Effects of posture and venous insufficiency on endothelial-dependent and -independent cutaneous vasodilation in the perimalleolar region

Testing the feasibility of a co-designed intervention, comprising self-managed, home-based, exercise training with embedded behavioural support and compression therapy for people with venous leg ulcers receiving treatment at home (FISCU-II)

BACKGROUND

Venous leg ulcers (VLUs) heal slowly, are painful for patients and are costly for healthcare systems; they also affect patients' quality of life. Previous work suggests that supervised exercise training used in combination with compression therapy may offer clinical benefits. However, a large population of people with VLUs are unable to access such an intervention due to frailty and age.

OBJECTIVES

To assess the feasibility of 'FISCU Home' (a co-designed, 12-week home-based self-managed lifestyle programme based on exercise and behaviour support) as an adjunct therapy to compression in people with VLUs.

METHODS

Forty people with VLUs, receiving treatment at home, were recruited from community nursing and tissue viability teams, and via a newspaper advertisement. Participants were randomized 1 : 1 either to exercise with behaviour support (three times per week) plus compression therapy or compression only. The feasibility of the programme was assessed using progression criteria that included exercise attendance rate, loss to follow-up, patient preference(s) and adverse events (AEs). Baseline assessments were repeated at 12 weeks and 6 months. Secondary outcomes (i.e. ulcer recurrence, healing rate and healing time) were also documented at these intervals. Intervention and healthcare utilization costs were calculated.

RESULTS

The study recruitment rate was 65%, while 75% of the exercise group participants attended all scheduled exercise sessions. All participants completed compression therapy. No serious AEs or exercise-related AEs were reported. Median (interquartile range) ulcer healing time was shorter in the exercise group [29 (7-108) vs. 42 (6-116) weeks].

CONCLUSIONS

The feasibility and acceptability of both a home- and exercise-based lifestyle intervention in conjunction with compression therapy and the study procedures are supported.

The utility of hyperspectral imaging in patients with chronic venous disorders

OBJECTIVE

The underlying pathophysiology of lower limb changes in chronic venous disorders (CVD) may involve alteration in microcirculation and tissue oxygenation. Hyperspectral imaging (HSI) is a noninvasive tool that is used clinically to measure transcutaneous oxygenation in peripheral artery disease and diabetic foot disease. However, there has been little application in venous disease. The aim of this study was to determine if transcutaneous oxygenation in the lower limb, as measured by HSI, changes depending on the clinical component of the Clinical-Etiological-Anatomical-Pathophysiological (CEAP) classification in CVD.

METHODS

This was an observational study of patients with CVD recruited from a vascular specialist clinic at a tertiary hospital from January 2020 to January 2021. Participants were allocated to eight groups according to the clinical component of CEAP classification of CVD. Baseline demographic and risk factor information were collected. Transcutaneous oxygenation was measured using HSI at seven sites around the foot and gaiter area in the supine and standing position. Participants rested supine for 15 minutes before the supine measurements and then stood for 15 minutes before the standing measurements. Tissue oxygenation was analyzed over a fixed circular surface area of 79 mm² at the target location. Calculations of oxyhemoglobin level (artificial unit [AU]), deoxyhemoglobin level (AU), oxygen saturation (%), and temperature (°C) were obtained. The Northern Ethics Committee (18/NTA/78) approved this conduct of the study and participants signed written consent forms.

RESULTS

There were 94 participants (164 lower limbs) included in the study. The median age was 59 years and 59 participants (63%) were women. At all sites except the heel, deoxyhemoglobin measurements increased in the standing position compared with the supine position (P < .001). In the gaiter region, there was nearly a doubling in deoxyhemoglobin level at 5 cm above the medial malleolus (supine 43.88 AU vs standing 80.46 AU; P < .001) and 5 cm above the lateral malleolus (supine 46.33 AU vs standing 87.72 AU; P < .001). When measurements were stratified by clinical class of the CEAP classification, there was a greater increase in deoxyhemoglobin levels with increasing clinical class in the standing position (P < .001). This finding was not observed in the supine measurements.

