P1826Computational fluid dynamic analysis of acute aortic dissection

Abstract Background Mechanism of acute aortic dissection still is not well understood. It is very difficult to predict where, when, and how acute aortic dissection occurs. This time we focused on blood flow velocity (FV), wall shear stress (WSS), and oscillatory shear index (OSI) which is three dimensional fluctuations of WSS inside ascending aorta. It is well recognized that a higher or lower WSS may cause intimal dysfunction, which could result in the progression of atherosclerosis. Furthermore, because of the non-slip boundary mechanical equilibrium of forces, WSS will separate the inner and outer layers of the aorta. This sheer force could stress the medial tissue and result in degeneration. OSI has been reported as important hemodynamic parameter that is highly associated with the progression of atherosclerosis by inducing radical oxygen production of the endothelial cells. Therefore, OSI may be more closely associated with the degeneration of the media in comparison with WSS. This time FV, WSS, and OSI was evaluated using computational fluid dynamics to identify the location of acute aortic dissection entry. Method Using computed tomography data of three patients (Case A, B, C) who had acute aortic dissection, each three pre-dissection aorta model was made. Computer simulation images of four dimensional pulsatile blood flow was made and pulsatile cardiac flow from one cardiac cycle was simulated. A three-dimensional movie was made to evaluate FV, WSS, and OSI. One normal size aorta was evaluated as a control. Results In control, blood flow inside ascending aorta was laminar, on the contrary, spiral flow was observed in three dissection cases. FV was slightly higher in dissection case (control: 0.56m/s, A: 0.77m/s, B: 1.05m/s, C: 0.35m/s). Maximum WSS in ascending aorta was 3.24Pa in control. In dissection cases, there was patchy high (A: 18.6Pa, B: 25.6Pa, C: 4.0Pa,) WSS lesion in ascending aorta. In case A and B, these patchy high lesions are close to the entry site. In all three dissection case, OSI was high around entry site. Figure 1 Conclusion According to our computer simulation, patchy high WSS and high OSI lesion is related with acute dissection entry site at the ascending aorta. Acknowledgement/Funding None