Hemodynamic and hemorheological variations in coronary arteries: impact of stenosis geometry and disease-driven viscosity changes

Purpose The purpose of this study is to investigate the combined effects of stenosis geometry and hematocrit (Hct)-dependent blood rheology on coronary hemodynamics. While geometric asymmetry and viscosity variation individually influence flow behavior, their coupled impact remains insufficiently characterized. Clarifying this interaction is important for improving the relevance of patient-specific numerical hemodynamic analyses in clinical diagnostic contexts, where variations in vascular structure and Hct can significantly affect disease progression. Design/methodology/approach A patient-specific left coronary artery with 70% luminal narrowing was reconstructed from computed tomography imaging and analyzed for concentric and eccentric (Type I and II) lesions. Pulsatile flow was simulated using a finite-element incompressible Navier–Stokes framework with a Carreau non-Newtonian viscosity model at Hct levels of 25%, 45% and 65%. The model was validated against established experimental and numerical simulation data, and key hemodynamic and energetic metrics were evaluated over the cardiac cycle. Findings Eccentric Type II lesions produced the greatest flow disruption, characterized by strong post-stenotic separation, elevated oscillatory shear and increased pressure losses. Hct regulated flow stability, with reduced viscosity enhancing inertial effects and residence time and increased viscosity amplifying dissipative losses. Geometric asymmetry caused uneven momentum redistribution, generating skewed jets and persistent secondary vortices that promoted transitions from coherent pulsatile flow to vortex-dominated dynamics. Originality/value This work presents a patient-specific computational framework that integrates lesion eccentricity with Hct-driven non-Newtonian blood behavior. By isolating the coupled effects of morphology and rheology, this study provides a physically grounded basis for interpreting coronary flow disturbances and supports improved non-invasive cardiovascular risk assessment.