In Vitro Evaluation of Aortic Stent Graft Deployment Accuracy in the Distal Landing Zone

Thoracic endovascular aortic repair technology focuses on accurately deploying the stent graft in the proximal landing zone in the proximal to distal direction. The aim of this in vitro study was to evaluate the accuracy of stent graft deployment in the distal landing zone.

It was hypothesised that a reverse implantation mechanism (in a distal to proximal deployment direction, when the operator starts to open the endoprosthesis from distal to proximal), might enhance landing accuracy in the distal LZ. The aim was to investigate this hypothesis by implanting stent grafts into the 3D printed aortas with the currently available deployment mechanism. Based on two human patients' computed tomography angiography scans, two aortas were 3D printed at 1:1 scale: "straight" and "crooked" aortas with distal aortic tortuosity of 1.006 and 1.078, respectively. They were used in order to test three endoprostheses (E-vita THORACIC 3G, Relay Plus, Valiant Captivia) 10 times by implanting them in three ways: proximal landing in the aneurysm, proximal landing in another stent graft, reverse implantation (via simulated antegrade access). The aim was to land just above the target vessel's upper edge. The distance to the target vessel and wedge apposition were assessed under a direct view using caliper.

The distance to the target vessel was 3 mm (IQR 0; 8) if the stent graft landed proximally in aneurysm, 2 mm (IQR 0; 5) if it landed proximally in another stent graft, and 0 mm (IQR 0; 0) when reverse implantation was applied. The distance to the target vessel measuring 5 mm or occurred in 45%, 30%, and 0%, respectively. Overall the median wedge apposition after stent graft implantation was 0 mm (IQR 0; 0) in the "straight" versus 18 mm (IQR 15; 20) in the "crooked" aorta (p < .001).

Reverse stent graft deployment is associated with more accurate landing in the distal landing zone. Distal aortic tortuosity constitutes an important impediment to covering the distal LZ's entire circumference with a stent graft.