The SPIDER-Graft: A Modified Frozen Elephant Trunk for Thoracoabdominal Aortic Repair

Introduction: The SPIDER-graft was developed based on reversed frozen elephant trunk technique for thoracoabdominal aortic (TAA) repair avoiding thoracotomy, extracorporeal circulation (ECC) and reducing cross-clamping time. The Spider-graft prosthesis, consisting of proximal stent graft connected to six-branched abdominal prosthesis, was compared with open aortic repair (OAR, control) in a pig model.

Material and Methods: Retroperitoneal access to the TAA was performed in 6 pigs per group (75–85 kg). For control total TAA was exposed. After cross-clamping proximal and distal aortic anastomosis were performed and successively celiac trunk (CT), superior mesenteric artery (SMA), right and left renal arteries (RA) and finally iliac arteries were implanted. For Spider-graft infradiaphragmatic aorta was exposed. Right iliac branch was first temporarily anastomosed to the distal aorta maintaining periprocedural retrograde visceral and antegrade aortoiliac blood flow. Proximal stent-grafted part was deployed in the thoracic aorta via the CT ostium. Visceral and renal arteries were successively anastomosed to the side-branches of the graft. Lumbar arteries were reimplanted into the access branch. Finally, transient distal aortic anastomosis was released and both iliac branches were anastomosed. Technical feasibility, operating and clamping time, blood flow and tissue perfusion in the related organs were evaluated before implantation and 3, and six hours after implantation using transit-time flow measurement (TTFM) and fluorescent microspheres (FM). After 6 hours observation final angiography and post-procedural CT-angiography were performed.

Results: Graft deployment was successful in all animals without hemodynamic instability. Total aortic clamping time was 88.3 ± 16.3min during OAR and 4.4 ± 1min during SPIDER-graft. Selective ischemic times of related organs were significantly longer during OAR. TTFM and FM confirmed clinical findings. Angiography and CT-scan confirmed successful graft implantation in both groups. FM confirmed good spinal cord perfusion.

Conclusion: SPIDER-graft can reduce cross-clamping time, ischemic time, and avoid ECC and thoracotomy during TAA repair in a pig model. Hemodynamic stability can be achieved easier with less blood loss compared with OAR. Reimplantation of lumbar arteries confirms good spinal cord perfusion assessed by FM. Further modifications of the graft are under evaluation to improve handling of the graft.