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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 4, July/August 2018
AFRICA
247
Transcatheter PDA closure was undertaken following
standardised procedures, described in full elsewhere.
8
In brief,
a descending aortogram in the lateral position was performed
at the start of each catheterisation in order to measure
the dimensions of the PDA. This was done to prevent any
interference with the PDA that may have caused constriction
and inaccurate measurements.
A full diagnostic catheterisation was performed in all
patients prior to attempted PDA occlusion; the shunt and
pulmonary vascular resistance were calculated. The narrowest
point and ampulla were routinely measured and these factors
were used to select an appropriate device. With experience, and
particularly for Amplatzer™ devices, additional measurements
were added. These included the length of duct and diameter of
the aorta just proximal to the duct (in smaller children), due to
concerns about possible aortic obstruction.
Selection of the size of Amplatzer™ device was based on the
manufacturer’s recommendation of at least 2 mm greater than
the narrowest point,
14
but other factors were also considered
in device selection, including PDA shape, ampulla size and the
size of the aorta. For sizing of the coils, the narrowest point
was also taken into account and a coil with a diameter twice the
narrowest measurement was chosen. Coils also have a variable
number of loops, the number of which depends on the space
available in the ampulla of the particular PDA.
15
Amplatzer™ devices were routinely delivered from the
pulmonary side, except in a patient who had an interrupted
inferior vena cava, where an Amplatzer™ duct occluder 2 was
placed from the aortic side. The majority of coils were delivered
from the aortic side; however, if multiple coils were placed in
a duct, they were sometimes placed from the pulmonary side,
or even using a combination of aortic and pulmonary routes.
Following device placement and prior to release, we
performed a number of checks to assess whether the device
was correctly placed. A repeat descending aortogram was
performed. Pressure gradients in the aorta across the newly
closed PDA were measured to ensure there was no significant
obstruction to flow in the descending aorta. Once it was
ascertained that the device was correctly positioned, it was
released. A repeat angiogram was done and a gradient was
measured between the ascending and descending aorta to
assess any change in position during release that may result
in a coarctation. Following the procedure, the patients were
observed in the ward until a follow-up echocardiography was
done and, provided there were no complications, discharged 24
to 48 hours later.
Patient characteristics consisted of age, gender and
anthropometric variables. Clinical details, haemodynamic data,
and anatomical details, such as PDA shape and dimensions at
echocardiogram and at angiography were used to describe the
PDA and resultant haemodynamics. To assess the time taken
to close the PDA, the fluoroscopy time for each procedure was
captured, where possible. The shape of each PDA was assessed
angiographically by reviewing each angiogram and classifying
them according to the Krichenko classification (A1-3, B1-3,C1-
3,D,E ).
16
Failure of transcatheter procedure was defined as any
patient requiring a second procedure to effect closure. Early
complete occlusion was defined based on an echocardiogram
done within 48 hours of the procedure.
Statistical analysis
Data with a normal distribution were described using means
and standard deviations, or medians and interquartile ranges for
non-normal data. The
χ
2
test was used to compare categorical
variables, such as patient characteristics and outcomes between
those treated with a coil or an Amplatzer™ device. Continuous
data were compared using a Student’s
t
-test (normally distributed
data) or Wilcoxon rank sum test (non-normal data).
Results
Over the 15-year study period, 1 254 PDAs were diagnosed,
of which 293 required an intervention to effect closure (23%).
Surgical ligation was performed on 167 children and 139
underwent transcatheter closure.
No differences were detected in the demographics of patients
who had their PDA closed with an Amplatzer™ device and
those who had coiling of their PDA (Table 1). Two-thirds of the
study patients were female and the median age was 1.8 years. The
anthropometric indices between those who had an Amplatzer™
device or coils to close their PDA were similar. The majority
of patients who had a PDA closure weighed more than 6 kg.
Amplatzer™ devices were occasionally used in children under 6
kg, even though the product guidelines recommend use only in
children above this weight.
14
As shown in Table 2, the average PDA size at its narrowest
point was 3.2 mm [standard deviation (SD)
=
1.6 mm]. There was
a difference in the mean size of coiled PDAs (2.6 mm) compared
to those closed with the Amplatzer™ device (4.0 mm). The
majority of PDAs under 2.5 mm were closed with coils and the
PDAs larger than 2.5 mm were more likely to be closed with the
Amplatzer™ device (
p
=
0.005).
Krichenko type A PDAs (conical shaped) dominated,
accounting for 73% of cases, with type E (long, tubular with
narrowed pulmonary end) the next most frequent at 18%. Type
B (short window like) was rare (2% of all patients).
As presented in Table 2, the haemodynamic measurements
of the PDAs showed a significant mean left-to-right shunt
with a Qp:Qs of 2:1 (SD
=
1.2). The mean pulmonary vascular
resistance was 2.1 Woods units (SD
=
1.8), with a pulmonary-
to-systemic pressure ratio of 0.39 (SD
=
0.2). Chest X-rays
documented cardiomegaly in 85% of the patients, with plethoric
lung fields noted on 66% of the X-rays. Several differences were
noted in comparisons between haemodynamic features of PDAs
Table 1. Characteristics of patients who had
transcatheter procedures, by closure device
Variable
Total patients
(
n
=
139)
Coils
(
n
=
101)
Amplatzer™
devices
(
n
=
49)
p
-value
Age, median years (IQR) 1.8 (1–4.5)
1.8 (1.0–4.4) 2.1 (1.1–4.5)
0.47
Gender, % (
n/N
)
0.54
Female
66.2 (92/139) 68.3 (69/101) 63.3 (31/49)
Male
33.8 (47/139) 31.7 (32/101) 36.7 (18/49)
Weight, mean kg (SD)
12.8 (7)
13.1 (8.1)
12.9 (9.6)
<
6 kg, % (
n/N
)
5.4 (7/130)
5.3 (5/95)
4.4 (2/45)
0.87
≥ 6 kg, % (
n/N
)
94.6 (123/130) 94.7 (90/95 95.6 (43/45)
0.84
Height, mean cm (SD)
87.4 (22.9)
87.0 (23)
89.2 (24.3)
0.62
N
varied due to missing data. The total sum of coils and Amplatzer devices
exceeded the number of patients as more than one device was used in some
patients. IQR: inter-quartile range. SD: standard deviation.