Usefulness of cardiac troponin T and echocardiography in the diagnosis of hypoxic myocardial injury of full-term neonates

Feasibility Analysis of ECG-Based pH Estimation for Asphyxia Detection in Neonates

Birth asphyxia is a potential cause of death that is also associated with acute and chronic morbidities. The traditional and immediate approach for monitoring birth asphyxia (i.e., arterial blood gas analysis) is highly invasive and intermittent. Additionally, alternative noninvasive approaches such as pulse oximeters can be problematic, due to the possibility of false and erroneous measurements. Therefore, further research is needed to explore alternative noninvasive and accurate monitoring methods for asphyxiated neonates. This study aims to investigate the prominent ECG features based on pH estimation that could potentially be used to explore the noninvasive, accurate, and continuous monitoring of asphyxiated neonates. The dataset used contained 274 segments of ECG and pH values recorded simultaneously. After preprocessing the data, principal component analysis and the Pan-Tompkins algorithm were used for each segment to determine the most significant ECG cycle and to compute the ECG features. Descriptive statistics were performed to describe the main properties of the processed dataset. A Kruskal-Wallis nonparametric test was then used to analyze differences between the asphyxiated and non-asphyxiated groups. Finally, a Dunn-Šidák post hoc test was used for individual comparison among the mean ranks of all groups. The findings of this study showed that ECG features (T/QRS, T Amplitude, Tslope, Tslope/T, Tslope/|T|, HR, QT, and QTc) based on pH estimation differed significantly (p < 0.05) in asphyxiated neonates. All these key ECG features were also found to be significantly different between the two groups.

Asphyxia, Therapeutic Hypothermia, and Pulmonary Hypertension

Neonates with a perinatal hypoxic insult and subsequent neonatal encephalopathy are at risk of acute pulmonary hypertension (aPH) in the transitional period. The phenotypic contributors to aPH following perinatal asphyxia include a combination of hypoxic vasoconstriction of the pulmonary vascular bed, right heart dysfunction, and left heart dysfunction. Therapeutic hypothermia is the standard of care for neonates with moderate-to-severe hypoxic ischemic encephalopathy. This review summarizes the underlying risk factors, causes of aPH in neonates with perinatal asphyxia, discusses the unique phenotypical contributors to disease, and explores the impact of the initial insult and subsequent therapeutic hypothermia on aPH.

Correlation of cardiac troponin T levels with inotrope requirement, hypoxic-ischemic encephalopathy, and survival in asphyxiated neonates

BACKGROUND

Cardiac involvement in neonates with perinatal asphyxia not only complicates perinatal management but also contributes to increased mortality.

AIM

To assess cardiac troponin T (cTnT) levels in asphyxiated neonates and their correlation with echocardiography findings, inotrope requirement, hypoxic-ischemic encephalopathy (HIE) stages, and mortality.

METHODS

cTnT levels, echocardiographic findings, the requirement of inotropes, HIE stages, and outcome were studied in neonates of gestational age ≥ 34 wk with perinatal asphyxia.

RESULTS

Among 57 neonates with perinatal asphyxia, male gender, cesarean section, forceps/vacuum-assisted vaginal delivery and late preterm included 33 (57.9%), 23 (40.4%), 3 (5.3%), and 12 (21.1%) respectively. The mean gestational age was 38.4 wk (1.6 wk). HIE stages I, II, and III were observed in 7 (12.3%), 37 (64.9%), and 9 (15.8%) neonates respectively. 26 (45.6%) neonates had echocardiographic changes and 19 (33.3%) required inotropes. cTnT levels were elevated in 41 (71.9%) neonates [median (IQR); 0.285 (0.211-0.422) ng/mL]. The Median cTnT level showed an increasing trend with increasing changes in echocardiography (P = 0.002). Two neonates with mitral regurgitation and global hypokinesia had the highest cTnT levels (1.99 and 0.651 ng/mL). Of 31 neonates with normal echocardiography, 18 (58.06%) showed elevated cTnT. cTnT levels were significantly higher in those who required inotropic support than those who did not (P = 0.007). Neonates with HIE stage III had significantly higher cTnT levels compared to those with HIE stage I/II (P = 0.013). Survivors had lower median cTnT levels [0.210 (0.122-0.316) ng/mL] than who succumbed [0.597 (0.356-1.146) ng/mL].

CONCLUSION

cTnT levels suggestive of cardiac involvement were observed in 71.9% of asphyxiated neonates. cTnT levels correlated with echocardiography findings, inotrope requirement, HIE stages, and mortality.

Cardiac adaptation in asphyxiated infants treated with therapeutic hypothermia

BACKGROUND

Hypoxic ischemic encephalopathy (HIE) affects  one to two newborns per 1,000 live births and oftentimes involves multi-organ insult. The objectives were to assess the evolution of cardiac function in infants with HIE treated with therapeutic hypothermia using echocardiography (ECHO).

METHODS

Archived data during the period 2010-2016 was assessed. Amongst the infants with baseline ECHO assessments, a sub-cohort which had assessments in all the three phases (baseline/pre-active cooling [T1], cooling [T2] and rewarming [T3]) was analyzed separately.

RESULTS

Thirty three infants formed part of the overall cohort, the gestation and birthweight were 39.6 ± 1.6 weeks and 3306 ± 583 g, respectively. Baseline (T1) information noted impaired cardiac performance (right ventricle stroke volume 1.08 ± 0.04 ml/kg, fractional area change [FAC] 24 ± 0.5% and tricuspid annular peak systolic excursion [TAPSE] 7.46 ± 0.11mm). Serial information was available for 24 of 33 infants. Cardiac function improved significantly between the cooling and the re-warming kphases. This included changes in right ventricular output (127 ± 34 vs 164 ± 47 ml/kg/min, p <0.01) and FAC (20 ± 3 vs 28 ± 2%, p<0.01). Pairwise comparisons for fractional shortening did not show significant changes. From the cooling to the rewarming phase, maximum change was noted in FAC (26.3 ± 9.8%) while minimum change was noted in fractional shortening (median, interquartile range) of 4.6% (1.4, 9.1). Significant correlation between TAPSE and time to peak velocity as a proportion of right ventricular ejection time was noted (r2 = 0.68, p <0.001).

CONCLUSIONS

In infants with moderate to severe HIE, cardiac function evolves during various phases of therapeutic hypothermia. Low output state during cooling may be due to a combination of the disease state (HIE) and cooling therapy.

The effect of patent ductus arteriosus on coronary artery blood flow in premature infants: a prospective observational pilot study

OBJECTIVE

To compare coronary flows between premature infants with and without hemodynamically significant patent ductus arteriosus (hsPDA) and to determine if coronary flow is influenced by medical PDA treatment.