CONCLUSIONS

In CVD, HSI shows an increase in deoxyhemoglobin in the standing compared with supine position, particularly in the gaiter region. Furthermore, standing deoxyhemoglobin increases as the CEAP clinical class increases. Thus, this noninvasive tool may respond to venous physiology and may supplement the clinical class of the CEAP classification system.

Venous stent placement ameliorates cutaneous microvascular function in iliocaval venous obstruction

BACKGROUND

The role of cutaneous microvascular dysfunction is well known in the development of chronic venous disease. However, the effects of venous obstruction on microcirculation have not been well investigated. The aim of this study was to assess cutaneous microvascular function in patients with iliocaval venous obstruction (ICVO) before and after venous stent placement.

METHODS

Endothelium-dependent and endothelium-independent vasodilator responses to iontophoretic administration of incremental doses of acetylcholine (ACh) and sodium nitroprusside (SNP) were evaluated using a laser Doppler scanner in the perimalleolar region in the supine and sitting positions in patients with ICVO (n = 11) and in healthy control subjects (n = 15). Cutaneous microvascular function, the Venous Clinical Severity Score (VCSS), and the Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) clinical class were re-evaluated 3 months after stent placement in patients with ICVO.

RESULTS

The vasodilatory responses to ACh and SNP in the cutaneous microcirculation were lower in patients with ICVO than in healthy subjects in the sitting position (P < .05). Recanalization and stent placement were successful in all patients in the evaluation of VCSS and clinical class, and a significant decrease was determined in the signs and symptoms of the venous disease (P < .01). Stent placement resulted in a significant increase in vasodilation response to both ACh and SNP in the supine position and no improvement in the sitting position in patients with ICVO.

CONCLUSIONS

ICVO impairs endothelium-dependent and endothelium-independent vasodilation in the perimalleolar region. Iliocaval venous stent placement may recover microvascular dysfunction at different levels.

Effects of supervised exercise training on lower-limb cutaneous microvascular reactivity in adults with venous ulcers

Purpose

To investigate the effects of a 12-week supervised exercise programme on lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration.

Methods

Thirty-eight adults with unilateral venous ulceration who were being treated with lower-limb compression therapy (58% male; mean age 65 years; median ulcer size 5 cm²) were randomly allocated to exercise or control groups. Exercise participants (n = 18) were invited to attend thrice weekly sessions of lower-limb aerobic and resistance exercise for 12 weeks. Cutaneous microvascular reactivity was assessed in the gaiter region of ulcerated and non-ulcerated legs at baseline and 3 months using laser Doppler fluxmetry coupled with iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP). Cutaneous vascular conductance (CVC) was calculated as laser Doppler flux (AU)/mean arterial pressure (mmHg).

Results

Thirty-seven participants completed follow-up assessments. Median session attendance was 36 (range 2–36). Analyses of covariance revealed greater peak CVC responses to ACh in the exercise group at 3 months in both the ulcerated (adjusted difference = 0.944 AU/mmHg; 95% CI 0.504–1.384) and non-ulcerated (adjusted difference = 0.596 AU/mmHg; 95% CI 0.028–1.164) legs. Peak CVC responses to SNP were also greater in the exercise group at 3 months in the ulcerated leg (adjusted difference = 0.882 AU/mmHg; 95% CI 0.274–1.491), but not the non-ulcerated leg (adjusted difference = 0.392 AU/mmHg; 95% CI − 0.377 to 1.161).

Conclusion

Supervised exercise training improves lower-limb cutaneous microvascular reactivity in adults with venous leg ulceration.

Effect of diabetes on the cutaneous microcirculation of the feet in patients with intermittent claudication

AIMS

To evaluate endothelial-dependent and - independent cutaneous vasodilator responses in the feet of patients with peripheral arterial disease (PAD) with or without Type 2 diabetes.

METHODS

Cutaneous microvascular responses in the dorsum of both lower limbs were measured in the supine position using Laser Doppler Fluximetry combined with iontophoretic administration of endothelial-dependent (acetylcholine, Ach) and -independent (sodium nitroprusside, SNP) vasodilators in diabetic (n = 19) and non diabetic (n = 17) patients with PAD (presenting as unilateral calf intermittent claudication (IC).

