Importance of neonatal strain imaging: what are we measuring?

Increasing region of interest width reduces neonatal circumferential strain

OBJECTIVE

There is growing interest in speckle tracking echocardiography-derived strain as a measure of left ventricular function in neonates. However, knowledge gaps remain regarding the effect of image acquisition and processing parameters on circumferential strain measurements. The aim of this study was to evaluate the effect of using different region of interest (ROI) widths on speckle tracking derived circumferential strain in healthy neonates.

METHODS

Thirty healthy-term-born neonates were examined with speckle-tracking echocardiography in the short-axis view. Circumferential strain values were acquired and compared using two different ROI widths. Furthermore, strain values in the different vendor-defined wall layers were also compared.

RESULTS

Increasing ROI width led to a decrease in global circumferential strain (GCS) in the midwall and epicardial layers, the respective decreases in strain being -23.4 ± .6% to -22.0 ± 1.1%, p < .0001 and 18.5 ± 1.7% to -15.6 ± 2.0%, p < .0001. Segmental analyses were consistent with these results, apart from two segments in the midwall. There was no statistically significant effect on strain for the endocardial layer. A gradient was seen where strain increased from the epicardial to endocardial layers.

CONCLUSION

Increasing ROI width led to a decrease in GCS in the midwall and epicardium. There is an increase in circumferential strain when moving from the epicardial toward the endocardial layer. Clinicians wishing to implement circumferential strain into their practice should consider ROI width variation as a potential confounder in their measurements.

Left atrial strain in neonates with congenital diaphragmatic hernia and length of stay in pediatric intensive care unit

Introduction

The role of cardiac left ventricle (LV) dysfunction in children with congenital diaphragmatic hernia (CDH) has gained increasing attention. The hernia allows abdominal mass to enter thorax and subsequently both dislocating and compressing the heart. The pressure on vessels and myocardium alters blood flow and may interfere with normal development of the LV. A dysfunctional LV is concerning and impacts the complex pathophysiology of CDH. Hence, assessing both the systolic and diastolic LV function in the newborn with CDH is important, and it may add value for medical treatment and prognostic factors as length of stay (LOS) in pediatric intensive care unit (PICU). LV strain is considered an early marker of systolic dysfunction used in the pediatric population. Left atrial (LA) strain is an echocardiographic marker of LV diastolic dysfunction used in the adult population. When filling pressure of the LV increases, the strain of the atrial wall is decreased. We hypothesized that reduced LA strain and LV strain are correlated with the LOS in the PICU of newborns with CDH.

Methods

This retrospective observational cohort study included data of 55 children born with CDH between 2018 and 2020 and treated at Karolinska University Hospital, Sweden. Overall, 46 parents provided consent. Echocardiograms were performed in 35 children <72 h after birth. The LA reservoir strain (LASr), LV global longitudinal strain, LV dimensions, and direction of blood flow through the patent foramen ovale (PFO) were retrospectively assessed using the echocardiograms.

Results

Children with LASr <33% (n = 27) had longer stays in the PICU than children with LA strain ≥33% (n = 8) (mean: 20.8 vs. 8.6 days; p < 0.002). The LASr was correlated with the LOS in the PICU (correlation coefficient: -0.378; p = 0.025). The LV dimension was correlated with the LOS (correlation coefficient: -0.546; p = 0.01). However, LV strain was not correlated to LOS.

Conclusion

Newborns with CDH and a lower LASr (<33%) had longer stays in the PICU than children with LASr ≥33%. LASr is a feasible echocardiographic marker of diastolic LV dysfunction in newborns with CDH and may indicate the severity of the condition.

The influence of region of interest width in fetal 2D-speckle tracking echocardiography late in pregnancy

Speckle tracking echocardiography is a promising method for assessment of myocardial function in fetal and neonatal hearts, but further studies are necessary to validate and optimize the settings for use in fetal cardiology. Previous studies have shown that the definition of the region of interest (ROI) affects strain values in adults. The aim of this study was to investigate how different widths of ROI influences measurements of four-chamber longitudinal systolic strain in fetuses late in pregnancy. Thirty-one singleton, healthy fetuses born to healthy mothers underwent an echocardiographic examination during gestational week 37. Speckle tracking was performed with two different settings for ROI width; the narrowest and second most narrow, provided both widths were assessed as suitable for the myocardial wall thickness of the fetus. We found an inverse correlation between the ROI width and the strain values. Four-chamber longitudinal strain changed from - 20.7 ± 3.6% to - 18.0 ± 4.4% (p < 0.001) with increasing ROI width. Further, strain decreased from the endocardium to the epicardium with multilayer measurements. Different widths of ROI influenced the strain measurements significantly in the fetal heart, comparable to what has been reported in adults. A standardization of the ROI setting could improve the interpretation, and reduce variability in fetal strain measurements.