A Fluid Structure Interaction Workflow For Studying Aortic Dissections

Introduction: After diagnosis and treatment of aortic dissections, there is the potential for future complications such as the growth or rupture of pre-existing aneurysms or further dissection of the aorta. This susceptibility to future complications is what we refer to as “aortic fragility”. Current computational models of aortic dissection rely upon computational fluid dynamics (CFD) or finite element analysis (FEA); however, there are limitations to using either method alone. Using a healthy patient aorta as our control case, we developed a novel method of coupling CFD with FEA in a fluid surface interaction (FSI) model for studying aortic dissection. Methods: We developed this FSI model by first segmenting aortas from CT scans to generate patient-specific models. With these meshes, we used a cardiac cycle fluid velocity profile to perform CFD and extracted static pressure values on the aortic wall at systole and diastole. We applied these pressures to our FEA model as the mechanical load driving wall deformation. Results: We successfully completed the CFD portion of our FSI simulation with results consistent with our expectations. Velocity data at the ascending and descending aorta, branches and arch correctly reflect our input cardiac cycle velocity profile. Histograms of static pressure values on the aortic wall at systole and diastole show that the mean systolic pressure is greater than the mean diastolic pressure, thus reflecting our expectations. Heat maps of this data reveal the aortic arch and branches to be areas of highest pressure, with pressure gradually decreasing in the distal aorta. Conclusion: With our healthy aorta control, we have successfully validated the CFD component of our FSI model. Our methods improve upon previous models by coupling CFD with FEA, allowing the use of realistic pressure loads derived from fluid analysis. We plan to further improve by validating the FEA component of our model and applying our methodology to dissection geometries. With this FSI workflow, we hope to more accurately model and predict the deformation patterns of aortic dissection in fragile aortas.