Aorta is anterior and to the right.

Coronaries arise from the aorta.

The two circulations are in parallel.

Usually, there is only a small PFO as communication between the two circulations- hence there is deep cyanosis.

S2 is single as PA is posterior.

No significant murmur is present.

Cardiomegaly- this occurs after PVR falls in the first month- this is due to low PVR causing volume overload to LA and LV.

Cardiac failure- this occurs due to two reasons- (i) volume overload to LV and (ii) poor LV function due to low oxygen content in coronaries and acidosis (acidosis occurs due to systemic hypoxia). HF occurs in the first week of life.

Increased pulmonary vascularity- this occurs when PVR falls during the first month.

RVH- is present in the ECG as RV is supporting the systemic circulation.

Thus, the neonate with deep cyanosis, single S2, no murmur, cardiomegaly and increased pulmonary vascularity on the CXR and RVH in ECG is likely to be having D-TGA.

Less commonly, a large ASD or a large VSD is present- there will not be cyanosis- HF will be present.

VSD + PS- The VSD does not lead to alleviation of cyanosis due to the PS which decreases pulmonary blood flow. The VSD does not lead to cardiac failure due to the PS which decreases pulmonary blood flow. In addition to the RVH, there is LVH also due to the PS- thus BVH is present. Thus there is deep cyanosis without cardiac failure. Due to the low pulmonary blood flow, there is early death.