PREVENTION OF SPINAL-CORD INJURY AFTER TRANSIENT AORTIC CLAMPING WITHTISSUE FACTOR PATHWAY INHIBITOR

Background. Lower limb paralysis that occurs in 11% of patients after treatment of thoracic and thoracoabdominal aortic aneurysms is unpredi ctable and at present not preventable. The proposed cause for the neur ologic changes is believed to be spinal cord ischemia combined with is chemia/reperfusion injury. Recombinant tissue factor pathway inhibitor (rTFPI), a multivalent Kunitz-type inhibitor that binds to tissue fac tor-VIIa complex, was evaluated. Methods. The effectiveness of rTFPI a s an agent to limit spinal cord ischemia/reperfusion injury teas studi ed in a rabbit spinal cord made ischemic for 20 minutes. rTFPI or phos phate-buffered saline solution (control) was given in randomized blind ed fashion at the onset and conclusion of ischemia. Animals underwent neurologic evaluation at 24 hours in a blinded fashion with a modified Tarlov Scale to rate the lower limb paralysis (score of 4 = normal fu nction, score of 0 = complete paralysis). Results. Seventy-five percen t of the TFPI-treated animals had Tarlov scores of 3 to 4, whereas onl y 29% of the animals treated with phosphate-buffered saline solution h ad such scores (p < 0.0014). Spinal cord histologic findings correlate d with the neurologic findings. Conclusions. We believe that TFPI has unique inhibitory properties that make it an effective agent In limiti ng postoperative paraplegia ia associated with spinal ischemia.