Comparison of left ventricular rotational mechanics between term and extremely premature infants over the first week of age

OBJECTIVE: Left ventricle (LV) rotational mechanics is an emerging tool to characterise LV function, but warrants further evaluation in neonates. The aim of this study was to compare LV rotational mechanics between term and extremely preterm babies over the first week of age. METHODS: In this prospective study, we serially assessed LV rotational parameters in 50 term infants and compared them with a historical dataset of 50 preterm infants born <29 weeks gestation. LV basal and apical rotation, LV twist, LV twist/untwist rate and torsion were derived using two-dimensional speckle tracking echocardiography at three time points over the first week of age. RESULTS: There was no change in LV twist, LV torsion, basal rotation or apical rotation in term infants over the study period (all p>0.05). LV twist and torsion were higher in preterm infants, and increased over time. In preterm infants, basal rotation evolved from anticlockwise to clockwise rotation. Apical rotation remained anticlockwise in both groups (all p>0.05). LV twist rate (LVTR) and untwist rate was higher in preterm infants and increased over the three time points (all p>0.05). There was a strong positive correlation between LV torsion and LV untwist rate (LVUTR) in the entire cohort during the third scan. CONCLUSION: Term infants exhibit minimal LV twist which remains unchanged over the first week of age. This is in contrast to premature infants who demonstrate increasing indices of twist, torsion, LVTR and LVUTR over the first week, likely as a compensatory mechanism for reduced LV compliance.