  Finite element simulations are an enticing tool to evaluate heart valve
function in healthy and diseased patients; however, patient-specific
simulations derived from 3D echocardiography are hampered by several technical
challenges. In this work, we present an open-source method to enforce matching
between finite element simulations and in vivo image-derived heart valve
geometry in the absence of patient-specific material properties, leaflet
thickness, and chordae tendineae structures. We evaluate FEBio Finite Element
Simulations with Shape Enforcement (FINESSE) using three synthetic test cases
covering a wide range of model complexity. Our results suggest that FINESSE can
be used to not only enforce finite element simulations to match an
image-derived surface, but to also estimate the first principal leaflet strains
within +/- 0.03 strain. Key FINESSE considerations include: (i) appropriately
defining the user-defined penalty, (ii) omitting the leaflet commissures to
improve simulation convergence, and (iii) emulating the chordae tendineae
behavior via prescribed leaflet free edge motion or a chordae emulating force.
We then use FINESSE to estimate the in vivo valve behavior and leaflet strains
for three pediatric patients. In all three cases, FINESSE successfully matched
the target surface with median errors similar to or less than the smallest
voxel dimension. Further analysis revealed valve-specific findings, such as the
tricuspid valve leaflet strains of a 2-day old patient with HLHS being larger
than those of two 13-year old patients. The development of this open source
pipeline will enable future studies to begin linking in vivo leaflet mechanics
with patient outcomes
