Influence of variable bifurcation angulation and outflow boundary conditions in 3D finite element modelling of left coronary artery on coronary diagnostic parameter

Theoretical impact of left coronary bifurcation angulation (BA) variations and percentage of flow distribution variations (FDV) in coronary artery branches (CAB) on anatomic assessment of bifurcated lesions, is investigated by considering fractional flow reserve (FFR) as a standard diagnostic parameter. According to Medina classification, computational models of coronary bifurcation lesions types of (1, 0, 0), (0, 1, 0) and (0, 0, 1) were developed. The models included BA of 30°, 45°, 60°, 75°, 90° and 120°. Computational fluid dynamics analysis was performed under hyperaemic flow condition and FFR was evaluated with percentage of FDV in CAB. For any fixed percentage of flow in the CAB and change in BA, FFR was significantly affected in the lesion type (1, 0, 0) whereas no significance was found in the lesion types (0, 1, 0) and (0, 0, 1). Percentage of FDV in CAB for any fixed BA significantly altered FFR in all the lesion types. Overall, 5%, 41% and 73% variations in FFR were found in (1, 0, 0), (0, 1, 0) and (0, 0, 1) respectively. The variation of BA could not be neglected in in vitro anatomical assessment for lesion type (1, 0, 0) but not in case of (0, 1, 0) and (0, 0, 1). Nevertheless, percentage of FDV in CAB is significantly altered FFR in the left coronary bifurcation lesions, which lead to underestimation of stenosis severity and postponement of coronary interventional procedure.