Lokale Hämodynamik und Energieverluste von cruralen Bypassanastomosen, in-vitro Untersuchung mittels Particle Image Velocimetry

Abstract

ObjectiveTo study the local hemodynamics and energy losses of crural anastomoses using Particle Image Velocimetry.MethodsSilastic models of a Taylor patch, a Miller cuff and a femoro-crural patch prosthesis (FCPP) were attached to a circuit driven by a Berlin Heart, providing pulsatile flow. Instantaneous velocity fields were obtained by means of Particle Image Velocimetry (PIV) and shear rates as well as shear stresses calculated. In addition perfusion pressures were measured at the anastomotic inlet and outlets. The resulting energy losses due to flow separation and distal fluid acceleration were calculated based on the Bernoulli equation.ResultsInside the Taylor patch and Miller cuff anastomoses large hood and heel separations were found. The FCPP equally showed separation areas at the hood and heel, although these were smaller compared to the other anastomoses. The mainstream velocities at the inlet levels were comparable. A significant fluid acceleration was present at the antegrade as well as retrograde outlets of the Taylor and Miller cuff, while the fluid acceleration at the antegrade outflow of the FCPP was small. The resulting antegrade and retrograde energy losses for the Taylor form were 0.214 and 0.279 m, for the Miller cuff 0.226 and 0.303 m and for the FCPP 0.12 and 0.32 m, respectively.ConclusionsThe flow pattern inside end-to-side anastomoses consists of large separation zones, which are thought to be associated with intimal hyperplasia development. In addition unbalanced fluid accelerations at the distal outlets result in energy losses, which may contribute to impaired crural perfusion.