|Year : 2022 | Volume
| Issue : 1 | Page : 71-73
A rare anomalous origin of the right vertebral artery from the right aortic arch with the left aberrant subclavian artery arising from kommerell's diverticulum
Gulay Acar1, Mustafa Koplay2
1 Department of Anatomy, Meram Faculty of Medicine, Necmettin Erbakan University, Konya, Turkey
2 Department of Radiology, Faculty of Medicine, Selcuk University, Konya, Turkey
|Date of Submission||23-Jan-2021|
|Date of Acceptance||27-Oct-2021|
|Date of Web Publication||17-Mar-2022|
Dr. Gulay Acar
Department of Anatomy, Meram Faculty of Medicine, Necmettin Erbakan University, Yunus Emre Mh. Unzile Sk., 42090 Meram, Konya
Source of Support: None, Conflict of Interest: None
Right-sided aortic arch (RAA) with left aberrant subclavian artery (LASA) is a rare vascular variant due to the failure in regression process during embryologic development of the aortic arch. The prevalence of it ranges from 0.04% to 0.1% in radiology series. We report the case of a 44-year-old female shown to have the presence of a RAA with LASA arising from the Kommerell's diverticulum, and also in association with an aberrant aortic origin of the right vertebral artery using computed tomography angiography. Considering the diameter of the diverticulum <5 cm and the absence of severe external esophageal or tracheal compression, thoracic surgery was not indicated and it was decided to keep the patient under clinical follow-up at regular intervals. Based upon this present case and literature review, the knowledge of this anomalous anatomy and its embryologic basis appear to be important for diagnostic endovascular interventions and planning thoracic surgery.
Keywords: Aberrant left subclavian artery, computed tomography angiography, Kommerell's diverticulum, right-sided aortic arch, right vertebral artery
|How to cite this article:|
Acar G, Koplay M. A rare anomalous origin of the right vertebral artery from the right aortic arch with the left aberrant subclavian artery arising from kommerell's diverticulum. J Anat Soc India 2022;71:71-3
|How to cite this URL:|
Acar G, Koplay M. A rare anomalous origin of the right vertebral artery from the right aortic arch with the left aberrant subclavian artery arising from kommerell's diverticulum. J Anat Soc India [serial online] 2022 [cited 2022 Aug 17];71:71-3. Available from: https://www.jasi.org.in/text.asp?2022/71/1/71/339874
| Introduction|| |
Right-sided aortic arch (RAA) is a rare and mostly asymptomatic variant of the aortic arch (AA) with a frequency of <0.1% in adult population. Type II RAA associated with the left aberrant subclavian artery (LASA) arising from the Kommerell's diverticulum (KD) is observed in <50% of the RAA.,, We reported this case with an anomalous aortic origin of the right vertebral artery (RVA) using computed tomography angiography (CTA). An aberrant origin of vertebral artery (VA) observed mostly on the left side may cause vertebrobasilar insufficiency. To the best of our knowledge, this is the second documented report of Type II RAA with an aberrant aortic RVA in the literature.
| Case Report|| |
A 44-year-old woman with a history of systemic hypertension presented at the emergency department with severe headache, dizziness, and dyspnea. Furthermore, she had complaints of anxiety episodes, dyspnea on exertion, and no other cardiovascular symptoms. The amplitude of arterial pulse and systolic blood pressure value were found lower in the left upper limb than right on physical examination. Thoracic CTA (128-slice CT scanner; Siemens Somatom Definition Flash, Munich, Germany) was performed to rule out pulmonary embolism after written informed consent was obtained from the patient. Evaluation of CTA images revealed an incidental finding of the RAA with the LASA arising from the KD with a diameter of 3.9 cm, as well as an anomalous aortic origin of the RVA [Figure 1].
|Figure 1: Computed tomography angiography volume-rendered reconstruction showing Type II RAA with aberrant RVA. (a) Anterolateral and (b) posterolateral aspect. RCCA: Right common carotid artery, LCCA: Left common carotid artery, RSA: Right subclavian artery, ALSA: Left aberrant subclavian artery, RVA: Right vertebral artery, KD: Kommerell's diverticulum|
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The KD has a mild mass effect on the trachea, and the LASA forms a retroesophageal vascular ring. The RVA was found to arise directly from the AA between the right common carotid artery (RCCA) and the right subclavian artery (RSA), and extend upward to the transverse process of cervical vertebrae to pass through the foramen of C4 and all of the upper transverse processes [Figure 2]. Considering her imaging findings and medical history with the absence of dysphagia, the patient was interpreted as unsuitable for surgical intervention. Regular follow-up without medication was recommended to the patient. Furthermore, the patient confirmed written informed consent for publication of this case report with images.
