Dysfunctional arteriovenous anastomoses in the hands of systemic sclerosis patients with digital ulcers

Objective. Previous studies indicate that the arteriovenous anastomoses (AVAs) and the arterioles with the nutritive flow are involved in the pathophysiologic process disturbing hand blood flow in systemic sclerosis (SSc). However, impact of different part of the microvascular system involved in digital ulcers (DU) is not well known. Here, we aimed to assess the vasomotor activity of the AVAs in the hands of patients with and without DU in SSc. Methods. Simultaneous recordings were made of laser Doppler flux in the finger pulp and thenar eminence, together with ipsilateral radial artery blood velocity and mean arterial blood pressure (MAP) in 22 non-smoking SSc patients and 13 aged-matched healthy controls. Results. AVA responses in the finger pulp to spontaneous vasoconstrictor nerve impulses were abolished in 64% of the SSc patients. Correlation and cross-spectra analysis showed positive correlation between blood flow changes and MAP changes, indicating a passive vascular bed in the SSc finger pulp with blood flow variations depending on short-term variability in MAP. Dysfunctional AVA:s were identified in all the patients with a history of DU (n=8), while none of the patients with normal AVA function had episodes of DU (n=8) (p= 0.017). Conclusion. We found that in SSc patients with DU there is a dysfunction of the AVAs of the finger pulp. This proof-of-concept study supports the notion that AVA dysfunction may play a critical role in SSc-related DU. AVA dysfunction may be a part of autonomic dysfunction in SSc.