DESIGN

Prospective, observational pilot study. Forty-three infants <32 weeks gestation underwent echocardiography when routinely indicated. Study group included infants with hsPDA requiring treatment. Comparison groups included infants with nonsignificant PDA and infants without PDA.

RESULTS

The study group (n = 13), compared with the comparison groups with nonsignificant PDA (n = 12) and without PDA (n = 18) had higher troponin levels (p = 0.003 and 0.004, respectively). In infants with hsPDA compared with infants with no PDA there was a significant increase in myocardial oxygen demand and decrease in left main coronary artery flow, with nonsignificant increase in cardiac output.

CONCLUSIONS

Decrease in coronary artery flows and higher troponin values may suggest a "steal effect," not allowing to meet the elevated myocardial oxygen demand in infants with hsPDA.

Cardiac Troponin T in Healthy Full-Term Infants

In this prospective cohort study of healthy full-term infants, we hypothesized that high-sensitivity cardiac troponin T (hs-cTnT) would be elevated in cord blood, compared with adult reference values, and that it would further increase over the first days of age. Cardiac troponin T has been shown to be significantly increased in healthy full-term newborns compared with adult reference values, but there is no established reference range. Most studies of cTnT in newborns have been performed before the introduction of high-sensitivity cTnT (hs-cTnT) assay. We conducted a study including 158 full-term newborns, at Stockholm South General Hospital. High-sensitivity cTnT was analyzed in umbilical cord blood and at 2-5 days of age. Median hs-cTnT (interquartile range) in cord blood was 34(26-44) ng/L; 99th percentile 88 ng/L. Median hs-cTnT at 2-5 days of age was 92(54-158) ng/L; 99th percentile 664 ng/L. We conclude that hs-cTnT is elevated in cord blood in healthy, full-term newborn infants compared with adult reference values, and that it increases significantly during the first days of life. Our findings further underline the need of caution when using hs-cTnT as a measurement of cardiac impact in newborns.

High-sensitivity troponin T in preterm infants with a hemodynamically significant patent ductus arteriosus

OBJECTIVE

To investigate if a hemodynamically significant patent ductus arteriosus (hsPDA) leads to elevated high-sensitivity troponin T (hsTnT) and NTproBNP levels in serum.

STUDY DESIGN

Infants <34 weeks and <1500 g were prospectively enrolled, except those with major congenital or chromosomal anomalies. An echocardiogram (ECHO) was performed and hsTnT and NTproBNP were measured within 5 days of life and repeated after treatment of hsPDA. Clinical, ECHO, and hsTnT data were analyzed using Student t-test, two proportion z-test, and regression analysis.

RESULTS

Seventy infants were enrolled. Infants in the hsPDA group had lower gestation and birth weight. Mean hsTnT and NTproBNP levels in the hsPDA group were higher compared to the group without an hsPDA, with levels being 251.54 vs 161.6 pg/ml, p < 0.01 for hsTnT and 18181.02 vs 3149.23 pg/ml, p < 0.001 for NTproBNP.

CONCLUSION

HsPDA leads to increased hsTnT and NTproBNP levels in preterm infants without affecting cardiac function.

Cardiac Troponin-T as a Marker of Myocardial Dysfunction in Term Neonates with Perinatal Asphyxia

OBJECTIVES

To describe the diagnostic test properties of Cardiac Troponin-T (cTnT) in predicting myocardial dysfunction in asphyxiated term neonates by taking echocardiography as the gold standard and to establish the optimum cut-off values of cTnT for myocardial dysfunction, shock, severe hypoxic ischemic encephalopathy (HIE) and mortality by receiver operator characteristic (ROC) curve analysis.

METHODS

This was a prospective study based on diagnostic test evaluation. The study included 120 term asphyxiated neonates in a tertiary care neonatal intensive care unit (NICU) in Southern India from June 2011 through June 2015. All the neonates were clinically evaluated. Venous blood was taken at 4 h of life for cTnT estimation. Echocardiography was done within 24 h of birth.

RESULTS

The mean cTnT level of asphyxiated term neonates was 0.207±0.289 ng/ml (mean ± SD). Asphyxiated neonates with myocardial dysfunction had higher cTnT levels (0.277±0.231) as compared to those without myocardial dysfunction (0.061±0.036, p = 0.0001). Using ROC curve, the cut-off cTnT values for myocardial dysfunction was 0.1145 ng/ml with sensitivity 92.4% and specificity 94.1%. Cardiac Troponin-T levels were significantly higher among asphyxiated neonates with shock (0.378±0.348, p = 0.0001) and the levels also correlated positively with increasing grades of HIE. The cut-off cTnT value for mortality was 0.2505 ng/ml with sensitivity 83.9% and specificity 96.6%.

CONCLUSIONS

In asphyxiated term neonates, early cTnT elevation is a marker for predicting myocardial dysfunction and elevated cTnT levels had high sensitivity and specificity. There was significant relation with increasing cTnT values and increasing grades of HIE.

Application of Neonatologist Performed Echocardiography in the Assessment and Management of Neonatal Heart Failure unrelated to Congenital Heart Disease

Neonatal heart failure (HF) is a progressive disease caused by cardiovascular and non-cardiovascular abnormalities. The most common cause of neonatal HF is structural congenital heart disease, while neonatal cardiomyopathy represents the most common cause of HF in infants with a structurally normal heart. Neonatal cardiomyopathy is a group of diseases manifesting with various morphological and functional phenotypes that affect the heart muscle and alter cardiac performance at, or soon after birth. The clinical presentation of neonates with cardiomyopathy is varied, as are the possible causes of the condition and the severity of disease presentation. Echocardiography is the selected method of choice for diagnostic evaluation, follow-up and analysis of treatment results for cardiomyopathies in neonates. Advances in neonatal echocardiography now permit a more comprehensive assessment of cardiac performance that could not be previously achieved with conventional imaging. In this review, we discuss the current and emerging echocardiographic techniques that aid in the correct diagnostic and pathophysiological assessment of some of the most common etiologies of HF that occur in neonates with a structurally normal heart and acquired cardiomyopathy and we provide recommendations for using these techniques to optimize the management of neonate with HF.

Biventricular function on early echocardiograms in neonatal hypoxic-ischaemic encephalopathy

AIM

To compare early (<24 hours) echocardiograms (ECHOs) in infants with perinatal hypoxic-ischaemic encephalopathy (HIE) undergoing (i) therapeutic hypothermia (TH), (ii) normothermia and (iii) normal controls.

