Abnormal amplitude and kinetics of digital postocclusive reactive hyperemia in systemic sclerosis

Analysis of Hand Function, Upper Limb Disability, and Its Relationship with Peripheral Vascular Alterations in Raynaud's Phenomenon

This study aimed to compare vascular involvement, hand functionality, and upper limb disability between Raynaud's phenomenon participants and controls. Also, we analyzed the relationships between vascular impairment, mobility, and strength with disability in this Raynaud population. We conducted a case-control study with fifty-seven participants. We registered sociodemographic and clinical data; vascular variables (temperature, cold test, blood flow, and oxygen saturation); functional variables (pinch strength, range of motion), and disability (Shortened Disabilities of the Arm, Shoulder and Hand Questionnaire) (Q-DASH). Raynaud participants present more disability in all Q-DASH subscales, lower hands' temperature pre and post cold test, decreased blood flow on radial artery, decreased ranges of motions at passive extension of index finger, and active flexion and extension of thumb than the healthy controls. The multivariate regression analysis showed that extension of the index finger, lateral pinch strength, and oxygen saturation were significantly associated with disability in RP, almost the 55% of the total variance on the upper limb, 27% at sports/arts, and 42% at work. Our findings suggest that RP has a disabling effect on the upper extremities and a practice of activities in people who suffer it. Also, disability in Raynaud seems to be more related with hand mobility and strength impairment than vascular injury.

Correlation between Microvascular Damage and Internal Organ Involvement in Scleroderma: Focus on Lung Damage and Endothelial Dysfunction

BACKGROUND

Systemic sclerosis (SSc) is an incurable connective tissue disease characterized by decreased peripheral blood perfusion due to microvascular damage and skin thickening/hardening. The microcirculation deficit is typically secondary to structural vessel damage, which can be assessed morphologically and functionally in a variety of ways, exploiting different technologies.

OBJECTIVE

This paper focuses on reviewing new studies regarding the correlation between microvascular damage, endothelial dysfunction, and internal organ involvement, particularly pulmonary changes in SSc.

METHODS

We critically reviewed the most recent literature on the correlation between blood perfusion and organ involvement.

RESULTS

Many papers have demonstrated the link between structural microcirculatory damage and pulmonary involvement; however, studies that have investigated correlations between microvascular functional impairment and internal organ damage are scarce. Overall, the literature supports the correlation between organ involvement and functional microcirculatory impairment in SSc patients.

CONCLUSIONS

Morphological and functional techniques appear to be emerging biomarkers in SSc, but obviously need further investigation.

Definition and application of proximal-distal gradient finger perfusion in systemic sclerosis by laser speckle contrast analysis

OBJECTIVE

In patients with systemic sclerosis (SSc) the perfusion of the fingers shows an alteration of the physiological proximal-distal gradient (PDG). The aim of this study is to provide a generalizable definition of PDG, applying it in a cohort of SSc patients and healthy controls (HC) using laser speckle contrast analysis (LASCA).

METHODS

Adult consecutive SSc patients and HC were enrolled. Peripheral blood perfusion of the hands was evaluated by LASCA, subsequently obtaining 3 different regions of interest: from the distal interphalangeal joint to the fingertip (DIST), from the metacarpophalangeal joint to the distal interphalangeal joint (PROX), and of the whole finger (TOT). A PDG formula independent of both intra- and inter-personal factors was then built. The PDG formula so obtained was: [(DIST × 2.63) - PROX]/TOT.

RESULTS

Ninety-four SSc patients (79.8% female, mean age 58.7 years) were enrolled. Applying the PDG formula, SSc patients revealed mean PDG values significantly lower than HC (1.82 ± 0.44 PU vs 2.70 ± 0.38 PU; p < 0.0001). Patients with a previous history of digital ulcers presented significant lower PDG values (p = 0.002). The ROC curve analysis identified in 2.28 PU the best PDG cut-off value between SSc and HC, with 86% sensibility and 90% specificity.

CONCLUSION

This study provided a PDG formula generalizable to all kind of subjects, applying it in SSc with great sensibility and specificity using LASCA, the best non-invasive imaging technique for the dynamical evaluation of peripheral perfusion. LASCA-PDG appears also as a tool able to identify a subclinical microangiopathic impairment.

