Maturational Patterns of Systolic Ventricular Deformation Mechanics by Two-Dimensional Speckle-Tracking Echocardiography in Preterm Infants over the First Year of Age

Abstract

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.

Keywords: Cardiac function; Echocardiography; Prematurity; Strain imaging.

Copyright © 2017 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Enrollment and follow-up of study participants

BPD, bronchopulmonary dysplasia; PH, pulmonary hypertension; PDA, patent ductus arteriosus. *119/222 infants were excluded from the healthy uncomplicated cohort because they either were: a) diagnosed with BPD, defined as the requirement any respiratory support at 36 weeks PMA, and based on a modified NIH workshop definition; b) evidence of PH on echocardiogram at 32 and/or 36 weeks PMA, defined as any infant with any conventional echocardiographic signs identified, by an estimated RV systolic pressure > than 40 mm Hg, a ratio of RVSP to systemic blood pressure > than 0.5, any cardiac shunt with right-to-left flow, unusual degree of RV hypertrophy or dilatation, or any degree of ventricular septal wall flattening; or c) evidence of a hemodynamically significant PDA by Day 5–7, (defined by PDA characteristics, signs of pulmonary over circulation, and left heart-loading condition), or any PDA at 32 and 36 week PMA. There was significant overlap between these four categories. ** There were 239 infants recruited for this study (137 infants from the Washington University School of Medicine site in Saint Louis, USA and 102 infants from the Royal College of Surgeons in Ireland site in Dublin, Ireland). Echocardiograms were performed at Day 1 (n=30), Day 2 (n=30), 32 weeks PMA (n=117), 36 weeks PMA (n=117), and one year CA (n=81) in Saint Louis, USA. Echocardiograms were performed at Day 1 (n=102), Day 2 (n=102), Day 5 (n=98), and 36 weeks PMA (n=47) in Dublin, Ireland.

Figure 2. Maturational patterns of Ventricular Deformation over the first year of age

(A) RV FW longitudinal strain (RV FWLS%): In all infants RV FWLS % increased from Day 5–7 to one year CA (p

Figure 2. Maturational patterns of Ventricular Deformation over the first year of age

(A) RV FW longitudinal strain (RV FWLS%): In all infants RV FWLS % increased from Day 5–7 to one year CA (p

Figure 2. Maturational patterns of Ventricular Deformation over the first year of age

(A) RV FW longitudinal strain (RV FWLS%): In all infants RV FWLS % increased from Day 5–7 to one year CA (p

Figure 3. Left and right ventricle strain and systolic strain rate in infants with and without a hemodynamically significant patent ductus arteriosus on Day 5 – 7

(A) LV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher LV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (B) LV GLSRs. There was no difference in the magnitude of LV GLSRs between cohorts at any time point in the first week of age; (C) RV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher RV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (D) RV GLSr. There was no difference in the magnitude of RV GLSRs between cohorts at any time point in the first week of age. *= p

Figure 3. Left and right ventricle strain and systolic strain rate in infants with and without a hemodynamically significant patent ductus arteriosus on Day 5 – 7

(A) LV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher LV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (B) LV GLSRs. There was no difference in the magnitude of LV GLSRs between cohorts at any time point in the first week of age; (C) RV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher RV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (D) RV GLSr. There was no difference in the magnitude of RV GLSRs between cohorts at any time point in the first week of age. *= p

Figure 3. Left and right ventricle strain and systolic strain rate in infants with and without a hemodynamically significant patent ductus arteriosus on Day 5 – 7

(A) LV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher LV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (B) LV GLSRs. There was no difference in the magnitude of LV GLSRs between cohorts at any time point in the first week of age; (C) RV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher RV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (D) RV GLSr. There was no difference in the magnitude of RV GLSRs between cohorts at any time point in the first week of age. *= p

Figure 3. Left and right ventricle strain and systolic strain rate in infants with and without a hemodynamically significant patent ductus arteriosus on Day 5 – 7

(A) LV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher LV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (B) LV GLSRs. There was no difference in the magnitude of LV GLSRs between cohorts at any time point in the first week of age; (C) RV GLS. On Day 5 – 7, infants with a hsPDA (Green diamond, dotted green lines) had higher RV GLS than the healthy uncomplicated cohort (blue circle, solid blue line); (D) RV GLSr. There was no difference in the magnitude of RV GLSRs between cohorts at any time point in the first week of age. *= p