METHODS

This was a single-centre retrospective review of clinical early ECHOs of term infants with moderate or severe HIE and controls (with a normal ECHO <72 hours of age). Right (RVO) and left ventricular output (LVO), RV and LV myocardial performance index (MPI), systolic to diastolic duration ratio (S/D) and eccentricity indices (EI) in systole and diastole were compared using ANOVA.

RESULTS

Among infants with HIE (n = 56, 38 in the TH and 18 in normothermia groups), 14 (25%) infants died and 42 survived. Significantly elevated biventricular MPI, lower RVO and LVO and pulmonary hypertension (abnormal EI, higher RV S/D and bidirectional or right-to-left ductal shunt) were found in groups with HIE, compared to controls (n = 35). LV MPI was lower in HIE-TH, compared to the HIE-normothermia group. Infants with HIE who died (n = 14) had a significantly lower EId [0.77 (0.09) vs. 0.83 (0.08), p = 0.021] compared to survivors (n = 42).

CONCLUSION

Infants with perinatal HIE have ventricular dysfunction; those who died had significantly lower EId than survivors; this association needs to be further validated.

The Diagnostic Value of Troponin T Level in the Determination of Cardiac Damage in Perinatal Asphyxia Newborns

Perinatal asphyxia is a clinical condition which results from oxygen deprivation of the fetus or newborn and the breakdown of perfusion in various organs. The aim of this study was to evaluate and compare troponin T levels over time as a marker of cardiac injury in cases of perinatal asphyxia and healthy newborns. The study included a total of 30 newborns diagnosed with perinatal asphyxia with a gestational age of 32-41 weeks, based on the last menstruation date, and 30 healthy newborns with a gestational age of 34-40 weeks, as the control group. Levels of troponin T and creatinin kinase MB were recorded for all participants. No difference was determined between the groups in terms of gestational age, manner of birth, electrocardiographic findings, and PaO2 and PaCO2 values. The umbilical artery pH levels and bicarbonate levels in the study group were found to be statistically lower than those in the control group (p < 0.001). The troponin T and creatinin kinase MB levels in the patients in the study group were higher than those within the control group, at all times. The periods when specificity and sensitivity were highest together for troponin T were the 12th and 24th h. Specificity for troponin T reached the highest value at the 24th h and sensitivity reached the highest value in the cord blood. A positive correlation was found between the troponin T and creatinin kinase MB values at the 6th and 12th h. However, no correlation could be found in the blood between the serum troponin T and creatinin kinase MB levels at the 3rd and 24th h. The troponin T level is a useful test for showing cardiac damage in hypoxic patients in the neonatal period. The sensitivity and specificity of cardiac specific troponin T levels in detecting cardiac damage are much higher according to telecardiography and electrocardiography, while the implementation of the method is simple.

Troponin T and NT ProBNP Levels in Gestational, Type 1 and Type 2 Diabetic Mothers and Macrosomic Infants

This study compares NT proBNP and troponin T levels in umbilical cord arterial blood and postnatal echocardiographic findings for infants of gestational and pregestational diabetic mothers and macrosomic infants. Twenty-seven infants of pregestational diabetic mothers, 61 infants of gestational diabetic mothers and 37 macrosomic infants of nondiabetic mothers were prospectively enrolled in this study along with a control group of 58 healthy infants of mothers without any pregestational or gestational disorders as the control group. All enrollees were born after 34 weeks of gestation. For this study, umbilical cord blood was drawn during delivery to determine NT proBNP and troponin T levels. Echocardiography was performed 24-72 h after the delivery. Umbilical cord troponin T and NT proBNP levels were found to be higher in the diabetic and macrosomic groups than in the control group (all of them p < 0.001). NT proBNP levels were positively correlated with interventricular septum thickness in the pregestational and gestational infants of diabetic mothers groups (r = 0.564 and r = 0.560, respectively, p < 0.01). Both pregestational and gestational diabetic mothers were divided into two groups according to HbA1c levels in the third trimester as good (<6.1 %) and suboptimal (>6.1 %) metabolic control. In the good and suboptimal metabolic control diabetic groups, NT proBNP levels were also positively correlated with interventricular septum thickness (r = 0.536 and r = 0.576, respectively, p < 0.01). In the suboptimal metabolic control diabetic group, NT proBNP was only found to be positively correlated with the left ventricular mass index (r = 0.586, p < 0.01). While there was no correlation in the myocardial performance index between infants of diabetic mothers and the control group, the myocardial performance index of macrosomic infants was lower than that of the control group (p = 0.017). Cardiac biomarkers (NT proBNP and troponin T) were elevated in infants of diabetic mothers and macrosomic infants. While there was a positive correlation between NT proBNP levels and cardiac structure in infants of pregestational and gestational diabetic mothers, there was no relationship between NT proBNP levels and cardiac function.

Evidence-based versus pathophysiology-based approach to diagnosis and treatment of neonatal cardiovascular compromise

With the advances in biomedical research and neonatal intensive care, our understanding of cardiovascular developmental physiology and pathophysiology has significantly improved during the last few decades. Despite this progress, the current management of circulatory compromise depends primarily on experts' opinions rather than high level of evidence. The lack of reliable, accurate, continuous and preferably non-invasive monitoring techniques has further limited our ability to collect the information needed for the design and execution of more sophisticated clinical trials with a better chance to provide the evidence we need. Given the lack of randomized, placebo-controlled trials investigating clinically relevant outcomes of novel treatments of neonatal cardiovascular compromise, we must now use the available lower level of evidence and our present understanding of developmental physiology and pathophysiology when providing cardiovascular supportive care to critically ill neonates. However, with recent advances in cardiovascular monitoring capabilities, direct and more objective assessment of the changes in cardiovascular function, organ blood flow, and tissue oxygenation have become possible. These advances have helped in our clinical assessment and enabled us to start designing more sophisticated interventional clinical trials using clinically relevant endpoints.

The myocardial function during and after whole-body therapeutic hypothermia for hypoxic-ischemic encephalopathy, a cohort study

BACKGROUND

Therapeutic hypothermia has become standard treatment for moderate and severe neonatal hypoxic-ischemic encephalopathy (HIE) to reduce cerebral morbidity and mortality. The effect on the heart is incompletely explored.

AIM

To assess the myocardial function during and after whole-body therapeutic hypothermia for HIE.

STUDY DESIGN

Observational cohort study.

SUBJECTS

Forty-four infants with HIE cooled for 72hours were compared with 48 healthy term infants and 20 normothermic infants with HIE.

OUTCOME MEASURES

Tissue Doppler deformation indices of myocardial function (peak systolic strain, peak systolic strain-rate, early diastole strain-rate and strain-rate in atrial systole) during (days 1 and 3) and after (day 4) therapeutic hypothermia.

