Identifying Hemodynamic Predictors of Aortic Growth After Thoracic Endovascular Aortic Repair for Type B Aortic Dissection

Abstract

Objective:

To explore independent predictors of aortic growth in patients with type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR), utilizing computational fluid dynamics (CFD) simulation.

Materials and Methods:

Patients who underwent TEVAR for TBAD in a single center between April 2014 and April 2023 were evaluated retrospectively. Rapid enlargement (defined as ≥5 mm/year) or aortic rupture were used to categorize patients into aortic growth and nongrowth groups. The analyzed hemodynamic parameters included wall pressure, flow velocity, flow rate, wall shear stress (WSS), time-averaged WSS, oscillatory shear index (OSI), and relative residence time. Four parallel cross-sections (L1–L4) were utilized to extract data from the hemodynamic cloud maps. Multivariate logistic regression analysis was conducted to identify independent predictors. Receiver operating characteristic (ROC) curves and the area under the curve (AUC) for these predictors were also determined.

Results:

The aortic growth rate was 17.9%. A total of 51 geometric models were successfully constructed, 17 in the growth group and 34 in the nongrowth group. For morphological variables, the growth group exhibited more re-entry tears (p=0.011) and a longer patent false lumen (p=0.028), compared with the nongrowth group. For hemodynamic variables, the growth group had higher L2 pressure (p=0.040), L3 flow rate (p=0.048), and L3 OSI (p=0.020). Multivariate analysis revealed that L3 OSI (OR=7.82, 95% CI 4.122–11.33, p=0.020) and L2 pressure (OR=1.05, 95% CI 1.001–1.099, p=0.044) were independent risk factors for aortic growth. The AUC for L3 OSI and L2 pressure as predictors of aortic growth were 68.25% (95% CI 53.85–82.66) and 64.36% (95% CI 49.13–79.59), respectively.

Conclusions:

CFD simulation demonstrated that elevated pressure and increased OSI in false lumen could independently predict aortic growth following TEVAR. Monitoring these specific metrics could help identify high-risk patients immediately after stent graft implantation. However, the predictive value of these predictors was low, indicating a need for larger sample, higher-quality studies to validate these findings.

Clinical Impact

Thoracic endovascular aortic repair (TEVAR) is the important treatment for patients with acute type B aortic dissection (TBAD). However, aortic growth following TEVAR remains an important unresolved issue. Previous case/ cases reports found aortic growth was not solely driven by anatomical factors but influenced by hemodynamics within the false lumen. However, no further higher-quality studies supported the conclusion. In this comparative study, aortic growth and non-growth groups were divided. The computational fluid dynamics (CFD) simulation showed that elevated pressure and oscillatory shear index (OSI) in the false lumen could independently predict aortic growth after TEVAR. Our conclusions allowed vascular surgeons to make a decision on further intervention for distal aortic dissection immediately after stent graft implantation, to prevent potentially post-dissection aortic aneurysm (PDAA) and rupture in the future.