Patient-specific CFD evaluation of his angle and stoma caliber in stomach-partitioning gastrojejunostomy

This study employs patient-specific computational fluid dynamics coupled with a Lagrangian discrete-phase model to quantify the influence of His angle and anastomotic caliber on intragastric hemodynamics after stomach-partitioning gastrojejunostomy (SPGJ). Three His angles (3°, 7°, 11°) and three stoma widths (narrow, intermediate, wide) were systematically analyzed. Within the physiological range, His angle altered global velocity and pressure by <5%, yet extreme values prolonged mean particle residence up to 1.9-fold, indicating a moderate angle (∼7°) minimizes stasis without elevating pressure loss. Stoma size proved decisive: very narrow or very wide orifices produced low-velocity seepage, high stagnation, and either excessive or moderate pressure drops, whereas an intermediate aperture yielded the lowest Δp and the shortest residence time. The results suggest that optimizing SPGJ requires maintaining a moderate His angle and designing an intermediate-sized anastomosis to maximize emptying efficiency while limiting tumor irritation and reflux risk. Clinically, these findings provide actionable guidance for intraoperative configuration and stoma sizing to balance functional patency with complication avoidance.