* Radiology department, Kasr Alainy hospitals, Cairo University, Egypt;
** Fetal medicine Unit, Cairo University, Egypt.
A 33-year-old woman, G3P2 presented to our office at 24 weeks of gestation diagnosed as TOF with suspected aortic arch unusual anomaly. Our evaluation revealed:
- Dilated aortic root overriding a large outlet sub aortic VSD. The main pulmonary artery was seen totally disconnected from the infundibulum of the right ventricle (valvular pulmonary atresia) with hypoplastic both central confluent branch pulmonary arteries.
- Right sided aortic arch with mirror image branching. The arch was seen in a high thoracic location (opposite to sternoclavicular joint).
- Retrograde filling of the main and central pulmonary arteries through a tortuous ductus arteriosus arising from the left innominate artery in a trifurcation pattern (cranially the left common carotid artery, horizontally the left subclavian artery and caudally the ductus arteriosus). This was concurrent with marked ductal folding and excessive lengthening on its way to reach the base of left pulmonary artery, mimicking a shepherd hook. Despite being at mid gestation, there was 2D sonographically evident annular constriction of the ductus arteriosus at its kink that was confirmed on high definition color Doppler study with spatiotemporal image correlation technique.
- Severe hypoplasia of the thymus gland.
Tetralogy of Fallot with pulmonary atresia associated with high thoracic right aortic arch, left ductus arteriosus and severe thymic hypoplasia was confirmed, which raised our suspicion of 22q11 chromosomal micro deletion as supported by previous reports1, 2 for which amniocentesis and fluorescent in situ hybridization were performed and confirmed the presence of this chromosomal micro deletion. Parents opted for termination of pregnancy.
In our case, more than one imaging finding has important consideration. The ductus arteriosus was left sided while the aortic arch was right sided with mirror image branching with lack of vascular ring and this comes in agreement with the recent report by Haiyan et al3. However, in their report, the left sided ductus arised from the left subclavian artery while in our case, it arised from the left innominate artery. No prenatal reports are present about this anomalous origin despite being a well-known very rare finding in postnatal life as recently reported by Ng et al4 in a magnetic resonance study.
Moreover, the ductus arteriosus showed excessive lengthening and severe kinking nearly 180 degrees mimicking a shepherd hook. At 2010, Constantine and his colleagues5 reported this abnormal ductal configuration in autopsy specimens of two cases, both showed segmental annular constriction by an obstructive kink in one case and intimal proliferative ridges in the other one. High definition color flow angiography with 4D STIC was much more helpful adding confidence to clear sonographic visualization of this obstructive kink of the arterial duct in our case. Despite complete ductal dependent pulmonary circulation which requires early post natal prostaglandin infusion prior to urgent surgical BT shunt (arterial duct stenting is not practical due to its marked tortuosity), this abnormal ductal configuration with evident obstructive kink should raise concern about close follow up for fear of premature ductal constriction with consequent in utero fetal death or immediate sudden post-partum neonatal death5.
Figures 1, 2, 3, 4, 5 videos 1, 2, 3, 4, and 5: show normal appearance of 4 chamber view, midline descending thoracic aorta, dilated overriding aortic root and valvular pulmonary atresia.
Figures 6, 7, 8, 9, 10, 11, 12, 13, 14 videos 6, 7, 8 and 9: show the hypo plastic central confluent branch pulmonary arteries, origin of the shepherd hook ductus arteriosus from left innominate artery filling into base of left pulmonary artery, high thoracic right aortic arch, severely hypo plastic thymus gland.
Figures 19, 20, 21, 22, 23, 24 videos 13, 14, 15, 16, 17 and 18: Sequential axial, sagittal and cranio-caudal STIC recorded 4D color Doppler angiography of aortic arch, innominate arteries and veins, central pulmonary arteries and the shepherd hook ductus arteriosus showing the relationship of great vessels in the upper mediastinum with characteristic focal annular constriction at the level of ductal kink (obstructive kink).
1-Momma K, Kondo C, Matsuoka R. Tetralogy of Fallot With Pulmonary Atresia Associated With Chromosome 22q11 Deletion. Journal of theAmerican College of Cardiology. 1996; 1(27):198-202.
2- Chen CP, Chien SC. Prenatal sonographic features of 22q11. 2 microdeletion syndrome. Journal of Medical Ultrasound. 2016; 16(2), 123-129.
3-Haiyan C, Han W, Hong L, Wang Y, Peng Y, Hu Y, Huang W, Xie M. GW27-e1106 Anomalous ductus arteriosus connection in fetus: an anomaly always associated with right aortic arch. Journal of the American College of Cardiology. 2016; 68(16), C165.
4- Ng MY, Thavendiranathan P, Crean AM, Li Q, Deva DP. Left-Sided Patent Ductus Arteriosus in a Right-Sided Aortic Arch. Case reports in radiology. 2014; (2014).
5- Mavroudis CD, Fitchev P, Plunkett BA, Crawford SE. Shepherd Hook Anomaly of Ductus Arteriosus With Sudden Intrapartum Fetal Demise Two Case Reports. World Journal for Pediatric and Congenital Heart Surgery. 2010; 1(1), 137-139.