Retrograde perfusion of the spinal cord during aortic crossclamping: initial observations in the swine model.
BACKGROUND
Retrograde perfusion has emerged as a useful technique for the preservation of the heart and brain when arterial circulation is interrupted. Herein, this study was designed to test the hypothesis that retrograde perfusion of the azygos vein is sufficient to maintain viability of the spinal cord during aortic occlusion in the swine model.


METHODS
Female swine, 17 to 22 kg, underwent left thoracotomy, creation of a shunt between the aortic arch and the azygos vein, and aortic crossclamping for 60 minutes: the shunt was open in the retrograde perfusion group (n = 5) and closed in the control group (n = 4). The animals were evaluated for neurologic function for 8 days and killed. Spinal cords were processed for histologic examination. Additional animals underwent left thoracotomy and injection of a casting solution in the azygos vein (n = 2), left thoracotomy and angiography of the azygos vein (n = 2), and a compartmentalization procedure to separate the azygos vein from the caval system followed by angiography (n = 2).


RESULTS
Differences in the neurologic (2-sample t test, P =.11) and histologic (2-sample t test, P =.65) scores of retrograde perfusion and control groups were likely due to chance. Casting and angiography groups showed extensive collaterals between azygos and caval systems, only partially interrupted by compartmentalization.


CONCLUSIONS
Retrograde perfusion does not protect the spinal cord from ischemic injury. The collateral network between the azygos and caval systems prevents the oxygenated blood from reaching the cord. Surgical separation between the 2 systems was only partially successful in this study.
Follis
F
F
University of New Mexico Health Sciences Center, Department of Cardiothoracic Surgery, Albuquerque, New Mexico, USA. follis99@hotmail.com
Dragan
R
R
Blisard
K S
KS
Hartshorne
M
M
Temes
T
T
Pett
S B
SB
Wernly
J A
JA
D000792:Angiography; D000818:Animals; D001011:Aorta / Q000601:surgery*; D001013:Aorta, Thoracic / Q000601:surgery; D001166:Arteriovenous Shunt, Surgical / Q000295:instrumentation / Q000379:methods; D001401:Azygos Vein / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D003097:Collateral Circulation / Q000502:physiology; D003250:Constriction; D004195:Disease Models, Animal; D005260:Female; D006614:Hindlimb / Q000294:innervation; D007431:Intraoperative Complications; D007601:Jugular Veins / Q000601:surgery; D008026:Ligation; D009460:Neurologic Examination; D010100:Oxygen / Q000097:blood; D010477:Perfusion / Q000379:methods*; D012039:Regional Blood Flow / Q000502:physiology; D013116:Spinal Cord / Q000098:blood supply* / Q000473:pathology / Q000503:physiopathology; D020760:Spinal Cord Ischemia / Q000209:etiology / Q000473:pathology; D013552:Swine; D013908:Thoracotomy; D014022:Tissue Survival; D014682:Vena Cava, Inferior / Q000601:surgery; D014683:Vena Cava, Superior / Q000601:surgery
D010100:Oxygen