Impact of weight loss due to sleeve gastrectomy on shear stress of the femoral vein in morbid obesity.

BACKGROUND: Studies have shown that obesity is associated with venous flow disturbances that lead to changes of the biomechanical forces on the venous wall known as shear stress. We hypothesized that weight loss due to bariatric surgery affects the venous hemodynamics and biomechanical forces on the venous wall. The aim of this study was to evaluate the effects of laparoscopic sleeve gastrectomy (LSG) on the wall shear stress (WSS) and the venous hemodynamics of the femoral vein. METHODS: We studied ten morbidly obese patients who underwent LSG. We investigated venous hemodynamics before, 6 and 12 months after LSG. The femoral vein diameter, cross-sectional area, peak (PeakV) and maximum (TAmax) velocities, WSS, and shear rate (SR) were assessed. RESULTS: PeakV and TAmax were significantly lower in the obese patients compared with the control group. WSS and SR were significantly lower in the obese patients compared with the control subjects. Venous hemodynamic parameters increased in the postoperative period at baseline compared with 12 months after surgery: PeakV increased from 17.53 (14.25-20.01) cm/s to 25.1 (20.9-30.1) cm/s (P = 0.04) and the TAmax from 12.97 (11.51-14.6) cm/s to 18.46 (13.24-24.13) cm/s (P = 0.057). WSS significantly increased from 0.21 (0.19-0.23) Pa at baseline to 0.31 (0.23-0.52) Pa 12 months after surgery (P = 0.031). SR also significantly increased from 47.92 (43.93-58.55) s(-1) at baseline to 76.81 (54.04-109.5) s(-1) 12 months after surgery (P = 0.02). CONCLUSIONS: This study showed that weight loss due to LSG significantly changes the biomechanical forces on the femoral vein generated by blood flow.