[Evaluation on the early hemodynamic changes after cardiac surgery for congenital heart diseases in neonates]

To accurately evaluate the early hemodynamic status of neonates who undergo complex neonatal cardiac surgery, through monitoring the cardiac index (CI), serum lactate (Lac), mixed venous oxygen saturation (SvO(2)).

From January to November 2007, haemodynamic data of 80 patients who had open heart surgery for congenital heart disease were analyzed within 48 hours after operation. Of the 80 patients, 47 were neonates, their age ranged from 3 days to 29 days [mean (21.98 + or - 8.15) days] and weight ranged from 2.6 kg to 4.2 kg [mean (3.51 + or - 0.39) kg]. As the control group, 33 young infants at the age of 30 days to 180 days [mean (76.36 + or - 24.79) days] with body weight ranged from 3.1 kg to 6.0 kg [mean (4.59 + or - 0.59) kg] were also enrolled. The value of CI derived from pulse contour and was calculated by using the PiCCO system. Meanwhile, measurements of serum lactate level and SvO(2) were recorded. Serial measurements of the cardiac output were performed for the neonates.

CI in survivors of neonates (2.01 + or - 0.35) L/(min x m(2)) was lower than that of the infants (2.26 + or - 0.39) L/(min x m(2)) after cardiac surgery (P < 0.05) at 2 h, 6 h postoperatively. However, urine output remained normal. The value of pulse pressure in neonates was less than that in young infants. Serum lactate level in neonates was significantly higher than that of young infants during cardiac surgical procedures (P < 0.01) at 12 h postoperatively; the SvO(2) was more than 60% postoperatively in survived neonates, there was no significant difference (P > 0.05) in SvO(2) between neonates and young infants during preoperative and postoperative periods. There was a positive correlation between CI and SvO(2). Four neonates and 1 young infant died after surgical treatment, surgical mortality was 8.5% and 3.0%, respectively. The deaths of the neonates were related to the cardiocirculatory function decompensation, unrelieved severe acidosis preoperatively, and the transposition of great artery with coronary artery malformation and longer cardiopulmonary bypass. The patients with significantly high arterial blood lactate levels during the first 6 - 12 hours postoperatively had poor outcome. Lactate levels were higher than 10 mmol/L and SvO(2) less than 50% in neonates who developed multiple organ system failure. One young infant died of sudden arrhythmia after surgical treatment, whose death may be related the surgical procedure itself with pulmonary artery banding and blalock-taussig shunt leading to increased preload and afterload of the heart.

Elevated serum lactate level postoperatively may reflect intraoperative tissue hypoperfusion. Serial blood lactate level measurements may be an accurate predictor of clinical outcomes in children after pediatric open heart surgery. Mixed venous oxygen saturation changes more rapidly than other standard hemodynamic variables. The higher mortality of neonates with congenital heart disease is related to the malformation complexity itself and illness severity.