Introduction: The echocardiograph is an essential tool for cardiac evaluation and progress in pediatric cardiology has made this investigation more inevitable than before. However, normal values in neonatal cardiology are yet to be established for the Indian subcontinent.
Materials and Methods: We studied 99 healthy term infants, 0 – 7 days old in a tertiary center of Eastern India and documented the mean and standard deviation of 11 basic echocardiographic parameters for future reference.
Conclusions: RVAWd,
IVSd, LVEDd and LVEDs have significant correlation with infant body weight.
Keywords: Pediatric, neonates, echocardiography, nomograms
INTRODUCTION
A quantitative
assessment of cardiac chambers, valves, and great vessels is often of critical importance
in evaluating the severity of any congenital and acquired heart disease and in
planning the most appropriate medical, interventional, and/or surgical
treatment1-5. At present, pediatric echocardiographic nomograms of
good quality exist for cardiac valves, pulmonary arteries, the aorta, and the
aortic arch6-8. Pediatric nomograms for cardiac chamber diameters
and areas, however, are still limited or even absent. For the left ventricle,
there are sufficient nomograms for M-mode measurements, while normal values for
left ventricular diameters and areas evaluated in two- and four-chamber views
are almost absent. Furthermore, pediatric echocardiographic nomograms for right
ventricular dimensions and atrial dimensions are also extremely limited9,10.
The primary aim of
this work was to establish echocardiographic nomograms for ventricular and
atrial dimensions in a population of healthy neonates.
MATERIALS AND METHODS
This cross sectional
study was conducted at the Departments of Cardiology, Gynecology &
Obstetrics and Pediatric Medicine, at Nil Ratan Sircar Medical College, Kolkata
from February 2018 to December 2019. The study included 99 newborn infants who
fulfilled the following:
All the selected infants underwent a single echocardiographic examination within 7 days of birth, by a single examiner with appropriate transducers (7.5, 5.0 Hz) to define the cardiac structures and obtain measurements on the following M mode echocardiographic parameters:
All the newborns
underwent echocardiographic examination in the supine position on the mother’s
lap without any sedation. 2D and M mode echocardiography was performed in the
standard precordial positions using a Siemens Accuson CV70 machine. Left
ventricle (LV) dimensions were measured by 2D guided M mode echocardiogram of
LV at papillary muscle level using parasternal long axis view. Measurements at
end diastole were taken at the onset of QRS complex and the systolic internal
diameter was measured at maximum excursion of ventricular septum which normally
occurs before the maximal excursion of posterior wall. Internal diameter was
taken from trailing edge of septum to leading edge of posterior wall (tissue
blood interface). Septal thickness and posterior wall thickness was measured at
the onset of QRS complex in parasternal long axis. Aortic root dimensions were
obtained at the onset of QRS complex from leading age to leading edge of the
aortic wall in parasternal long axis view. Left atrium (LA) dimensions were
recorded at end-systole as the largest distance between posterior aortic wall
and the center of the line denoting the posterior LA wall in parasternal long
axis. Right ventricular end diastolic dimension was measured at tricuspid
annulus in the apical four chamber view. Diameter of pulmonary artery at the
annulus was measured in parasternal short axis view. From the above dimensions,
fractional shortening (FS) and ejection fraction (EF) were calculated.
Data was collected in a systematic way and compiled. The cardiac dimensions as obtained from echocardiography were correlated with the body weight of the infant. Keeping in mind that the body surface area changes minimally with body weight in newborns, the former was not taken into separate consideration. Ethical approval was obtained from the Institutional Ethical committee. The unpaired t-test was used to compare the means and establish or refute the statistical significance of these differences, with p values.
RESULTS AND ANALYSIS
We divided our cases into 3 groups based on body weight at the time of
performing the echocardiographic assessment as follows:
The mean body weight
in the study population was 2.87 ± 0.28 kg with Groups A, B and C recording
mean body weights of 2.31 ±
0.08, 2.74 ± 0.13 and 3.13 ± 0.14 kg respectively. The genders were equitably
distributed with male: female ratio of 1.11 in the study cohort (Table 1).
