Changes in Internal Thoracic Artery Blood Flow According to the Degree of Stenosis of the Anterior Descending Branch of the Left Coronary Artery

Abstract

Abbreviations and AcronymsLITA = left internal thoracic artery LAD = left anterior descending artery WSS = wall shear stress OSI = oscillatory shear index CFD = computational fluid dynamics CABG = coronary artery bypass grafting CT = computed tomography PI = pulsatility index TTFM = transit-time flow measurement RITA = right internal thoracic artery Purpose: Computational fluid dynamics has enabled the evaluation of coronary flow reserve. The purpose of this study was to clarify the hemodynamic variation and reserve potential of the left internal thoracic artery (LITA). Methods: Four patients were selected on the basis of various native coronary stenosis patterns and graft design. The wall shear stress and oscillatory shear index were measured, and one patient was selected. Next, we created three hypothetical lesions with 75%, 90%, and 99% stenosis in front of the graft anastomosis, and compared the changes in LITA blood flow and coronary flow distribution. Results: In the 75% to 90% stenosis model, blood flow was significantly higher in the native coronary flow proximal to the coronary artery bypass anastomosis regardless of time phase. In the 99% stenosis model, blood flow from the LITA was significantly dominant compared to native coronary flow at the proximal site of anastomosis. The range of LITA flow variability was the largest at 99% stenosis, with a difference of 70 ml/min. Conclusion: The 99% stenosis model showed the highest LITA flow. The range of LITA flow variability is large, suggesting that it may vary according to the rate of native coronary stenosis.