Presented at the Neonatal Society 2014 Spring Meeting.
Yajamanyam PK1, Negrine RJS1, Rasiah SV1, Ewer AK1,2
1 Neonatal Unit, Birmingham Women’s Hospital, Birmingham. West Midlands, UK
2 University of Birmingham, Birmingham, West Midlands, UK
Background: Infants affected by hypoxic ischaemic encephalopathy (HIE) may experience cardiovascular dysfunction as a result of ischaemic damage to the myocardium. Conventional echocardiographic measures such as fractional shortening (FS) and left ventricular output (LVO) may not accurately detect cardiac dysfunction in these patients (1). The aim of this study is to evaluate cardiac dysfunction in HIE using tissue Doppler imaging (TDI) (2).
Methods: Infants born at ≥36w gestation with a diagnosis of HIE requiring therapeutic hypothermia (TH) were evaluated by serial conventional echocardiography and TDI on days 1, 2, 3 and after re-warming. Structural integrity of the heart was confirmed before obtaining measures of myocardial function (peak systolic, early and late diastolic velocities, myocardial performance index (MPI) using TDI, FS and LVO). Measurements were also obtained from healthy term infants in the first 48 hours of life as controls. Regional ethical approval and written parental consent were obtained.
Results: 15 infants diagnosed with HIE and treated with TH were included. 10 term infants were included as controls. The median gestation of infants with HIE was 39.6 weeks and the median birth weight was 3110g. No significant structural cardiac abnormality was present in any of the infants. One baby with HIE had significant persistent pulmonary hypertension of the newborn. All myocardial velocities in the HIE group were significantly lower and MPI (apart from MPI at medial mitral annulus (MMA) on days 2, 3) was significantly higher on days1, 2 and 3 (p<0.05). After re-warming only the MMA peak systolic and early diastolic velocities remained abnormal. FS and LVO were similar between cases and controls on all days.
Conclusion: Conventional echocardiographic measurements did not detect myocardial dysfunction in infants with HIE receiving TH. TDI was able to demonstrate significant differences in myocardial velocities in these infants compared to well infants and may be better in detecting myocardial dysfunction in this group of babies.
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1. Armstrong K et al. Arch Dis Child. 2012;97(4):372-5.
2. Negrine RJS et al. Arch Dis Child Fetal Neonatal Ed 2012;97:F304-F306.