Introduction Hypoxic ischaemic encephalopathy (HIE) may lead to cardiovascular dysfunction in newborn infants and conventional echocardiographic measures such as fractional shortening (FS) and left ventricular output (LVO) may not accurately detect cardiac dysfunction in these patients.¹

Objective To evaluate cardiac dysfunction in HIE using tissue Doppler imaging (TDI).²

Methods 20 infants born at ≥36 w gestation with HIE requiring therapeutic hypothermia (TH) were examined with 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 (S’), early (E’) and late diastolic (A’) velocities, myocardial performance index (MPI) [using TDI], and FS and LVO). Measurements were also obtained from 10 healthy term infants as controls. Ethical approval and written parental consent were obtained.

Results Median gestation and birth weights of infants with HIE vs. controls was 39.6 w vs. 40 w and 3110 g vs. 3170 g. On days 1, 2, 3 all myocardial velocities (MV), except left ventricular A’ on day 3, were significantly lower (<0.05) and MPI was significantly higher (p ≤ 0.05) in the HIE group. After re-warming all MVs and MPIs were similar between the two groups. FS and LVO were similar between both groups on all days, except LVO on day 1 which was significantly lower in HIE infants (p < 0.05).

Conclusions TDI, compared to FS and LVO, may be better at detecting myocardial dysfunction in this group of babies and hence improve management of cardiac dysfunction.

References

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