RESULTS

In patients with diabetes and IC, endothelial-dependent vasodilation was significantly impaired in the symptomatic limb [74 (57,105) vs 68 (24,81) PU, Z =-2.79, p = 0.005] compared to the asymptomatic limb. Patients without diabetes showed no impairment of vasodilation. Resting ankle-brachial pressure index did not identify the presence of abnormalities in microvascular function.

CONCLUSIONS

The combination of diabetes and PAD is associated with a reduction in endothelial-dependent cutaneous vasodilation in the feet without an associated reduction in endothelial independent vasodilation.

Effects of surgery on microvascular function in venous insufficiency

BACKGROUND

The aim of our study was to assess the effects of venous stripping on microvascular functions in isolated great saphenous vein insufficiency.

METHODS

Two groups of participants were prospectively evaluated. The first group included 15 healthy participants without any evidence of venous insufficiency. The second group included 20 patients with varicose veins because of great saphenous vein insufficiency. The demographics, venous clinical severity scores, and CEAP classifications of the patients were recorded. Next, all individuals underwent evaluations for microvascular vasoreactivity using an iontophoretic laser Doppler imager, and the outcomes were recorded. Patients with varicose veins underwent stripping surgeries, and microvascular vasoreactivity evaluations were repeated 6 weeks postoperatively.

RESULTS

There was a statistically significant decrease in the patients with varicose veins compared with the control group in response to nitroprusside (SNP) applied at 4 mC in the supine position. Furthermore, there was also a significant difference in the response to acetylcholine (ACh) in patient group in the sitting position (P < 0.05). We also observed a statistically significant decrease in the responses to SNP applied for 1, 2, and 4 mC (P < 0.05) in the patients in the sitting position. The relief of pain and edema after surgery was found to be significant (P < 0,001). In the subgroup in which ACh was applied for 1 and 4 mC in the supine position, postoperative microvascular flow was significantly increased (P < 0.005). Moreover, based on the measurements taken in the supine position, the patients in the subgroup in which SNP was applied for 1, 2, or 4 mC exhibited significantly increased postoperative microvascular dilatation (P < 0.005).

CONCLUSIONS

Saphenous vein insufficiency impairs the endothelium-dependent vasodilatation response in the perimalleolar region, and partial recoveries in microvascular function were observed after surgical treatment.

Long-term effects of an exercise and Mediterranean diet intervention in the vascular function of an older, healthy population

BACKGROUND

Preserving endothelial function and microvascular integrity is suggested to reduce cardiovascular disease risk. It was recently shown that the age-dependent decline in endothelial and microvascular integrity may be reversed when combining exercise with Mediterranean diet (MD) in an 8-week intervention. The present study investigates whether the risk-reduction improvement in microcirculatory and cardiorespiratory functions are sustained in this age-group after a 1-year follow-up.

DESIGN AND METHODS

Twenty sedentary healthy participants (age, 55±4years) from the original study underwent cardiopulmonary exercise tolerance test and were assessed for their upper- and lower-limb vascular endothelial cutaneous vascular conductance (CVC) using laser Doppler fluximetry (LDF) with endothelium-dependent [ACh (acetylcholine chloride)] and endothelium-independent [SNP (sodium nitroprusside)] vasodilation, 1year after completing the intervention.

RESULTS

Both MD and exercise groups appeared to have an improved microvascular responses, in comparison to baseline as far as ACh is concerned. Exploring the interactions between the time point and the original group, however, revealed a stronger improvement in the MD group in comparison to the exercise group, for ACh (p=0.04, d=0.41). In the upper body, the time point and group interaction for ACh, indicated a better improvement for MD, without however statistical significance (p=0.07, d=0.24). Additionally, cardiorespiratory improvement in ventilatory threshold was maintained, 1year after (12.2±3.0 vs. 13.2±3.2ml∙kg(-1)∙min(-1), p<0.05).

CONCLUSIONS

The original improvements from an 8-week exercise and MD intervention were still evident, particularly in the microcirculatory and cardiorespiratory assessments, 1year after the initial study. This suggests that a brief intervention combining MD with exercise in this high-risk group promises long-term health benefits.

