Establishment of Fetal Extra-corporeal circulation for Fetal Cardiac Surgery : Elucidation of Pathophysiology of Fetal Circulation and Placental Function by Oxidative Stress

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Objective : Endothelial dysfunction due to fetal extra-corporeal circulation may have an important role in, establishment of feral cardiac surgery. This study investigates the endothelial function of umbilical artery after fetal extra-corporeal circulation by reliable method. Methods : This study was undertaken in 14 fetal lambs. Fetuses were, divided into 2 groups; control group (n=7) and pump group (n=7). In pump group, extra-corporeal circulation was established for 30 minutes by centrifugal pump. Hemodynamic measurements and blood gas analysis were performed pre, during, and every 30 minutes after extra-corporeal circulation. Umbilical artery was harvested 60 minutes after cessation' of extra-corporeal circulation, and endothelium-dependent relaxation (bradykinin (BK), calcium ionophore (A23187)) and endothelium-independent relaxation (sodium nitroprusside (SNP)) were exmined after smooth muscle contraction by serotonin. Results : Umbilical artery flow and aortic pressure were significantly decreased 30 and 60 minutes after extra-corporeal circulation. Hypoxia and hypercapnia were recognized after extra-corporeal circulation. Metabolic acidosis progressed during and after extra-corporeal circulation. Endothelium-dependent relaxation was impaired in pump group compared with control group (BK: 43.6±6.4% in control group, 18.9±2.5% in pump group, p<0.01, A23187: 37.8±4.6% in control group, 19.6±3.9% in pump group, p<0.01). Meanwhile, endothelium-independent relaxation was preserved, in both groups. Conclusions : Fetal extra-corporeal circulation certainly caused endothelial impairment of umbilical artery and hemodynamic deterioration due to metabolic acidosis. Prevention of endothelial damage and metabolic acidosis could be the main target to success fetal cardiac surgery.