Discussion
In patients with PA, VSD and SPCAs several strategies are reported
during the last 30 years indicating the challenging management [2,
13-16]. In 1989 we choose to follow one strategy for all consecutive
patients and have sticked to this protocol since then. This allows to
present after 30 years our long term results showing that 81% of the
patients surviving after unifocalization are suitable for biventricular
correction with a conduit between RVOT and the unifocalized pulmonary
artery system. We consider this an adequate success rate in the complete
and unselected cohort of these complex patients also compared to other
series and strategies [2, 14, 17-21]. The use of a central
aorto-pulmonary shunt to promote growth in diminutive pulmonary arteries
is still subject of several studies [15, 22]. In a preliminary
report of our first six cases we concluded that central shunts did not
preclude the need for unifocalization with no significant growth of the
pulmonary arteries [23].
Over the years of working with the staged approach several aspects
evolved. We reduced the diameter of the MBT shunts during our
experience. We learned to avoid as much tissue of the SPCAs as possible.
Closure of unnecessary collateral arteries and intrapulmonary
anastomoses are two factors to prevent later problems with stenosis or
dilatation. Nevertheless these problems do occur due to the histological
characteristics of the collateral arteries [10]. During follow up
several dilatation and stenting procedures may be necessary and in some
cases adequate relieve of stenosis cannot be maintained at the long
term.
After our initial experience with central shunts with disappointing
results with regard to growth and increase of the pulmonary artery size
[23] we use these procedure for diminutive pulmonary arteries to
promote outgrowth as mentioned by other authors [24, 25]. In our
opinion rehabilitation of the pulmonary artery as promoted by several
authors [15, 26, 27] may be useful, but still does not preclude
further unifocalization in most of our cases.
During long term follow up allograft degeneration and replacement
occurred as expected. An explanation for this could be that these
allografts are placed in a more extra-anatomic position and in patients
with a younger mean age at correction. Also elevated right ventricular
pressures, probably due to an abnormal pulmonary vascular bed, can
contribute to this degeneration process [28].
Considering the complex patient group we realize that there life
expectancy is below normal, but we lack long term data comparable with
other with right-sided allograft placement i.e. tetralogy of Fallot
[29].
A limitation of this study is the relatively small group of patients.
However we treated all cases consecutively and without selection during
a long period of time with the same strategy by the same team. Because
of these numbers we did not perform sub analysis for example for
patients operated later on after our learning curve.
In conclusion staged repair of PA, VSD and SPCAs offers an adequate
solution for most patients with a high correction rate and low operative
mortality. Surgical or catheter interventions are necessary during
follow up for pulmonary artery stenosis and allograft degeneration. Long
term survival seems to be diminished.
We continue to follow these patients to achieve more data on long term
outcome. The function of the right ventricle is a point of concern
Echocardiography and cardiac MRI showed moderate and severe dilatation
of the right ventricle (75%) and impairment of the function in 25% of
the patients. Additional genetic abnormalities, in particular 22q11
deletion seems to be risk factor for adverse outcome[30].
Another limitation is the retrospective collection of data which
resulting in incomplete data on exercise testing and quality of life
studies. We are also looking forward to compare our long term results to
those of other strategies, to make better comparison between different
methods for this challenging patient group.