Fluid dynamics and atherosclerotic risk burden according as coronary bifurcation angle

Abstract

While recent advances in percutaneous coronary interventions, treatment of coronary bifurcation lesions is a challenging area. For increasing the success rate of complicated angioplasty and minimizing complication, micro-robot angioplasty which has the benefits of precision and miniaturization is emerging as one of treatment modalities. Atherosclerosis might be affected by the vascular geometry such as diameter, curved angle, bifurcation angle, and by the hemodynamic factor, such as oscillatory shear stress. The purpose of this study is investigating the flow characteristics and distributions of the hemodynamic wall parameters (HWP) and comparing atheroma volume (AV) according as bifurcation angle (BA). Coronary bifurcation model between left anterior descending artery and first diagonal branch according as different angle from computed tomogram data. HWP, such as time averaged wall shear stress (TAWSS), oscillating shear index (OSI), and wall shear stress (WSS) distributions in coronary bifurcation model were calculated under different bifurcation angle (30, 45, 60, and 90°). AV was analyzed quantitatively with CT and intravascular ultrasound (IVUS) from patients with stable angina (n=89). AV was compared according as BA. The bigger the BA, the lower TAWSS and the higher OSI at SB [TAWSS (Pa): 0.133, 0.020, 0.045, 0.060, OSI: 0.309, 0.472, 0.442, 0.469 at 30, 45, 60, and 90°, respectively]. The low shear zone was widening when the BA increasing. The mean AV of side branch in small BA (n= 40, <45°) was significantly smaller than large BA (n=49, <45°) (12.5±6.2 mm3 vs. 25.6±10.7 mm3), p = 0.035) and correlated positively (r2=0.15, p<0.05). In conclusion, over 45° of BA might have more hemodynamically atherogenic risk and might have restenosis risk of SB after main branch intervention. We suggest that small BA side branch might have lower risk for atherosclerosis and restenosis.