RESULTS

On days one and three all indices in both HIE groups were lower than the corresponding indices in the healthy infants. The two HIE groups had similar indices, except peak systolic strain-rate on days 1 and 3 and strain-rate in atrial systole on day 1. All strain-rate indices improved from day 3 to 4 (after rewarming) in the cooled group and achieved similar values to those in healthy infants on day 3. All indices were higher in the cooling-group after rewarming than in the normothermic infants with HIE on day 3, except early diastolic strain-rate.

CONCLUSIONS

Infants with HIE had similarly impaired myocardial function during days 1-3 whether normothermic or hypothermic. The myocardial function improved significantly at day 4 (after rewarming), approaching the day 3 levels in the healthy neonates.

Cardiac troponin I concentrations as a marker of neurodevelopmental outcome at 18 months in newborns with perinatal asphyxia

OBJECTIVE

To investigate whether creatine kinase-MB (CK-MB) and cardiac troponin I (cTnI) can be used to predict neurodevelopmental outcome at 18 months in infants with perinatal asphyxia (PA). The diagnostic value of cTnI to assess myocardial dysfunction was considered as well.

STUDY DESIGN

Retrospective study of 178 neonates admitted with PA. cTnI concentrations measured within 12 h of birth were compared with medium-term outcome assessed with the Bayley Scales of Infant Development. cTnI concentrations measured within 12 h of birth were compared with clinical grade of hypoxic-ischemic encephalopathy (HIE) and with duration of inotropic support. Two-dimensional Doppler and color Doppler findings were recorded. Fractional shortening, tricuspid and mitral regurgitation were evaluated.

RESULT

A statistically significant correlation between cTnI concentration and BSID-II score was found (mental development index r -0.69, P<0.05 and psychomotor development index r -0.39, P<0.05). There was no statistically significant correlation between CK-MB and BSID-II score (P>0.05).Serum cTnI concentrations and duration of inotropic support were significantly greater with increasing severity of PA. cTnI was negatively correlated with fraction shortening (r -0.64; P<0.05). The severity of tricuspid regurgitation was correlated with the cTnI concentration (r 0.61; P<0.05).

CONCLUSION

In asphyxiated neonates, cTnI concentrations within 12 h of birth correlate with medium-term outcome. Early cTnI concentration correlates with severity of HIE, myocardial dysfunction and with Bayley II scores at 18 months.

Fatal infant myocardial infarction caused by ball-IN-valve mechanism from a dysplastic aortic valve

BACKGROUND

Acute myocardial infarction (AMI) can occur in infants. Early identification of AMI can allow for specific therapies aimed at improving patient outcomes.

OBJECTIVE

This article describes a case of an infant with AMI caused by a previously unreported mechanism and reviews diagnostic and therapeutic strategies for dealing with this rare disease.

CASE REPORT

We present a case of a 5-week-old infant with a fatal AMI due to a pedunculated nodule from a dysplastic aortic valve leaflet creating a ball-in-valve mechanism and occluding the left main coronary artery.

CONCLUSION

AMI is an important diagnostic consideration in any infant presenting with signs of unexplained cardiogenic shock. Practitioners who care for children should be aware of diagnostic and therapeutic strategies for AMI in infants.

Speckle tracking derived strain in infants with severe perinatal asphyxia: a comparative case control study

BACKGROUND

Speckle tracking echocardiography is increasingly being used to assess cardiac function in neonates. The objective was to compare speckle tracking strain indices between asphyxiated infants and healthy controls and to ascertain correlations between strain and 2D Doppler derived indices and cardiac troponin (biochemical marker of myocardial injury).

METHODS

Clinical and echocardiographic data from severely asphyxiated infants undergoing therapeutic hypothermia was evaluated retrospectively. This was compared with prospective data from healthy infants. Correlations between variables were assessed using Pearson's coefficient of correlation.

RESULTS

Twenty four infants with severe perinatal asphyxia were admitted during the study period of which 3 were not cooled and were excluded. The gestational age and birth weights of cases and controls were comparable. The mean left ventricular global longitudinal strain (GLS) from apical 4 chamber view was noted to be significantly impaired in the asphyxiated infants (- 11.01% ± 2.48 vs - 21.45% ± 2.74, p <0.001). Cardiac output was significantly lower in the asphyxiated infants (97 ± 26 vs 230 ± 60 ml/kg/min). In asphyxiated infants, GLS correlated positively with cardiac output (r2 = 0.86, p< 0.001) and negatively with serum troponin levels (r2 = 0.64, p< 0.001). GLS was less impaired in infants on inotropes compared to those not on inotropic support, -12.55% (1.9) vs -10.2% (1.3), p= 0.018. Infants who died had a lower global strain value compared to survivors, - 9.7% (1.6) vs - 12.8% (2.6), p = 0.02.

CONCLUSIONS

2D Speckle derived strain was impaired in asphyxiated infants. Significant correlations between GLS and cardiac output and troponin were noted.

Left ventricular longitudinal strain and strain rate measured by 2-D speckle tracking echocardiography in neonates during whole-body hypothermia

The purpose of the study was to assess changes in cardiac performance in newborn infants with hypoxic-ischemic encephalopathy during therapeutic hypothermia and rewarming with two-dimensional speckle tracking echocardiography. For eight asphyxiated neonates (median birth weight (range): 3038 (2725-3253) g; umbilical artery pH: 6.9 (6.8-7.18) undergoing whole-body hypothermia (33-34°C), left ventricular longitudinal strain and strain rate, as well as heart rate, cardiac output and left ventricular fractional shortening, were determined at four points in time: the start (T1) and end of hypothermia (T2), immediately after rewarming (T3) and the age of 5 to 7 d (T4). Mean (standard deviation) heart rate increased from 93 (12) beats/min at T1 to 133 (12) beats/min at T4 (p < 0.001). Cardiac output was low during hypothermia (T1: 207 [43] mL/kg/min, T2: 240 [70] mL/kg/min) and increased significantly (p < 0.001) afterward (T3: 329 [70] mL/kg/min, T4: 388 [78] mL/kg/min). Left ventricular fractional shortening remained unchanged. Left ventricular global longitudinal peak systolic strain did not differ significantly between hypothermia and rewarming, whereas the systolic strain rate increased from -1.1 (0.3) s(-1) at T1 to -1.8 (0.26) s(-1) at T4 (p = 0.001). Hypothermia affects peak systolic strain rate, heart rate and cardiac output, with complete recovery after rewarming, whereas peak systolic strain and fractional shortening remain stable.

