Clinical Investigation
Fetal Echocardiography
Speckle-Tracking Echocardiography for the Assessment of Atrial Function during Fetal Life

https://doi.org/10.1016/j.echo.2020.06.011Get rights and content

Highlights

  • •

    Atrial strain is a new parameter that is feasible to measure in the fetal heart.

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    Strain values correlate well with normal fetal circulation physiology.

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    Gestational age and frame rate may influence the results.

Introduction

Speckle-tracking echocardiography has become a major tool in the evaluation of heart function. Atrial strain has emerged as an important component in the assessment of cardiac function, but there is a paucity of prenatal data. The aim of this study was to describe our initial experience of measurement of atrial strain in fetuses, with respect to both feasibility and the strain patterns observed.

Methods

Four-chamber Digital Imaging and Communications in Medicine loops were acquired prospectively for deformation imaging. Fifty-three normal fetuses with no morphologic or functional abnormalities were selected for analysis. The three strain components of atrial cycle for both left atrium (LA) and right atrium (RA) were acquired—reservoir (LAres or RAres), conduit, and contraction (LAct or RAct)—and are expressed as a percentage. Ratios of these components were calculated. Simple linear regression was used to analyze how the dependent variables changed according to gestational age and frame rate.

Results

The median gestational age was 30 weeks (range, 23-35), and the frame rate was 74 frames per second (fps; range, 35-121). Left atrial strain was feasible in 48/53 (91%), and right atrial strain in 46/53 (87%) of cases. The onset of LA contraction could be identified on the strain curves in 32 of 48 (67%) cases, and of the RA in 17 of 46 (37%) cases. The values of RAres and RAct were higher compared with those of LAres and LAct (33.9% vs 30.3%, P = .014; and 21.5% vs 16.8%, P = .005), and the contraction:reservoir ratio was also higher for RA (0.63 vs 0.55 for LA, P = .003). Higher values for LAres, LAct, RAres, and RAct were associated with higher frame rate (P = .007, .020, .049, and .012, respectively). The onset of LA contraction was better identified with a higher frame rate (mean 77 vs 59 fps when not seen, P = .007). A higher LA contraction:reservoir ratio was associated with a lower gestational age (P = .042).

Conclusion

Measurement of atrial strain is feasible in the fetal heart. The values are influenced by gestational age and frame rate, so it is necessary to account for these variables. Comparison of left versus right atrial strain values contrasts with those observed postnatally. Atrial function merits further study during fetal life, to aid understanding of maturational changes and disease states.

Section snippets

Study Population

This study was performed at the Evelina London Children's Hospital, a tertiary referral center for fetal cardiology. Echocardiographic examinations were undertaken from August 2016 to January 2019 as part of a prospective research study (iFIND-2, UK HRA REC reference: 14/LO/1806), which was primarily aimed at improving recognition of heart structures using a machine learning approach (www.ifindproject.com), and consent was obtained prospectively for use in research with respect to cardiac

General Characteristics and Strain Values

The clips of 53 fetuses with a median gestational age of 30 weeks (range, 23-35) were studied. Left atrial strain was feasible in 48 (91%) and right atrial strain in 46 (87%), and it was possible to identify left atrial contraction in 32 of 48 cases (67%) and right atrial contraction in 17 of 46 (37%).

Comparing second trimester (8/53, 15%, <28 weeks) with third trimester scans (45/53, 85%, ≥28 weeks), we found that feasibility was not different for LAres strain (88% vs 91% respectively, P

Discussion

In this paper we present our initial experience with STE assessment of atrial function in normal fetuses between 23 and 35 weeks of gestational age. To our knowledge, there has been only one other manuscript reporting this so far,14 where only the atrial lateral wall was assessed without assessment of the different components of the atrial cycle.

In our study, left atrial strain was feasible in 48/53 (91%) of studied fetuses and right atrial strain in 46/53 (87%), with acceptable agreement for

Conclusion

The analysis of atrial strain is feasible in the normal fetal heart in the second and early third trimester. In this study, only right atrial contraction was inconsistently measured. The patterns appear consistent with our understanding of normal prenatal circulatory physiology. They can, however, be affected by variables such as gestational age and frame rate, and further research needs to account for these. Quantification of atrial function merits further prospective testing both in health

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    • Conflict of Interest: The authors reported no actual or potential conflicts of interest relative to this document.

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    2020 by the American Society of Echocardiography.