Detection of microvascular changes in systemic sclerosis and other rheumatic diseases

Morphological and functional analysis of the microcirculation are objective outcome measures that are recommended for use in the presence of clinical signs of altered peripheral blood flow (such as Raynaud phenomenon), which can occur in systemic sclerosis (SSc) and other autoimmune rheumatic diseases. Several advanced non-invasive tools are available for monitoring the microcirculation, including nailfold videocapillaroscopy, which is the best-studied and most commonly used method for distinguishing and quantifying microvascular morphological alterations in SSc. Nailfold videocapillaroscopy can also be used alongside laser Doppler techniques to assist in the early diagnosis and follow-up of patients with dermatomyositis or mixed connective tissue disease. Power Doppler ultrasonography, which has been used for many years to evaluate the vascularity of synovial tissue in rheumatoid arthritis, is another promising tool for the analysis of skin and nailbed capillary perfusion in other autoimmune rheumatic diseases. Other emerging methods include raster-scanning optoacoustic mesoscopy, which offers non-invasive high-resolution 3D visualization of capillaries and has been tested in psoriatic arthritis and SSc. The principle functions and operative characteristics of several non-invasive tools for analysing microvascular changes are outlined in this Review, and the clinical roles of validated or tested imaging methods are discussed for autoimmune rheumatic diseases.

Laser Speckle Contrast Analysis: Functional Evaluation of Microvascular Damage in Connective Tissue Diseases. Is There Evidence of Correlations With Organ Involvement, Such as Pulmonary Damage?

Laser speckle contrast analysis (LASCA) is a non-contact technique able to quantify peripheral blood perfusion (PBP) over large skin areas. LASCA has been used to study hand PBP in several clinical conditions. These include systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) and LASCA showed that PBP was significantly lower in these conditions than in healthy subjects (HS). Moreover, it has been demonstrated that LASCA is a safe technique also able to monitor digital ulcer perfusion and their evolution in SSc patients, during systemic and local treatment. The use of LASCA, coupled with reactivity tests is commonplace in the field of microvascular function research. Post-occlusive hyperemia reactivity (POHR) and local thermal hyperemia, associated with laser techniques are reliable tests in the evaluation of perfusion in SSc patients. Other studies used laser speckled techniques, together with acetylcholine and sodium nitroprusside iontophoresis, as specific tests of endothelium function. In conclusion, LASCA is a safe, non-contact reliable instrument for the quantification of PBP at skin level and can also be associated with reactivity tests to monitor disease progression and response to treatment in different connective tissue diseases.

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.

Cooling-induced dilatation of cutaneous arteries is mediated by increased myoendothelial communication

Cold exposure causes cutaneous vasoconstriction via a reflex increase in sympathetic activity and a local effect to augment adrenergic constriction. Local cooling also initiates cutaneous dilatation, which may function to restrain cold-induced constriction. However, the underlying mechanisms and physiological role of cold-induced dilatation have not been defined. Experiments were performed to assess the role of endothelial-derived mediators in this response. In isolated pressurized cutaneous mouse tail arteries, cooling (28°C) did not affect the magnitude of dilatation to acetylcholine in preconstricted arteries. However, inhibition of nitric oxide (NO) [N^G-nitro-l-arginine methyl ester (l-NAME)] and prostacyclin (PGI₂) (indomethacin) reduced acetylcholine-induced dilatation at 37°C but not at 28°C, suggesting that cooling increased NO/PGI₂-independent dilatation. This NO/PGI₂-independent dilatation was reduced by inhibition of endothelial SK (UCL1684) and IK (TRAM34) Ca²⁺-activated K⁺-channels (K_Ca), consistent with endothelium-derived hyperpolarization (EDH). Cooling also increased dilatation to direct activation of K_Ca channels (SKA31, CyPPA) but did not affect dilatation to exogenous NO (DEA-NONOate). This cooling-induced increase in EDH-type dilatations was associated with divergent effects on potential downstream EDH mechanisms: cooling reduced dilatation to K⁺, which mimics an intercellular K⁺ cloud, but increased direct communication between endothelial and smooth muscle cells (myoendothelial coupling), assessed by cellular transfer of biocytin. Indeed, inhibition of gap junctions (carbenoxolone) abolished the EDH-type component of dilatation to acetylcholine during cooling but did affect NO-dominated dilatation at 37°C. Cooling also inhibited U46619 constriction that was prevented by inhibition of IK and SK K_Ca channels or inhibition of gap junctions. The results suggest that cooling dilates cutaneous arteries by increasing myoendothelial communication and amplifying EDH-type dilatation.NEW & NOTEWORTHY Cold causes cutaneous vasoconstriction to restrict heat loss. Although cold also initiates cutaneous dilatation, the mechanisms and role of this dilatation have not been clearly defined. This study demonstrates that cooling increases myoendothelial coupling between smooth muscle and endothelial cells in cutaneous arteries, which is associated with increased endothelium-derived hyperpolarization (EDH)-type dilatation. Dysfunction in this process may contribute to excessive cold-induced constriction and tissue injury.

