Biochemical markers of hypoxic myocardial injury in asphyxiated term neonates with hypoxic ischemic encephalopathy

ABSTRACT

Perinatal asphyxia is a common cause of neonatal morbidity and mortality and neurologic disabilities among survivors. However, no clear-cut physiologic parameters exist which enable an early identification of neonatal infants who are either at risk to develop brain damage or post-hypoxic heart failure. The main problem related to outcome is cerebral damage. 1] Assess the effect of perinatal asphyxia on the cardiac muscle function as reflected by changes in serum levels of CK, CK-MB, cTnl and cTnT. 2] Investigate the diagnostic value of these markers, their sensitivity, specificity, PPV and NPV as early predictors of the severity of cerebral damage and mortality in infants with HIE. 3] Correlate serum levels of CK, CK-MB, cTnl and cTnT in asphyxiated infants to the other markers of perinatal asphyxia. The study included 68 term newborns, 33 were asphyxiated [group I] and 35 were healthy non-asphyxiated as controls [group II]. Group I infants were considered eligible for the study when their Apgar score was blood p11 < 7.15. They were subdivided into Group Ia with no or mild HIE [n = 12] and group lb with moderate or severe HIE [n = 21]. All infants were subjected to a detailed perinatal history and clinical evaluation including mode of delivery, sex, gestational age and Apgar score at 1, 5 and 10 minutes. Demographic data were registered immediately after birth. All asphyxiated infants underwent a daily standard neurologic examination for 3 consecutive days to evaluate the neurological status and to record clinical signs of HIE. Cord arterial blood samples were collected from all studied infants for blood gas analyses performed for pH and base deficit, and blood samples for CK, CK-MB, cTnl and cTnT measurements were obtained from each infant at 6-12 postnatal hours. The serum levels of CK, CK-MB, cTnl and cTnT of Group I were significantly higher than that of group II. Group lb had serum CK, CK-MB, cTnl and cTnT levels significantly higher than that of group Ia and group II. Group Ia had significantly higher serum CK, CK-MB, cTnl and cTnT than group II. The serum levels CK, CK-MB, cTnl and cTnT of the non-survivors were significantly higher than that of the survivors. CTnl appears to be the most sensitive predictor of mortality in asphyxiated infants with HIE. CTnl and cTnT correlated significantly and negatively with cord arterial blood pH and cord arterial blood base deficit. Estimation of serum cTnI and cTnT levels in asphyxiated term infants may be useful for early identification and follow-up of infants with hypoxic myocardial dysfunction. CTnl [specificity 98%, PPV 89%] appears to be the most sensitive test for detection of severity of HIE and as an early predictor of mortality in infants with HIE