Digital iontophoresis of vasoactive substances as measured by laser Doppler imaging—a non-invasive technique by which to measure microvascular dysfunction in Raynaud's phenomenon

• Published in: Rheumatology (Oxford, England) Vol. 43; no. 8; pp. 986 - 991
• Main Authors: Anderson, M. E., Moore, T. L., Lunt, M., Herrick, A. L.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.08.2004; Oxford Publishing Limited (England)
• Subjects: Acetylcholine - analysis; Adult; Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Dermatology; Diseases of the osteoarticular system; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Endothelium; Endothelium, Vascular - physiopathology; Female; Fingers - blood supply; Humans; Iontophoresis; Iontophoresis - methods; Laser Doppler imaging; Laser-Doppler Flowmetry - methods; Male; Medical sciences; Microcirculation - physiopathology; Microvasculature; Middle Aged; Nitroprusside - analysis; Raynaud Disease - physiopathology; Raynaud's phenomenon; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Scleroderma, Systemic - physiopathology; Systemic sclerosis; Vascular disorders of the skin; Vasodilation - physiology; Vasodilator Agents - analysis; Acrosyndrome; Immunopathology; Connective tissue disease; Skin disease; Nervous system diseases; Raynaud's phenomenon; Rheumatology; Cardiovascular disease; Autoimmune disease; Laser Doppler imaging; Endothelium; Vascular disease; Iontophoresis; Microcirculation; Laser dopplerometry; Dysfunction; Systemic sclerosis; Systemic disease; Diseases of the autonomic nervous system; Raynaud phenomenon; Capillary vessel disease; Microvasculature; Technique; Scleroderma
• ISSN: 1462-0324; 1462-0332
• DOI: 10.1093/rheumatology/keh244

Objective. To test the hypothesis that microvascular vasodilation is impaired in patients with systemic sclerosis (SSc) compared with patients with primary Raynaud's phenomenon (PRP) and healthy controls, using the technique of laser Doppler imaging to quantify blood flow responses to iontophoresis of vasoactive agents. Methods. Microvascular blood flow was measured by laser Doppler imaging before, during and after 120 s iontophoresis (30 µA) of 1% acetylcholine chloride (ACh, endothelium-dependent) and 1% sodium nitroprusside (NaNP, endothelium-independent). Two adjacent fingers of the left hand were studied, and the procedure then repeated on the right. Ten patients with limited cutaneous SSc (LCSSc), 10 patients with PRP and 11 healthy control subjects were studied. Results. Vasodilation in response to both ACh and NaNP iontophoresis, as measured by ‘area under the blood flow.time curve’ (AUC), normalized for baseline flux, was similar in the control and PRP groups, but was diminished in the LCSSc group compared with both control and PRP groups (ACh results: control vs LCSSc P = 0.028, PRP vs LCSSc P = 0.005; NaNP results: control vs LCSSc P = 0.004, PRP vs LCSSc P = 0.005). There were no differences between groups in baseline flux values nor in voltages required to drive the 30 µA current. Conclusions. Both endothelium-dependent and endothelium-independent vasodilation are impaired in patients with LCSSc. Vasodilatory responses in patients with PRP are similar to those in controls. If reproducibility is confirmed to be satisfactory, then these techniques could be used to examine disease progression over time and responsiveness to vasoactive treatment, thus facilitating clinical trials.