Cardiovascular Journal of Africa: Vol 31 No 1 (January/February 2020)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 1, January/February 2020 38 AFRICA
possible to manoeuvre the device so that it was pulled into the
duct, and the central lobe was snuggly placed over the narrowest
diameter of the PDA. However, further research is needed into
ductal length and ductal closure outcomes using the ADO II AS,
as there is a lack of data in the literature in this regard.
In this study, we also examined the aortic diameter and ductal
closure outcomes. None of the study patients were documented
to have device-induced coarctation, which has previously been
defined by Kang et al. as a descending aorta catheterisation
gradient of more than 10 mmHg or a velocity of > 2 m/s during
echochardiography.18 In their cohort, there were 10 patients with
device-induced coarctation of the aorta immediately following
cardiac catheterisation.
On follow up, the velocity was reported to have normalised in
seven patients and there was only one patient that remained with
a high velocity but without a diastolic tail. In the remaining two
patients, the follow-up data were incomplete. This finding may
imply that device-induced coarctation of the aorta may resolve
with vessel growth and somatic growth of the patient.
One advantage of this device is that it can be delivered using
a delivery sheath of 4–5F. This avoids complications, such
as vascular access and injury. To reduce the risk of vascular
injury, we utilised a 0.014-inch wire and scalp vein needle
(Butterfly) sets for vascular access, particularly in preterm
infants, although this approach has not been reported in the
literature. Another advantage of the ADO II AS device is that it
can be delivered in both anterograde (pulmonic) and retrograde
(arterial) approaches. The anterograde approach is usually
the preferred approach in lower-weight infants as it eliminates
femoral arterial injury if this access is avoided.40 Therefore the
majority of our patients (about 70%) had closure of the PDA
through the pulmonic route.
Regarding radiation exposure, our patients were exposed to
higher doses of radiation than reported by Kobayashi et al.35
Their reference value at the 90th percentile was 130 µGym2/kg
for percutaneous PDA closure in their multicentre study. This
finding suggests that in our unit, we need to be more meticulous
and limit radiation exposure to the absolute minimum during
cardiac catheterisation.
Complications reported in our cohort have been documented
elsewhere when dealing with lower-weight infants, particularly
those that are premature.18,37-40 The one common complication in
this group was the need for blood transfusion.18,40 However, this
complication was well managed in our cohort.
In addition, there were three embolisations in this cohort
owing to the under-sizing of the device. Our 5% embolisation
rate is comparable to that reported by Kang et al. in their study
of 408 low-weight patients.18 With regard to embolisation of the
device, the learning curve in the use of this device in our unit was
a contributing factor. All the embolised devices were retrieved
percutaneously, two ducts were closed with larger alternative
devices, and one duct was surgically closed.
When it comes to outcomes, there were no medium- and
long-term complications noted in our study. In particular, there
was no LPA stenosis. To prevent LPA stenosis when using the
ADO II AS device, we positioned the device in such a way that
the pulmonary disk was against the roof of the main pulmonary
artery, with some tenting of the disk. In addition, the central
lobe and in some patients the aortic disk of the device were
placed in the duct (Fig. 2B).
With regard to limitations of the study, a clinical trial
comparing percutaneous PDA closure to surgical closure in
lower-weight infants would be a more robust study. A recent
study, which compared surgical ligation to percutaneous ductal
closure using this device, has shown that percutaneous closure
is feasible and safe. 42 However, patient numbers that underwent
percutaneous closure were very small in this study (25 subjects).
Conclusion
The Amplatzer Duct Occluder type two additional sizes is
practical, effective and has few complications in patients less
than 6 kg with a duct that is less than 4 mm in diameter, even
though the infant is from a from a LMIC with reduced resources,
such as South Africa. Owing to the small retention disks of the
device compared to the central lobe, the device may be deployed
in ducts that are longer than 8 mm, and there is a low risk for
device-induced coarctation of the aorta. More studies are needed
to examine the safety and efficacy of this device in ductal closure
in patients weighing less than 1 000 g.
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