Reduced cardiac output and its correlation with coronary blood flow and troponin in asphyxiated infants treated with therapeutic hypothermia

Perinatal asphyxia can lead to multi-organ insult which includes cardiovascular dysfunction. The objective was to study the relationship between cardiac function, perfusion and troponin. Unit database was accessed to identify infants with perinatal asphyxia over the last 2 years. Information from medical records and archived echocardiographic images was retrieved. Comparisons for echocardiographic information were made with healthy term infants. Seventeen infants with perinatal asphyxia were identified, of which three were excluded (one-33 weeks gestation, two-coagulopathy and pulmonary hypertension); 14 infants received therapeutic hypothermia. Median (range) gestation and birthweight were 39 (37-42) weeks and 3,550 (2,380-3,992) g respectively. Mean (S.D.) rectal temperature and time of echocardiogram were 33.5 ± 0.5 °C and median (range) 7.7 h [3-10] respectively. Majority of infants had low biventricular outputs. Median (range) SVC flow was 29.8 ml/kg/min (13-96.2). Median (range) troponin was 0.77 μg/L (0.17-2.6); normal ≤ 0.08 μg/L. Markedly low coronary flows (diastolic VTI median (range) 2.1 (1.3-2.9) cm were noted compared to controls. Coronary flow had a significantly positive correlation with left ventricular output. Higher troponin levels were associated with lower aortic stroke velocity. A close association between cardiac output, perfusion and troponin was noted. A dichotomy between blood pressure and flow parameters was noted, indicating the wide variation in vascular resistance in these infants. Biventricular output, coronary and SVC flows were significantly higher in the control population. In conclusion, inter-variable relationship between cardiac output, coronary flow and troponin is an important addition to the understanding of cardiovascular impact of perinatal asphyxia.

Use of cardiac biomarkers in neonatology

Cardiac biomarkers are used to identify cardiac disease in term and preterm infants. This review discusses the roles of natriuretic peptides and cardiac troponins. Natriuretic peptide levels are elevated during atrial strain (atrial natriuretic peptide (ANP)) or ventricular strain (B-type natriuretic peptide (BNP)). These markers correspond well with cardiac function and can be used to identify cardiac disease. Cardiac troponins are used to assess cardiomyocyte compromise. Affected cardiomyocytes release troponin into the bloodstream, resulting in elevated levels of cardiac troponin. Cardiac biomarkers are being increasingly incorporated into clinical trials as indicators of myocardial strain. Furthermore, cardiac biomarkers can possibly be used to guide therapy and improve outcome. Natriuretic peptides and cardiac troponins are potential tools in the diagnosis and treatment of neonatal disease that is complicated by circulatory compromise. However, clear reference ranges need to be set and validation needs to be carried out in a population of interest.

Cardiac troponin I levels and its relation to echocardiographic findings in infants of diabetic mothers

BACKGROUND

Cardiomyopathy is noted in up to 40% of infants of diabetic mothers, and the exact mechanisms responsible for it are unknown. The aim of this study was to compare between infants of diabetic mothers (IDM) and infants of non- diabetic mothers (INDM) as regards cardiac troponin I (cTnI) levels (as a marker of cardiac dysfunction) and to examine the relationship between this marker and neonatal echocardiographic changes (cardiac structure and function).

METHODS

A prospective, comparative study included eighty full term neonates during the first three days of life, during the period from April 2008 to June 2011. They were divided into 2 groups, group I: included 40 infants of diabetic mothers (IDMs)and group II: included 40 infants of non diabetic healthy mothers as a control group.

RESULTS

37.5% of the IDMs were large for gestational age and demonstrated a significantly lower blood glucose level than the control group (34.6 ± 11.3mg/dl Vs 77.2 ± 19.8 mg/dl respectively) , respiratory distress and cyanosis were the presenting signs in 67.5% of IDMs. Cardiac TnI on the second day of life increased significantly in infants of diabetic mothers in comparison to INDM (p < 0.006) . IDMs had a significant increase in left atrial thickness ( 11.5 ± 1.8mm in IDM Vs 10.5 ± 0.9mm in INDM P < 0.002*) and a significant increase in septal thickness (5.0 ± 1.2mm in IDM Vs 4.0 ± 0.5mm in INDM P < 0.001*). CTnI correlated positively with interventricular septum thickness (P-value = 0.002*). Cardiac TnI was significantly increased in IDMs with respiratory distress (P -value < 0.05).

CONCLUSIONS

This study demonstrated a highly significant positive correlation between cTnI level on the second day of life and the left ventricular end diastolic diameter (LVED) and interventricular septum diameter (IVSD). Cardiac troponin I (cTnI) is a useful biochemical marker for monitoring myocardial injury in infants of diabetic mothers. An elevated cTnI concentration in infants of diabetic mothers with respiratory distress was a good predictor for hypertrophic cardiomyopathy and/or left ventricular dysfunction.

Serum cardiac troponin T in asphyxiated term neonates delivered at two teaching hospitals in lagos, Nigeria

BACKGROUND

Asphyxia is a leading cause of perinatal morbidity and mortality in the developing countries. All organs including the myocardium are vulnerable to ischemic injury in asphyxia. The aim of the current study was to assess myocardial injury in asphyxiated full-term neonates using their serum cardiac troponin T levels.

METHODS

In all, 30 term asphyxiated neonates and 30 gestational age-, birth weight-, and sex-matched controls were studied. Asphyxia was defined by double criteria of low umbilical arterial blood pH <7.20 and low five-minutes Apgar score ≤6, while the controls were term nonasphyxiated neonates with umbilical arterial blood pH ≥7.20 and five minutes Apgar score >6. The umbilical arterial pH was done soon after delivery, while the serum cardiac troponin T was done within the first 4 to 24 hours of life.

RESULTS

Participants and controls were similar in terms of mean gestational age, mode of delivery, gender, and birth weight (P = 1.0, .07, 1.0, and 1.0, respectively). Two thirds of the asphyxiated babies had elevated serum cardiac troponin T in the high risk range (> 0.1 ng/mL). On the contrary, none of the controls had serum cardiac troponin T in that range. Serum cardiac troponin T showed negative correlation with pH (r = -.75), five-minute Apgar score (r = -.74), and one-minute Apgar score (r = -0.70).

CONCLUSION

The study identified perinatal asphyxia as a high-risk factor for elevated serum cardiac troponin T and hence for myocardial cellular injury.

Cardiac biomarkers in neonatal hypoxic ischaemia

Following a perinatal hypoxic-ischaemic insult, term infants commonly develop cardiovascular dysfunction. Troponin-T, troponin-I and brain natriuretic peptide are sensitive indicators of myocardial compromise. The long-term effects of cardiovascular dysfunction on neurodevelopmental outcome following perinatal hypoxic ischaemia remain controversial. Follow-up studies are warranted to ensure optimal cardiac function in adulthood.

