Prevention of paraplegia during thoracic aortic cross-clamping: importance of patent internal mammary arteries.
OBJECTIVE
Unexplained anatomic and physiologic factors account for the unacceptably high rate of paraplegia/paresis after thoracoabdominal aortic reconstruction. We assessed the neurologic significance of patent internal mammary arteries (IMAs) in a novel rat model of aortic clamping in which the aortic origins of the intercostal arteries (ICAs) were occluded.


METHODS
Twenty anesthetized, intubated, and halothane-ventilated adult male rats had catheters placed in the carotid and femoral arteries. ICAs arising from the aorta were divided at their origins through a left thoracotomy. IMAs were either divided (IMA-OUT, n = 10) or left intact (IMA-IN, n = 10). Proximal and distal descending aortic clamps were placed for 7 minutes. A neurologic deficit score (NDS) was assigned at 1, 4, 18, 24, and 48 hours by use of an established scoring system.


RESULTS
The mean IMA-IN NDS was statistically better than the mean IMA-OUT NDS at 1, 4, 18, and 24 hours with p = 0.0005, 0.0014, 0.0098, and 0.0151, respectively. Moreover, the mortality rate in the IMA-OUT group was statistically greater than in the IMA-IN group (p = 0.0036).


CONCLUSIONS
In this model, patent IMAs prevent paraplegia when the ICAs are occluded at their aortic origin and the aorta is clamped for 7 minutes.
Giglia
J S
JS
Department of Surgery, University of Michigan Medical School, Ann Arbor 48109-0622.
Zelenock
G B
GB
D'Alecy
L
L
D000818:Animals; D001013:Aorta, Thoracic / Q000601:surgery*; D003250:Constriction; D004195:Disease Models, Animal; D006439:Hemodynamics; D007431:Intraoperative Complications / Q000503:physiopathology / Q000517:prevention & control*; D008297:Male; D008323:Mammary Arteries / Q000502:physiology*; D010264:Paraplegia / Q000503:physiopathology / Q000517:prevention & control*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013895:Thoracic Arteries / Q000502:physiology / Q000601:surgery; D013997:Time Factors; D014654:Vascular Patency