Clinical applications of laser speckle contrast imaging: a review

When a biological tissue is illuminated with coherent light, an interference pattern will be formed at the detector, the so-called speckle pattern. Laser speckle contrast imaging (LSCI) is a technique based on the dynamic change in this backscattered light as a result of interaction with red blood cells. It can be used to visualize perfusion in various tissues and, even though this technique has been extensively described in the literature, the actual clinical implementation lags behind. We provide an overview of LSCI as a tool to image tissue perfusion. We present a brief introduction to the theory, review clinical studies from various medical fields, and discuss current limitations impeding clinical acceptance.

Performance of noninvasive laser Doppler flowmetry and laser speckle contrast imaging methods in diagnosis of Buerger disease: A case report

RATIONALE

Buerger disease (BD) is a nonatherosclerotic, inflammatory, segmental vascular occlusive disease, which affects small and medium-sized arteries and veins and is triggered by substantial tobacco exposure. Angiographic findings consistent with BD are required for diagnosis. Laser Doppler flowmetry (LDF) and laser speckle contrast imaging (LSCI) could represent potential noninvasive alternative techniques to angiography.

PATIENT CONCERNS

We report the case of a 49-year-old smoker who developed an ischemic ulcer in the distal segment of the second finger of the left hand. He had no medical history.

DIAGNOSES

In our vascular center, LDF and LSCI are conducted routinely for digital artery disease diagnosis. LDF was indicative of digital obstructive artery disease (DOAD). Postocclusive reactive hyperemia, assessed by LCSI, demonstrated no skin blood flow (SBF) perfusion in the distal phalanx of the thumb, index, middle, and auricular fingers. Angiography confirmed BD, showing distally located multisegmental vessel occlusion and corkscrew collaterals in this patient's hands.

INTERVENTIONS

Ilomedine treatment was initiated and smoking cessation was definitive.

OUTCOMES

Recently, the patient had an improvement in clinical condition despite the persistence of a small zone of necrosis of the left index finger 28 days post-treatment.

LESSONS

Our observation suggests that where suspicion of BD is based on clinical criteria, combining LDF and LSCI could represent a noninvasive, safe means of reaching BD diagnosis. Further clinical trials are necessary to confirm this novel observation.

Impairment of microcirculation and vascular responsiveness in adolescents with primary Raynaud phenomenon

BACKGROUND

Raynaud's phenomenon (RP) is a functional vascular disease, presenting with recurrent episodes of ischemia of extremities in response to cold and emotional stress. Investigating cutaneous microcirculation is an important tool in understanding the complex neuro-immuno-vascular interactions in its pathophysiological mechanisms. Since there is no available data on vascular responsiveness in RP in the paediatric population, we investigated skin perfusion and heat-induced hyperaemia in comparison with clinical severity and laboratory parameters of the disease.

METHODS

Fifty two adolescents (27 patients with primary RP and 25 age-matched healthy controls) were investigated in the study. Patients were divided into two groups according to the symptoms existing within the previous 2 months. Following baseline microcirculation measurement with Laser Doppler flowmetry (Periflux 5000 system), all subjects underwent local heating test at 42 °C and 44 °C. Besides routine laboratory parameters, immune-serological tests and the vasoactive sensory neuropeptides somatostatin and pituitary adenylate-cyclase activating polypeptide (PACAP) were measured.

RESULTS

Baseline perfusion measured in perfusion units (PU) at 32 °C was significantly lower in symptomatic RP patients (97.6 ± 22.4 PU) compared with both healthy volunteers (248.3 ± 23.5 PU, p < 0.001) and RP patients without symptoms (187.4 ± 24.9 PU, p < 0.05). After local heating to 42 °C maximum blood flow was significantly reduced in primary RP participants with current symptoms (358.6 ± 43.9 PU, p < 0.001), but not in asymptomatic ones (482.3 ± 28.7 PU, p > 0.05) when compared with healthy subjects (555.9 ± 28.2 PU). Both the area under the response curve and the latency to reach the maximum flow were significantly increased in both RP groups (symptomatic 164.6 ± 7.4 s, p < 0.001, asymptomatic 236.4 ± 17.4 s, p < 0.001) when compared with the control group (101.9 ± 4.7 s). The heat-induced percentage increase from baseline to maximal blood flow was significantly greater in symptomatic RP adolescents in comparison with healthy ones. Laboratory parameters and neuropeptide plasma levels were not altered in any groups.

