In vivo evaluation of a new hybrid graft using retrograde visceral perfusion for thoracoabdominal aortic repair in an animal model

Objectives: The SPIDER technique for hybrid thoracoabdominal aortic aneurysm repair can avoid thoracotomy and extracorporeal circulation. To improve technical feasibility and safety, the new Thoracoflo graft, consisting of a proximal stent graft connected to a 7-branched abdominal prosthesis, was evaluated in a pig model for technical feasibility testing, before implantation in humans.

Methods: Retroperitoneal exposure of the infradiaphragmatic aorta, including visceral and renal arteries, was performed in 7 pigs (75-85 kg). One iliac branch was temporarily attached to the distal aorta to maintain retrograde visceral and antegrade iliac perfusion after deployment of the thoracic stent graft segment (SPIDER technique). The proximal stent-grafted segment was deployed in the thoracic aorta via direct aortic puncture over the wire without fluoroscopy. The graft was deaired before flow via the iliac side branch to the visceral and iliac arteries was established. Visceral, renal, and lumbar arteries were subsequently sutured to the corresponding side branches of the graft. Technical feasibility, operating and clamping time, blood flow, and tissue perfusion in the related organs were evaluated before implantation and after 3 and 6 hours using transit-time flow measurement and fluorescent microspheres. Final angiography or postprocedural computed tomography angiography were performed.

Results: Over-the-wire graft deployment was successful in 6 animals without hemodynamic alteration (P = n.s.). In 1 pig, the proximal stent graft section migrated as the guidewire was not removed, as recommended, before release of the proximal fixation wire. Angiography and computed tomography scan confirmed successful graft implantation and transit-time flow measurement confirmed good visceral and iliac blood flow. Fluorescent microspheres confirmed good spinal cord perfusion.

Conclusions: Over-the-wire implantation of the Thoracoflo graft using the SPIDER technique is feasible in a pig model. No fluoroscopy was required. For safe implantation, it is mandatory to follow the single steps of implantation.