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.