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Articles » Cardiovascular » Situs anomalies » Left atrial isomerism
2011-06-07-18 Left atrial isomerism © Quiroga

Left atrial isomerism

Hector Quiroga, MD.

Centro Médico Profesional Rosancar. Barquisimeto, Estado Lara, Venezuela.


Cardiosplenic syndromes are disorders of lateralization characterized by symmetrical development of otherwise asymmetrical organs. Left atrial isomerism also called polysplenia syndrome is characterized by bilateral left-sidedness. Bilateral morphologically left bilobed lungs, abnormal visceral and venous anatomy, and cardiac abnormalities are all associated with left atrial isomerism.

Case report

A 22-year-old primigravida was referred to our unit at 28 weeks of her pregnancy for a routine ultrasound scan. The ultrasound examination revealed the following findings:
  • Situs ambiguous
  • Interruption of the inferior vena cava with azygos vein continuation
  • Persistent right umbilical vein
The final diagnosis based on the above findings was a left atrial isomerism. 

Images 1,2
: Image 1 shows a 4-chamber view with the heart on the left and stomach on the right. Image 2 shows a transverse view of the abdomen with aorta and azygos vein.


Images 3,4: Image 3 shows the color Doppler of the 4-chambers, note azygos vein and aorta. Image 4 shows a tricuspid regurgitation.  


Image 5,6: Image 5 shows a pulse wave demonstrating a tricuspid regurgitation. Image 6 shows a color and pulse wave Doppler of the azygos vein.


Images 7,8: Sagittal view showing azygos vein posterior to the aorta.


Images 9,10: Images show drainage of the azygos vein into the superior vena cava.


Images 11,12: Image 11 shows a color Doppler of the persistent right umbilical vein. Image 12 shows a color Doppler of the ductus venosus.


Videos 1,2: Video 1 shows a 4-chamber view, aorta descending on the left and azygos vein posterior to the aorta. Note the drainage of the azygos vein into the superior vena cava. The heart is on the left and stomach is on the right. Video 2 shows a color Doppler of the 4-chambers view and aorta and azygos vein.


Video 3,4: Video 3 shows a color Doppler of aorta (red) and azygos vein (blue). Video 4 shows the aorta and azygos vein.


Videos 5: Color Doppler of the persistent right umbilical vein. 

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