|
Total (n = 99) |
Group A (n= 8) |
Group B (n = 49) |
Group C (n = 42) |
Male |
52 |
2 |
22 |
28 |
Female |
47 |
6 |
27 |
14 |
M : F |
1.11 |
0.33 |
0.81 |
2.0 |
Mean BW (kg) |
2.87 ± 0.28 |
2.31 ± 0.08 |
2.74 ± 0.13 |
3.13 ± 0.14 |
Table 1: Gender distribution and
body weight (BW) (mean ± SD)
Measurement of various wall thicknesses in diastole was comparable across
the groups. The mean RVAWd was 3.39 ±
0.67 mm in the study with groups A, B and C having diastolic thickness of 3.64
± 0.57, 3.58 ± 0.58 and 3.13 ± 0.71 mm respectively. Coming to the IVSd as
measured in our study, Groups A, B and C revealed septal thickness of 3.51 ±
0.43, 3.59 ± 0.36 and 3.32 ± 0.55 mm respectively, with the overall mean in the
study being 3.47± 0.47 mm. Similarly, the mean LVPWd in the study was 3.12 ±
0.49 mm, with the Groups A, B and C showing post wall thickness of 2.98 ± 0.13,
3.25 ± 0.51 and 3.05 ± 0.49 mm respectively. Statistically significant
differences between mean values of RVAWd were observed between groups B and C,
while the difference was significant between groups A and B as also between B
and C when IVSd was considered (Table 2, Fig 1).
|
RVAWd (mm) |
IVSd (mm) |
LVPWd (mm) |
|
Total (n = 99) |
3.39 ± 0.67 |
3.47± 0.47 |
3.12 ± 0.49 |
|
Group A (n= 8) |
3.64 ± 0.57 |
3.51 ± 0.43 |
2.98 ± 0.13 |
|
Group B (n = 49) |
3.58 ± 0.58 |
3.59 ± 0.36 |
3.25 ± 0.51 |
|
Group C (n = 42) |
3.13 ± 0.71 |
3.32 ± 0.55 |
3.05 ± 0.49 |
|
A, B |
Unpaired t, df |
1.1232, 55 |
14.7565, 55 |
1.4791, 55 |
p value |
0.2662 |
0.0001 |
0.1448 |
|
B, C |
Unpaired t, df |
3.3273, 89 |
2.8069, 89 |
1.8989, 89 |
p value |
0.0013 |
0.0061 |
0.0608 |
|
A, C |
Unpaired t, df |
1.9278, 55 |
0.9220, 48 |
0.3983, 48 |
p value |
0.0590 |
0.3611 |
0.6922 |
Table 2: Subgroup analysis of
RVAWd (right ventricular anterior wall diastole), IVSd (intraventricular septum
thickness in diastole) and LVPWd (left ventricular posterior wall thickness in
diastole) (mean ± SD)
Fig 1: Distribution of mean BW
(body weight, in kg), RVAWd (right ventricular anterior wall diastole), IVSd
(intraventricular septum thickness in diastole) and LVPWd (left ventricular
posterior wall thickness in diastole), in mm.
Subsequently, we
analyzed the data for cavity size in our study population. The mean RVDd in the study was 10.96 ±
1.19 mm while this value was 11.04 ± 1.04, 11.12 ± 1.25 and 10.75 ± 1.13 mm in
the Groups A, B and C respectively. LVEDd and LVEDs was 14.95 ± 1.68 and 9.76 ±
1.65 mm in the study, 13.06 ± 1.23 and 8.09 ± 1.12 mm in Group A, 14.9 ± 1.83
and 9.53 ± 1.74 mm in Group B, and 15.37 ± 1.3 and 10.34 ± 1.32 mm in Group C.
A rising trend with increasing body weight was evident in these LV
measurements. However, the analysis of LAD in study population and Groups A, B
and C revealed values of 10.09 ± 1.47, 9.5 ± 0.76, 10.38 ± 1.41 and 9.86 ± 1.59
mm respectively, defying any corroboration with body weight. Statistically
different mean values were observed for LVEDd between Groups A and B and between A and
C. Considering LVESd, the means were
statistically different between Groups A and B, B and C and between A and C (Table
3, Fig 2).
Further, the pulmonary
and aortic valve diameters at the level of the semilunar valves were analyzed.
