Characterization in vitro of the biomechanical properties of anastomosed host artery-graft combinations

An in vitro investigation is described in which the biomechanical properties of several host artery-graft combinations are characterized under realistic hemodynamic environments. Canine carotid arteries served as the host vessel and were anastomosed to one of the following graft materials: 4 mm I.D. thin-walled expanded polytetrafluoroethylene (e-PTFE), 6 mm I.D. thin-walled e-PTFE, modified human umbilical vein, autogenous foreleg vein, and carotid artery. A novel feature of the experimental design is the use of a pulsatile perfusion apparatus that simulates realistic normotensive or hypertensive hemodynamics, including pulse rate, perfusion pressure, and flow rate. Measurements of dynamic transmural pressure and vessel radial motion (determined with a helium-neon laser micrometer) were obtained during pulsatile perfusion. From these data calculation of the mismatch in diameter and elasticity modulus between the host carotid artery and various graft materials is made. The longitudinal propagation of the non-uniform radial displacement associated with the construction of the anastomotic junction is also calculated and presented. The present methodology is directly applicable to testing of other vascular substitutes and provides repeatable and reliable biomechanical data.