Creation of an arteriovenous fistula is associated with significant acute local and systemic changes in microvascular function

BACKGROUND

Native arteriovenous fistulae (AVF) are the vascular access of choice for haemodialysis. The consequences of AVF formation on microvascular function, locally or systemically, are unknown.

METHODS

We recruited 43 predialysis patients undergoing AVF formation. Patients were studied 2 weeks prior to the planned AVF operation and 2 weeks postoperatively. Thirteen patients with failed AVF were subsequently utilised as sham controls. Laser Doppler perfusion imaging was used to measure subcutaneous microvascular blood flow. Microvascular function was assessed as an increase in perfusion in response to iontophoretic administration of vasodilatory stimuli assessing endothelial-dependent (ED) and non-endothelial-dependent (NED) vasodilatation.

RESULTS

Patients with successful AVF formation had a significantly reduced ED vasodilatation in the fistula arm (-36 ± 46%, p < 0.001). Only NED vasodilatation was significantly reduced in the non-fistula arm (23 ± 40%, p = 0.01). Patients who had an unsuccessful AVF operation exhibited no recordable changes.

CONCLUSIONS

Formation of an AVF was associated with local and remote changes in microcirculation. Further assessments are underway to examine the contributions of local shear stress, vasoreactive substances and the autonomic responses. Although the clinical significance of these findings is not yet clear, it is intriguing that AVF formation is associated with such widespread and profound changes in microperfusion.

Effects of upper-limb exercise on lower-limb cutaneous microvascular function in post-surgical varicose-vein patients

Regular walking exercise attenuates lower-limb cutaneous microvascular endothelial dysfunction in post-surgical varicose-vein patients. This study assessed the effects of upper-limb exercise training on lower-limb cutaneous microvascular function in this patient group. Six post-surgical (4-5 weeks) varicose-vein patients completed an 8-week arm-crank exercise training programme. Changes in cutaneous microvascular function of the lower leg were assessed using laser Doppler flowmetry and iontophoretic administration of endothelial-dependent and -independent agonists [acetylcholine (ACh) and sodium nitroprusside (SNP), respectively]. At 8 weeks, median lower-limb cutaneous vasodilator responsives to ACh and SNP remained unchanged relative to baseline (e.g. 6 mC: 37 (interquartile range 24-63) vs. 40 (20-71) PU and 35 (23-48) vs. 38 (21-64) PU, respectively for the supine position). Upper-limb exercise appears ineffective for improving lower-limb cutaneous microvascular function in post-surgical varicose-vein patients. Therefore, limb specificity appears an important factor in optimal exercise prescription for these patients.

Exercise training improves cutaneous microvascular endothelial function in post-surgical varicose vein patients

This study investigated the effects of exercise training on cutaneous microvascular function in post-surgical varicose vein patients. Sixteen post-surgical (4-5 weeks) varicose vein patients were randomised to a treadmill-walking exercise group or a non-exercise control group. The exercise group trained twice weekly for 8 weeks. Changes in cutaneous microvascular function of the gaiter area were assessed using laser Doppler flowmetry combined with incremental-dose iontophoretic administration of acetylcholine chloride (ACh) and sodium nitroprusside (SNP) in both supine and standing positions. At 8 weeks, peak flux responses to ACh in the supine position were increased in the exercise group (44+/-30 to 62+/-33 PU; P=0.03) with a similar trend in the standing position (37+/-27 to 74+/-31 PU; P=0.08). There were no such changes in the control group (P>0.05). Additionally, peak flux responses to SNP were unchanged in both groups and body positions (P>0.05). The results suggest that moderate-intensity lower-limb exercise training improves microvascular endothelial vasodilator function in post-surgical varicose vein patients.