The mean PAD was 8.09 ±
1.31, 8.15 ± 0.57, 8.17 ± 1.37 and 7.99 ± 1.34 mm for the study population and
Groups A, B and C respectively. Similarly, the mean AOD was 8.22 ± 1.01, 8.26 ±
0.67, 8.36 ± 1.13 and 8.04 ± 0.90 mm for the study population and Groups A, B
and C respectively. Neither of these parameters had any correlation with the
body weight. The mean FS was 37.14 ± 4.14%, 38 ± 6.16%, 37.65 ± 4.65% and 36.38
± 2.84% and the mean EF was 71.21 ± 5.37%, 71.63 ± 7.96%, 71.65 ± 5.92% and
70.62 ± 4.04% for the study population and
|
RVDd (mm) |
LVEDd (mm) |
LVESd (mm) |
LAD (mm) |
|
Total (n = 99) |
10.96 ± 1.19 |
14.95 ± 1.68 |
9.76 ± 1.65 |
10.09 ± 1.47 |
|
Group A (n= 8) |
11.04 ± 1.04 |
13.06 ± 1.23 |
8.09 ± 1.12 |
9.5 ± 0.76 |
|
Group B (n = 49) |
11.12 ± 1.25 |
14.9 ± 1.83 |
9.53 ± 1.74 |
10.38 ± 1.41 |
|
Group C (n = 42) |
10.75 ± 1.13 |
15.37 ± 1.3 |
10.34 ± 1.32 |
9.86 ± 1.59 |
|
A, B |
Unpaired t, df |
0.1712, 55 |
2.7339, 55 |
2.2560, 55 |
1.7160, 55 |
p value |
0.8647 |
0.0084 |
0.0281 |
0.0918 |
|
B, C |
Unpaired t, df |
1.4709, 89 |
1.3903, 89 |
2.4683, 89 |
1.6534, 89 |
p value |
0.1448 |
0.1679 |
0.0155 |
0.1018 |
|
A, C |
Unpaired t, df |
0.6728, 48 |
4.6419, 48 |
4.5118, 48 |
0.6230, 48 |
p value |
0.5043 |
0.0001 |
0.0001 |
0.5362 |
Table 3:
Subgroup analysis of RVDd (right ventricular diameter in
diastole), LVEDd (left ventricular end diastolic diameter), LVESd (left
ventricular end systolic diameter) and LAD (left atrial diameter) (mean ± SD)
Fig
2: Distribution of mean RVDd (right ventricular diameter in
diastole), LVEDd (left ventricular end diastolic diameter), LVESd (left
ventricular end systolic diameter) and LAD (left atrial diameter), in mm.
Groups A, B and C respectively (Table 4, Fig 3 and 4). The FS
appeared to have an inverse correlation with body weight, but no such trend was
evident when analyzing the EF. The mean values of PAD, AOD, FS and EF were not
statistically different when sub-group analysis was performed with unpaired t
test.
|
PAD (mm) |
AOD (mm) |
FS (%) |
EF (%) |
|
Total (n = 99) |
8.09 ± 1.31 |
8.22 ± 1.01 |
37.14 ± 4.14 |
71.21 ± 5.37 |
|
Group A (n= 8) |
8.15 ± 0.57 |
8.26 ± 0.67 |
38 ± 6.16 |
71.63 ± 7.96 |
|
Group B (n = 49) |
8.17 ± 1.37 |
8.36 ± 1.13 |
37.65 ± 4.65 |
71.65 ± 5.92 |
|
Group C (n = 42) |
7.99 ± 1.34 |
8.04 ± 0.90 |
36.38 ± 2.84 |
70.62 ± 4.04 |
|
A, B |
Unpaired t, df |
0.0405, 55 |
0.2423, 55 |
0.1885, 55 |
0.0084, 55 |
p value |
0.9679 |
0.8095 |
0.8511 |
0.9933 |
|
B, C |
Unpaired t, df |
0.6311, 89 |
1.4768, 89 |
1.5402, 89 |
0.9529, 89 |
p value |
0.5296 |
0.1433 |
0.1271 |
0.3432 |
|
A, C |
Unpaired t, df |
0.3299, 48 |
0.6553, 48 |
1.1915, 48 |
0.5438, 48 |
p value |
0.7429 |
0.5154 |
0.2393 |
0.5891 |
Table 4: Subgroup analysis of PAD
(pulmonary artery diameter), AOD (aortic root diameter), FS (fractional
shortening) and EF (ejection fraction) (mean ± SD)
Fig 3: Distribution of mean PAD (pulmonary artery diameter) and AOD (aortic root diameter), in mm.
Fig 4: Distribution of mean FS (fractional shortening) and EF (ejection fraction).
