Evaluation of the Haemodynamic Behaviour of Stenosed Aortic Heart Valves Using Fluid Structure Interaction Modelling

Aortic stenosis (AS) is a valvular heart disease characterised by the narrowing of the valve opening area. Calcific aortic stenosis (CAS) and rheumatic aortic stenosis (RAS) have distinctly different valve morphologies. The haemodynamic environment of generic calcific and rheumatic aortic valves (AV) of various severities is analysed through the use of 3D FSI modelling techniques. For moderate (AVA = 1-15 cm²), severe (AVA < 1 cm²) and very severe (AVA ≪ 1 cm²) cases of calcific and rheumatic AS, larger TPGs with higher velocity magnitudes are estimated in the rheumatic cases compared to the calcific cases. The additional work required by the left ventricle to overcome the TPG caused by the moderate, severe and very severe rheumatic valve lesions are 5.6%, 42.0% and 58.3% higher compared to the calcific valves of the same severity. The clinical approximation of the TPG is determined according to the simplified Bernoulli approximation and compared to the ground-truth TPG from the FSI results. The insensitivity of the clinical TPG approximation to the type and severity of stenosis is evident. Overall, the clinical approximation of the TPG either over- or underpredicts the TPG depending on the type and severity of the lesion, with smaller errors in the rheumatic cases compared to the calcific cases.