Abstract
Background : Partial anomalous pulmonary venous connection (PAPVC)
occurs when at least one pulmonary vein drains into the right atrium or
its tributaries rather than the left atrium, most commonly connecting
with the superior vena cava (SVC). The Warden procedure involves
transecting the SVC proximal to the uppermost connection of the
pulmonary vein followed by proximal SVC reattachment to the right atrial
appendage. However, descending thoracic aortic homograft replacement for
SVC translocation has recently been introduced as a modified technique.
Aims : This commentary aims to discuss the recent study by Said
and colleagues who reported their experiences with 6 PAPVC cases
undergoing a modified Warden procedure using thoracic aortic homograft
SVC translocation.
Methods : A comprehensive literature search was performed using
multiple electronic databases in order to collate the relevant research
evidence.
Results : The Warden procedure is associated with a 10% incidence
of SVC obstruction with many requiring reintervention. Meanwhile, using
the aortic homograft for SVC translocation, Said et al. observed no SVC
obstructions. In addition, this modified technique does not require
anticoagulation and has demonstrated an improvement in long-term SVC
patency. Nevertheless, it can be considered an expensive procedure.
Moreover, since the thoracic aortic homograft utilised is biological
tissue, only long-term follow-up will determine whether calcification
and graft degeneration is an issue.
Conclusion : It can be concluded that the modified Warden
procedure is a safe and effective method to reconstruct the systemic
venous drainage into the right atrium when a direct anastomosis under
tension might be prone to re-stenosis.
Partial anomalous pulmonary venous connection (PAPVC) occurs when at
least one pulmonary vein drains into the right atrium or its tributaries
rather than the left atrium. The PAPVC most commonly connects with the
superior vena cava (SVC) and is often associated with an atrial septal
defect. This persistent connection leads to a left to right shunt where
some of the output from the right ventricle continuously recirculates
oxygenated blood without entering the systemic circulation. This may, in
time, lead to an increase in pulmonary artery pressure resulting in
hypertension which is the reason for early stage intervention. The
Warden procedure, first described in 1984, involves transection of the
SVC proximal to the uppermost connection of the pulmonary vein. The
proximal SVC is then reattached to the right atrial appendage (RAA) with
the distal aspect draining blood to the left atrium (1).
We read with great interest the recent original article by Said et al.
who reported their experiences with 6 cases undergoing thoracic aortic
homograft replacement for SVC translocation as a modification of the
Warden procedure in PAPVC (2). This series of 6 patients (5 female: 1
male) with a mean age of 19 years all had a significant left to right
cardiac shunt. To avoid mobilisation of the RAA and the possibility of
re-stenosis and SVC occlusion a modified technique was adopted where an
aortic homograft is used as a conduit from the divided cranial SVC to
the right atrium. The follow-up period was 12 months, during which there
was no evidence of SVC stenosis observed.
Other large series performing the Warden procedure had follow-up for a
mean (range) of 5 years (1 month to 16 years). All the 30 patients
identified who underwent this procedure were less than 24 months old and
7kg in weight. Direct reimplantation of the SVC into the RAA was
performed, however, 3 patients (10%) developed SVC stenosis requiring
reintervention. Cavo-atrial re-stenosis occurred in less than 12 days in
the first two patients and by 11 months in the third (3). To reduce
re-stenosis rates it is important all the muscular trabeculae within the
appendage are removed under direct vision prior to any anastomosis being
performed. Furthermore, accurate imaging and assessment of the anatomy
of the PAPVC is crucial in planning any drainage procedure. Also, a
differentiation must be made as to whether the level of the PAPVC is low
or high. A low insertion is classified as close to the cavo-atrial
junction, whilst high is considered to be near to the azygous vein
termination. Direct surgery at the cavo-atrial junction may also cause
trauma to the sinus node with possible onset of atrial fibrillation (4).
For this reason DeLeon modified the procedure and performed two
incisions: one on the distal SVC and the other on the crest of the RAA
avoiding the sinus node (4).
The limitations of the Warden procedure for high anomalous PV drainage
is the surgical length created after the SVC is divided. The cranial
aspect of the SVC can be difficult to mobilise caudally and may require
the azygous vein to be ligated in order that a tension free anastomosis
can be performed to the RAA. Others have also stressed on the importance
of adequate tissue mobilisation in order to reduce re-stenosis and
sinus-node dysfunction rates (5). When the length between the cranial
SVC to the RAA or atrium is considered excessive, or to avoid inordinate
RAA mobilisation, there have been reports of manufactured ringed
interposition grafts being used. This has the disadvantage of requiring
long-term anticoagulation to maintain patency optimum patency rates in
the slow flow venous system (6). On the other hand, others have reported
the use of biological grafts, such as pedicled autologous pericardial
flaps, as a conduit between the RAA and the SVC (7). The use of aortic
homografts as a conduit in a modified Warden procedure has been
described by others but invariably are limited to case reports with very
few patients and short follow-up periods (8).
The modified technique described by Said et al may be considered
expensive, however, one advantage is there is no need for
anticoagulation as only long-term antiplatelet therapy is required.
Furthermore, there is an excellent size match with the SVC cranially in
addition to the ability to distend and increase in length which, in
turn, improves long-term patency. The authors have proposed a safe and
tension-free procedure to reconstruct the systemic venous drainage into
the right atrium when a direct anastomosis under tension might be prone
to develop re-stenosis. Since biological tissue in the form of an aortic
homograft is utilised, only long-term follow-up will determine whether
calcification and graft degeneration is an issue. It can be concluded
that Said et al. have provided a useful additional method to modify and
possibly improve long-term results of the Warden procedure for PAPVC
(2).