Impaired microvascular endothelial function is restored by acute lower-limb exercise in post-surgical varicose vein patients

Evidence exists that cutaneous microvascular endothelial dysfunction persists in patients following varicose vein surgery. This study compared cutaneous microvascular function between post-surgical varicose vein patients and healthy controls and investigated whether any impairment of function can be attenuated by acute lower-limb exercise. Cutaneous flux responses of the gaiter area were measured in supine and standing positions before and after a 25-min walk using laser Doppler fluximetry and incremental-dose administration of acetylcholine (ACh) and sodium nitroprusside (SNP). The pre-exercise peak responses to ACh (standing) were lower in patients than controls (48+/-11 vs. 96+/-28 PU; P=0.032), whereas treadmill exercise abolished this difference (P=0.819). In contrast, the pre-exercise responses to SNP (standing) appeared higher in patients than controls (3 mC responses: 24+/-4 vs. 10+/-2 PU, respectively; P=0.023), with no effect of acute exercise (P>0.05). These findings suggest that acute treadmill exercise augments microvascular endothelial function in post-surgical varicose vein patients to levels observed in age-matched controls.

Vascular calcification is associated with impaired microcirculatory function in chronic haemodialysis patients

Although vascular calcification (VC) in dialysis patients is associated with increased cardiovascular events, the pathophysiology is still largely obscure. Microcirculatory dysfunction may contribute to demand myocardial ischaemia. We have studied cutaneous microcirculatory function in haemodialysis (HD) patients with and without large-vessel VC. 37 non-diabetic subjects (20 HD and 17 healthy controls) were studied. VC was assessed using CT scanning of a standardised segment of superficial femoral artery (11 VC+, 9 VC-). Laser Doppler imaging was undertaken using a Periscan PIM II(R) at rest and under vasodilator challenge. Baseline perfusion was not statistically different in VC+ patients than VC- patients or controls (1.03 +/- 0.2, 1.08 +/- 0.2, 0.93 +/- 0.3 PU respectively). Overall, the maximum vasodilatory response to both ACh (p < 0.001) and SNP (p = 0.004) was lower in the HD than the control group. In addition, the HD patients took longer to reach a maximum vasodilatation than the controls (p = 0.008 for ACh, n.s. for SNP). Further, the maximum vasodilatory response in the VC+ patients was lower and patients took longer to reach maximum vasodilatation than the VC- group. We have demonstrated, for the first time, impaired and dysregulated microcirculatory function in patients with VC. This may be important in understanding the pathophysiology of the complications and cardiovascular consequences of VC.

A descriptive study of skin temperature, tissue perfusion, and tissue oxygen in patients with chronic venous disease

Chronic inflammation and microcirculatory disturbances of the skin have been implicated as causative factors of complications associated with chronic venous disease (CVD). The purpose of this study is to describe the mean differences between and correlations among three measures of microcirculation: skin temperature (Tsk), tissue perfusion/blood flow (BF), and tissue oxygen (tcPO(2)) of CVD-inflamed skin compared to normal controls. In a convenience sample of 55 patients with CVD (n = 31) and without CVD (n = 24), Tsk was measured with an infrared thermometer, BF with a laser Doppler flowmeter, and tcPO( 2) with a transcutaneous oximeter across three measurements periods 1 week apart (Times 1, 2, and 3) at the medial aspect of both lower legs. Tsk was higher (1.2 degrees C) across all measurement periods (p < .05), BF was higher at Times 1 and 3 (p = .002 and .012, respectively), and tcPO(2) was lower at Times 1 and 3 (p = .013 and .050, respectively) in the CVD group as compared to the non-CVD group. BF and Tsk were positively correlated at Times 1 and 2 (r = .516, p < .005; r = 0.278, p = .04) but not at Time 3 (r = 0.235, p > .05). No consistently significant correlations were found between tcPO(2) and BF or tcPO(2) and Tsk (p > .05). Tsk and BF were higher in the skin of lower legs affected by CVD than in those not affected. Pathological processes in the skin produce heat detectable by an infrared thermometer. Measurement and monitoring of Tsk can augment clinical findings and guide treatment when localized inflammation is suspected. Future studies of Tsk should be directed toward the usefulness of infrared technology to develop a CVD leg ulcer prediction model.

Comparison of new continuous measurements of ambulatory venous pressure (AVP) with conventional tiptoe exercise ambulatory AVP in relation to the CEAP clinical classification of chronic venous disease

INTRODUCTION

Quantitative measurements of chronic venous insufficiency (CVI) are sensitive in detecting the presence of CVI but have low specificity in differentiating clinical severities of CVI as defined by the CEAP classification. One possible reason for this is measurement techniques do not assess variables that reflect hemodynamic changes that occur during normal exercise. Our aim was to compare the association of variables determined from a new technique, continuous ambulatory venous pressure monitoring (CAVPM), and those of conventional AVP measurement with the clinical severity of chronic venous insufficiency in patients with primary venous reflux.

