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Newborn infants show distinct systolic time intervals, including a longer preejection period (PEP), compared to older children. These findings suggest potential left ventricular adaptation challenges in neonates transitioning to systemic circulation.
Area of Science:
- Cardiology
- Neonatology
- Pediatric Physiology
Background:
- Systolic time intervals (STI) assess left ventricular (LV) performance.
- Established normal STI values exist for adults and older children.
- Limited, often contradictory, data exists for normal newborn infants.
Purpose of the Study:
- Establish normal STI values for newborn infants.
- Compare STI in neonates and young infants.
- Investigate potential differences in LV adaptation to systemic circulation.
Main Methods:
- Carotid artery pulse curve analysis to calculate STI.
- Study included 29 normal newborns (0.5-119 hours old).
- Included 9 infants aged 2-3 months for comparison.
Main Results:
- STI values in newborns differ significantly from adults and older children.
- Newborns exhibit a relatively prolonged preejection period (PEP).
- Statistically significant differences in PEP (82 ms vs. 68 ms) and PEP/LVET ratio (0.41 vs. 0.35) were observed between neonates and 2-3 month olds (p<0.01).
Conclusions:
- Neonatal STI values are distinct, particularly the PEP.
- Observed differences suggest initial difficulties for the neonatal left ventricle adapting to systemic circulation.
- These adaptation challenges may persist even up to 3 months of age.
Abstract:
Systolic time intervals, calculated from the carotid artery pulse curve have been used for some time to assess left ventricular performance. Normal values have been established for adults and older children, but few investigations have been made on newborn infants, generally with partly contradictory results. Therefore a study has been undertaken in 29 normal newborn infants 1/2-119 hours old, and 9 infants 2-3 months old to establish normal values for different intervals. They were found to differ from those reported for adults and older children, most clearly seen in the relatively long preejection period (PEP). Statistically significant differences were found between the PEP of 20 infants below 47 hours of age and 9 infnats 2-3 months old: PEP 82 ms and 68 ms respectively. (p less than 0.01); the same is true of the quotient PEP/LVET (left ventricular ejection time), which was found to be 0.41 and 0.35 resp. (p less than 0.01). By adult standards this would mean impairment of left ventricular function. A possible explanation of this could be a difficulty for the left ventricle to cope with the systemic circulation during the first days of life even in normal newborns, a difficulty not fully compensated for even at 3 months of age.