Vascular Ring anomalies(PRAA)

161569 & 115806

Buster

• 8 week old Border collie

• Regurgitation/vomiting recently since starting to feed kibble

• Smaller than the rest of his littermates

• Always hungry

Thoracic Radiographs

Cranial thoracic megaesophagus

Leftward deviation of the tracheaAbsent left margin of the aorta

EMBRYOLOGY

Vascular Ring Anomalies: Case Report and Brief Overview. Can. Vet. J. 20: 78-81(March 1979)

Embryology• The FIRST and SECOND arches regress and the internal and external

carotids are formed by the dorsal and ventral aortas respectively. • The dorsal aortas between the third and fourth arches regress leaving

the THIRD arch as part of the internal carotid artery. • The left FOURTH arch enlarges to form the main aortic arch while • The right FOURTH arch becomes the right subclavian artery. • The FIFTH arch is vestigial and of no apparent clinical significance. The

SIXTH arches become the pulmonary arteries. • The left SIXTH arch retains its connection with the left dorsal aorta as

the ductus arteriosus. • Many variations of the vascular ring anomaly based on degrees of

patency and association with other cardiac lesions have been described.Vascular Ring Anomalies: Case Report and Brief Overview. Can. Vet. J. 20: 78-81(March 1979)

VRAs

• Congenital malformations of the major arteries of the heart that entrap the intrathoracic esophagus causing esophageal obstruction

• PRAA is the most common: R aa rather than the L 4th aa becomes the functional aorta

• Causes: Circular entrapement of the esophagus– Aorta on the right, ligamentum arteriosum

dorsolaterally on the left, PT on the Left and the heart base ventrally

5 MAIN FORMS OF VASCULAR RING ANOMALIES

• 1. Double aortic arch: both fourth arches maintain their attachment to the adult descending aorta.

• 2. Right aortic arch with left ductus arteriosus: ring formed by the normal ductus arteriosus from the left pulmonary arch joining to the abnormal right aortic arch.

• 3. Left aortic arch with right ductus arteriosus: ring formed by the abnormal communication between the right pulmonary arch and the normal aortic arch.

• 4. Aberrant right subclavian artery: origin of the artery such that the vessel must pass retro-esophageal and thus put pressure on the esophagus, trachea, etc.

• 5. Aberrant left subclavian artery: as for the aberrant right subclavian artery.

Clinical Signs

• Result from constricted esophagus– Regurgitation of solid food after weaning– Wt loss with failure to thrive despite good

appetite– Moist cough, fever, dyspnea: if aspiration

pnuemonia present– PE: thin stunted animal– Breed predisposition: Irish Setters and German

Shephards

Diagnosis

• Thoracic rads:– cranial megaesophagus cranial to the base of the

heart– Leftward deviation of the trachea near the cranial

border of the heart• Esophagram: Confirm location of esophageal

constriction and evaluate esophageal motility to help give prognosis of function post-sx

Diagnostics

• CT: to confirm type of VRA present.– Some animals may have more than 1 anomalous

vessel– Will give surgeon more information to plan sx

accordingly• Echocardiogram– May be able to identify anomalous vessel and/or

other congenital abnormalities

PRAA

MEGAESOPHAGUSAORTA

DUCTUS ARTERIOSUS

Left pulmonary arch

Multiple anomalous vessels

• 3 month old GSD: PRAA, PDA, persistent retroeshageal left subclavian artery, persistent left cranial vena cava and left azygous vein

Multiple vascular anomalies in a regurgitating German shepherd puppy. Christiansen, Snyder, Buchanan, and Holt. Journal of Small Animal Practice(2007) 48, 32-35

Persistent left cranial vena cava

Treatment

• Surgical ligation and transection of the ligamentum arteriosum

• Tx aspiration pneumonia if present

• Esophageal hypomotility and regurgitation may persist elevated feedings and promotility medications

PRAA

Thrall. Textbook of Veterinary Radiology. Fifth edition; 2007. p 505-506

Double Aortic Arch

Thrall. Textbook of Veterinary Radiology. Fifth edition; 2007. p 505-506

Aberrant Right Subclavian

Thrall. Textbook of Veterinary Radiology. Fifth edition; 2007. p 505-506