Clinical Investigation
Heart Disease in Infants and Children
Maturational Patterns of Systolic Ventricular Deformation Mechanics by Two-Dimensional Speckle-Tracking Echocardiography in Preterm Infants over the First Year of Age

https://doi.org/10.1016/j.echo.2017.03.003Get rights and content

Highlights

  • Two-dimensional (2D) speckle-tracking echocardiography (STE)–derived myocardial strain is a feasible and reproducible imaging modality that can be used to characterize systolic ventricular function in premature infants.

  • This study establishes ventricular-specific systolic strain maturational patterns by 2D STE in a large cohort of extremely preterm infants from birth through 1 year corrected age.

  • Common cardiopulmonary morbidities, such as bronchopulmonary dysplasia and pulmonary hypertension, appear to leave a negative impact on right ventricular strain, while left ventricular strain remains stable through the first year of age.

  • With the establishment of the range of maturational patterns of strain mechanics and associated variations up to 1 year corrected age, deformation imaging by 2D STE may now be implemented in preterm infants as a means to identify cardiovascular compromise earlier, guide therapeutic intervention, monitor treatment response, and improve overall outcome.

Background

The aim of this study was to determine the maturational changes in systolic ventricular strain mechanics by two-dimensional speckle-tracking echocardiography in extremely preterm neonates from birth to 1 year of age and discern the impact of common cardiopulmonary abnormalities on the deformation measures.

Methods

In a prospective multicenter study of 239 extremely preterm infants (<29 weeks gestation at birth), left ventricular (LV) global longitudinal strain (GLS) and global longitudinal systolic strain rate (GLSRs), interventricular septal wall (IVS) GLS and GLSRs, right ventricular (RV) free wall longitudinal strain and strain rate, and segmental longitudinal strain in the RV free wall, LV free wall, and IVS were serially measured on days 1, 2, and 5 to 7, at 32 and 36 weeks postmenstrual age, and at 1 year corrected age (CA). Premature infants who developed bronchopulmonary dysplasia or had echocardiographic findings of pulmonary hypertension were analyzed separately.

Results

In uncomplicated preterm infants (n = 103 [48%]), LV GLS and GLSRs remained unchanged from days 5 to 7 to 1 year CA (P = .60 and P = .59). RV free wall longitudinal strain, RV free wall longitudinal strain rate, and IVS GLS and GLSRs significantly increased over the same time period (P < .01 for all measures). A significant base-to-apex (highest to lowest) segmental longitudinal strain gradient (P < .01) was seen in the RV free wall and a reverse apex-to-base gradient (P < .01) in the LV free wall. In infants with bronchopulmonary dysplasia and/or pulmonary hypertension (n = 119 [51%]), RV free wall longitudinal strain and IVS GLS were significantly lower (P < .01), LV GLS and GLSRs were similar (P = .56), and IVS segmental longitudinal strain persisted as an RV-dominant base-to-apex gradient from 32 weeks postmenstrual age to 1 year CA.

Conclusions

This study tracks the maturational patterns of global and regional deformation by two-dimensional speckle-tracking echocardiography in extremely preterm infants from birth to 1 year CA. The maturational patterns are ventricular specific. Bronchopulmonary dysplasia and pulmonary hypertension leave a negative impact on RV and IVS strain, while LV strain remains stable.

Section snippets

Study Population

All data were prospectively obtained as part of an observational research study that included patients who were enrolled between August 2011 and January 2016 at hospitals affiliated with two academic institutions (Washington University School of Medicine, St. Louis Children's Hospital, and the Royal College of Surgeons in Ireland, Rotunda Hospital). Two hundred thirty-nine preterm infants (born at 23-0/7 to 28-6/7 weeks gestation) were recruited at birth and longitudinally followed until 1 year

Study Population Characteristics

Two hundred thirty-nine infants with a median gestational age of 27.0 weeks (interquartile range, 26.0–28.0 weeks) and a median birth weight of 960 g (interquartile range, 800–1,138 g) were recruited in this study (137 patients from the Washington University site and 102 patients from the Royal College of Surgeons site). Of the 239 patients, 17 infants (7% with equal distribution among centers) died before hospital discharge and were excluded from the analysis, leaving 222 infants with data to

Discussion

In a prospective multicenter longitudinal study of a large cohort of premature infants (≤29 weeks at birth), we evaluated ventricular mechanics with 2D STE–derived deformational indices from birth to 1 year CA to determine the maturational patterns of postnatal cardiac adaptation. The main findings of this study are as follows: (1) RV LS has a distinct regional magnitude distribution with a base-to-apex gradient and an incremental progression, while LV strain has an apex-to-base magnitude

Conclusions

In this study we tracked the maturational patterns of ventricular mechanics with global and regional deformation imaging by 2D STE in extremely preterm infants during the first year of age. The maturational patterns are ventricular specific. It appears that BPD and PH have a negative impact on RV and IVS strain, while LV strain remains stable through the first year of age, independent of birth weight, postnatal age, and clinical status. This study suggests that 2D STE–derived strain can be used

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    This study was supported by grants from the Premature and Respiratory Outcomes Program (National Institutes of Health [NIH] grants 1U01 HL1014650 and U01 HL101794), NIH grant R21 HL106417, the Pediatric Physician Scientist Training Grant (NIH grant 5 T32 HD043010-09), and the Postdoctoral Mentored Training Program in Clinical Investigation (NIH grant UL1 TR000448). Dr. EL-Khuffash is funded by multiple sources: EU FP7/2007-2013 grant (agreement no. 260777, The HIP Trial), the Friends of the Rotunda Research Grant (reference: FoR/EQUIPMENT/101572), and the Health Research Board Mother and Baby Clinical Trials Network Ireland (CTN-2014-10). Drs. Levy and El-Khuffash equally contributed to writing the first draft of this report.

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