063 - Cardiac efficiency in preterm infants with a patent ductus arteriosus: A blood speckle tracking study

Publication Number: 63.4448

Koert de Waal, John Hunter Children's Hospital, Newcastle, New South Wales, Australia; Enrico Petoello, John Hunter Children’s Hospital, Tavagnacco, Friuli-Venezia Giulia, Italy

Background: Blood entering the left ventricle (LV) forms a vortex to conserve kinetic energy, minimise shearing impact, and maximise flow propulsion in systole. Vorticity (VOR, rotational movement) and energy loss (EL, kinetic energy dissipated by viscous friction and turbulence) are determinants of cardiac efficiency with higher EL indicating lower efficiency of the system. Cardiac efficiency can be measured with a novel ultrasound technology called high frame rate echocardiography with blood speckle tracking.

Objective: The aim of this study is to explore cardiac efficiency during volume overload due to a patent ductus arteriosus (PDA).

Design/Methods: Preterm infants less than 30 weeks gestational age underwent echocardiography between day 5 to 10. Conventional echocardiography views were used to group infants as PDA volume load based on PDA diameter (>1.5mm), left atrial size (> 1.25 ml/kg) and early diastolic inflow velocity (> 55 cm/s) or as stable preterm infants (closed PDA, minimal respiratory support).
High frame rate images (400-600 fps) of 2 cardiac cycles were acquired from the apical 4-chamber view and analysed offline using PyUSview software (figure) that allows for estimation of blood flow velocity and direction from frame to frame and calculate VOR and EL. Simple t-test was used to compare infants with and without PDA volume load.

Results: Sixty-six infants (mean gestation 27 weeks, birthweight 922 gram) were included. 22 infants had PDA volume overload and showed lower blood pressure, higher ejection fraction and longitudinal strain, decreased LV sphericity and evidence of increased left atrial pressure with reduced atrial function (table). VOR and EL indexed to body surface area were significantly higher during diastole with volume load.
PDA volume load in preterm infants is associated with increased preload, decreased afterload, higher systolic work and diastolic dysfunction. During diastole, the high-volume throughput drives increased vorticity and turbulence as mechanism for early cardiac remodeling with reduced LV sphericity. Higher EL during diastole signifies reduced cardiac efficiency and increased energy demand.

Conclusion(s): High frame rate echocardiography with blood speckle tracking is a novel ultrasound method to assess cardiac efficiency in preterm infants. Volume load reduces cardiac efficiency in diastole. This finding could provide added value in selecting infants for definitive PDA closure.

PyUSview analysis software
apical 4 chamber images with blood speckle tracking, vorticity and energy loss

results
PAS abstract 2025 EL v2 table.pdfdata presented as mean(SE) for stable and volume load infants