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.
Pocar
Marco
M
Cattedra di Cardiochirurgia, Università degli Studi di Milano, IRCCS MultiMedica - Via Milanese 300, MI 20099, Sesto San Giovanni, Milano, Italy. marco.pocar@unimi.it
Rossi
Vincenzo
V
Addis
Alessandro
A
Monaco
Ario
A
Sichel
Sergio
S
Addis
Flaminio
F
Grossi
Adalberto
A
Donatelli
Francesco
F
D000818:Animals; D001013:Aorta, Thoracic / Q000601:surgery; D001794:Blood Pressure; D004195:Disease Models, Animal; D006614:Hindlimb / Q000098:blood supply / Q000503:physiopathology; D008297:Male; D009068:Movement; D010100:Oxygen / Q000032:analysis / Q000097:blood; D010264:Paraplegia / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D012039:Regional Blood Flow; D012720:Severity of Illness Index; D013116:Spinal Cord / Q000098:blood supply / Q000503:physiopathology; D020760:Spinal Cord Ischemia / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D013552:Swine; D013908:Thoracotomy / Q000009:adverse effects / Q000379:methods*; D014549:Urinary Incontinence / Q000209:etiology / Q000503:physiopathology
D010100:Oxygen