Newborn Heart Study - Novel Echocardiographic and Biomarker Measurements in Health & Disease
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Neonatal myocardial dysfunction may impact negatively on survival outcomes in preterm and term infants. Early identification and subsequent intervention may improve outcomes in preterm infants and term infants following a hypoxic ischaemic injury. Current echocardiographic measures for assessing Left Ventricular systolic and diastolic function have limitations in preterm infants. Newer techniques such as tissue Doppler Imaging (TDI) and Speckle Tracking Imaging (STI) provide a global assessment of myocardial systolic and diastolic function and have been introduced in adult cardiology. However there is a paucity of data on these modalities in children and neonates. Cardiac biomarkers, Troponin T and NT pro BNP reflect myocardial dysfunction and are elevated in preterm infant with a Patent Ductus Arteriosus and in term infants with neonatal encephalopathy.
Sixty healthy term control infants were recruited who underwent echocardiography on Day 2-4 of life. Normal data for Left and Right ventricular diastolic velocities were obtained using Tissue Doppler Imaging. A further 20 healthy term infants underwent echocardiography for longitudinal strain analysis using Speckle Tracking Imaging.
Infants < 32 weeks or < 1500kg underwent serial echocardiography to compare measures of shortening and ejection fraction with Tissue Doppler velocities. There was a significant increase in the RV systolic and diastolic velocities over the first week of life. There was a significant increase in the LV diastolic velocities over the first week of life. There was no significant increase in either LV shortening or ejection fraction over the first week of life. Tissue Doppler velocities were significantly lower SUMMARY OF THESIS XI over the first week of life in infants who developed Chronic Lung Disease, Necrotising Enterocolitis and in those infants who required surgical PDA ligation. Vitamin D levels were low in preterm infants enrolled in the study, and Tissue Doppler systolic and diastolic velocities were significantly lower in preterm infants compared to term infants on Day one of life.
Our final part of the study was the validation of the Cobas h232 Point of Care Analyser for analysis of Troponin T and NT pro BNP. We found that the Cobas h232 had correlation with the gold standard laboratory Roche 800 analyser.
In conclusion serial echocardiography in the NICU may improve outcomes in preterm infants by allowing early therapeutic intervention. Analysis of Troponin T and NT pro BNP at the bedside in conjunction with echocardiography may aid in the diagnosis of myocardial dysfunction, more timely therapy and ultimately improve survival and neurodevelopmental outcomes in preterm infant and in those with Neonatal Encephalopathy.