Spinal cord retrograde perfusion: review of the literature and experimental observations.

Background: Spinal cord damage represents a devastating complication of thoracic and tho- racoabdominal aortic surgery. Retrograde perfusion as an alternative route to protect the spinal cord has recently been investigated with controversial results. We reviewed the literature and analyzed addi- tional experimental observations. Methods: Ten juvenile pigs were divided into control and study groups (A and B, respectively). Through a lateral thoracotomy the distal aortic arch was cannulated and con- nected to a cardiotomy reservoir. All animals underwent 40-minute single cross-clamping of the prox- imal descending aorta while keeping proximal systolic arterial pressure above 100 mmHg. In group B, normothermic arterial blood was delivered retrogradely through the azygos vein, maintaining perfusion pressure within 25-30 mmHg. Animals were allowed to recover to perform a primary neurologic eval- uation. Results: Flaccid paraplegia was uniformly observed in group A. In group B, all animals showed mild-to-moderate voluntary hind limb movements on awakening (p = 0.007). Controls also showed urine incontinence short after cross-clamping, and this was not observed in group B (p = 0.008). A different veno-arterial oxygen step-down was observed in blood collected from the excluded aorta in the two groups (p < 0.001). Conclusions: Preliminary results indicate that controlled retrograde normothermic per- fusion alone through the azygos system provides some degree of protection from spinal cord ischemia. Bladder dysfunction may represent a simple test to detect massive cord damage intraoperatively. Ret- rograde spinal cord perfusion warrants further investigation. doi: 10.1111/j.1540-8191.2006.00368.x