The effect of bosentan on digital ulcers (DU) was studied in two randomized
placebo-controlled trials (RAPIDS-1 and RAPIDS-2). A limitation of these studies was the
heterogeneous study population. More importantly, there were no endpoints that assessed
changes in vasculopathy and / or perfusion. Laser Doppler imaging has been shown to
effectively demonstrate blood flow restrictions in the hands of patients with Systemic
Sclerosis (SSc). The relation between blood flow restriction in the hands measured by laser
Doppler imaging and the extent of DU disease has not been studied. The current study will
attempt to demonstrate this relation. In addition, the impact of bosentan on the blood flow
in the hands, in a defined cohort of SSc-DU patients with a history of DU within the past 2
years and a clinically relevant reduction of blood flow in the hands, will be assessed.