Comprehensive comparison of different BITA graft configurations: a computational study integrating TTFM and hemodynamic predictors.

Bilateral internal thoracic artery (BITA) grafting utilizes both the left (LITA) and right (RITA) internal thoracic arteries simultaneously and is recommended in the literature. However, the optimal configuration for BITA grafting remains uncertain. In this study, three-dimensional numerical simulations of different BITA configurations were conducted to identify the optimal configuration and assess their performance using the fractional flow reserve (FFR), transit time flow meter (TTFM), and hemodynamic parameters. The vessel geometry of a patient who underwent a BITA grafting with a Y-graft configuration was extracted from CT angiography images, and three other configurations (pedicle, LITA as free graft, and RITA as free graft) with different degrees of stenosis were reconstructed. Results showed that, in mild to moderate stenosis (FFR > 0.7), the Y-graft configuration was less favorable for graft quality, as it had higher pulsatility index (PI) and systolic reverse flow (SRF) values, leading to increased competitive flow. However, as stenosis severity increased, these differences decreased, and for severe stenosis, the results were similar for all BITA configurations. Furthermore, the results showed that the Y-graft configuration was less effective in reducing TAWSS compared to other configurations. Oscillatory shear index (OSI) and relative residence time (RRT) did not show significant differences.