Blunted increase of digital skin vasomotion following acetylcholine and sodium nitroprusside iontophoresis in systemic sclerosis patients

Objectives. To test the hypothesis that finger skin vasomotion (FSV), a known factor influencing microvascular blood flow motion, is impaired in SSc patients. Possible relationships between FSV abnormalities and the severity and/ or activity of SSc were also investigated. Methods. FSV was investigated by means of spectral Fourier analysis of finger skin laser Doppler flowmetry (LDF) tracing, recorded before and following acetylcholine (ACh) or sodium nitroprusside (SNP) iontophoresis in 26 SSc patients and in 20 age-matched healthy controls. The power spectral density (PSD) of the 0.01-0.02, 0.02-0.06 and 0.06-0.2 Hz LDF oscillations (related to endothelial-, sympathetic-and myogenic-dependent FSV, respectively) was measured in PU2 (perfusion units)/ Hz. Results. Compared with controls, SSc patients exhibited a significantly lower post-ACh and/ or post-SNP percentage increase in PSD of 0.01-0.02 Hz (492 +/- 297% vs 283 +/- 167%; P < 0.005), of 0.02-0.06 Hz (336 +/- 205% vs 239 +/- 170%; P < 0.05) and of 0.06-0.2 Hz (223 +/- 91% vs 194 +/- 227%; P < 0.01) skin LDF oscillations. The post-SNP normalized PSD value of the 0.01-0.02 Hz and of the 0.02-0.06 Hz LDF oscillations was negatively related to SSc severity index (r =-0.407, P < 0.05 and r =-459, P < 0.05, respectively). Conclusions. This study showed a selective abnormality of the endothelial, sympathetic and myogenic-dependent FSV in SSc patients, consistent with a parallel endothelial, sympathetic and myogenic macrovascular dysfunction. This study also suggests a possible role of endothelial and sympathetic dysfunction in the progression of SSc.