Histological investigation of persistent fifth aortic arch with arch obstruction in a neonate

Persistent fifth aortic arch (PFAA) is a rare congenital heart disease caused by maldevelopment of the primitive aortic arch and can cause obstruction of the aortic arch. The histological structure of a fifth aortic arch differs from that of normal aortic arches. Therefore, it is unclear whether the tissue of a fifth aortic arch can be safely utilized to reconstruct the aortic arch during surgical repair of arch obstruction. We herein report the case of a neonate who underwent surgical repair of a PFAA with interrupted aortic arch, right aortic arch, and aberrant left subclavian artery. Similar to those for a ductus arteriosus, the histological findings of the resected PFAA in this case showed intimal thickening, myxoid deposition in the intima and media, and proliferation and migration of smooth muscle cells into the intima. When reconstructing the aortic arch, we suggest that, if possible, the fifth aortic arch tissue be resected.

The histological findings of a persistent fifth aortic arch (PFAA) are important in determining the treatment strategy because the tissue may be unsuitable for reconstruction of the aortic arch. In the present case, the tissue of the PFAA was histologically similar to that of a ductus arteriosus and thus may have caused re-stenosis or formation of an aneurysm in the future. We therefore recommend resecting the PFAA tissue during aortic arch reconstruction.