol level 0.05 (0.005; 0.11) and HDL 0.11 (0.06; 0.17). This is the first study showing that post-ischemic skin microvascular peak oxygen saturation is associated with virtually all established cardiovascular risk factors in a population-based middle-aged cohort.

Reactivity of skin microcirculation as a biomarker of cardiovascular events. Pilot study

BACKGROUND

The role of microcirculatory disorders is progressively being accepted in the pathogenesis of cardiovascular diseases.

OBJECTIVE

The purpose of current study is to assess whether we can consider skin microcirculation disorders as a biomarker of cardiovascular events.

METHODS

Group 1 consisted of healthy volunteers (n = 31); group 2 (n = 42) consisted of patients with diseases that increase the risk of cardiovascular events; group 3 (n = 39) included patients with the history of cardiovascular events. Skin microcirculation measurement was performed using laser Doppler flowmetry during the heating test.

RESULTS

LDF parameters reflecting the rapid response of microcirculation to heating ("Slope 120 s" and "Slope 180 s") significantly differed in three groups (p <  0.05). A decrease in the "Slope 180 s" parameter less than 0.5 PU/s is associated with cardiovascular events (sensitivity 69.2%, specificity 66.7%; the area under the ROC curve, 0.667; 95% confidence interval [CI], 0.545-0.788, p = 0.01). Multivariable logistic regression analysis revealed that "Slope 180 s≤0.5 PU/s" was significantly related to cardiovascular events (adjusted odds ratio = 3.9, p = 0.019, CI 95% 1.2-12).

CONCLUSIONS

Reduced reactivity of the skin microcirculation may be useful as a biomarker of severe damage to the cardiovascular system and is promising as a risk factor for cardiovascular events.

Feasibility of using thermal response to Ka band millimeter wave heating to assess skin blood flow

OBJECTIVE

Implementation of clinical guidelines for diagnosing peripheral artery disease will demand screening many millions of patients who are considered at-risk. This will require faster, easier screening technologies to identify patients with compromised blood flow to the extremities.

APPROACH

The feasibility of using surface temperature response to K_a band (26.5-40 GHz) near-field irradiation to assess skin blood flow was explored using an animal model. Ears of domestic rabbits were subjected to low-power continuous wave radio frequency heating from an open-ended waveguide (WR-28) at f  =  35 GHz. Three flow conditions were evaluated: (1) a baseline flow condition, (2) occluded flow and (3) reactive hyperemia. Surface temperatures were monitored continuously by means of an infrared thermography camera during each 2 min exposure.

MAIN RESULTS

Ensemble average results showed significant differences (p  <  .05) at exposure times 30, 60, 90 and 120 s between baseline and occluded conditions, and between baseline and reactive hyperemia conditions. The occluded condition (N  =  12) resulted in an average temperature increase of 21.4 °C  ±  3.9 after 2 min, compared with an average increase of 12.1 °C  ±  1.6 for baseline conditions (N  =  9) and 4.7 °C  ±  3.6 for post-occlusion/hyperemic conditions (N  =  8).

SIGNIFICANCE

Results are compared with the results of a simple two parameter mathematical model. These results suggest a method for non-invasive skin blood flow assessment to screen for peripheral artery disease and associated risk of cardiovascular events.

Diabetes, cardiovascular disease and the microcirculation

Cardiovascular disease (CVD) is the leading cause of mortality in people with type 2 diabetes mellitus (T2DM), yet a significant proportion of the disease burden cannot be accounted for by conventional cardiovascular risk factors. Hypertension occurs in majority of people with T2DM, which is substantially more frequent than would be anticipated based on general population samples. The impact of hypertension is considerably higher in people with diabetes than it is in the general population, suggesting either an increased sensitivity to its effect or a confounding underlying aetiopathogenic mechanism of hypertension associated with CVD within diabetes. In this contribution, we aim to review the changes observed in the vascular tree in people with T2DM compared to the general population, the effects of established anti-diabetes drugs on microvascular outcomes, and explore the hypotheses to account for common causalities of the increased prevalence of CVD and hypertension in people with T2DM.

