Left isomerism with Kommerell diverticulum and interventricular membranous septal diverticulum

The distal aortic arch is dilated with an aneurysmal origin of the retro-esophageal aberrant right subclavian artery (Kommerell diverticulum).

There are thoracic and abdominal anatomic variants and anomalies:

• atrial situs, atrioventricular and ventriculoarterial connections are normal; one may discuss two atria with left morphology. No abnormal pulmonary venous return. There is absence of the hepatic segment of the IVC with azygos continuation.  No persistent left SVC.
• the bilateral mainstem bronchi show left morphology and each lungs have two lobes and one fissure (bilateral bilobed lungs) 
• liver and gallbladder are essentially median in position
• polysplenia 
• the stomach is on the right, small bowel loops all located on the left, large bowel is located on the right: findings suggestive of a mirrored intestinal nonrotation
• mesenteric vessels are reversed

There is a pouch-like structure located below the level of the aortic valve annulus, consistent with a membranous diverticulum of the interventricular septum, while the sinus of Valsalva and aortic valve cusps are grossly normal.

This case is a joint interpretation of imaging with Dr P. Mascarel, who is the prime reporter.