Low-flow perfusion via the innominate artery during aortic arch operations provides only limited somatic circulatory support.
BACKGROUND
Aortic arch operations in pediatric patients using low-flow perfusion techniques have been standardized to a certain degree, but some of the often-stated beneficial effects have never been proven. Especially, the existence or efficacy of any subdiaphragmal perfusion still remains unclear.


METHODS
Twenty-six newborn male piglets (10-15 kg) underwent aortic arch surgery under general anesthesia using either low-flow perfusion via the innominate artery (LF, 30 ml/(kg min), 25 degrees C, n=12) or conventional deep hypothermic circulatory arrest (DHCA, 20 degrees C, n=14). Cortical somatosensory-evoked potentials (SSEPs), carotid, and subdiaphragmal blood flows were measured. The animals of both groups have been randomized to either pH-stat or alpha-stat management on cardiopulmonary bypass (CPB).


RESULTS
During low-flow perfusion via the innominate artery only negligible flows of maximum 1-3 ml/min in the femoral arteries were detected, whereas the right carotid artery flow doubled. During reperfusion, serum-lactate and aspartate amino-transferase (AST) levels were significantly higher compared to the circulatory arrest group, whereas alanine amino-transferase (ALT), gamma-glutamyl transpeptidase (gamma-GT), AP, and creatinine did not show any significant differences. Cortical SSEP returned to preoperative values in all but two low-flow animals. There was no return of SSEP in all piglets operated under deep hypothermic circulatory arrest (p<0.01).


CONCLUSIONS
Compared to DHCA, low-flow perfusion via the innominate artery provides superior neuroprotection despite higher tissue temperatures. Although collateral blood flow via the subclavian artery and the circulus arteriosus willisii has often been presumed, only 'trickle-flow' with some protective potential was detectable in the femoral arteries during low-flow perfusion. Origin of elevated lactate and AST levels seems to be the lower limbs.
Roerick
Olaf
O
Department of Cardiothoracic Surgery, University Hospital Erlangen, University of Erlangen-Nuremberg, Krankenhausstrasse 12, 91054 Erlangen, Germany. olaf.roerick@herz.imed.uni-erlangen.de
Seitz
Timo
T
Mauser-Weber
Petra
P
Palmaers
Thomas
T
Weyand
Michael
M
Cesnjevar
Robert
R
D000137:Acid-Base Imbalance / Q000209:etiology; D000818:Animals; D000831:Animals, Newborn; D001013:Aorta, Thoracic / Q000601:surgery*; D001831:Body Temperature; D016122:Brachiocephalic Trunk / Q000502:physiology*; D001927:Brain Diseases / Q000517:prevention & control; D002560:Cerebrovascular Circulation; D005073:Evoked Potentials, Somatosensory; D006324:Heart Arrest, Induced; D006439:Hemodynamics; D007430:Intraoperative Care / Q000379:methods*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010477:Perfusion; D012039:Regional Blood Flow; D013552:Swine
D019344:Lactic Acid