Eicosapentaenoic Acid (EPA) Induced Macrophages Activation through GPR120-Mediated Raf-ERK1/2-IKKβ-NF-κB p65 Signaling Pathways

Objectives: To investigate the immunomodulatory effect and molecular mechanisms of Eicosapentaenoic acid (EPA, a typical kind of n-3PUFAs) on RAW264.7 cells. Methods: A variety of research methods, including the RAW264.7 cells culture, cell proliferation assays, morphologic observations, measurements of NO production, cytokine assays, nuclear protein extractions, western blot analyses and NF-κB p65 immunofluorescence assays were used in this study. Results: The results showed that EPA could increase the proliferation index and enhance the release of nitric oxide (NO) and cytokines in RAW264.7 cells. Western blotting results revealed that the protein level of GPR120 increased significantly in RAW264.7 cells after EPA treatment. Meanwhile, EPA elevated the phosphorylation status of Raf, which may act as an upstream regulator of EPA-induced phosphorylated ERK1/2. In addition, the phosphorylated ERK1/2 may then promote IKKβ in endochylema and translocate the NF-κB p65 subunit into the nucleus, thus regulating the production of inducible nitric oxide synthase (iNOS) and cytokines. Conclusions: EPA (0.6–3.0 μmol) activates RAW264.7 cells through GPR120-mediated Raf-ERK1/2-IKKβ-NF-κB p65 signaling pathways.

Peripheral and Autonomic Neuropathy in South Asians and White Caucasians with Type 2 Diabetes Mellitus: Possible Explanations for Epidemiological Differences

Objectives. To compare the prevalence of diabetic peripheral neuropathy (DPN) and that of cardiac autonomic neuropathy (CAN) between South Asians and White Caucasians with type 2 diabetes and to explore reasons for observed differences. Methods. A cross-sectional study of casually selected South Asian and White Caucasian adults attending a hospital-based diabetes clinic in the UK. DPN and CAN were assessed using the Michigan Neuropathy Screening Instrument (MNSI) and heart rate variability testing, respectively. Results. Patients (n = 266) were recruited (47.4% South Asians). DPN was more common in White Caucasians compared to South Asians (54.3% versus 38.1%, p = 0.008). Foot insensitivity as assessed by 10 g monofilament perception was more common in White Caucasians (43.9% versus 23.8%, p = 0.001). After adjustment for confounders, White Caucasians remained twice as likely to have DPN as South Asians, but the impact of ethnicity became nonsignificant after adjusting for adiposity measures or height. No difference in prevalence of standardized CAN test abnormalities was detected between ethnicities. Skin microvascular assessment demonstrated that South Asians had reduced heating flux but preserved acetylcholine response. Conclusions. South Asians with type 2 diabetes have fewer clinical signs of DPN compared to White Caucasians. Differences in adiposity (and its distribution) and height appear to explain these differences.

Severely impaired microvascular reactivity in diabetic patients with an acute coronary syndrome

Background

Microvascular function is impaired in patients with stable coronary artery disease. The aim was to study microvascular function in patients with diabetes and acute coronary syndrome (ACS).

Methods

Microvascular function was evaluated in 83 patients by laser Doppler fluxmetry (LDF) [PU; perfusion unit, median (interquartile range)] measuring resting LDF and peak LDF following a six min heating of the skin to 44 °C at the foot, respectively. All patients with ACS and without previously known diabetes underwent oral glucose tolerance test. Thirty-nine patients with type 2 diabetes mellitus free from coronary artery disease served as controls.

Results

Peak LDF was significantly (P = 0.03) lower in patients with ACS and diabetes (n = 22; 72 (52)) and diabetes without coronary artery disease (n = 39; 69 (51)) as compared to patients with ACS without diabetes (n = 46; 97 (60)), and patients without ACS (n = 15; 140 (121)), respectively. Patients with ACS (n = 68) had significantly (P = 0.04) lower peak LDF (92 (49)) as compared to patients without ACS (n = 15) (140 (121)).

Conclusion

Microvascular reactivity is severely impaired in patients with diabetes and ACS. Diabetes has a major influence on microvascular function in patients with coronary artery disease.

Sex-dependent association between coronary vessel dominance and cardiac syndrome X: a case-control study

BACKGROUND

Previous studies have demonstrated the relevance of left coronary artery dominance in the outcome and prognosis of obstructive coronary artery disease (CAD). However, no studies have investigated the influence of coronary vessel dominance on non obstructive CAD. The aim of this study was to establish the association of left and mixed dominance of the major epicardial arteries with the development of non obstructive CAD and evaluate potential sex-dependent differences in the coronary artery supply.

METHODS

A total of 484 patients underwent the same diagnostic procedures. The patients were divided into two groups based on their coronary angiogram results: the control group (242 patients with obstructive CAD; coronary artery stenosis of ≥50%) and the experimental group (242 patients with non obstructive CAD; coronary artery stenosis of <50%).

