Description
A 25-year-old man underwent CT angiography (CTA) for evaluation of aortic coarctation. Review of CTA images demonstrated juxta-ductal coarctation with the left subclavian artery (LSCA) arising from the site of coarctation itself (yellow arrow). Incidentally, the left vertebral artery (LVA) was seen arising distal to the LSCA, from the dilated poststenotic segment of descending thoracic aorta (DTA) (figure 1).
Figure 1.
Cinematic volume rendered images (A, B and C) reveal juxta-ductal coarctation with the left subclavian artery (LSCA) arising from the site of coarctation (yellow arrow) and the left vertebral artery (LVA) seen arising distal to the LSCA, from the descending thoracic aorta. *The proximal part of the LVA appears ectatic.
Anomalous origin of the LVA from DTA, distal to LSCA, is an exceedingly rare anomaly and can be explained embryologically by the persistence of left eighth cervical intersegmental artery. Such an origin poses the artery to be at an increased risk of arterial dissection compared with LVA from LSCA or a right vertebral artery from right subclavian artery because of its longer extracranial course which increases its susceptibility to shear stress.1 An anomalous origin may be wrongly misinterpreted as the LVA being congenitally absent, occluded or diseased. The knowledge of anomalous origin of vertebral artery is also important for vascular or non-vascular surgeries in the neck region and angiographies for intravascular cranial or extracranial pathologies. Its presence may also complicate surgical procedures requiring isolation of arch vessels or access to the aortic arch itself because of the danger of disrupting cerebral blood flow. The bulbous dilatation observed at the origin of LVA can be misinterpreted as a Kommerell’s diverticulum which is also seen as a diverticulum arising from the proximal DTA giving rise to an aberrant subclavian artery.
Aberrant LVA from DTA in association with juxtaductal aortic coarctation, as seen in our case, is a previously unreported combination. In our case, this variation may provide protection to the posterior cerebral circulation in the event of an inadvertent iatrogenic dissection extending into the precariously placed LSCA, complicating therapeutic balloon dilatation of aortic coarctation.2
Learning points.
Anomalous origin of the left vertebral artery from descending thoracic aorta is an exceedingly rare anomaly and can be explained embryologically by the persistence of left eighth cervical intersegmental artery.
In the presence of origin of left subclavian artery (LSCA) arising from the site of coarctation itself, this variant origin may provide protection to the posterior cerebral circulation in the event of an inadvertent iatrogenic dissection extending into the LSCA.
Footnotes
Contributors: NNP has participated sufficiently in the conception of the idea, development of the intellectual content, design, writing and final approval of the manuscript.MS has participated sufficiently in the conception of the idea, development of the intellectual content, design, writing and final approval of the manuscript.AS has participated sufficiently in the conception of the idea, development of the intellectual content, design, writing and final approval of the manuscript.SK has participated sufficiently in the conception of the idea, development of the intellectual content, design, writing and final approval of the manuscript.
Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests: None declared.
Patient consent for publication: Obtained.
Provenance and peer review: Not commissioned; externally peer reviewed.
References
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