The Beneficial Effect of Swirling Flow on Platelet Adhesion to the Surface of a Sudden Tubular Expansion Tube: Its Potential Application in End-to-End Arterial Anastomosis

Abstract

The size mismatch in an end-to-end vascular anastomosis between the host vessel and the graft may cause flow disturbance and possibly result in thrombosis. To test the hypothesis that intentionally induced swirling flow in an end-to-end anastomosis could suppress flow disturbance, impeding thrombus formation by affecting platelets adhesion, a comparative study was designed to investigate the effect of swirling flow on the adhesion and activation of platelets in a glass sudden tubular expansion tube coated with calf skin type I collagen. The results revealed that the swirling flow generated in the expansion could reduce the length of the flow recirculation zone distal to the expansion and significantly reduce the total number of adherent platelets in the test tube when compared with that for the normal flow. No significant difference was observed in the activation of platelets between the swirling flow group and the normal flow group. This study therefore suggests that intentionally introduced swirling flow in an end-to-end anastomosis has no adverse effect on platelet activation and may indeed be a solution to improve the patency of end-to-end microvascular anastomoses by suppressing thrombus formation.

Effect of swirling flow on platelet concentration distribution in small-caliber artificial grafts and end-to-end anastomoses

“…We tested this hypothesis experimentally by studying the effect of swirling flow on platelet adhesion and activation in a straight glass tube and a sudden tubular expansion tube, which were used to mimic a small-caliber graft and an end-to-end anastomosis [12,13]. The experimental study demonstrated that swirling flow could indeed significantly reduce the number of adherent platelets in both the straight glass tube and the sudden expansion tube.…”

“…The present numerical simulation is a supplementary study to our previous experimental study [12,13]. Two groups of numerical models were created based on our previous study: the straight tube group and the sudden tubular expansion tube group (Fig.…”

“…Its viscosity and density were measured as 1.1×10 −3 kg·m −1 ·s −1 and 1 040 kg·m −3 , respectively. In the flow simulation, the Reynolds number was set at 120 based on our previous experiments [12,13]. At such a low Re, though the spiral flow guider may somewhat disturb the flow, the flow in the tube with the flow guider should still remain laminar.…”

“…The density ratio of fluid to platelet particles was set at 0.98 [15]. The initial concentration of platelets was 0.45 mg/mL based on our previous experimental study in which the platelet concentration of the perfusion solution was 3×10 4 platelets per microliter [12,13].…”

“…The working fluid was the modified Tyrode buffer (MTB) [12,13], which was a homogeneous, incompressible and Newtonian fluid. Its viscosity and density were measured as 1.1×10 −3 kg·m −1 ·s −1 and 1 040 kg·m −3 , respectively.…”