Changes

[[Image:Praa.gif|right|thumb|125px|<small><center>Dextra-aorta (Courtesy of Alun Williams (RVC))</center></small>]]

[[Image:Praa.gif|right|thumb|125px|<small><center>Dextra-aorta (Courtesy of Alun Williams (RVC))</center></small>]]

*Vascular rings are congenital abnormalities of the aortic arch system which interfere with [[Oesophagus - Anatomy & Physiology|oesophageal]] function. Normally, the aortic arch, pulmonary artery and ductus arteriosus (ligamentum arteriosum) all lie on the left side of the [[Oesophagus - Anatomy & Physiology|oesophagus]].  

*Vascular rings are congenital abnormalities of the aortic arch system which interfere with [[Oesophagus - Anatomy & Physiology|oesophageal]] function. Normally, the aortic arch, pulmonary artery and ductus arteriosus (ligamentum arteriosum) all lie on the left side of the [[Oesophagus - Anatomy & Physiology|oesophagus]].  

*However, when there is anomalous development of the aortic arch, for example in the [[right-sided arch]], the [[Oesophagus - Anatomy & Physiology|oesophagus]] becomes enclosed within a ring formed by the '''heart base''', '''aorta''', '''ductus arteriosus''' and '''pulmonary artery'''.

*However, when there is anomalous development of the aortic arch, for example in the right-sided arch, the [[Oesophagus - Anatomy & Physiology|oesophagus]] becomes enclosed within a ring formed by the '''heart base''', '''aorta''', '''ductus arteriosus''' and '''pulmonary artery'''.

*The compression and stricture produced by the “ring” prevents passage of solid food beyond the heart base and food accumulates rostral (cranial) to the obstruction, resulting in dilatation or megaoesophagus.  

*The compression and stricture produced by the “ring” prevents passage of solid food beyond the heart base and food accumulates rostral (cranial) to the obstruction, resulting in dilatation or megaoesophagus.  

*In most cases food is eventually regurgitated undigested.

*In most cases food is eventually regurgitated undigested.