A related problem is persistence of both 4th arches. After the intersegmentals come forward both the right and left 4th arches remain attached to the dorsal aorta. This causes a vascular ring constriction of the esophagus and trachea in addition to the constriction caused by the ligamentum.
The surgical approach to this abnormality is to divide one of the aortic arches, whichever is least functional. All 6 cases encountered in this hospital have had a small atretic left arch, in which case we divide the left arch and left ligamentum and leave the right arch as the functional arch, as illustrated in the following slides.
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Surgical exposure through the left 4th intercostal space reveals stricture of the esophagus and enlargement of the esophagus cranial to the stricture.
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The ligamentum arteriosum crosses from the right-sided aorta to the left-sided pulmonary artery at the level of the left vagus nerve. Stricture was caused by the ligamentum arteriosum and in addition an atretic left aortic arch.
Two ligatures are placed around the ligamentum, and this is divided between ligatures.
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The atretic left aortic arch can be seen extending cranioventrally near the ligamentum, causing additional constriction of the esophagus. This is separately ligated and divided.
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This slide shows the ballooning of the esophagus as it is relieved of the second constriction. If the surgeon fails to dissect cranially and caudally from the ligamentum arteriosum and discover extra vessels causing compression, surgery will be a failure.
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