CONCLUSION

To our knowledge this is the first study in paediatric population to show altered heat-induced cutaneous hyperaemia responses in relation with the clinical severity and symptomatology.

Cold-induced sympathetic tone modifies the impact of endothelium-dependent vasodilation in the finger pulp

OBJECTIVE

In thermoneutral and cold subjects, the sympathetic nervous system regulates skin blood flow by adjusting frequency of the tonic vasoconstrictor impulses. However, the way these thermoregulatory impulses influence the vascular endothelium is not well known. We studied how the sympathetic nervous system influences endothelium-dependent vasodilation (EDV) caused by shear stress in skin containing arteriovenous anastomoses (AVAs) and arterioles in healthy subjects.

METHODS

Thirteen healthy subjects were exposed to thermoneutral (29°C) and cold (22°C) ambient temperatures on separate days. EDV was induced by releasing suprasystolic pressure cuff applied to the forearm or third finger after 4min. Bilateral laser Doppler flux from the finger pulp, dorsal finger and dorsal wrist was measured together with ultrasound Doppler from the right radial artery. Absolute EDV response (EDV peak minus baseline) and normalized relative EDV response (ratio EDV peak/baseline) were calculated (median, 95% confidence interval). The relative EDV response reflect the size of EDV response independent of the baseline level and is thus used to compare the EDV responses in the finger pulp and wrist skin in the two temperature conditions.

RESULTS

In finger pulp (dominated by AVAs), the absolute EDV response (flux, au) in thermoneutral (137.8 (67.5, 168.8)) and cold (130.3 (97.2, 154.9)) was the same (p=0.85), whereas the relative EDV response was significantly higher in cold (3.6 (2.5, 5.9)) than in thermoneutral (1.4 (1.1, 1.6), p=0.002). The same patterns were found in the radial artery. In the dorsal wrist (dominated by arterioles) the absolute EDV response (flux, au) was smaller in cold (30.9 (15.91, 38.0)) than in thermoneutral (52.1 (38.4, 57.8), p=0.04), whereas the relative EDV responses in cold (3.5 (2.3, 4.2)), and thermoneutral (2.3 (1.6, 2.7)) were equal (p=0.16).

CONCLUSIONS

The relative EDV responses show that the impact of EDV on skin perfusion in cold conditions is significantly greater in the finger pulp than in wrist skin. However, the absolute EDV responses indicate that vascular smooth muscle relaxation during EDV is probably not affected by higher mild cold-induced sympathetic activity either in AVAs or in arterioles.

Laser Speckle Contrast Imaging for Monitoring Changes in Microvascular Blood Flow

BACKGROUND/AIMS

Microvascular blood flow is essential for healing and predicts surgical outcome. The aim of the current study was to investigate the relation between fluxes measured with the laser speckle contrast imaging (LSCI) technique and changes in absolute blood flow. In addition, we studied the reproducibility of the LSCI technique when assessing the intra-abdominal microcirculation of the pig.

METHODS

During trial 1, a fish gill arch was mechanically perfused with heparinized fish blood under controlled stepwise-altered flow rates alongside mechanically induced movement artefacts. The microcirculation of the fish gill was simultaneously assessed with the LSCI technique. In trial 2, microcirculation was measured in the stomach, liver, and small intestine of 10 pigs by two observers.

RESULTS

A linear correlation was observed between flux and volumetric flow. During conditions of no volumetric flow, the high recording speed with the LSCI technique registered the movement artefacts as flow signals. The LSCI measurements showed good correlation and agreement between the two observers when assessing microcirculation in the stomach, liver, and small intestine (r2 = 0.857, 0.956, and 0.946; coefficients of variation = 6.0, 3.2, and 6.4%, respectively).

CONCLUSION

Due to the non-contact and real-time assessment over large areas, LSCI is a promising technique for the intraoperative assessment of intra-abdominal microcirculation. A linear correlation between flux and volumetric flow was found, in accordance with previous experimental studies. However, movement artefacts affect flux measurements, and the choice of the sampling speed must be made with care, depending on the given setting.