[Clinical study of myocardial damage induced by neonatal jaundice in normal birth weight term infants].

Objective: To clarify whether neonatal jaundice may cause myocardial damage to term infants with normal birth weight (BW).

Methods: Totally 178 term neonates admitted during March, 2004 to December, 2010 with normal BW were enrolled. Infants with antenatal or neonatal asphyxia, temperature abnormality, septicemia, antenatal viral infection, congenital dysmorphia, congenital heart disease, 21-trisomy, and polycythemia were excluded. There was no maternal complications during the pregnancy. Serum total bilirubin (TB), creatine kinase (CK), MB isoenzymes of creatine kinase (CK-MB), and cardiac troponin-I (cTnI) were measured. Patients with transcutaneous bilirubin level (TcB) ≥ 342 µmol/L (20 mg/dl) were in Group A (n = 32), and those with TcB below phototherapy level at matched time point were in Group B (n = 25). ECG, for correct Q-T intervals (QTc) and correct QT intervals dispersion (QTcd), and ECHO, for left ventricular ejection fraction (EF), the ratio of the peak velocity of early stage and advanced stage of diastolic phase at the mitral orifice (E/A), were applied to patients in Group A and B. SPSS 13.0 software was used for the data analysis. The coefficients of correlation among age in hours on admission (hr), TB, CK, CK-MB, CK-MB/CK, and cTnI were studied by multiple and partial correlation analysis. Data in Group A and B were compared by independent-samples Mann-Whitney U test (nonparametric method) or Student t-test.

Results: When the data were analyzed by multiple correlation, there were significant correlation between TB and cTnI, CK-MB, respectively (r = 0.212, -0.161, respectively, all P < 0.05). But, when the data were analyzed by partial correlation, there was no correlation between TB and cTnI, CK-MB, respectively (r' = 0.112, -0.112, respectively, all P > 0.05), negative correlation between hr and TB, cTnI, respectively (r' = -0.490, P = 0.000; r' = -0.162, P = 0.032). There was no significant difference in CK (Z = -1.384, P = 0.166), CK-MB (Z = -0.821, P = 0.412), cTnI (Z = -1.159, P = 0.246), QTc (t = 1.146, P = 0.257), QTcd (t = 1.342, P = 0.185), EF (t = 1.558, P = 0.125), E/A (t = -0.640, P = 0.525) between group A and B. There was significant difference in CK-MB/CK (Z = -3.187, P = 0.001) between group A and B with a lower value in group A [0.075 (0.032 - 0.102)] comparing to that in group B [0.160 (0.073 - 0.284)].

Conclusion: There is no sufficient evidence to support the hypothesis that neonatal jaundice may induce myocardial damage in normal birth weight term infants.