Persistent right aortic arch associated with an aberrant left subclavian artery arising from a patent ductus arteriosus in a puppy

PERSISTENT RIGHT AORTIC ARCH ASSOCIATED WITH AN ABERRANT LEFT SUBCLAVIAN ARTERY ARISING FROM A PATENT DUCTUS ARTERIOSUS IN A PUPPY
Rizza M.*, Claeys S.**, Billen F.***, Mc Entee K. ***, Bolen G.*
*Diagnostic Imaging Section, **Small Animal Surgery Section, ***Small Animal Internal Medicine Section, Department of Clinical Sciences (Companion Animal and Equides), Faculty of Veterinary Medicine, University of Liege, Belgium.
Introduction
Vascular anomalies develop during foetal development and single or multiple aberrant vessels can be present. Persistent right aorta arch (PRAA) represents over 90% of described vascular ring anomalies and can be accompanied by a left ligamentum arteriosum or a patent left ductus arteriosus (approximately 10% of patients) that causes oesophageal entrapment and secondary sub-obstruction.
Radiography is an effective means of detecting vascular ring anomalies when oesophageal dilation and left-sided tracheal displacement are visible. Computed tomography angiography (CTA) is necessary to confirm the nature and the patency of the vascular anomalies present and to identify which of the identified anomalies is causing the clinical signs.

Materials and methods
A 3.5-month-old, male French Bulldog was presented for regurgitation and vomiting since weaning. Besides a low body score, physical exam was unremarkable. Hypoglycemia was observed on routine blood analysis.
Thoracic radiographs and CTA of the thorax were performed.

Results
The radiographs revealed severe oesophageal dilation cranial to the base of the heart and a ventral and left-sided tracheal displacement. A congenital oesophageal diverticulum secondary to a vascular anomaly was suspected.
CTA showed multiple vascular anomalies. A PRAA was observed. An aberrant right subclavian artery (ARSA) was identified originating from the PRAA next to the brachiocephalic trunk. A patent left-to-right patent ductus arteriosus (PDA) was detected between the aorta and the pulmonary trunk and an aberrant left subclavian artery (ALSA) originated from the PDA. The oesophagus was compressed between the PDA and the trachea and was dilated cranially to this narrowing.
Endoscopy revealed severely esophageal distension cranially to an extraluminal stenosis. Surgery was performed to ligate and cut the PDA.
Discussion
Seven types of vascular ring anomaly are described: types I - III have a PRAA, type IV has a double aortic arch, and types V -VII have a left aortic arch with combinations of persistent right ligamentum arteriosum and right subclavian arteries. In the patient described here, the vascular ring anomalies are a novel variant of the defined types. To the authors’ knowledge, an ALSA originating from a PDA has not been described previously. The severe compression of the oesophagus with severe dilation cranial to the heart was caused by the PDA and was resolved by surgical intervention.
In conclusion, CTA is necessary to determine which vascular anomalies are present and to identify which of these anomalies is responsible for the clinical signs. This technique enables accurate pre-operative planning.

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