METHODS

Fifty-four limbs of 49 patients with CVI and 15 healthy controls were studied. CVI clinical severity was classified according to CEAP as C2&C3 (mild disease), C4 (moderate disease), and C5&C6 (severe disease). All participants underwent duplex ultrasound scanning to rule out the presence of reflux in the control group and to confirm it in the patient groups. Conventional AVP measurements, including 90% refilling time (RT90), were compared with the new CAVP variables of mean walking pressure (MWP) and percentage fall in walking pressure (%FWP). Data were analyzed by analysis of variance using the Kruskal-Wallis test, and comparisons between groups were performed using Mann-Whitney tests. Discriminant analysis was used to determine the ability of a test to classify limbs into clinical classes.

RESULTS

Conventional AVP measurements could not differentiate between the control group and the presence of mild disease (P = .56) but did differentiate between controls and severe disease as well as mild and severe disease (P < .001). RT90 detected differences between controls and reflux groups (P < .001) but not between moderate (C4) and severe (C5&C6) clinical groups (P > .5). MWP and %FWP showed significant differences between all clinical severities and controls (P < .001).

CONCLUSION

In the assessment of CVI, mean walking pressure and percent fall in walking pressure are more reliably associated with anatomic distribution of reflux and clinical severity of CVI than the gold standard investigations of conventional AVP and RT90.

Contrasting Effects of Varicose Vein Surgery on Endothelial-dependent and -independent Cutaneous Vasodilation in the Perimalleolar Region

OBJECTIVES

To evaluate the effects of varicose vein surgery on cutaneous microvascular perfusion and vasodilator responses to acetylcholine (Ach) and sodium nitroprusside (SNP) in the gaiter area of patients with great saphenous vein insufficiency.

METHODS

Twenty-nine patients with isolated great saphenous vein incompetence attended three study mornings (before surgery, and 6-8 weeks and 6 months after sapheno-femoral ligation+partial stripping) during which cutaneous microvascular responses were measured in the supine and standing positions using laser Doppler fluximetry (LDF) combined with incremental-dose iontophoretic administration of endothelial-dependent (Ach) and -independent (SNP) vasodilators.

RESULTS

Varicose vein surgery had no significant effect on baseline cutaneous perfusion or the microvascular response to Ach: e.g. peak vasodilator responses to the 1000 microC stimulus were mean 58 SEM 7, 64 SEM 6 and 65 SEM 7PU on the pre-operative, 6-8 weeks and 6 months assessments. In contrast, the corresponding responses to SNP were significantly increased following surgery: e.g. at 2000 microC, mean 63 SEM 9, 142 SEM 4 and 157 SEM 9PU (p<0.0001) in the upright position.

CONCLUSIONS

Sapheno-femoral ligation and partial stripping in patients with great saphenous vein insufficiency improves endothelial-independent cutaneous vasodilator function at the gaiter area, which may at least partly explain the benefits of surgery in reducing the risk of venous ulceration.

Evaluation of the microcirculation in vascular disease

Insufficient blood flow through end-resistance arteries leads to symptoms associated with peripheral vascular disease. This may be caused in part by poor macrocirculatory inflow or impaired microcirculatory function. Dysfunction of the microcirculation occurs in a similar fashion in multiple tissue beds long before the onset of atherosclerotic symptoms. Impaired microcirculatory vasodilatation has been shown to occur in certain disease states including peripheral vascular disease, diabetes mellitus, hypercholesterolemia, hypertension, chronic renal failure, abdominal aortic aneurysmal disease, and venous insufficiency, as well as in menopause, advanced age, and obesity. Microcirculatory structure and function can be evaluated with transcutaneous oxygen, pulp skin flow, iontophoresis, and capillaroscopy. We discuss the importance of the microcirculation, investigative methods for evaluating its function, and clinical applications and review the literature of the microcirculation in these different states.