Left isomerism

Alaa Alebrashy, MD*; Sameh Abdel Latif Abdel Salam, M.Sc.**; Islam Badr, M.Sc.***; Mahmoud Alalfy, M.Sc.****

* Head of fetal medicine unit, obstetric and gynecology department, kasr alainy hospitals, Cairo university, Egypt;
** Radiodiagnosis department, Kasr Alainy teaching hospitals, Cairo university, Egypt;
*** Fetal medicine unit, Cairo university, Egypt;
**** Obstetric and gynecology department, National research center, Egypt.

Case report

A 24-year-old woman was referred to our fetal medicine unit at 34 weeks of gestation due to abnormal 4-chamber-view of the heart. She was known to have type 1 diabetes mellitus on regular insulin therapy.

Our ultrasonographic examination revealed following findings:

- Interrupted inferior vena cava with enlarged hemiazygos vein seen posterior to the abdominal aorta;
- Direct drainage of the hepatic veins into the right atrium;
- Enlarged symmetric the liver;
- Fetal stomach is seen on the left side but shifted to the middle position denoting possibility of gastric malrotation;
- The heart is seen in the left side of the chest but with leftward cardiac axis deviation;
- Mitral atresia with hypoplastic left ventricle and dominant anteriorly located right ventricle;
- Double outlet right ventricle with malpositioned (transposed) great vessels;
- Dilated coronary sinus with persistent left superior vena cava;
- Aortic arch is seen on the right side of the chest but in rather oblique course and in front of the trachea;
- Small sized left atrium with bulging foramen ovale flap into the huge right atrium;

From a hemodynamic point of view, in our case the blood was directed across the left atrium through foramen ovale into the right atrium then through the tricuspid valve into the right ventricle and then ejected into both great vessels. Moderate tricuspid regurgitation was also noted, mostly due to tricuspid annular dilatation as a result of right ventricular dilatation.

Our final diagnosis was left isomerism with double outlet right ventricle and persistent left superior vena cava draining a left hemi azygos vein.

Here are some images and videos that we obtained:

Images 1, 2, and videos 1, 2, 3: Transverse scans of the fetal abdomen showing enlarged hemiazygos vein seen posterior to the abdominal aorta; inferior vena cava is not seen (interruption of the inferior vena cava) and hepatic veins join together end enter the right atrium of the heart; fetal stomach is seen on the left side but shifted to the middle position denoting possibility of gastric malrotation; enlarged symmetric the liver can be seen.

Fig_01
Fig_02

Images 3, 4, and videos 4, 5, 6: Transverse scans of the fetal thorax - the heart is seen on the left side of the chest but with leftward cardiac axis deviation; mitral atresia with hypoplastic left ventricle and dominant anteriorly located right ventricle; tricuspid regurgitation can be seen.

Fig_03
Fig_04

Image 5, and videos 7, 8: Transverse scans of the fetal thorax - double outlet right ventricle with parallel course of the malpositioned (transposed) great vessels and persistent left superior vena cava can be seen.

Fig_05

Image 6 and video 9: Division of the main pulmonary artery into the right main branch and a tortuous arterial duct; left sided arch of hemi azygos entering the persistent left superior vena cava.

Fig_06

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