Left atrial-inferior vena cava bypass achieves retroperfusion of the porcine spinal cord: morphologic and preliminary physiologic studies

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

BACKGROUND

Spinal cord damage represents a devastating complication of thoracic and thoracoabdominal 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 additional 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 connected to a cardiotomy reservoir. All animals underwent 40-minute single cross-clamping of the proximal 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 evaluation.

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 perfusion 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. Retrograde spinal cord perfusion warrants further investigation.

General handling and anesthesia for experimental surgery in pigs

The pig is a common large animal for experimental settings in many fields of surgery. In experimental surgery, there is a need for different narcotic procedures depending on the complexity of the surgical investigation. Narcotic procedures have to be safe, easy to handle, and should not influence the experimental results. We hereby present important aspects of handling and narcotic procedures for pigs. The aim of this publication is to supply an introduction for young surgical investigators who are planning or already have started investigations using pigs as an experimental animal. This publication is based on our institutional experience of narcotic and surgical procedures in more than 400 cases.