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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 1, January/February 2017
AFRICA
37
•
In the apical, four-chamber view, with the use of pulsed
Doppler, evaluation of mitral inflow velocities was done. The
sample volume was placed at the mitral valve annulus and the
peak of early mitral inflow velocity (E wave in early diastole),
the peak of atrial mitral inflow velocity (A wave in atrial
systole) and the E/A ratio were assessed.
•
In the apical, five-chamber view, with the use of pulsed
Doppler, left ventricular inflow and outflow were recorded
with the sample volume placed between the aortic and mitral
valves to evaluate isovolumetric relaxation time (IRT) and
deceleration time (DecT). On the basis of these measure-
ments, myocardial performance index, defined as quotient
of the sum of the isovolumetric contraction time (ICT) and
IRT-to-left ventricular ejection time (ET), were calculated.
•
In the apical, five-chamber view, with the use of pulsed
Doppler, aortic flow was recorded and heart rate calculated.
Each measurement was obtained for three cardiac cycles. For
statistical analysis the mean value was used.
Pulsed and colour tissue Doppler imaging were performed in
the apical four-chamber view. The sample volume was positioned
as parallel as possible with the lateral mitral annular motion.
The maximal myocardial velocities during systole (S), and early
(E
′
) and late (A
′
) diastole were measured at the interventricular
septum (septal) and lateral annulus (lateral). The ratio of the
early to late diastolic velocities was calculated for IVS (E
′
/A
′
septal) and for the posterior wall (E
′
/A
′
lateral). The ratio of peak
transmitral E velocity to early diastolic mitral annular velocity
(E/E
′
) was calculated for both the interventricular septum and
posterior wall (E/E
′
septal and E/E
′
lateral, respectively).
Statistical analysis
Descriptive statistics were executed by computing the mean and
standard deviation (SD) for scale variables, or frequencies for
nominal variables. The significance level was computed for the
differences between variables in the IUGR and control groups.
To evaluate the differences between the two groups, a parametric
t
-test and a non-parametric Mann–Whitney test were performed.
Distributions were checked for normality with the Kolmogorow–
Smirnov test. Statistical significance was defined as a
p
-value
<
0.05. Pearson and Spearman correlation coefficients were
computed to evaluate the degree of association between variables
for either the control or study group.
Results
Analysis of the medical records confirmed statistically
significant differences in birth weight (IUGR group: 2 541.62
±
218.47 g versus control group: 3 394.33
±
522.35 g;
p
<
0.001), while there was no significant difference for gestational
age between the groups. Physical examinations did not reveal
statistically significant differences between the mean values for
weight and body mass index, whereas in the IUGR group, the
children were significantly smaller compared to healthy subjects
(Table 1).
Analysis of echocardiographic left ventricular diameters did
not reveal any significant differences in diastolic wall dimensions
(IVSd: interventricular septum in diastole, LVPWd: posterior
wall diameter in diastole) or left ventricular lumen diameters
between the two groups. Left atrial diameter also did not differ
significantly.
The mean values of ejection fraction as well as shortening
fraction were within normal limits and similar between the
groups. The mean values were as follows: IUGR group: EF 69.32
±
2.99%, SF 38.33
±
2.55%; control group: EF 69.20
±
3.14%, SF
38.30
±
2.73%.
According to parameters evaluating left ventricular diastolic
function, there were statistically significant differences between
mean values of E wave, A wave and E/A ratio. The mean values
of E wave and E/A ratio were significantly lower in children with
intrauterine growth retardation compared to the control group.
The mean values of the A wave were significantly higher in that
group of patients.
The mean values of isovolumetric relaxation time and
deceleration time were significantly higher in children with
IUGR compared to the healthy peers (102.47
±
8.72 vs 96.58
±
6.08 min; 180.81
±
38.69 vs 160.83
±
25.63 min, respectively). The
mean values of myocardial performance index obtained in the
IUGR group were significantly higher than those of the control
group. The heart rate was similar in both groups of patients (
p
=
0.095) (Table 2).
Estimation of left ventricular function using tissue Doppler
imaging did not reveal significant differences between the mean
values of systolic myocardial velocity, either at the level of IVS,
or at the posterior wall. The mean values of septal and posterior
wall E
′
/A
′
ratio were also similar. The mean values of E/E
′
for
the interventricular septum and E/E
′
for the posterior wall were
significantly higher in patients with IUGR (Table 3).
Table 1. Patients’ characteristics
Characteristics
Study group (
n
=
77)
mean
±
SD
Control group (
n
=
30)
mean
±
SD
p
-value
Gender (M/F)
35/42
14/16
NS
Age on examination 7 y 8 m
±
1 y 4 m 7 y 7m
±
1 y 10 m NS
Birth weight (g)
2541.62
±
218.47
3394.33
±
522.35
<
0.001
Gestational age (hbd)
39.03
±
0.90
39.07
±
0.74
NS
Height (cm)
124.46
±
10.40
129.30
±
10.27
<
0.05
Weight
25.20
±
9.10
27.20
±
8.10
NS
BMI
15.87
±
3.01
16.09
±
2.60
NS
n,
number of children; SD, standard deviation; NS, not significant; M, male; F,
female; y, years; m, months; hbd, weeks of gestation; BMI, body mass index.
Table 2. Echocardiographic parameters
Parameters
Study group (
n
=
77)
mean
±
SD
Control group (
n
=
30)
mean
±
SD
p
-value
LVDd (mm)
37.23
±
4.27
37.03
±
3.96
0.81 (NS)
IVSd (mm)
5.40
±
0.89
5.36
±
0.85
0.78 (NS)
LVPWd (mm)
5.93
±
0.91
5.92
±
0.91
0.95 (NS)
EF (%)
69.32
±
2.99
69.20
±
3.14
0.86 (NS)
SF (%)
38.33
±
2.55
38.3
±
2.73
0.95 (NS)
E (cm/s)
91.71
±
14.99
101.07
±
10.59
0.002
A (cm/s)
68.37
±
9.91
44.78
±
9.15
<
0.001
E/A ratio
1.44
±
0.13
2.01
±
0.29
<
0.001
IRT (ms)
102.47
±
8.72
96.58
±
6.08
0.002
DecT (ms)
180.81
±
38.69
160.83
±
25.63
0.011
MPI
0.58
±
0.08
0.43
±
0.09
<
0.001
HR/min
85.00
±
11.41
81.77
±
8.94
0.095 (NS)
n
, number of children; SD, standard deviation; NS, not significant; LVDd,
left ventricular diameter in diastole; IVSd, interventricular septum in diastole;
LVPWd, posterior wall diameter in diastole; EF, ejection fraction; SF, shorten-
ing fraction; E, E wave; A, A wave; IRT, isovolumetric relaxation time; DecT,
deceleration time; MPI, myocardial performance index; HR, heart rate.