(IP049) Computational hemodynamic performance analysis of an off-the-shelf multi-branched endoprosthesis for repair of thoracoabdominal aortic aneurysms

Objectives: The recently approved thoracoabdominal multi-branched endoprosthesis (TAMBE) is the first commercially available off-the-shelf device in the U.S. for treating thoracoabdominal aortic pathology. This pilot study aims to evaluate the hemodynamic performance of the TAMBE device using patient-specific computational fluid dynamics (CFD) modeling.

Methods: Retrospective analysis was conducted on 10 consecutive patients undergoing elective thoracoabdominal aortic aneurysm (TAAA) repair with the Gore TAMBE device. Pre- and post-operative thoracoabdominal anatomy was segmented from CT angiograms to generate three-dimensional volume meshes using SimVascular. Patient-specific, allometrically scaled pulsatile inflow conditions were applied. Outlet boundary conditions were modeled using three-element Windkessel representations. Rigid-wall, pulsatile flow simulations were performed for pre- and post-operative models under identical inflow and outflow conditions. Computationally derived pressure, flow rates, and wall shear stress (WSS) for renal and visceral branches were compared between pre- and post-operative states using paired t-tests.

Results: TAMBE implantation resulted in a modest reduction in computationally estimated peak renal artery flow rates (15.54 ± 0.67 vs. 15.05 ± 0.75 ml/s, p = .046) and peak renal artery pressure (113.1 ± 2.0 vs. 108.7 ± 1.9 mmHg, p = .025). Most stented renal arteries (75%) experienced less than a 10% change in hemodynamics. However, five stented renal arteries showed significant reductions (12–23%) in peak pressure and flow rates (Figure 1). There were no clinical sequelae, stenosis, or patency loss of the branches at the latest follow-up. 3D visualization revealed that these reductions were associated with acute branch angles at the transition from the aortic lumen to the renal ostia (Figure 2). No significant hemodynamic changes were observed in the celiac or superior mesenteric arteries (p = .12–.87). Additionally, the fractional area of abnormal wall shear stress (WSS < 10 or >70 dynes/cm²) remained largely unchanged in all stented branches post-operatively (p = .80–.99).

Conclusions: Following TAAA repair with TAMBE, structural changes in aortic flow geometry were associated with relatively preserved renovisceral branch hemodynamics, with only a modest reduction in post-operative renal artery perfusion metrics. This did not lead to any relevant clinical outcomes at short-term follow-up. Larger cohort studies with duplex ultrasound validation will be needed to confirm these findings and identify branch artery anatomies best suited for TAMBE implantation.