Normal ranges of tissue Doppler imaging echocardiographic parameters in healthy term and preterm newborns: a systematic review and meta-analysis

Reference values for tissue Doppler imaging (TDI) parameters in neonates remain limited and are not consistently defined across gestational ages or postnatal periods. We conducted a systematic review and meta-analysis to define normal ranges for TDI-derived myocardial performance indices in healthy term and preterm newborns, stratified by gestational age (GA) and day of life (DOL). We searched MEDLINE, EMBASE, and CENTRAL up to April 2024 for observational studies reporting TDI measures in neonates grouped by GA (< 32, 32-36, ≥ 37 weeks) and DOL (≤ 7, > 7). Study quality was assessed using the checklist, and evidence certainty was evaluated with a modified GRADE approach. Thirty-five studies including 3747 neonates were included in the analysis, comprising 1635 term and 2112 preterm infants. We analyzed peak systolic (s'), early (e') and atrial (a') diastolic velocities, as well as isovolumic contraction and relaxation times, ejection time, and ventricular filling time. TDI parameters increased with GA and DOL, reflecting early postnatal hemodynamic changes. CONCLUSION: This meta-analysis provides robust, clinically relevant reference ranges for TDI parameters in neonates across gestational and postnatal ages, supporting their broader use in functional cardiac assessment and informing future research directions. WHAT IS KNOWN: • Tissue Doppler imaging (TDI) has been widely applied to assess myocardial function in neonates. Reference ranges for TDI parameters in newborns exist but are not uniformly established across gestational ages and postnatal days. Variations in myocardial velocities and cardiac cycle times are known to reflect developmental changes in cardiac function. WHAT IS NEW: • This systematic review and meta-analysis define comprehensive normal ranges for TDI velocities and cardiac cycle time intervals in healthy term and preterm newborns, stratified by gestational age and days of life. It highlights hemodynamic adaptations in early life and provides clinically relevant benchmarks for assessing neonatal cardiac function.