Aortic Arch Anomalies

Posted by e-Medical PPT
The aortic arches are a series of six paired embryological vascular structures which give rise to several major arteries. The first and second arches disappear early, but the dorsal end of the second gives origin to the stapedial artery, a vessel which atrophies in humans but persists in some mammals. The third aortic arch constitutes the commencement of the internal carotid artery, and is therefore named the carotid arch.The fourth right arch forms the right subclavian as far as the origin of its internal mammary branch; while the fourth left arch constitutes the arch of the aorta between the origin of the left carotid artery and the termination of the ductus arteriosus.The fifth arch disappears on both sides.The proximal part of the sixth right arch persists as the proximal part of the right pulmonary artery while the distal section degenerates; The sixth left arch gives off the left pulmonary artery and forms the ductus arteriosus; this duct remains pervious during the whole of fetal life, but then closes within the first few days after birth due to increased O2 concentration.
Most defects of the grest arteries arise as a result of persistence of aortic arches that normally should regress or regression of arches that normally shouldn't.
    Aberrant subclavian artery; with regression of the right aortic arch 4 and the right dorsal aorta, the right subclavian artery has an abnormal origin on the left side, just below the left subclavian artery. To supply blood to the right arm, this forces the right subclavian artery to cross the midline behind the trachea and esophagus, which may constrict these organs, although usually with no clinical symptoms.
    A double aortic arch; occurs with the development of an abnormal right aortic arch in addition to the left aortic arch, forming a vascular ring around the trachea and esophagus, which usually causes dificutly breathing and swallowing. Occasionally, the entire right dorsal aorta abnormally persists and the left dorsal aorta regresses in which case the right aorta will have to arch across from the esophagus causing difficulty breathing or swallowing.
    Patent ductus arteriosus
    Coarctation of the aorta

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