Experimental Two-Stage Simulated Repair of Extensive Thoracoabdominal Aneurysms Reduces Paraplegia Risk

Background In a pig model, we compared spinal cord injury after extensive segmental artery (SA) sacrifice in a single stage with recovery after a two-stage procedure: lumbar artery followed by thoracic SA sacrifice. Methods Twenty juvenile Yorkshire pigs were randomly assigned to undergo extensive SA sacrifice at 32°C in a single operation (group 1, n=10), or thoracic SA ligation 7 days after lumbar artery sacrifice (group 2, n=10). Spinal cord perfusion pressure (SCPP) was monitored using a catheter placed in the distal stump of L1. Hind limb function was evaluated intraoperatively using motor-evoked potentials and for 5 days postoperatively using a modified Tarlov score. Results Motor-evoked potentials were intact in all pigs until 1 hour after surgery. All pigs in group 2 fully recovered hind limb function, whereas 40% in group 1 experienced paraplegia (median Tarlov scores 9 versus 7; p = 0.004). Group 1 SCPP fell to 28 ± 6 mm Hg after SA sacrifice, compared with 44 ± 8 mm Hg in group 2 ( p p = 0.0002). Histopathologic analysis showed more severe ischemic damage to the lower thoracic ( p p = 0.01) in group 1. Conclusions In contrast with the single-stage approach, a two-stage procedure, starting with ligation of six or fewer lumbar SAs, leads to only a mild drop in SCPP and stimulates vascular remodeling, minimizing the impact of subsequent SA sacrifice on spinal cord function. The greater safety of extensive SA sacrifice when undertaken in two stages has important implications for endovascular and hybrid aneurysm repair.