Development of left ventricular systolic and diastolic function in preterminfants during the first month of life: A prospective follow-up study

Objectives: We studied the left ventricular systolic and diastolic function in preterm infants during the first month of life in comparison with the r espective patterns in term neonates. Study design: Serial 2-dimensional/M-mode and Doppler transmitral flow velo city measurements were performed in 20 preterm (gestational age, 32 to 36 w eeks) and 25 term infants between days 2 and 5 after birth and at age I mon th. Results: After birth, the early velocity, early integral, early filling fra ction, early and atrial velocity ratios, and early and atrial integral rati os were lower in the preterm than in the term infants (P < .01). During the first 4 weeks of lire, these values, the atrial velocity, and the atrial i ntegral increased gradually, whereas the atrial Filling fraction, diastolic filling time, and deceleration time of early diastolic filling decreased s lightly with postnatal age (P < .01) in the preterm infants. At age I month their diastolic function reached the level of term infants with the except ion of early and atrial integral ratios and atrial filling fraction. The me asures of systolic performance were within normal range, but midwall fracti onal shortening at 2 to 5 days (P < .05), and fractional shortening area (P < .05), as well as midwall fractional shortening (P < .01) at 1 month of a ge, were slightly inferior in the preterm than in the term infants. During the First month the left ventricular mass and left ventricular mass/body su rface area ratio increased more markedly in the preterm than term infants, significantly in both groups (P < .05). Conclusions: The preterm diastolic patterns represent a transition between the patterns of the fetus and those of term neonates. These changes reflect an improvement in the left ventricular diastolic function, more markedly i n relaxation than in compliance. The postnatal increase in the transmitral measures and left ventricular mass suggest marked myocardial adaptation to the extrauterine environment in the preterm infant already during the First month.