Post-occlusive reactive hyperaemia (POHR) in systemic sclerosis: very early disease (VEDOSS) represents a separate entity compared to established disease

Description of Peripheral Blood Perfusion by Laser Speckle Contrast Analysis (LASCA) in 'Early' versus 'Clinically Overt' Systemic Sclerosis in Routine Clinics

OBJECTIVE

To investigate in an unselected, systemic sclerosis (SSc) cohort if baseline laser speckle contrast analysis (LASCA) peripheral blood perfusion (PBP) measurements differ between 'early' SSc (without skin involvement, or 'limited' SSc-LSSc) and 'clinically overt' SSc (with skin involvement, limited cutaneous SSc-LcSSc and diffuse cutaneous SSc-DcSSc) in routine setting.

METHODS

A group of twenty consecutive 'early' SSc patients and forty consecutive 'clinically overt' SSc patients (twenty LcSSc and twenty DcSSc) underwent clinical and LASCA examinations (to assess the peripheral blood perfusion [PBP] of both hands volar).

RESULTS

No statistically significant difference in adjusted PBP was found in the 'early' versus the 'clinically overt' group (p = 0.77) when adjusted for possible confounding factors (e.g., vasoactive medication, active smoking, history of DTL and disease duration). A wide variability was noted when observing the individual datapoints of each subset.

CONCLUSION

This study with an unselected SSc population in daily routine, non-research setting, showed there was no difference in adjusted PBP at baseline between 'early' SSc and 'clinically overt' SSc when corrected for possible confounding factors. Interestingly a wide variation of individual datapoints were observed in each subset, which emphasizes the heterogeneity of SSc.

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.

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

BACKGROUND

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).

METHODS

We included 59 patients with SSc between March 2013 and September 2019. We divided patients into 4 groups: (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).

RESULTS

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).

CONCLUSIONS

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.

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.

Monitoring the microcirculation in the diagnosis and follow-up of systemic sclerosis patients: Focus on pulmonary and peripheral vascular manifestations

Systemic sclerosis (SSc) is a connective tissue disease, characterized by vascular damage and progressive fibrosis, affecting the skin and internal organs. The vascular changes include functional and structural abnormalities in the microcirculation, which play a central role not only in diagnosis but also in the prognosis and follow-up of systemic sclerosis patients. Nailfold videocapillaroscopy (NVC) is a safe, validated, noninvasive, inexpensive, reliable, and reproducible method that allows for the evaluation of structural changes in scleroderma microangiopathy. However, capillary blood flow/perfusion cannot be measured by NVC under standard conditions and, consequently, must rely on various laser techniques and thermography for the assessment and quantification of cutaneous blood perfusion. Other emerging technologies, such as optical Doppler tomography and spectroscopy, may be used to evaluate the skin flow. This review updates current knowledge on the use of microvascular evaluation techniques in SSc, including complications such as digital ulcers and pulmonary arterial hypertension.

Painless local pressure application to test microvascular reactivity to ischemia

BACKGROUND

Forearm cutaneous blood flux (CBF) measurement with post-occlusive reactive hyperemia (PORH) is uncomfortable and may not be devoid of risks. We aimed to investigate post-compression reactive hyperemia (PCRH) with a custom-made indenter that was designed to be easily used routinely by inexperienced observers.

METHODS

Medical students evaluated PCRH with 1- to 4-min pressure applications of 16 to 34 kPa and PORH with 3-min forearm cuff occlusion using laser speckle contrast imaging in 15 healthy volunteers. Participants were asked to quantify their discomfort with a visual analogue scale (VAS) of 10 cm. Total ischemia (ISCH) was quantified by the product of CBF during ischemia and ischemia duration (min). We subtracted the CBF changes in the skin from a reference ipsilateral (PCRH) or contralateral (PORH) non-stimulated area.

RESULTS

The average VAS was 1.0 for PCRH vs. 6.0 for PORH (p < 0.001). A strong linear relationship between ISCH and peak PCRH (r² = 0.915, p < 0.001) was noted. Peak PORH values (63.9 laser perfusion units (LPU)) were significantly lower than all values of the 3-min PCRH (72.6 LPU), including the one obtained with 16 kPa.

CONCLUSION

Inexperienced observers could test microvascular reactivity with PCRH without inducing the discomfort that is typically experienced with PORH. Further, PCRH elicits a higher peak response to ischemia compared with PORH. This extremely simple method could influence a broad spectrum of routine cutaneous microcirculation investigations, especially when a painful approach is particularly inadequate or if the patient is fragile.

CLINICAL TRIAL REGISTRATION

NCT02861924.

Advances in nailfold capillaroscopic analysis in systemic sclerosis

Systemic sclerosis is an autoimmune connective tissue disease characterized by early and persistent microvascular impairment which leads to functional and organic manifestations, with progressive fibrosis of the skin and internal organs. Morphological and functional assessment of the peripheral microvasculature is a must, not only for diagnosis but also for the prognosis and therapeutical follow-up of systemic sclerosis patients, as reported in recent studies. Nailfold videocapillaroscopy is the validated technique for the study of scleroderma microangiopathy as it is able to detect peripheral microvascular morphology and both classify and score the capillary abnormalities into different microangiopathy patterns ('Early', 'Active' and 'Late'). Indeed, the possibility to early diagnose and follow the microvascular changes and the safety of the technique have made nailfold videocapillaroscopy a mandatory tool for patient evaluation and included its assessment in the new systemic sclerosis classification criteria. Important links between nailfold videocapillaroscopy patterns and systemic sclerosis clinical manifestations have been described.

Optical methods for quantitative and label-free sensing in living human tissues: principles, techniques, and applications

We present an overview of quantitative and label-free optical methods used to characterize living biological tissues, with an emphasis on emerging applications in clinical tissue diagnostics. Specifically, this review focuses on diffuse optical spectroscopy, imaging, and tomography, optical coherence-based techniques, and non-linear optical methods for molecular imaging. The potential for non- or minimally-invasive assessment, quantitative diagnostics, and continuous monitoring enabled by these tissue-optics technologies provides significant promise for continued clinical translation.