CONCLUSION

Cardiac biomarkers may improve the diagnosis of myocardial injury, help guide management, estimate mortality risk and may also aid in longterm neurodevelopmental outcome prediction following neonatal hypoxic-ischaemia.

Cardiac troponin T as a marker of myocardial injury in a group of asphyxiated African neonates

BACKGROUND

In caucasian newborns, troponin T (cTnT) is a specific marker for myocardial injury in perinatal asphyxia. This is the first such study in negroid neonates.

AIMS

To evaluate myocardial injury in a group of asphyxiated African newborns and determine the influence of mode of delivery on cTnT levels.

METHODS

Serum cTnT and clinical parameters in 40 asphyxiated and 40 healthy negroid neonatal controls were measured within the first 72 hours of life by chemiluminescence immune-assay. Perinatal asphyxia was assessed by APGAR score. The infants were followed up until discharge or death.

RESULTS

Mean (SD) cTnT values were significantly higher in asphyxiated infants [0.03 (0.04) ng/ml] than in healthy controls [0.01 (0.006) ng/ml, P = 0.002]. Asphyxiated infants delivered by forceps and vacuum extraction had significantly higher levels of cTnT [0.04 (0.018) ng/ml] than those born by caesarian section [0.02 (0.008) ng/ml] and by normal delivery [0.03 (0.01) ng/ml, P = 0.003]. cTnT levels were higher in infants who died (P = 0.037).

CONCLUSION

In the asphyxiated infants, mean cTnT levels were significantly higher than in controls. They were also significantly higher in those born by vacuum and forceps delivery and asphyxiated infants who died.

The assessment of time-dependent myocardial changes in infants with perinatal hypoxia

OBJECTIVE

The aim of the study was to assess myocardial damage in infants due to perinatal hypoxia.

METHODS

The findings of 29 infants with perinatal hypoxia and 20 healthy infants were compared. Blood gas analysis, serum lactate, cardiac troponin I (cTnI), troponin T (cTnT), creatine kinase-MB (CK-MB) and B-type natriuretic peptide (BNP) were evaluated. Echocardiography together with tissue Doppler imaging was performed.

RESULTS

cTnT, CK-MB and BNP were higher in patients at the first day. There were positive correlations between the left ventricular (LV) myocardial performance index (MPI) and cTnT at first day and also at first month. LV ejection fraction and fractional shortening were lower at first day and at first month in patients. Myocardial systolic (Sm) and diastolic (Em and Am) velocities at all segments were lower at first day, and interventricular septum Sm, LV Sm, LV Em, right ventricular Em and LV Am were still lower at first month in patients. Isovolumic relaxation time at all segments together with LV MPI was higher at first day, ejection time values were lower and MPI values were higher at all segments at first month in patients.

CONCLUSIONS

These findings demonstrated that the signs of myocardial damage due to perinatal hypoxia still present at first month.

Myocardial performance assessment in neonates by one-segment strain and strain rate analysis by tissue Doppler - a quality improvement cohort study

OBJECTIVES

To investigate one-segment strain and strain rate indices as measures of myocardial performance in asphyxiated term neonates.

DESIGN

Quality improvement cohort study.

SETTING

Newborns admitted to a neonatal intensive care unit at a Norwegian University Hospital for perinatal asphyxia and non-asphyxiated newborn recruited from the maternity ward at the same hospital.

PARTICIPANTS

Twenty asphyxiated and 48 non-asphyxiated term neonates.

PRIMARY OUTCOME MEASURE

Strain and strain rate indices and repeatability measures. One-segment longitudinal strain and strain rate by tissue Doppler were assessed on days 1, 2 and 3 of life in nine heart walls. Repeatability was compared against measurements from two-segment analyses previously performed in the same images.

RESULTS

The 95% limits of agreement were significantly better for the one-segment than two-segment repeatability analyses, the inter-rater peak systolic strain (PSS) was (-3.1, 3.3) vs (-11.4, 18.3)%, the inter-rater peak systolic strain rate (PSSR) was (-0.38, 0.40) vs (-0.79, 1.15)/s, the intra-rater PSS was (-2.5, 2.6) vs (-8.0, 9.8)% and the intra-rater PSSR was (-0.23, 0.25) vs (-0.75, 0.80)/s (p<0.05). The myocardial performance was lower in the asphyxiated neonates (indices closer to zero) than in the non-asphyxiated neonates, PSS was -17.8 (0.6) (mean (SEM)) vs -21.2 (0.3)%, PSSR -1.43 (0.08) vs -1.61 (0.03)/s, early diastolic strain rate 1.72 (0.11) vs 2.00 (0.11)/s and strain rate during the atrial systole 1.92 (0.17) vs 2.27 (0.10)/s (p<0.05), despite no difference in fractional shortening (29.0 (0.5) vs 29.1 (1.0)%) (p>0.05).

CONCLUSIONS

One-segment strain and strain rate assessed the reduced myocardial performance in asphyxiated neonates with significantly improved reproducibility as compared with two-segment analysis and was therefore more feasible than two-segment analyses for assessment of myocardial performance after perinatal asphyxia.

Functional echocardiography in assessment of the cardiovascular system in asphyxiated neonates

Perinatal asphyxia commonly results in multi-organ damage, and cardiovascular dysfunction is a frequent association. Myocardial damage, right ventricular dysfunction, abnormal circulatory transition, and impaired autoregulation may all contribute to postnatal neurological damage. Adequate monitoring and appropriate targeted treatment therefore are essential after an asphyxial insult. Standard methods of cardiovascular monitoring in the neonate have limitations. Point of care ultrasound scanning or functional echocardiography offers extra information to assist the clinician in identifying when there is significant cardiovascular impairment, classifying the underlying abnormal physiology and potentially targeting appropriate therapy, thereby optimizing the post-insult cerebral blood flow and oxygen delivery.