RESULTS

Significantly more women than men were affected by non obstructive CAD (P = 0.005). Left dominance was more frequent in the non obstructive CAD group than in the control group (P = 0.018) and was more pronounced in women than in men (P = 0.013). Among men with non obstructive CAD, a left supply was more frequent than a mixed supply (P = 0.012). Women with non obstructive CAD had a higher frequency of a left supply, whereas a mixed supply was less frequent in men than in patients with obstructive CAD (P = 0.013 and 0.018, respectively).

CONCLUSION

These results suggest that left dominance (particularly in women) and the absence of a mixed supply in men could cause regional ischemia, thus affecting the development of non obstructive CAD. Furthermore, sex may determine the incidence of specific coronary artery supply types, therefore influencing disease development and prognosis.

Attenuated systemic microvascular function in men with coronary artery disease is associated with angina but not explained by atherosclerosis

INTRODUCTION

Refractory angina is the occurrence of clinical symptoms despite maximal therapy. We investigated associations between microvascular function, atherosclerotic burden, and clinical symptoms in subjects with CAD.

METHODS

Skin microvascular response to heating and ischemia was assessed in 167 male volunteers by laser Doppler fluximetry; 82 with CAD on maximal therapy and 85 with no known CAD (noCAD). CAC scores, carotid IMT, and femoral IMT were measured and symptoms were scored using the Rose angina questionnaire.

RESULTS

Patients with CAD had poorer microvascular response to heating (114[95% CI 106-122]au CAD vs. 143[134-153]au no CAD; p < 0.0001) and ischemia (42[38-46]au CAD vs. 53[78-58]au. noCAD; p = 0.001). Thirty-eight percent of the noCAD group had elevated CAC scores. There were no associations between markers of atherosclerosis and microvascular function. Forty-two percent of the CAD group had refractory angina. This was associated with impaired microvascular function compared to those with elevated CAC scores but no symptoms (109 [95-124]au vs. 131[122-140]au; p = 0.008).

CONCLUSIONS

Men with symptomatic CAD have poorer microvascular function compared to individuals without CAD. Microvascular function does not correlate with atherosclerosis, but is impaired in individuals with refractory angina. Microvascular dysfunction may play a role in the symptomatology of angina.

Microcirculation on a large scale: techniques, tactics and relevance of studying the microcirculation in larger population samples

The role of microcirculatory dysfunction is increasingly being recognized in the etiopathogenesis of cardiovascular disease. Whilst the importance of detailed mechanistic studies to determine the exact nature of these disturbances is without question, it was large-scale population-based studies that first identified the associations between deranged microvascular perfusion, autoregulation or structure, and subsequent target organ damage. This is the subject of considerable studies to establish whether there is a causal effect in either direction, or simply represents shared risk factors, although it is most likely to be a complex combination of bidirectional interactions. The techniques for investigating microcirculatory function have evolved almost exponentially over the last 75 years: So too have the strategies for investigation. Current epidemiological studies are focusing on attempting to untangle the inter-relationship between risk factors and pathological mechanisms to attempt to determine whether these represent therapeutic targets or simple markers of unmeasured risk. We plan to review the techniques used for these population-based studies, the advances made, and the clinical implications derived.

Effect of modest salt reduction on skin capillary rarefaction in white, black, and Asian individuals with mild hypertension

Microvascular rarefaction occurs in hypertension. We carried out a 12-week randomized double-blind crossover trial to determine the effect of a modest reduction in salt intake on capillary rarefaction in 71 whites, 69 blacks, and 29 Asians with untreated mildly raised blood pressure. Both basal and maximal (during venous congestion) skin capillary density were measured by capillaroscopy at the dorsum and the side of the fingers. In addition, we used orthogonal polarization spectral imaging to measure skin capillary density at the dorsum of the fingers and the hand web. With a reduction in salt intake from 9.7 to 6.5 g/day, there was an increase in capillary density (capillaries per millimeter squared) from 101+/-21 to 106+/-23 (basal) and 108+/-22 to 115+/-22 (maximal) at the dorsum, and 101+/-25 to 107+/-26 (basal) and 110+/-26 to 116+/-26 (maximal) at the side of the fingers (P<0.001 for all). Orthogonal polarization spectral imaging also showed a significant increase in capillary density both at the dorsum of the fingers and the web. Subgroup analysis showed that most of the changes were significant in all of the ethnic groups. Furthermore, there was a significant relationship between the change in 24-hour urinary sodium and the change in capillary density at the side of the fingers. These results demonstrate that a modest reduction in salt intake, as currently recommended, improves both functional and structural capillary rarefactions that occur in hypertension, and a larger reduction in salt intake would have a greater effect. The increase in capillary density may possibly carry additional beneficial effects on target organs.