Objective Compare heart function assessment by strain and strain-rate and by fractional shortening (%FS) in healthy and asphyxiated term neonates.
Methods Healthy and asphyxiated term neonates were examined daily on day 1–3 of life. At each examination we measured %FS and in eighteen heart segments peak systolic strain (PSS) and peak systolic strain-rate (PSSR).
Results Analyses were performed in 138 examinations from 48 healthy term neonates (gestational age (GA) 41 (37, 41) weeks (median and range), 5 min Apgar score 9 (8, 10)) and 54 examinations from 20 asphyxiated neonates (GA 40.5 (37, 42) weeks, 5 min Apgar score 5 (4, 6)). PSS and PSSR were lower (closer to zero) in the asphyxiated neonates (PSS −19.4 (−20.2, −18.6) % (mean (95% confidence interval)), PSSR −1.63 (−1.70, −1.56)/s) than in the healthy term neonates (PSS −21.8 (−22.3, −21.4) %, PSSR −1.79 (−1.84, −1.74)/s) (p<0.05). %FS was similar in the asphyxiated (28.9 (26.8, 31.0) %) and healthy term neonates (29.0 (28.0, 29.9) %) (p = 0.982). PSS differed significantly between the asphyxiated and healthy term neonates for the left apical, left basal and right basal segments (p<0.05) but not for the right apical, septum apical or septum basal segments. PSSR differed significantly only for the septum apical segments.
Conclusions The PSS and PSSR detected impaired heart function in asphyxiated neonates the first three days of life not detected by %FS. PSS and PSSR were more sensitive parameters than %FS for assessing reduced myocardial function in asphyxiated term neonates.