  Objective: Severe congenital aortic valve pathology in the growing patient
remains a challenging clinical scenario. Bicuspidization of the diseased aortic
valve has proven to be a promising repair technique with acceptable durability.
However, most understanding of the procedure is empirical and retrospective.
This work seeks to design the optimal gross morphology associated with surgical
bicuspidization with simulations, based on the hypothesis that modifications to
the free edge length cause or relieve stenosis.
  Methods: Model bicuspid valves were constructed with varying free edge
lengths and gross morphology. Fluid-structure interaction simulations were
conducted in a single patient-specific model geometry. The models were
evaluated for primary targets of stenosis and regurgitation. Secondary targets
were assessed and included qualitative hemodynamics, geometric height,
effective height, orifice area and prolapse.
  Results: Stenosis decreased with increasing free edge length and was
pronounced with free edge length less than or equal to 1.3 times the annular
diameter d. With free edge length 1.5d or greater, no stenosis occurred. All
models were free of regurgitation. Substantial prolapse occurred with free edge
length greater than or equal to 1.7d.
  Conclusions: Free edge length greater than or equal to 1.5d was required to
avoid aortic stenosis in simulations. Cases with free edge length greater than
or equal to 1.7d showed excessive prolapse and other changes in gross
morphology. Cases with free edge length 1.5-1.6d have a total free edge length
approximately equal to the annular circumference and appeared optimal. These
effects should be studied in vitro and in animal studies.
