Aims and objective:Arterial Switch Operation (ASO) beyond the first month of life has been considered at high risk for complete TGA with intact inter ventricular septum (IVS) because of concern over the ability of LV to support the systemic circulation.Ten infants underwent single stage ASO beyond 1 month of life and responsible factors for LV preparedness were identified.
Patient and method: Prospective observational study ,October 2006-October 2008,n=10
Age 30 -150 days (median 64) weight 3.0-4.6 Kg (median 3.4) Oxygen Saturation 40-55%.Echocardiography was done in all while cardiac catheterization was done in two infants and CT angiography in one to look for the cause of LV preparedness. LV preparedness was defined by mass, LV posterior wall (LVPW) and its comparison to right ventricle (RV) free wall. Patient with large patent ductus arteriosus , ventricular septal defect or LV outflow tract obstruction were excluded.
Results: Echocardiography parameters were:LV mass 30-36 gm/m2, LVPW 3.2mm-3.4mm. RV free wall 3.6 – 3.9 mm.
Median ICU stay was 6 days (5 – 12 days),no operative mortality.
Factors for trained LV identified are:
1. Aortopulmonary collaterals (n=4,coiling- 3, surgical ligation -1)
2. Unusual origin of Pulmonary artery (PA) (flower vase appearance) leading to physiological branch PA stenosis (n=4).
3. No anatomical cause could be identified in 2, severe hypoxia with polycythemia was considered as the responsible factor.

Conclusion:Complete TGAIVS of late referrals can benefit from single stage ASO even beyond 1 month after carefully screening the LV preparedness parameter and factor responsible for it.