Different functional cardiac characteristics observed in term/preterm neonates by echocardiography and tissue doppler imaging

Abstract

Background and aim: To establish, using echocardiography, color-flow Doppler and tissue doppler imaging (TDI), physiological values of systolic/diastolic indexes in healthy term/pre-term newborns, and to identify how different degrees of maturity influence morpho-functional cardiac alterations during the transitional period.

Study design and subjects: 33 term newborns (M = 19, F = 14; gestational ages: 37th-41st week), and 20 pre-term infants (M = 11, F = 9; gestational ages: 31st-36th week) admitted to our department were studied. All infants underwent to clinical and Doppler ultrasound evaluations, carried out by the third to fourth day. Investigations included: M-mode echocardiography, color-flow Doppler and TDI.

Outcome measures and results: Term and preterm neonates differed for: interventricular septum and left systolic/diastolic ventricle diameters (p<0.01 and <0.05 respectively); left ventricle posterior wall in systole (p<0.01); shortening and ejection fraction (p<0.05). Color-flow Doppler parameters on the tricuspid (peak E, peak A, ratio E/A; p<0.05) and on the mitral (peak E and E/A ratio; p<0.01) significantly differed between the two groups. Significant differences were also present for basal left ventricular lateral wall and right ventricular lateral wall in the Ew (p<0.01 and <0.05 respectively), Sw peak (p<0.01 and <0.05 respectively), and Ew/Aw (p<0.05). The isovolumetric relax time and the E/Ew measured on the medial mitral annulus also demonstrated significant differences (p<0.01) between the two groups.

Conclusions: TDI is feasible in preterm neonates and enables assessment of myocardial velocities. With increasing gestational age, higher myocardial velocities and lower E/E' Πratios were found. TDI addition to standard neonatal echocardiography may provide further important information about cardiac function.