L. Petravi?1,2, A. Varsanik1, B. Nnate1, N. Nguyen1, K. Cao1, S. Rajendran3, R. Milner1, L. Pocivavsek1 1University Of Chicago, Department Of Surgery, Chicago, IL, USA 2University of Maribor, Faculty Of Medicine, Maribor, MARIBOR, Slovenia 3Royal Prince Alfred Hospital, Department Of Surgery, Sydney, SYDNEY, Australia
Introduction: Kommerell's diverticulum (KD) is a congenital anomaly characterised by the presence of a remnant from the fourth dorsal aortic arch. An increased risk of aortic dissection and rupture is linked to KDs. The available treatment modalities encompass a spectrum from open surgical repair to total endovascular repair. We hypothesize that EVAR will increase the inferior aortic pressure which will cause the KD to grow since the endograft does not absorb forces as well as the aortic wall. The objective of this study is to employ employ CFD and FEA to study KD growth post-EVAR.
Methods: Segmentation of an aorta, left and right subclavian arteries, and the right carotid arteries was done from a CT scan of a patient with KD post-EVAR using Simpleware ScanIP. The root border was the takeoff point of the left coronary artery, while the inferior border was the takeoff point of the iliac artery. The CFD analysis was performed using XFlow. The simulations were conducted with boundary conditions set at 100 mmHg of pressure at the end of each branch, and 100/140/180 mmHg pressure at the inferior boundary. A waveform derived from arterial pulsatile blood flow was used as the inlet velocity. The pressure output from CFD at the third diastole and systole points were projected onto the initial geometry as the loading conditions for finite element modeling in Abaqus. The average wall deformation, shear stress, and static pressure were extracted for each condition within the KD region.
Results: We discovered that when the pressure in the inferior aorta rises, so does the static pressure on the KD. This is also true for the extent of displacement and matter misplacement. The quantitative findings are depicted in the table. This has been qualitatively corroborated by a velocity simulation that shows the same flow into the KD regardless of outflow pressure.
Discussion: We discovered that hemodynamics had a major impact on growth of KD. According to the findings of this study, the pressures in the KD increases if the inferior aortic pressure rises, leading to increase in KD size. If the EVAR hypothesis is correct, and the EVAR does in fact increase the inferior aortic pressure, this would explain the clinical growth of KD following EVAR. Future studies should include simulations of various material characteristics for the aorta and KD. Furthermore, a CFD model of EVAR should be established to study the effects EVAR has on the fluid dynamics.
