Computational analysis on physiological significance of coronary artery stenosis morphology: Influence of stenosis length on FFR

AUTHORS:

Bititi Muhindwa Junior

ABSTRACT:

For many years, coronary artery disease has been the main cause of death in population of developing countries. In this study, we investigated the influence of coronary artery stenosis length on fractional flow reserve FFR to measure pressure differences across the coronary artery stenosis and then understand the outcome of the flow distribution after stenosis. Many studies have been conducted for concentric stenosis, we focused our research on the eccentric stenosis. Considering the physiological significance of coronary artery stenosis morphology, a computational analysis was applied to establish the correlation between the lengths of the stenosis with the FFR change. Eccentric stenosis of 2mm of diameter was designed, with a total branch length of 45mm. The lesion length was distributed through 5mm, 10mm and 15mm. Using SolidWorks, a computer-generated model of coronary artery was created to design a model with 50%, 60%, and 70% diameter stenosis. For the boundary condition, we coupled the computational fluid dynamics CFD with the lumped parameter model LPM to assess the inlet and the outlet flow by solving the ordinary differential equation. We then simulated the model numerically using supercomputer to assess the value of FFR. By analyzing the results, the eccentric stenosis was found to be quite different from concentric one. Eccentric stenosis causes considerable pressure drop starting from stenosis to the rest of the branch. Fractional flow reserve FFR was measured on all branches from 50% to 70%, FFR varied between 0.87 for a 50% stenosis and nearly 0.35 for a 70% stenosis. Lesion length and FFR correlated quite well, FFR considerably decreased from a short to a longer stenosis lesion. The flow after stenosis was qualified with recirculation zone increasing with the degree of stenosis. The recirculation zone varied between 9mm and 12mm long. Eccentric stenosis just like concentric one, in the coronary arteries lead to the development of greater blood flow recirculation zones that result in areas of low velocity. We noticed that recirculation zone is another issue related to thrombosis and atherogenesis.

KEYWORDS:

Coronary Artery, Spasm, Stenosis