Conclusions
In this retrospective study we compared the early, late and overall
occurrence of arrhythmias in adult and pediatric patients who underwent
surgical repair of PAPVC + sinus venosus ASD over a thirty-years period.
Nearly all patients were treated by means of single-patch and
double-patch surgical technique (42.6% and 56.5% respectively). The
incidence of transient and permanent arrhythmias in relation to the age
at repair and to the type of surgical procedure is the main endpoint of
our analysis. When comparing the surgical techniques, we did not find a
significant difference between the 2 groups in regard to overall
incidence rate of arrhythmias at any point of follow-up. In particular,
the presence of EAR, intended as a direct consequence of an iatrogenic
injury to the SA node, was not different between double- and
single-patch repair groups. This is consistent with the work of Said et
al (12), who did not observe a significant difference in the incidence
number of SND and supraventricular arrhythmias among 124 patients
treated by single or double patch technique or Warden procedure. On the
contrary, other institutions reported different results in terms of
incidence of postoperative arrhythmias between surgical groups, with a
significantly higher frequency of non-sinus rhythm in patients who
underwent double-patch repair. Stewart et al (13) showed a 55%
incidence of supraventricular arrhythmias in the double-patch group,
compared to significant lower incidence in single-patch and Warden
groups (24% and 0%, respectively). Similarly, a recent paper by
Jaschinski et al (14) displayed analogous features, where patients
treated with the double-patch technique had a significantly higher
incidence of non-sinus rhythm.
The reason behind the higher risk of iatrogenic SA node injury using the
double-patch repair technique lies intuitively in the need for a more
extensive superior cavo-atrial incision, which is a peculiar feature of
this operation (7). In this surgical scenario, the possibility of
damaging the SA node is certainly increased than in other procedures
where the surgeon remains far away from this area, such as in the Warden
and in the double-decker operations (10;15).
The SA node is the natural pacemaker of the heart. It is a complex
sub-epicardial structure located in the antero-lateral aspect of the
superior cavo-atrial junction. Its yellowish appearance on the external
surface should allow the surgeon to identify and avoid it when carrying
out the cavo-atrial incision. Nevertheless, anatomic variations of its
extension and blood supply are common, thus explaining the high rate of
postoperative SA node dysfunction.
In our analysis, we found a significantly higher incidence of SA node
impairment in the pediatric population, and we acknowledge this may be
of great importance. Perioperative incidence (early-onset) of EAR had a
non-statistically significant increased trend in children compared to
the adults, but when considering the long-term follow-up this difference
becomes statistically significant, as EAR occurred overall in 32% of
pediatric cases vs 8% of adult cases (p=0.02). In our opinion, this is
likely to be the result of a much more common iatrogenic injury of the
SA node in smaller patients, no matter which surgical technique is
utilized. In young children indeed, the presence of small anatomical
structures forces the surgeon to perform the cavo-atrial incision very
close to the conduction system, increasing the risk of damaging the SA
node. In adults instead, restoration of sinus rhythm over time occurred
more frequently, perhaps because the larger dimension of the superior
cavo-atrial junction and its distance from the SA node, makes the
incision of cavo-atrial junction less likely to affect the conduction
system. Conversely though, arrhythmias causing hemodynamic consequences
were a significantly more common complication in adult patients, both in
the early post-operative period and long-term. This is probably due, at
least in part, to the long-standing volume overload and to the
consequent distention of the right atrial fibres.
To our knowledge, this is the first study to analyze the different
timing and pattern of post-operative arrhythmias in pediatric and adult
patients undergoing PAPVC + sinus venosus ASD repair. We strongly
believe that the significantly higher incidence of permanent SND with
junctional or atrial ectopic escape among the pediatric patients could
be related to the limited space between SA node area and cavo-atrial
incision. In single-patch and especially in double-patch technique, a
surgical incision of variable extension is performed across the
cavo-atrial junction very close to the SA node (Figure 3). When the
distance between the PV connection plan and the SA node is relatively
wide, as in adult patients, the chance to interfere with the SA node
activity is fairly minimal. On the other hand, when this distance is
shorter, such as in pediatric patients, the probability of SA node
dysfunction is increased. Therefore, the choice of surgical technique
may play a crucial role to avoid the occurrence of iatrogenic SA node
injuries causing certain arrhythmias, especially in the pediatric
population. As initially mentioned, the Warden procedure is the most
reproducible option to avoid surgical damage to the SA node, and there
is nowadays increasing evidence of its superiority in terms of
postoperative freedom from SND and EAR, compared to single- and
double-patch procedures (9;10).
If results are confirmed by further larger studies, surgical procedures
that completely avoid invasiveness and trauma at the level of superior
cavo-atrial junction should probably be preferred in pediatric patients.
Among the available techniques, although not free from other
complications, the Warden procedure could be considered the safest and
most reproducible (15). In our study population only one patient
underwent the Warden procedure, and this was due exclusively to the
surgeon’s preference. In view of our results and new insights, we
believe that multicenter randomized prospective studies are needed to
compare the arrhythmogenic effects of the Warden and double-patch
techniques in children. In adult patients, in whom Warden procedure may
present technical challenges in view of a lower mobility of the SVC, the
double-patch technique will remain our preferred approach. Further
studies are needed to specifically investigate the impact of EAR during
growth in the pediatric population and to validate the protocol that
will currently advocate at our institution.
The retrospective nature and the relatively small sample size are the
main limitations of the present study. The bias may potentially be less
if we take into account the consistency of a single center and the
homogeneous surgical strategy, nevertheless larger and prospective
studies are certainly warranted.
We also acknowledge that the follow-up was not complete for all
patients, as 45 of them were lost at follow-up and were therefore
excluded from the analysis. Nonetheless, their demographic and surgical
characteristics were not dissimilar to those of patients who completed
the follow-up.
The surgical management of PAPVC with sinus venosus ASD, requiring
superior cavo-atrial incision, is associated with high incidence of
postoperative SND (16). In our experience, this finding has been
significantly higher among pediatric patients, probably due to the
smaller cavo-atrial junction size and the subsequent close proximity of
the SA node to the PV connection site and surgical incision, hence
increasing the risk of iatrogenic damage. Surgical techniques which
avoid manipulation of the superior cavo-atrial junction should therefore
be preferred in pediatric patients.