Longitudinal strain and strain rate by tissue Doppler are more sensitive indices than fractional shortening for assessing the reduced myocardial function in asphyxiated neonates

The function of the heart was studied in 20 asphyxiated term neonates by measuring the longitudinal peak systolic strain and peak systolic strain rate by tissue Doppler in 18 segments of the heart on days 1, 2, and 3 of life. The fractional shortening was assessed at each examination as well. Measurements were compared against measurements in 48 healthy term neonates examined by the same protocol. The function of the heart was lower in the asphyxiated neonates - peak systolic strain (mean (95% confidence interval) -19.4% (-20.4, -18.5), peak systolic strain rate -1.65 (-1.74, -1.56) per second) than in the healthy term neonates (peak systolic strain -21.7% (-22.3, -21.0), peak systolic strain rate -1.78 (-1.84, -1.74) per second; p < 0.001). Fractional shortening was similar in the asphyxiated (29.2% (26.8, 31.5)) and healthy term neonates (29.0% (27.9, 30.1); p = 0.874). The peak systolic strain differed significantly between the asphyxiated and healthy term neonates for the left basal and right basal groups of segments (p < 0.05) but not for the left apical, right apical, septum apical, or septum basal groups of segments. The peak systolic strain rate differed significantly only for the septum apical group of segments. The differences were largest on the second day of life. Measurements were similar in asphyxiated neonates with elevated and normal cardiac troponin T levels. The peak systolic strain and strain rate were in this study more sensitive indices than fractional shortening for assessing the reduced myocardial function in asphyxiated term neonates.

Early left ventricular diastolic dysfunction in premature infants born to preeclamptic mothers

AIM

To evaluate the cardiac function in premature infants born to preeclamptic mothers and its clinical consequences.

METHODS

This was a prospective observational cohort study performed in a tertiary neonatal intensive care unit. Fifty-three premature infants born to preeclamptic mothers comprising the study group were evaluated and compared with 42 premature infants born to normotensive mothers (control group). Relationship between echocardiographic measures and neonatal morbidity were assessed as the main outcome measures.

RESULTS

Left ventricle end-diastolic dimension (LVEDD), peak flow velocities during early diastole (peak E wave), peak flow velocities during atrial contraction (peak A wave), and peak E/A ratio were significantly lower in the study group. Within the study group, these parameters were also significantly lower in infants with respiratory problems. LVEDD was significantly smaller in preeclamptic infants with intrauterine growth retardation (IUGR).

CONCLUSION

Left ventricle diastolic dysfunction (LVDD) was detected in premature infants born to preeclamptic mothers in the first week after delivery. LVDD was associated with higher incidence of respiratory problems, transient tachypnea of the newborn, longer duration of oxygen requirement, and IUGR.

The relation between delivery type and cord blood levels of chitotriosidase and Troponin T

The operative deliveries can expose the fetus to acute and systemic hypoxia along with an increase in perinatal morbidity. The aim of this study was to reveal any relationship between delivery type and Chitotriosidase and Troponin T levels in cord blood. Ninety babies born in Ankara Etlik Maternity and Women’s Health Teaching Hospital were involved in the study. The babies were divided into three groups; Group 1: Normal vaginal; Group 2: Caesarean section; Group 3: Forceps application. Cord blood samples were drawn from umbilical arteries of the babies soon after the birth. Chitotriosidase enzyme activities in group 3 (141 nmol/ml/h (0–246)) were found higher than groups 1 (100 nmol/ml/h (0–208)) and 2 (91 nmol/ml/h (0–202)) (p<0.01 and p<0.03 respectively). Although cardiac Troponin T levels were higher in group 3, the difference among groups was not statistically significant (p=0.79). Acute or systemic hypoxic exposure of the organism gives rise to a microvascular response characterized by interactions between leukocytes and endothelium. We are hypothesizing that the high levels of chitotriosidase found in the forceps group were due to hypoxia, and that chitotriosidase level can be used as a marker of acute and systemic hypoxia.

Myocardial performance in asphyxiated full-term infants assessed by Doppler tissue imaging

The aim of this study was to assess myocardial performance of full-term infants with perinatal asphyxia using Doppler tissue imaging (DTI) and to correlate it with serum cardiac troponin T (cTnT) concentrations. Twenty-five asphyxiated and 20 nonasphyxiated term infants were investigated. Serum cTnT concentrations were measured between 12 and 24 h of life. Conventional two-dimensional Doppler echocardiography and DTI were done during the first 72 h of life. Right ventricular (RV) and left ventricular (LV) Tei indexes were significantly higher in asphyxiated neonates (mean +/- SD: 0.45 +/- 0.05 vs. 0.28 +/- 0.05, P < 0.001 and 0.51 +/- 0.04 vs. 0.38 +/- 0.04, P < 0.001, respectively). Mitral and tricuspid systolic (Sm) velocities were significantly lower in asphyxiated neonates (mean +/- SD: 5.06 +/- 0.89 vs. 6.89 +/- 0.94 cm/s, P < 0.001 and 5.78 +/- 0.58 vs. 6.69 +/- 0.87 cm/s, P < 0.001, respectively). cTnT concentrations were significantly higher in asphyxiated neonates [median (range): 0.17 (0.05-0.23) vs. 0.03 (0-0.07) microg/l, P < 0.001)], and they correlated positively with the LV Tei index (r = 0.67, P < 0.001) and the RV Tei index (r = 0.68, P < 0.001) and negatively with the mitral systolic (Sm) velocity (r = -0.68, P < 0.001) and tricuspid systolic (Sm) velocity (r = -0.41, P = 0.01). A higher cTnT was a significant predictor of mortality, whereas fractional shortening (FS) and DTI measurements did not show any significant predictive value. The DTI technique appears to be more sensitive than conventional echocardiography in the early detection of myocardial dysfunction induced by perinatal asphyxia in full-term infants.

Staphylococcus aureus Septicemia with a fatal transmural myocardial infarction in a 27-week-gestation twin infant: a case study

Septicemia, one of the major causes of morbidity and mortality in the neonatal period, often has a rapid and fulminant course. Low-birth-weight infants with persistent Staphylococcus aureus septicemia, possibly associated with percutaneous central venous catheters, may develop metastatic infections including endocarditis with large vegetations. This article describes a neonate with S. aureus bacteremia that resolved with treatment who died secondary to decreased left ventricular function. At autopsy, organizing microthrombi were seen within both atria, the left ventricle, and the left coronary arterial system. Extensive infarcts were noted throughout the entire myocardium of the left ventricle. It was suspected, but not proven, that the thrombotic sequelae from septicemia caused this neonate's death.

Transient ventricular dysfunction after an asphyxiation event: stress or hypoxia?

OBJECTIVE

This report of a pediatric patient with acute upper airway obstruction causing asphyxiation emphasizes the need to maintain clinical suspicion for acquired myocardial dysfunction, despite the presumed role of noncardiogenic causes for pulmonary edema after an acute upper airway obstruction.

DESIGN

Case report.

SETTING

A tertiary pediatric intensive care unit.

PATIENT

A 10-year-old girl with no significant medical history who developed flash pulmonary edema and acute myocardial dysfunction after an acute upper airway obstruction.

INTERVENTIONS

Serial echocardiograms, exercise stress test, and coronary angiography were performed. Serial pro-brain natriuretic peptide, troponins, and CK-MB levels were also followed.

