Purpose: Premature coronary artery bypass graft (CABG) failure has been linked to geometric, mechanical, and compositional discrepancies between host and graft tissues. Acute hemodynamic disturbances and the introduction of wall stress gradients trigger a myriad of mechanobiological processes at the anastomosis that can be associated with restenosis and graft failure. Although the origins of coronary artery disease dictate the anastomotic target, an opportunity exists for graft-vessel optimization through rationale graft selection.
Methods: Here we explored the four distinct regions of the left (L) and right (R) ITA (1 = proximal, 2 = submuscular, 3 = middle, 4 = distal), and four common target vessels in the coronary circulation including the proximal and distal left anterior descending (PLAD & DLAD), right coronary (RCA), and left circumflex (LCX) arteries. Benchtop biaxial mechanical data was used to acquire constitutive model parameters of these tissues and enable vessel-specific computational models to elucidate the mechanical consequences of 32 unique graft-target combinations.
Results: Simulations revealed the maximum principal wall stresses for the PLAD, RCA, and LCX occurred when anastomosed with LITA1, and the maximum flow-induced shear stress occurred with LITA4. The DLAD, on the other hand, reached stress maximums when anastomosed to LITA4. Using a normalized objective function of simulation output variables, we found LITA2 to be the best graft choice for both LADs, RITA3 for the RCA, and LITA3 for the LCX.
Conclusion: Although mechanical compatibility is just one of many factors determining bypass graft outcomes, our data suggests improvements can be made to the grafting process through vessel-specific regional optimization.
Keywords: Computational fluid dynamics (CFD); Finite element analysis (FEA); Histomechanics; Vascular biomechanics.
© 2023. The Author(s) under exclusive licence to Biomedical Engineering Society.