The distribution of the study parameters were analyzed as percentiles and
tabulated. The percentile values
(5th, 10th, 25th, 50th, 75th, 90th, and 95th centiles) for all echocardiographic
parameters documented in this study were documented for future reference (Table 5).
|
Percentiles |
||||||
|
5th |
10th |
25th |
50th |
75th |
90th |
95th |
RVAWd (mm) |
2.205 |
2.410 |
3.000 |
3.400 |
3.800 |
4.200 |
4.490 |
RVDd (mm) |
9.000 |
9.200 |
9.850 |
11.200 |
11.975 |
12.400 |
12.700 |
IVSd (mm) |
2.400 |
3.000 |
3.225 |
3.500 |
3.800 |
4.100 |
4.100 |
LVEDd (mm) |
11.310 |
13.310 |
14.100 |
14.850 |
16.000 |
17.090 |
17.785 |
LVESd (mm) |
7.105 |
7.330 |
8.500 |
9.550 |
11.100 |
11.790 |
12.795 |
LVPWd (mm) |
2.40 |
2.42 |
2.80 |
3.00 |
3.48 |
3.80 |
4.10 |
PAD (mm) |
5.820 |
6.400 |
7.200 |
8.000 |
9.100 |
9.400 |
9.690 |
AOD (mm) |
6.500 |
7.100 |
7.350 |
8.200 |
9.000 |
9.300 |
10.295 |
LAD (mm) |
7.330 |
8.400 |
9.200 |
10.100 |
11.000 |
11.790 |
12.000 |
FS (%) |
31.00 |
32.00 |
35.00 |
37.00 |
39.00 |
42.00 |
45.00 |
EF (%) |
64.00 |
65.00 |
68.00 |
71.00 |
75.00 |
76.00 |
80.00 |
Table 5: Percentile values of the echocardiographic measurements (n = 99)
DISCUSSION
The echocardiogram forms the cornerstone for
pediatric cardiac evaluation, an important aspect of which is a quantification
of cardiac structure in terms of dimensions. The dimensions of a child’s
cardiac structure are affected by his or her hemodynamics and somatic growth11.
Our study observed standard echocardiographic measures in healthy term newborns
in Eastern India. There have been several other publications on this subject
from across the globe but very little similar documentation from our part of
the world.
Eleven parameters such
as right ventricular anterior wall thickness at end diastole (RVAWd), right
ventricular end diastolic dimension (RVDD) at tricuspid annulus, thickness of the interventricular septum at
end diastole (IVSd), left ventricular dimension at end diastole (LVEDD), left ventricular dimension at end systole (LVESD), left ventricular
posterior wall thickness at end diastole (LVPWd), pulmonary and aortic diameter at the level of
semilunar valve(PAD and AOD), left atrial diameter (LAD), fractional shortening
(FS) and ejection fraction (EF) were recorded for each subject.
The measurements of
cardiac structures and their comparison with nomograms are essential for
preoperative planning for most congenital heart defects12. A study comprising 2000 subjects in Europe
where newborn babies had larger internal left ventricular diameter both during
diastole and systole compared to that of the subjects of present study13.
The IVS and LVPWd in our study were thinner compared to those of European
newborn babies. Dimension of great vessels were smaller in our study than that
of the European newborn babies. The mean right ventricular anterior wall
thickness was found to be more in our subjects and the right ventricular
internal diameter was also found to be more in the present study compared to
those in European newborn. Mean left atrial diameter was found to be smaller in
our newborn babies than that of European newborns. The mean values of cardiac
dimensions in Indian newborns were found to be different from European newborn.
These differences indicate that cardiac dimensions have racial differences and
Western data cannot be extrapolated to fit the Indian pediatric cardiology
nomograms.
Z‑Scores are essential
to monitor the disease progression for the management of various acquired heart
diseases such as Kawasaki disease or rheumatic heart disease14. Major pediatric cardiac centers across the
world have developed their own nomograms15. The Z scores of cardiac
structures of the Indian pediatric population remains a challenge. An Indian
study from Ajmer, Rajasthan and Mohali, Punjab included the population between
4 and 15 years of age16. A
study from Maharashtra published in 2018 included individuals aged 0 days to 16
years17. Our study is possibly the first publication from this
subcontinent with exclusive focus on the first week of life. However, larger
data bases and more representation from various social and economic backgrounds
will provide more robust data in future.
LIMITATIONS
This study was
conducted at Eastern India and failed to include subjects from different ethnic
origins. However, this may paradoxically result in a strength of the study,
because different racial compositions in a study group may present a bias when
interpreting data. Moreover, the use of a homogeneous cohort makes it possible
to derive normal values for a specific population and to compare these data
with those from populations composed of different races and ethnicity.
CONCLUSIONS
This observational
study concludes that Indian pediatric cardiac normative values are different
from those established from Western experiences. Few parameters like RVAWd, IVSd, LVEDd and LVEDs have significant correlation with infant body weight. We
further establish that all cardiac structural parameters of neonates do not
corroborate with their body weight in a linear manner. Moreover, our literature
search concludes that data on this subject is virtually non-existent from our
part of the world. South East Asian populations differ from those of European
descent and separate echocardiographic norms are needed from our part of the
world.
REFERENCES