Abstract
Fractional flow reserve (FFR) has proved its efficiency in improving patient diagnosis. In this paper, we consider a 2D reconstructed left coronary tree with two artificial lesions of different degrees. We use a generalized fluid model with a Carreau law and use a coupled multidomain method to implement Windkessel boundary conditions at the outlets. We introduce our methodology to quantify the virtual FFR and conduct several numerical experiments. We compare FFR results from the Navier–Stokes model versus generalized flow model and for Windkessel versus traction-free outlet boundary conditions or mixed outlet boundary conditions. We also investigate some sources of uncertainty that the FFR index might encounter during the invasive procedure, in particular, the arbitrary position of the distal sensor. The computational FFR results show that the degree of stenosis is not enough to classify a lesion, while there is a good agreement between the Navier–Stokes model and the non-Newtonian flow model adopted in classifying coronary lesions. Furthermore, we highlight that the lack of standardization while making FFR measurement might be misleading regarding the significance of stenosis.
Highlights
Fractional flow reserve (FFR) has proved its efficiency in improving patient diagnosis
We investigate some sources of uncertainty that the fractional flow reserve (FFR) index might encounter during the invasive procedure, in particular, the arbitrary position of the distal sensor. e computational FFR results show that the degree of stenosis is not enough to classify a lesion, while there is a good agreement between the Navier–Stokes model and the nonNewtonian flow model adopted in classifying coronary lesions
We calculated the fractional flow reserve (FFR) corresponding to a multistenotic patient-specific coronary tree. e two lesions of interest were not present in the original angiography but were artificially incorporated inside the vascular tree. us, the used geometry is sufficiently realistic to represent important features of the flow in a real diseased coronary tree. e two intermediate lesions of interest have degrees of stenosis of 68% and 56%. e strategy of FFR computation was based on a stabilized semi-implicit time discretization scheme of the nonlinear problem, using triangular elements
Summary
Fractional flow reserve (FFR) has proved its efficiency in improving patient diagnosis. In the case of a significant lesion, a revascularization is necessary In this case, a realistic simulation of vascular blood flow inside the coronary arteries can be a better alternative to the invasive FFR (see [2,3,4]). Concerning the outlet, the most common boundary condition for blood flow corresponds to a constant pressure. This choice is not realistic when it comes to complex geometries, with many outlets. We present the pressure and the flow distributions obtained for three different outlet boundary conditions. E FFR calculation is performed using two different flow models: Navier–Stokes model and the generalized flow model, and considering diverse outlet boundary conditions In the last section, we give an estimation of the fractional flow reserve (FFR) for two lesions using the pressure pattern in the stenotic coronary tree. e FFR calculation is performed using two different flow models: Navier–Stokes model and the generalized flow model, and considering diverse outlet boundary conditions
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