 Good evening. I'm Dr. Sujata Arvani. I am DMPediatric Cardiology resident from Amrita Hospital, Kochi. I'm presenting Segmental Approach to Cardiac Diagnosis, a prenatal case scenario. This a 25-year-old private-rividal lady referred to us for fetal echo for suspected fetal CHD at 33 weeks of gestation. The pregnancy is a natural conception from a non-consanguinous marriage. No maternal or fetal risk factors were noted and no extra cardiac abnormality detected in the anomaly's scan. We started our examination by determining the cytos of the fetus. The left and right side of the fetus are marked on all the slides. The stomach is on the left and liver is on the right, suggestive of cytosolitis. This is the fourth chamber view which is showing liver cardiac with normal offsetting of the tricuspid valve with two balanced ventricular ventricles with good ventricular function. The fourth chamber color view shows normal, mitral and tricuspid inflows. The puny veins were seen draining to the left atrium and SVC and IVC to the right atrium. The outflow tract view showed a large defect in the interventricular septum and conoventricular region, suggestive of conoventricular VST and the first outflow tract seen overriding the VST. Here the first outflow tract is seen overriding the VST and it is bifurcating, suggesting that it is pulmonary artery and not iota. Once again we can see the first outflow tract which is pulmonary artery as it is bifurcating. Here both outflows are seen where the iota is to the left of the pulmonary artery. This is the three vessel view where usually three vessels are visualized from left to right in the order of pulmonary artery, iota and SVC. However in this case only two vessels are seen that is the iota and SVC. The pulmonary artery is not visualized as pulmonary artery is much posterior and not visualized in this plane. This is the three vessel tracheal view where we can see the iotic arch and ductile arch forming a V-shaped confluence at the level of isthymus. This is essentially a normal three vessel tracheal view. The great artery relationship is beautifully seen in this echo loop where we can see the iota is anterior and to the left of pulmonary artery, suggestive of L-post iota. The iotic arch was normal. This is the inversion mode stick rendering of the fetal heart. Iota is seen arising from the right ventricle and pulmonary artery is seen overriding the VST marked by the star. Iota is anterior and to the left of main pulmonary artery, suggestive of transposition of great arteries with L-post iota. So the complete segmental diagnosis is cytosolitis with levocardia, kV concordance with D looped ventricles, normal systemic and pulmonary venous drainage and connoventricle of VST, transposition of great artery with Iota left and anterior with no obstruction. The diagnosis was confirmed by postnatal echo showing transposition of great arteries with Iota anterior and to the left of pulmonary artery. The significance of transposition of great arteries with L-post iota is that it is very rare in occurrence. The incidence is 2.9 percent of all TGA cases in the cardiac registry of Boston children's hospital. Secondly, because of the L-post iota, the diagnosis may be confused with congenitally corrected transposition of great arteries. However, in CCTGA there is a atrioventricular concordance as well as ventricular arterial disc. There is discordance at both atrioventricular and ventricular arterial levels. However, in TGA there is only discordance at the level of ventricular arterial level. Embryologically, this is a mild formation of the corners as well as the ventricular segment. So, high prevalence of RV-hycoplasia and ventricular mild position is seen. Also, the L-post iota is because of the lever rotation of the infendicular arterial segment. So, the greater the lever rotation, greater is the probability that the VST will be subiotic, there will be pulmonary outflow tract stenosis and that the conal septum will be hypoplastic. So, the associations of TGSTL were beautifully described by Kuyall et al in 1995, where they describe that VST is typically present in 96% of the cases and that is conoventricular in location. And also conal septal malalignment is seen in 80% of the patients with pulmonary outflow tract stenosis in 27% of the patients. Half the cases were noted to have RV-hycoplasia and ventricular mild position was seen in 23% of the cases and also an absent left pulmonary iosteum residing in single right pulmonary artery was seen. All these associations are important for surgical consultation and usually the flow chart for management of TGSTL is that when there is no pulmonary stenosis, the babies will go for arterial switch operation and single right pulmonary should be taken care of and when there is pulmonary stenosis, the treatment would be LV2 iota tunneling with reconstruction of RVOT. VST is usually large and the routing is easy to do whereas when there is a restrictive VST, the resection of conal septum would be needed. These two cartoons are beautiful representation of transposition of great artery with L-posed iota. In the first cartoon, we can see single right pulmonary artery with absence of left coronary iosteum and also we can see in the second diagram where there is posterior and left for deviation of the conal septum and a large conventary pulmonary iosteum. These are my references. Thank you. I especially thank my mentor Dr. Balu and the organizers for giving me this opportunity.