Accurate Calculation of FFR Based on a Physics-Driven Fluid-Structure Interaction Model.

Area of Science:

• Cardiovascular physiology
• Biomedical engineering
• Computational fluid dynamics

Background:

• Conventional fractional flow reserve from computed tomography (FFRct) calculations use rigid-wall computational fluid dynamics (CFD) models.
• These models neglect crucial fluid-structure interactions (FSI) and microcirculatory resistance during hyperemia, potentially leading to FFRct errors.

Purpose of the Study:

• To enhance FFRct calculation accuracy by integrating vascular elasticity and coronary microcirculation.
• To develop and validate a physics-driven 3D-0D coupled model incorporating FSI for precise FFRct determination.

Main Methods:

• A novel multi-scale geometric modeling approach was employed.
• A 3D FSI coronary artery model was coupled with a 0D lumped parameter model for microcirculation.
• Bidirectional coupling ensured physiological relevance of boundary conditions.

Main Results:

• The 3D-0D coupled model achieved FFRct accuracy, sensitivity, specificity, and predictive values of 86.7%, 66.7%, 84.6%, 66.7%, and 91.7% respectively.
• Mean squared error (MSE) was significantly reduced from 5.9% (basic CFD) to 1.9% (coupled model).
• The coupled model demonstrated a higher accuracy rate compared to the basic CFD model.

Conclusions:

• The physics-driven 3D-0D coupled model accurately simulates FSI and provides realistic microvascular resistance.
• This approach yields FFRct values closer to physiological conditions, improving calculation accuracy.
• Enhanced FFRct accuracy can lead to more informed clinical decisions regarding percutaneous coronary intervention (PCI).