Prevention of paraplegia in pigs by selective segmental artery perfusion during aortic cross-clamping

Purpose: During thoracoabdominal aortic aneurysm repair, a prolonged interr uption of the spinal cord blood supply can result in irreversible spinal co rd damage, The aim of this study was to investigate whether selective segme ntal artery perfusion during aortic clamping could prevent paraplegia in pi gs. Methods: Specially designed segmental artery perfusion catheters, which cou ld be attached to an extracorporeal bypass graft system, were used. In expe riment I (n = 10), it was assessed whether selective segmental artery perfu sion could reverse electrophysiologic evidence of spinal cord ischemia and maintain transcranial motor evoked potentials (tc-MEPs) during 60 minutes o f aortic cross-clamping. The abdominal aorta, containing critical segmental arteries, was bypassed through use of an aortoaortic bypass graft system. After the disappearance of tc-MEPs, an aortotomy was followed by selective segmental artery perfusion. In experiment II (n = 10), the aim was to deter mine whether selective segmental artery perfusion could prevent paraplegia. In five animals (group A), aortic cross-clamping was followed by selective segmental artery perfusion; five control animals (group B) underwent segme ntal artery blockade only. Postoperative hind limb function and spinal cord histopathology were evaluated on the third postoperative day. Results: In experiment I, tc-MEPs disappeared within 3.7 +/- 3.7 minutes af ter crossclamping and returned in all animals in 8.5 +/- 5.3 minutes after selective perfusion. During the study period, tc-MEP amplitudes recovered t o a median of 49% (range, 28%-113%) of baseline values. Total bypass graft flow was 880 +/- 294 mL/min, of which 184 +/- 54 mL/min was directed to the selective perfusion catheters, The flow in individual catheters was 52 +/- 13 mL/min, In experiment II, all perfused animals demonstrated normal hind limb function, whereas four of five control animals were paraplegic on day 3 (P = .04) In the perfused animals, histopathologic examination showed ei ther no spinal cord damage or eosinophilic neurons only, whereas in paraple gic controls there was infarction in large areas of the cord (P < .0001). Conclusion: In pigs, selective segmental artery perfusion can provide suffi cient spinal cord blood flow to prevent paraplegia resulting from 60 minute s of aortic clamping, as shown by clinical outcomes and histopathologic exa mination.