RESULTS

Troponin level normalized approximately 7 days after the acute event. CK-MB and pro-brain natriuretic peptide levels decreased but had not completely normalized by time of discharge. The patient was discharged home 10 days after the event on an anticipated 6-month course of metoprolol without any signs or symptoms of cardiac dysfunction.

CONCLUSIONS

Myocardial dysfunction is rarely documented in children after an acute upper airway obstruction or an asphyxiation event. Pediatric intensivists and hospitalists should maintain a high degree of clinical suspicion and screen for possible myocardial dysfunction in the pediatric patient with an acute severe hypoxic event especially when accompanied by pulmonary edema. Prompt evaluation ensures appropriate support. Additionally, some role may exist for early adrenergic receptor blockade.

Multiple molecular forms of circulating cardiac troponin: analytical and clinical significance

Cardiac troponin T (cTnT) and I (cTnI) are highly specific and sensitive biomarkers of myocardial cell damage and are now accepted as the ‘gold standard’ diagnostic test for acute coronary syndrome and supersede the classical muscle enzyme biomarkers. While the understanding of the development and structure of the troponins has advanced, detailed biochemistry of the troponin molecules is complex and poorly understood. Many post-translational molecular forms of troponin are known to exist. The diversity of these circulating forms may have a clinical impact and the notion of a disease-specific troponin protein signature has been suggested. However, the effects of these multiple forms on commercial assay performance and their impact clinically are currently unknown and should be the focus of future research and assay design.

Serum troponin in neonatal intensive care

Cardiac troponins have a major role in screening and diagnosis of myocardial ischaemia in adults and children. Their introduction has redefined the diagnosis of myocardial infarction in adults and provided valuable prognostic information. In the paediatric population, troponins show a good correlation with the extent of myocardial damage following cardiac surgery and cardiotoxic medication, and can be used as predictors of subsequent cardiac recovery and mortality. This review discusses the current established reference values in term and preterm infants and demonstrates their potential use in neonatology. They may serve as a useful adjunct in the assessment of the magnitude of myocardial injury in respiratory distress syndrome and asphyxia. They may also benefit centres without on-site echocardiography with some evidence showing good correlation with echo-derived markers of myocardial function. The use of troponins in the neonatal unit remains a research tool. More work is needed to explore their prognostic role and monitoring response to treatment following cardioprotective strategies. In preterm infants the effect of inotropes on myocardial function needs further study and troponin may form an integral part of this research.

Is serum troponin T a useful marker of myocardial damage in newborn infants with perinatal asphyxia?

AIM

To assess the correlation of echocardiographic signs of myocardial damage to serum cardiac troponin T (cTnT) concentrations in newborn infants with perinatal asphyxia.

METHODS

Electocardiograms (ECG) and echocardiograms (Echo) were obtained during the first 24 h of life from 29 asphyxiated and 30 control infants and correlated with cTnT concentrations. The echocardiographic parameters included systolic ventricular performance, preload, afterload, diastolic function, stroke volume (SV), left ventricular output (LVO), hyperechogenity of the papillary muscles and insufficiency of the atrioventricular valves.

RESULTS

LVO and SV were lower but CTnT were significantly higher in asphyxiated than in control infants: 0.15 (010-0.23) vs. 0.05 (0.02-0.13), p < 0.001). Asphyxiated infants with signs of myocardial damage were associated with significantly higher cTnT than those without, 0.20 (0.11-0.28) and 0.11 (0.05-0.14 ug/L), p = 0.04.

CONCLUSION

Cardiac troponin may prove to be valuable in evaluating myocardial damage in birth asphyxia. However, the degree of prematurity may complicate the assessment.

Cardiac troponin T: a useful early marker for cardiac and respiratory dysfunction in neonates

BACKGROUND

Cardiac troponin T (cTnT) has been proposed as specific biochemical marker for myocardial infarction in adults. Cardiac function in neonates could be influenced by the severity of respiratory distress and its ventilatory management.

OBJECTIVES

To establish a normal range of cTnT in healthy neonates, compare troponin concentrations among healthy neonates and those in respiratory distress (sick) and detect whether any correlation occurs between severity of respiratory distress and troponin concentrations.

METHODS

Concentrations of cTnT were compared between sick and healthy infants, accounting for confounding variables in a prospective investigation manner. Age at sampling, need for ventilation, duration of respiratory support, and inotropic use in addition to neonatal and maternal characteristics were assessed.

RESULTS

Samples were collected from 164 neonates (116 healthy and 48 sick). The medians [interquartile ranges] of cTnT in healthy and sick infants were 0.044 [0.027-0.073]mug/l and 0.121 [0.065-0.238] microg/l, respectively, with p < 0.0001. The 99th percentile for healthy neonates was 0.244 microg/l. Comparing both groups, there were significant differences concerning gestation, birth weight, Apgar at 5 min and admission to neonatal intensive care unit. Troponin concentrations in subgroups of sick infants including hypotensive, ventilated and dead infants were higher than other infants of the same subgroup. CTnT was positively correlated to the duration of respiratory support in ventilated neonates.

CONCLUSION

CTnT may prove to be a useful early marker for cardiac and respiratory dysfunction in newborns.

Retrospective diagnosis of hypoxic myocardial injury in premature newborns

Perinatal asphyxia has a high impact on neonatal mortality, morbidity, and neurological outcome. The hypoxic effects on brain, kidney and gastrointestinal system are well recognized in newborns. While it is known that hypoxia also effects cardiac function, there are few studies of quantitative myocardial injury in premature infants who suffered hypoxia.

AIM

To investigate usefulness of cardiac troponin (cTnT) and creatinine kinase MB (CK-MB) in the diagnosis of myocardial injury due to birth hypoxia and to correlate these markers with cardiac functions as measured by echocardiogram.

METHODS

We studied 43 preterm infants: 21 with birth asphyxia and 22 controls. Echocardiographic studies and quantitative determination of cTnT and CK-MB in blood serum was performed between the 12(th) and the 24(th) h of life.

RESULTS

cTnT and CK-MB levels were higher in asphyxiated infants compared to controls (0.287 +/- 0.190 vs. 0.112 +/- 0.099 ng/mL, P < 0.001) and (18.35 +/-14.81 vs. 11.09 +/- 5.17 ng/L, P < 0.05). Among controls, we observed an elevated value of cTnT in those with respiratory distress syndrome (RDS). We found a decrease in fractional shortening (P < 0.05) and an increase in tricuspid insufficiency (P < 0.01) in asphyxiated newborns.

CONCLUSIONS

cTnT and CK-MB levels are strong indicators of myocardial injury due to perinatal hypoxia. The cTnT level was most strongly related to RDS.