Computational Modeling of Human Bicuspid Pulmonary Valve Dynamic Deformation in Patients with Tetralogy of Fallot

Abstract

Pulmonary valve stenosis (PVS) is one common right ventricular outflow tract obstruction problem in patients with tetralogy of Fallot (TOF). Congenital bicuspid pulmonary valve (BPV) is a condition of valvular stenosis, and the occurrence of congenital BPV is often associated with TOF. Dynamic computational models of normal pulmonary root (PR) with tri-leaflet and PR with BPV in patients with TOF were developed to investigate the effect of geometric structure of BPV on valve stress and strain distributions. The pulmonary root geometry included valvular leaflets, sinuses, interleaflet triangles and annulus. Mechanical properties of pulmonary valve leaflet were obtained from biaxial testing of human PV leaflet, and characterized by an anisotropic Mooney-Rivlin model. The complete cardiac cycle was simulated to observe valve leaflet dynamic stress/strain behaviors. Our results indicated that stress/strain distribution patterns of normal tri-leaflet pulmonary valve (TPV) and the BPV were different on valve leaflets when the valve was fully open, but they were similar when valves were completely closed. When the valve was fully open, the BPV maximum stress value on the leaflets was 197.2 kPa, which was 94.3% higher than of the normal TPV value (101.5 kPa). During the valve was fully open, the stress distribution in the interleaflet triangles region of the PR was asymmetric in the BPV model compared with that in the TPV model. The geometric orifice area value in the completely opened position of BPV model was reduced 55.6 % from that of the normal PV. Our initial results demonstrated that valve geometrical variations with BPV may be a potential risk factor linked to occurrence of PVS in patients with TOF. Computational models could be a useful tool in identifying possible linkage between valve disease development and biomechanical factors. Large-scale clinical studies are needed to validate these preliminary findings.

Porcine and bovine aortic valve comparison for surgical optimization: A fluid-structure interaction modeling study

“…1 shows the geometry of aortic root including aortic wall, valvular leaflets, sinuses, interleaflet triangles, sinutubular junction and annulus. Details of the aortic root geometry reconstruction procedure was previously published and details are omitted here to avoid repetition [19]. Eight aortic root models with 4 different sizes of bioprosthetic valves (19 and the leaflets of both the porcine and bovine models were first assumed to have a uniform thickness of 1.5 mm and 0.4 mm, respectively [20,21].…”

“…Details of the aortic root geometry reconstruction procedure was previously published and details are omitted here to avoid repetition [19]. Eight aortic root models with 4 different sizes of bioprosthetic valves (19 and the leaflets of both the porcine and bovine models were first assumed to have a uniform thickness of 1.5 mm and 0.4 mm, respectively [20,21]. Since porcine leaflet thickness clinically available is approximately half that of bovine pericardium, four additional PAV FSI models were made with leaflet thickness adjusted from to 0.24 mm to perform leaflet thickness comparisons.…”

“…To consider the impact of valve leaflet thickness, also because porcine leaflet thickness is approximately half that of bovine pericardium in clinical usage, four additional PAV FSI models were made with leaflet thickness adjusted from previous 0.4 to 0.24 mm. The four models with 0.24 mm leaflet thickness were denoted by TP19-TP25 (Thin PAV, size [19][20][21][22][23][24][25]. Flow velocity, pressure, stress and strain of the 4 thin porcine models are provided by Supplement Figs.…”

“…Several limitations of this study are worth noting: a) Image-based patient-specific 3D valve geometry reconstruction was not included and data from root bioprosthesis and previous work were used [19]. Quantifying in vivo geometry of valve leaflets is very challenging.…”

New Insights into Valve Hemodynamics

“…Capelli et al 130 used numerical models of patient-specific anatomies to predict the clinical outcomes of Melody valve implantation and found good agreement between their results and clinical fluid-dynamic parameters. Recently, Li et al 131 presented fluid-structure interaction models of pulmonary valve stenosis as a result of congenital bicuspid pulmonary valve. While the flow dynamics was modeled, most of their results focused on the geometrical differences between tricuspid and bicuspid configurations, and the only hemodynamically relevant finding was related to the geometric orifice area.…”