Discussion
An un-operated d-TGA case with secundum type ASD survived to late
adulthood is very rare. According to the previous data, only three cases
were reported with the longest survival of un-operated d-TGA (3-5). None
of these cases were accompanied by dextrocardia, situs inversus, PH, and
PA aneurysm at the same time. The incidence of patients with
simultaneous d-TGA, dextrocardia and situs inversus is unknown (6).
In the presence of large ASD, sufficient oxygenated blood for systemic
circulation and sufficient pulmonary blood flow for pulmonary
circulation are provided during ventricular diastole and systole. That
is the reason why our un-operated patient survives into late adulthood.
However, prolonged exposure of the pulmonary circulation to high blood
pressure and oxygen-free blood flow of the systemic circulation caused
PH by causing an increase in pulmonary blood flow and pulmonary
vasoconstriction due to hypoxia (7). Although PA dilatation is generally
seen in patients with PH, it is rare for the PA diameter to be above 40
mm. PA aneurysm of this width can cause life-threatening complications
such as dissection, rupture or lung compression.
Another issue to be emphasized is the ability of the right ventricle
(RV), which is morphologically right but functionally left, to adapt to
the systemic circulation in long term. Extreme RV hypertrophy may be a
response to remodeling of the RV in the systemic circulation (8).
Eventually, myocardial scarring secondary to chronic cyanosis and
insufficient vascular capacity not to meet the demands of the
hypertrophied ventricle may contributes to ventricular dysfunction. The
greatest chance of our case was that the functional insufficiency of the
systemic ventricle had not developed yet and he did not experience a
life-threatening arrhythmia until this age.
If d-TGA is accompanied by dextrocardia, situs inversus and abnormal
origin of the coronary artery, surgery should be performed by applying a
correct coronary transfer with appropriate modifications to the
technique for a successful outcome in the arterial switch operation
(ASO). These complex and altered anatomy can make the surgery difficult.
We did not consider to include our patient, who lived longer than the
operated patients without any corrective surgery, into a surgical
process that we could not predict consequences, even if it was a
transplant surgery. Because while ASO with the best long-term survival
and functional outcome has a survival rate of> 95% between
15 and 25 years (9), in another study on long-term morbidity and quality
of life of TGA after atrial switch surgery, the 25-year survival rate
has been reported as 78%. (10). We also do not have a literature
support regarding the use of specific therapies for PH. We aimed to
monitor our patient routinely with EKG and Holter in order to detect
possible arrhythmias and follow-up with routine echocardiography to
evaluate ventricular function. We preferred beta blocker, digoxin and
furosemide therapy for their functional class improvement effect, heart
rate and arrhythmia control. We planned to follow up the patient closely
for volume status, hyperviscosity, iron deficiency and microcytosis.
Treatment strategies, complications that may develop, points to be
considered in follow-up, long-term survival rates in d-TGA are
determined by evaluating only patients who underwent surgical approach.
Since there are no large-scale studies and evidence-based data, we
believe that case-based reports will guide the follow-up and treatment
of patients that survive into late adulthood without corrective surgery.