Abstract 16777: Augmentation of Spinal Cord Pre-Collateralization to Prevent Paraplegia After Aortic Surgery

Abstract

Introduction: Spinal cord ischemia from complex aortic surgery can lead to paraplegia. Spinal cord is supplied by a rich collateral network of segmental arteries. Emerging data demonstrate that patients with staged aortic repairs suffer fewer spinal cord injuries than those with a single operation. Hypothesis: Paraplegia can be induced in a swine model by ligation of segmental spinal arteries. Induction of spinal cord pre-collateralization by staging the spinal segmental arterial coverage can minimize the risk of paraplegia. Methods: Twenty-four female Yorkshire pigs (50-70kg) underwent abdominal exposure of the aorta. Lumbar aortic group underwent ligation of the lumbar segmental arteries (5-7) and median sacral trunk. Thoracic aortic coverage consisted of stent graft placement from the left subclavian to celiac artery. Full coverage un-staged group underwent a simultaneous lumbar and thoracic coverage. Similar procedure was performed one week apart in staged full coverage group. Fluorescent microspheres were injected to evaluate regional spinal cord flow distribution. Protein expression in the spinal cord was analyzed using Western Blot. Results: Reproducible paresis was demonstrated in full coverage animals. This was associated with decreased viable spinal cord neurons. In the staged full coverage, complete motor recovery occurred within 24h of the second stage. Neurologic recovery was associated with higher levels of Neuropilin-1. Regional blood flow was quantified by microsphere density in various segments of spinal cord using laser confocal microscopy. Conclusions: A reproducible model of spinal cord injury can be carried out in swine by disrupting spinal cord segmental blood flow. This injury can be ameliorated by partial or staged coverage of the segmental arteries. Induction of regional spinal cord pre-collateralization can be demonstrated using fluorescent microspheres. This may be dependent on Neuropilin-1 expression in the tissue.