1. Fetal medicine unit, Kasr Alainy hospital, Cairo University, Egypt.
2. Radiology department, Kasr Alainy hospital, Cairo University, Egypt.

Case report

27 year old woman, (G2P1) with unremarkable family history was referred to our institution at 27 weeks of gestational age for antenatal ultrasound study.

Ultrasound examination revealed:
- Dilated hypertrophied right ventricle with the cardiac apex still formed by the left ventricle (moderate ventricular disproportion).
- Prominent main pulmonary artery compared to the ascending aorta.
- Severe narrowing of the transverse aortic arch (distal arch and isthmus) with focal tight isthmic coarctation and isthmus to ductal ratio less than 0.3.
- Normal drainage of pulmonary veins into left atrium.
- No evidence of persistent left SVC, dilated coronary sinus, premature closure of ductus arteriosus or FOV restriction./>- Normal tri leaflet appearance of the aortic valve.

Our final diagnosis was coarctation of the aorta with hypoplastic transverse arch. The retrograde diastolic filling of the aortic arch noticed during this gestational age together with marked narrowing of the aortic arch and the tight focal isthmic coarctation reflect the severity of the lesion. The ductal dependent systemic circulation was confirmed even with systolic antegrade flow in the aortic arch and postnatal measures to support systemic circulation were performed until corrective surgery.

Following images and videos represents the coarctation with hypoplastic transverse aortic arch: