## 3 Results
### Flow Analysis
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**Blood Flow [mL/s]**} \\ \cline{2-5}
**Artery Type** & \multicolumn{4}{c}{**USG-Doppler**} & \multicolumn{4}{c}{**CFD**} \\ \cline{2-5}  & **Pre-TEVAR** & **Post TEVAR** & **Pred TEVAR** & **Pred TEVAR** & **Pred TEVAR** \\  & **Median [Q¡Q2]** & **Median [Q¡Q2]** & **Median [Q¡Q2]** & **Median [Q¡Q2]** & **_p_ Value** \\ \hline \multirow{2}{*}{**Thoracic trunk**} & 7.724 & 65.220 & \multirow{2}{*}{\(p\) Value} & 9.100 & 61.720 \\  & (7.089; 9.600) & (64.996; 6.300) & \(p\) = 0.043 & (9.100; 9.100) & (61.700;63.050) & \(p\) = 0.043 \\ \multirow{2}{*}{**Brachiocephalic trunk**} & 5.300 & 5.00 & \multirow{2}{*}{\(p\) Value} & 5.470 & \multirow{2}{*}{\(p\) Value} & 4.860 \\  & (4.810;5.920) & (4.370;5.200) & & (4.760;5.848) & (4.760;5.280) & \(p\) = 0.273 \\ \multirow{2}{*}{**Carotid arteries**} & 4.840 & 4.610 & \multirow{2}{*}{\(p\) Value} & 5.00 & \multirow{2}{*}{4.620} & \multirow{2}{*}{\(p\) Value} \\  & (4.505;5.360) & (4.230;5.100) & & (4.470;5.320) & (4.470;5.070) & \(p\) = 0.715 \\ \multirow{2}{*}{**Subclavian arteries**} & 4.290 & 4.170 & \multirow{2}{*}{\(p\) Value} & 4.250 & \multirow{2}{*}{4.110} & \multirow{2}{*}{\(p\) Value} \\  & (4.140;7.200) & (4.020;4.040) & & (4.010;4.664) & (3.820;4.250) & \(p\) = 0.273 \\ \multirow{2}{*}{**Renal arteries**} & 9.300 & 9.705 & \multirow{2}{*}{\(p\) Value} & 9.280 & \multirow{2}{*}{10.400} & \multirow{2}{*}{\(p\) Value} \\  & (8.870;9.430) & (9.500;9.925) & & (9.175;9.472) & (9.885;10.495) & \(p\) = 0.043 \\ \multirow{2}{*}{**Iliac arteries**} & 2.320 & 1.985 & \multirow{2}{*}{\(p\) Value} & 2.135 & \multirow{2}{*}{2.007} & \multirow{2}{*}{\(p\) Value} \\  & (2.1352;3.77) & (1.9122;0.50) & & (2.045;2.138) & (1.947;2.047) & \(p\) = 0.079 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Changes in blood flow [mL/s] for pre- and post- thoracic endovascular aortic repair (TEVAR) for ultrasonography (USG-Doppler) and computational fluid dynamics (CFD). Data are presented as the median (Q¡Q3). N = 5. \(p\)-values were calculated using the Wilcoxon Ranked Sign test. CFD analysis in the area of the true lumen indicated a significant decrease in blood velocity post-TEVAR compared to pre-TEVAR (0.22 \(\pm\) 0.03 m/s and 0.32 \(\pm\) 0.01 m/s, respectively, \(p\) = 0.043; Table 3). Also, a significant decrease in velocity was observed for USG-Doppler data (0.23 \(\pm\) 0.03 m/s to 0.29 \(\pm\) 0.05 m/s, post- and pre-TEVAR, (_p_ = 0.043; Table 3). The accuracy of CFD calculations was 96% post-TEVAR (Table 3) and 90% pre-TEVAR (Table 3). There was a moderate positive relationship between CFD and USG-Doppler data (_r_ = 0.706). Contrary to the thoracic aorta, calculated blood velocity in renal arteries increased post-TEVAR compared to pre-TEVAR (0.36 \(\pm\) 0.01 m/s and 0.32 \(\pm\) 0.01 m/s, respectively, \(p\) = 0.043; Table 3). Analysis of USG-Doppler data in the same area confirmed a similar trend (0.34 \(\pm\) 0.01 m/s vs. 0.32 \(\pm\) 0.01 m/s post-TEVAR vs. pre-TEVAR, \(p\) = 0.043; Table 3). The accuracy of CFD calculations in the renal arteries was 95% post-TEVAR (Table 3) and 97.2% pre-TEVAR (Table 3). Also, a moderate positive relationship between CFD and USG-Doppler data was shown (_r_ = 0.661). Detailed analysis of changes in blood velocity contours in the aortic arch and the left renal artery pre- and post-TEVAR is presented in Figures 2 and 3, respectively. We observed high-velocity flow in the ascending aorta, with a pronounced jet into the dissection entry tear from the true lumen to the false lumen, and a slow-flow zone with recirculation patterns adjacent to the false lumen wall. Moreover, in our study the dissecting membrane created an artificial barrier characterized by high velocity (Figure 2). Additionally, the post-operative character of velocity contours contours distribution was more uniform, and no cross-sectional flow between the true and false lumen was observed for all five analysed patients (Figure 2).