Patient-Specific Fluid-Structure Interaction Simulations of a Quadricuspid Neonatal Valve Before and After Truncus Arteriosus Repair

  • Bornemann, Karoline-Marie (Stanford University)
  • Choi, Perry S (Stanford University)
  • Huber, Jay (Stanford University)
  • Reed, Alexander K (Stanford University)
  • Sharir, Amit (Stanford University)
  • Maskatia, Shiraz A (Stanford University)
  • Marsden, Alison L (Stanford University)
  • Ma, Michael R (Stanford University)
  • Kaiser, Alexander D (Stanford University)

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Truncus arteriosus is a rare and severe congenital heart disease in which a septal defect between both ventricles allows blood to pass through the truncal valve. Downstream of the valve, the systemic and pulmonary circulation share one great artery. Around 25% of all truncal patients have a quadricuspid truncal valve featuring four, usually thickened, leaflets, which are associated with valve regurgitation and increased re-operation risk [1, 2]. During truncal repair surgery, the pulmonary arteries are reconnected to the right ventricle and the septal defect is closed, separating the systemic and pulmonary circulation. How the resulting sudden change in pressure and flow conditions affects valve performance remains unclear. In this study, we simulate the interaction between blood flow and quadricuspid valve to investigate pre- and postoperative valve performance in a neonate. Patient-specific pre- and postoperative vessel geometries are segmented from CT images using SimVascular [3]. An elasticity-based design method is used to construct the quadricuspid valve based on the patient valve’s free edge length and geometric height extracted from echocardiography [4]. The interaction between blood flow and valve is simulated with the Immersed Boundary Method [5]. Boundary conditions are tuned with a 0D-model based on patient data [6]. During systole, an accelerating jet deflects toward the outer vessel curvature with a four-lobed starting vortex and elongated hairpin vortices. During diastole, insufficient valve coaptation leads to a central regurgitant jet towards the right ventricle in the preoperative configuration. Altered postoperative hemodynamics lead to improved valve coaptation, eliminating regurgitation. Our study shows the first fluid-structure interaction simulations of a patient-specific neonatal geometry with quadricuspid valve before and after truncal repair. Analysis of the interaction between blood flow patterns and quadricuspid valve kinematics predicts in vivo pre- and postoperative valve performance and reveals mechanisms behind improved valve performance after truncal repair.