Maintained geometry, elasticity and contractility of human saphenous vein segments stored in a complex tissue culture medium

Back to Basics: Autologous Tissue: 1.5 www.aornjournal.org/content/cme

Perioperative personnel manage autologous tissue when they care for patients undergoing procedures requiring the use of bone, soft tissue, or other autologous tissue to repair or replace defects. Use of autologous tissue can minimize the risk of rejection, disease transfer, and infection compared with the use of artificial materials. There are important steps to follow when handling autologous tissue to ensure it is safe for replantation and does not become contaminated. This Back to Basics article provides strategies for managing some types of autologous tissue, including bone flaps, parathyroid tissue, skin grafts, and veins. Tissue management strategies include creating strict documentation policies, standardizing processes and communication, and implementing routine audits to assess compliance.

Twist buckling of veins under torsional loading

Veins are often subjected to torsion and twisted veins can hinder and disrupt normal blood flow but their mechanical behavior under torsion is poorly understood. The objective of this study was to investigate the twist deformation and buckling behavior of veins under torsion. Twist buckling tests were performed on porcine internal jugular veins (IJVs) and human great saphenous veins (GSVs) at various axial stretch ratio and lumen pressure conditions to determine their critical buckling torques and critical buckling twist angles. The mechanical behavior under torsion was characterized using a two-fiber strain energy density function and the buckling behavior was then simulated using finite element analysis. Our results demonstrated that twist buckling occurred in all veins under excessive torque characterized by a sudden kink formation. The critical buckling torque increased significantly with increasing lumen pressure for both porcine IJV and human GSV. But lumen pressure and axial stretch had little effect on the critical twist angle. The human GSVs are stiffer than the porcine IJVs. Finite element simulations captured the buckling behavior for individual veins under simultaneous extension, inflation, and torsion with strong correlation between predicted critical buckling torques and experimental data (R²=0.96). We conclude that veins can buckle under torsion loading and the lumen pressure significantly affects the critical buckling torque. These results improve our understanding of vein twist behavior and help identify key factors associated in the formation of twisted veins.