Skin vasodilator function and vasomotion in patients with morbid obesity: effects of gastric bypass surgery

Obesity-associated microvascular dysfunction (MVD) involves different body tissues, including skin, and concurs to increased cardiovascular risk in obese patients (Ob-P). Generalized improvement of MVD is an important goal in obesity treatment. Since skin MVD mirrors generalized systemic MVD, skin microvascular investigation in prospective studies in Ob-P may surrogate microvascular investigation in organs more important for cardiovascular risk of the studied patients. In this prospective study, we measured forearm skin post-occlusive reactive hyperaemia (PORH), as percentage flow increase from baseline, and skin vasomotion in 37 Ob-P before Roux-en-Y gastric bypass (RYGB), and in 24 of them about 1 year after RYGB, using laser Doppler flowmetry (LDF). The spectral contribution of skin LDF signal oscillations in the frequency intervals of 0.01-0.02 Hz, 0.02-0.06 Hz, and 0.06-0.2 Hz--corresponding to endothelial-, sympathetic-, and myogenic-dependent vasomotion, respectively, was measured by means of spectral Fourier analysis. The same measurements were also performed in 28 healthy, lean subjects (HLS). Before RYGB, Ob-P had a significant reduction in PORH and in the all vasomotion parameters investigated, compared with HLS. After RYGB, Ob-P who completed the follow-up, had a significant weight loss (∼40 kg on average), together with a full normalisation in PORH and in vasomotion parameters, regardless of diabetes status. Surgically induced sustained weight loss resulted in full normalisation of skin microvascolar function in Ob-P about 1 year after RYGB. This result suggests a beneficial effect of sustained weight loss on generalized MVD of the studied Ob-P.