Background
Establishment of the range of normal values and associated variations
of two-dimensional speckle-tracking echocardiography (2DSTE) derived right
ventricular (RV) strain is a prerequisite for its routine clinical
application in children. The objectives of this study were to perform a
meta-analysis of normal ranges of RV longitudinal strain measurements
derived by 2DSTE in children and identify confounders that may contribute to
differences in reported measures.
Methods
A systematic review was launched in PubMed, Embase, Scopus, Cochrane,
and ClinicTrials.gov. Search hedges were created to cover the concepts of
pediatrics, speckle-tracking echocardiography, and right heart ventricle.
Two investigators independently identified and included studies if they
reported the 2DSTE derived RV strain measures: RV peak global longitudinal
strain (pGLS), systolic strain rate (pGLSRs), early diastolic strain rate
(pGLSRe), late diastolic strain rate (pGLSRa), or segmental longitudinal
strain at the apical, mid, and basal ventricular levels in healthy children.
Quality and reporting of the studies were assessed. The weighted mean was
estimated by using random-effects with 95% confidence intervals
(CI), heterogeneity was assessed by the Cochran's Q statistic and
the inconsistency index (I2), and publication bias was evaluated
using funnel plots and the Egger test. Effects of demographic, clinical,
equipment, and software variables were assessed in a meta-regression.
Results
The search identified 226 children from 10 studies. The reported
normal mean values of pGLS among the studies varied from
−20.80% to −34.10% (mean,
−29.03%, 95%CI, −31.52% to
−26.54%), pGLSRs varied from −1.30 to −2.40
1/sec (mean, −1.88, 95%CI, −2.10 to −1.59),
pGLSRe ranged from 1.7 to 2.69 1/sec (mean, 2.34, 95%CI, 2.00 to
2.67) and pGLSRa ranged from 1.00 to 1.30 1/sec (mean, 1.18, 95% CI,
1.04 to 1.33). A significant base-to-apex segmental strain gradient (p
<0.05) was observed in the right ventricular free wall. There was
significant between-study heterogeneity and inconsistency
(I2>88% and p<0.01 for each strain
measure), which was not explained by age, gender, body surface area, heart
rate, frame rate, tissue tracking methodology, equipment, or software. The
meta-regression showed that these effects were not significant determinants
of variations among normal ranges of strain values. There was no evidence of
publication bias (Egger test, p=0.59).
Conclusions
This study is the first to define normal values of two-dimensional
speckle tracking echocardiographic (2DSTE) derived right ventricle strain in
children on the basis of a meta-analysis. The normal mean value in children
for RV global strain is −29.03% (95% CI,
−31.52% to −26.54%). The normal mean value
for RV global systolic strain rate is −1.88 1/sec (95% CI,
−2.10 to −1.59). RV segmental strain has a stable
base-to-apex gradient that highlights the dominance of deep longitudinal
layers of the RV that are aligned base to apex. Variations among different
normal ranges do not appe...
