263 - Physiological determinants of Pulmonary Venous flow: an ultrasound study in preterm infants

Publication Number: 4259.263

Enrico Petoello, Children's Hospital, london, England, United Kingdom; Koert de Waal, John Hunter Children's Hospital, Newcastle, New South Wales, Australia

Background: A typical pulmonary vein (PV) flow pattern starts after QRS with single or bifid peaked forward flow (S-wave) due to left atrial (LA) relaxation. S-wave deceleration driven by LA compliance (S wave deceleration rate, S-DR) is followed by a second forward flow wave (D-wave) with mitral valve opening and corresponding LA pressure decay. The PV cycle ends with a negative wave (A-wave) corresponding with atrial contraction. (Figure 1)
Pilot studies have shown direct correlation of PV flow parameters and left atrial pressure. Despite the investigation of PV flow patterns in neonatal population in literature, this issue remains unexplored.

Objective: The aim of this study is to determine feasibility and physiological determinants of PV flow characteristics in preterm infants with and without high left atrial pressure (LAP).

Design/Methods: This retrospective observational study analysed echocardiograms for PV flow characteristics obtained from the apical 4-chamber view. A 10-point image quality score was used to determine PV flow characteristics feasibility. Additional measures included pulmonary artery flow, mitral valve EA, Tissue Doppler and Left Atrial Strain at reservoir (LASr). LA stiffness was calculated from E/e’ divided by LASr.
High LAP was determined by LAVi, e’, E/e’ ratio and LASr and scans were analysed as with or without evidence of high LAP.

Results: 49 infants (24 to 34 weeks gestation) were included thus far. Feasibility was appropriate with a median quality score of 7 (IQR 6-8). Bifid S-waves, SD-wave fusion or absent A-wave were observed in 51%, 30% and 17% of scans respectively.
High LAP was associated with higher peak D-wave corresponding with high LA stiffness and rapid pressure decay, and longer A-wave duration.
(Table 1).
Peak D-wave was correlated with E/e’ ratio and A-wave duration was inversely correlated with LASr.
(Figure 2)

Conclusion(s): PV flow characterises can be acquired with appropriate image quality score feasible for analysis in neonatal population. The physiological determinants of PV flow include LA compliance during volume load, LA pressure fall and LA contractility.
Like atrial pressure and atrial compliance in relation to volume load, PV flow represents an informative tool in the assessment of left atrial function.

Table 1
Table 1 PAS.pdfEchocardiographic parameters and PV characteristics

Figure 1
Figure 1 PAS.pdfComponents of PV flow pattern

Figure 2
Figure 2 PAS.pdfCorrelations between D wave and Ee’ ratio and A wave duration and LASr