Cardiovascular Journal of Africa: Vol 28 No 1 (January/February 2016)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 1, January/February 2017 38 AFRICA
Discussion
In recent years, more attention has been paid to changes in
cardiac function in children with features of intrauterine growth
retardation. Many articles describe the disorders appearing
as early as in the foetus, revealing subclinical changes in the
myocardium detected on echocardiographic examination.3,4,7
Changes in utero due to chronic hypoxia and malnutrition,
with increased placental vascular resistance, result in pressure
and volume overload of the foetal heart, which in turn induces
abnormal cardiac function.8,9
In our study we evaluated the cardiac function in small-for-
gestational-age children with features of IUGR with the use
of conventional as well as tissue Doppler echocardiographic
parameters. We analysed left ventricular diameters (IVSd,
LVPWd and LVDd) but did not find significant differences
between the groups. This is similar to the findings of Bjarnedard
et al. and Crispi et al., who studied, respectively, young adults
and children the same age as our study patients.7,10
On the other hand, Turkish authors demonstrated that left
ventricular diastolic dimension in neonates and infants were
significantly higher in children with IUGR.11 These differences
may have been due to the different age groups examined by the
researchers.
Other conventional echocardiographic parameters assessed
in our study were shortening fraction (SF) and ejection fraction
(EF) of the left ventricle. As in other reports, there were no
differences between the groups.7,11,12
Altin et al. describes a significantly higher heart rate in
children with growth restriction, which was not observed in our
study.11 Presumably this difference may have been due to the
fact that the authors evaluated neonates and infants, not older
children, as in our study. These observations may indicate that
predominance of the sympathetic nervous system in children
with SGA tends to disappear with age. However, Crispi et al.
studied children of a similar age as ours and showed similar
heart rates to ours in children with IUGR.7
E/A ratio is a conventional index evaluating ventricular filling
during diastole. In adults, reduced E/A ratios indicate diastolic
dysfunction. Cohen et al. measured a mean E/A index of 1.9 in
healthy people over 21 years of age and Eto et al. of 1.77 ± 0.53
in children. We had similar findings in the control group, but in
children with IUGR, the mean E/A ratio was lower.13,14
Other articles on children with IUGR describe different
values for this index. In most recent reports in foetuses, the E/A
ratio was significantly higher compared with the control group.
In older children authors describe a normalisation of the E/A
ratio, with no differences between a group of healthy children
and those born with IUGR features.7,10,11,15,16
The lower E/A index in children with IUGR seems to be
dependent on the increase in A wave and decrease in E wave
in those patients. This could be explained by a lower free
inflow (E wave) than active left ventricular filling (A wave),
which is associated with susceptibility of the left ventricle to
abnormalities, and may be one of the symptoms of diastolic
dysfunction. Such abnormalities are described in children
with connective tissue diseases, due to the higher content
of connective tissue in cardiac muscle, which diminishes its
susceptibility to stretching.
The results of research on deceleration time in adults, which is
an indicator of left ventricular ‘stiffness’, support this theory.17 In
our study, deceleration time in the IUGR group was only slightly
higher but a statistically significant difference was observed
between the groups. It may indicate the start of myocardial
changes in susceptibility/stiffness of the left ventricle.
With regard to the IRT, results in the literature are not
consistent. Sehgal et al., who studied a slightly younger group of
children with growth restrictions, described a similar tendency to
our results.18 By contrast, Crispi et al ., in a similar age group to
ours, did not report such differences. 7
In our study, MPI was significantly higher in the IUGR
group.11,19 Similar observations have been reported in foetuses,
which may indicate that myocardial function is already impaired
in utero.20 However, observations from Swedish authors who
studied adults who were born with IUGR (22–25 years old) did
not confirm this theory.10 These differences may have been due to
the degree of restriction abnormalities, which was different in the
various groups studied.
There are few reports on diastolic cardiac function in children
with IUGR. Altin et al. evaluated diastolic function in neonates
and infants and revealed that indices that were abnormal in
the foetal period (E′, A ′, E′/A′, E/E′ septal and E/E′ lateral)
tended to decrease with age.11 Similar findings were described
by Bjarnegard et al., who estimated diastolic function in young
adults. They found no differences in these indices between the
IUGR and control groups.10 On the other hand, a multicentre
study by Crispi et al. showed different results.
Other researchers evaluated a similar age group to those
in our study and, as in our analysis, some diastolic function
parameters were significantly higher in IUGR children. Perhaps
the observed anomalies due to intrauterine chronic hypoxia
leading to cardiac volume overload and cardiac remodelling
resulted in impaired cardiac function.7
Conclusion
From our results, we found that diastolic function may be
impaired in IUGR patients, but further studies with larger
sample sizes are needed. This group of patient should be
monitored long term and evaluated for cardiovascular status,
due to the high risk of cardiovascular disease in adulthood.
Table 3.Tissue Doppler echocardiography parameters
Parameters
Study group (n= 77)
mean ± SD
Control group (n= 30)
mean ± SD p-value
S septal 7.71 ± 1.20 7.88 ± 1.43 0.58 (NS)
S lateral 9.62 ± 1.37 9.90 ± 1.57 0.40 (NS)
E′ septal 15.29 ± 1.88 14.80 ± 1.83 0.22 (NS)
A′ septal 6.71 ± 1.41 6.32 ± 1.01 0.17 (NS)
E′ lateral 20.38 ± 2.94 20.85 ± 2.24 0.43 (NS)
A′ lateral 7.76 ± 1.86 7.56 ± 0.94 0.56 (NS)
E′/A′ septal 2.41 ± 0.40 2.36 ± 0.43 0.59 (NS)
E′/A′ lateral 2.82 ± 0.42 2.75 ± 0.54 0.51 (NS)
E/E′ septal 6.89 ± 1.11 4.62 ± 1.16 < 0.001
E/E′ lateral 6.10 ± 1.27 4.91 ± 0.88 < 0.001
n, number of children; SD, standard deviation; NS, not significant; S septal,
myocardial velocity during systole at interventricular septum; S lateral, myocar-
dial velocity during systole at posterior wall; E′ /A′ septal, ratio of early to late
diastolic velocities for the interventricular septum; E′ /A′ lateral, ratio of early to
late diastolic velocities for the posterior wall; E/E′ septal, ratio of peak transmi-
tral E velocity to early diastolic mitral annular velocity for the interventricular
septum; E/E′ lateral, ratio of peak transmitral E velocity to early diastolic mitral
annular velocity for the posterior wall.