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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 3, May/June 2019
152
AFRICA
of full widening of the aortic valve, and the diastolic diameter
(AoDD) was measured at the peak of the QRS complex on the
electrocardiogram. The ASI was calculated from the following
equation:
ASI
=
systolic blood pressure/diastolic blood pressure
____________________________________
(AoSD–AoDD)/AoDD
× 100.
3
For brain natriuretic peptide (BNP) measurement,
blood samples were collected by venepuncture into
ethylenediaminetetraacetic acid (EDTA) tubes within two hours
of assessing the first echocardiogram for all children in the study,
and six months after device closure of the PDA for children
with PDA only. The samples were kept at room temperature and
examined within four hours of sampling.
Blood samples were centrifuged and the plasma was frozen
for one to two days at –70°C. Before the examination, each tube
was shaken a few times to guarantee homogeneity. The BNP
assay is a sandwich immunoassay in which 250 ml EDTA–anti-
coagulated blood or plasma had been added. The triage metre
was used to measure the BNP concentration by detecting a
fluorescent signal that reflected the amount of BNP in the
sample.
4
The upper limit of the normal laboratory reference for
BNP was 30 pg/ml.
4
Cardiovascular catheterisation was performed for the
evaluation of pulmonary artery pressure (PAP) and shunt
measurement. Pulmonary artery hypertension (PAH) was
characterised as PAP
>
25 mmHg.
5
Angiograms were performed
in the standard horizontal view for PDA estimation. The
PDA was crossed from the pulmonary end in all patients. An
Amplatzer delivery sheath (AGA Medical, Plymouth, MN)
was placed in the venous route over an Amplatzer super-stiff
guidewire (Boston Scientific, Natick, MA, USA) and was left in
the descending thoracic aorta.
The device was delivered according to the standard method.
6
The aortogram was performed 10 minutes after withdrawal
to confirm device position and rule out the remaining shunt.
After device placement, echocardiographic examination was
performed to assess the device location and the descending
thoracic aortic and left pulmonary arterial velocity. The ductal
occluder device was withdrawn after eliminating the residual
shunt and obstruction in the aorta and/or left pulmonary artery.
Statistical analysis
Analyses were performed using the Statistical Package for Social
Sciences, version 16.01 for Windows (SPSS Inc, Chicago, IL).
Correlation between aortic stiffness and different parameters was
determined via univariate analysis and correlation coefficients.
Results
At the time of the examination, the mean age in group A was
6.8
±
3.4 months and 70% were female. In group B, the mean age
was 51.1
±
43 months and 83% were female. Demographic data
are shown in Table 1. All study patients with PDA experienced
percutaneous closure with either a device or a coil. In these
children, no other heart deformities were detected.
Follow up was possible for all patients over a period of six
months. During the subsequent period, none of the patients
had any progression in their peak velocities or gradients across
the left pulmonary artery or the aortic isthmus, and no residual
shunt was detected.
There was no significant difference between groups A and B
with regard to duct size, as determined using echocardiography
or during the intervention. The mean PDA measurement in
group A was 4.0
±
0.97 mm, and 4.7
±
1.7 mm in group B (
p
=
0.1). Prior to PDA closure, the ASI was significantly higher
in group B than in group A (
p
<
0.05) (Table 2), and was
significantly higher in both groups than in the control group (
p
<
0.05) (Tables 3, 4). However, the ASI was significantly higher in
group B than in group A at the six-month follow-up assessment
(
p
<
0.05) (Table 2).
Prior to PDA intervention, the LVEF of group B was
significantly lower than that of group A (52.6
±
2.2 vs 59.4
±
5.3%) (
p
<
0.05) (Table 2), and was significantly lower in both
groups than in the control group (66.7
±
3.4) (
p
<
0.05) (Tables 3,
4). After PDA closure, the LVEF improved significantly in both
groups (
p
<
0.05).
In group A, there was no significant difference between
patients and controls regarding LVEF (
p
=
0.6) at the six-month
follow-up assessment (Table 3). It was still significantly lower in
group B than that in control group (
p
<
0.05) at the six-month
assessment (Table 4).
The BNP level was significantly higher in children in group
B than those in group A (
p
<
0.05) prior to PDA closure
(Table 2). However, the BNP level was significantly enhanced
in both groups after PDA closure (
p
<
0.05) and approached
non-significance compared with that in the control group (
p
=
0.9 and 0.5, respectively) (Tables 3, 4).
Table 1. Demographic characteristics of patients with PDA
and the control group
Variables
Patients
(
n
=
60)
Control group
(
n
=
60)
p
-value
Age (months) mean
±
SD
28.9
±
38.0
29.2
±
34.2
0.2
Gender
Male,
n
(%)
25 (42)
20 (33)
0.8
Female,
n
(%)
35 (58)
40 (77)
BWT (kg) mean
±
SD
12.8
±
11.4
11.2
±
4.1
0.3
SBP (mmHg) mean
±
SD
94.8
±
9.4
96
±
8.4
0.4
DBP (mmHg) mean
±
SD
61
±
6.9
62.1
±
6.4
0.3
HR (b/m) mean
±
SD
99
±
12
90
±
11
0.6
p
≤ 0.05 was considered statistically significant; SD: standard deviation; BWT:
body weight; SBP: systolic blood pressure; DBP: diastolic blood pressure; HR
(b/m): heart rate (beats per minute).
Table 2. Comparison between group A and B with regard to ASI, BNP, PAP
and cardiac function before and after PDA closure
Variables
Group A (
n
=
30)
Group B (
n
=
30)
p
-value
p
-value
†
Before
closure After closure
Before
closure
After
closure
ASI, mean
±
SD
6.7
±
2.8 3.8
±
1.4 9.4
±
2.7 6.3
±
2.4
<
0.05
<
0.05
LVEF (%)
mean
±
SD
59.4
±
5.3 66
±
4.2 52.6
±
2.2 58
±
2.5
<
0.05
<
0.05
LVEDD (mm)
mean
±
SD
3.4
±
0.85 3
±
0.82 4.1
±
0.98 3.7
±
0.93
<
0.05
<
0.05
BNP, mean
±
SD
57.7
±
15.1 18.9
±
5
70
±
14.7 20.2
±
6.3
<
0.05 0.3
PAP, mean
±
SD
40.3
±
6.2 23.9
±
4.9 47.6
±
8.1 21.9
±
4.7
<
0.05 0.2
p
: significance between group A and group B before closure,
p
†
: significance
between group A and group B after closure. ASI: arterial stiffness index; LVEF:
left ventricular ejection fraction; LVEDD: left ventricular end-diastolic diameter;
BNP: brain natriuretic peptide; PAP: pulmonary artery pressure.