Staged Approach Prevents Spinal Cord Injury in Hybrid Surgical-Endovascular Thoracoabdominal Aortic Aneurysm Repair: An Experimental Model

Background. In a porcine model, we investigated the impact of sudden stent graft occlusion of thoracic intercostal arteries after open lumbar segmental artery (SA) ligation. Methods. After randomization into two groups, 20 juvenile Yorkshire pigs (27.1 +/- 0.6 kg) underwent open lumbar SA sacrifice (T-13-L-5) followed by endovascular coverage of all thoracic SAs (T-4-T-12) at 32 degrees C, either in a single operation (group 1) or in two stages separated by seven days (group 2). Collateral network pressure (CNP) was monitored by catheterization of the SA L-1, and postoperative hind limb function was assessed using a modified Tarlov score. Results. The CNP in group 1 decreased to 34% of baseline, whereas CNP after lumbar SA ligation in group 2 fell to 55% of baseline (74 +/- 2.4 to 25 +/- 3.6 mm Hg vs 74 +/- 4.5 to 41 +/- 5.5 mm Hg; p < 0.0001). Subsequent thoracic stenting (group 2) led to another significant but milder drop (p = 0.002 versus stage 1) from the restored CNP (71 +/- 4.2 to 54 +/- 4.9 mm Hg). Five of ten pigs in group 1 suffered paraplegia, in contrast to none in group 2 (median Tarlov score 6, vs 9; p = 0.0031). Histopathologic analysis showed more severe ischemic damage to the lower thoracic (p = 0.05) and lumbar spinal cord (p = 0.002) in group 1. Conclusions. These results underline the potential of the staged approach in hybrid procedures. Furthermore they highlight the need for established adjuncts for preventing paraplegia in hybrid and pure stent-graft protocols in which sudden occlusion of multiple SAs occurs. (Ann Thorac Surg 2011;92:138-46) (C) 2011 by The Society of Thoracic Surgeons