|Figure 2: Thoracic computed tomography angiography sagittal maximum intensity projection image showing an aberrant origin of the right vertebral artery from the aortic arch. RCCA: Right common carotid artery, RSA: Right subclavian artery, RVA: Right vertebral artery|
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| Discussion|| |
The classic left-sided AA (LAA) gives rise to three branches from right to left: the brachiocephalic trunk, the left common carotid artery (LCCA), and finally, the left subclavian artery (LSA). Normally, the VA is originated as the first branch of the ipsilateral subclavian artery. In the literature, the AA branching variations are a common finding with a diversity of frequencies ranging from 5% to 35%., RAA anomaly has three subtypes based on Edwards classification: mirror image RAA (Type I, 59%), RAA with LASA (Type II, 39.5%), and RAA with direct communication between isolated LSA and pulmonary artery (Type III, 1.5%) [Figure 3]., The KD is a bulbous dilatation of an anomalous origin of the LASA which leads to a relatively loose vascular ring mostly behind the esophagus. The LASA coexists with congenital heart diseases in 5%–10% of cases. Ichikawa et al. reported the prevalence of KD as 100% in Type II RAA, while it was found in 62% in the study by Tyczyński et al.,, Owing to compression of the esophagus or trachea, the KD can cause miscellaneous symptoms such as dyspnea and dysphagia and rarely results in an aortic dissection or ruptured aneurysm. Considering the diameter (≥5 cm) of the KD and severe symptoms such as an aortic aneurysm and a cerebrovascular insufficiency, surgical intervention can be required.,,
|Figure 3: Schematic diagram showing the left-sided aortic arch and subtypes of the right-sided aortic arch. Type I; Mirror image right-sided aortic arch, Type II; Right-sided aortic arch with left aberrant subclavian artery, Type III; Right-sided aortic arch with direct communication between the isolated left subclavian artery and left pulmonary artery|
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During the 4th and 8th weeks of intrauterine life, a series of aortic regression and reformation result in the formation of the LAA, which was reported in about 74%–89.4% of cases. Initially, the primitive AA consists of ventral and dorsal aortic trunks. Between these trunks, six paired branchial arch arteries develop and seven cervical intersegmental arteries (CIAs) arise from the dorsal aorta at different stages of the organogenesis. Normally, the LAA is formed by the regression of the dorsal aortic trunk and ductus arteriosus on the right side. In contrast, the failure of this involution results in RAA, which is subdivided into three types.,, First, the RAA was identified by Fioratti and Aglietti in 1763. Due to the persistence of the right fourth branchial arch and involution or regression of the left fourth dorsal aortic segment between the LCCA and LSA, the RAA with LASA is formed, and also, the KD develops as a remnant of the fourth primitive dorsal arch during embryonic period. Type II RAA is a rare (0.05%–0.1%) and mostly an asymptomatic incidental finding unless the KD becomes a compressive mass or ruptured.,, After the obliteration of six CIAs, the seventh CIA converts into the proximal subclavian artery giving origin to the VA, which is the further development of the intercostal longitudinal anastomosis. The failure of involution in these developmental stages results in different anomalous origins of the VA. If the first or the second CIA does not regress, the VA arises from the external or internal carotid artery, whereas the persistence of other CIAs (3–6) causes an anomalous origin of the VA from the AA or common carotid artery.,,, Hence, in this case, we suggested that the right anastomosis between the sixth and seventh CIAs may not occur and the sixth CIA fails to regress.
We presented a rare case of Type II RAA having branches, in a proximal to distal progression, with the following order: LCCA, RCCA, RVA, RSA, and LASA arising from the KD. A review of the literature from 2011 to date showed that 32 case reports of Type II were reported. Concerning the higher incidence of ruptured aneurysm or dissection associated with the KD, the prevalence of it was reported by Cinà et al. as 53%, by Kouchoukos and Masetti as 20%, and by Austin and Wolfe as 19%.,,,, Detailed identification of this aberrant vascular anatomy is crucial for accurate surgical and endovascular intervention planning and to prevent intraoperative vascular complications during surgery and diagnostic cerebral angiography.,,
In the recent literature, an aberrant origin of the RVA is less common than the LVA, whereas the prevalence of the aortic origin of the RVA associated with Type II RAA is even more the rarest of all. Generally, an anomalous aortic origin of the RVA most commonly occurs as the last branch of the AA distal to the origin of the LSA.,, To our knowledge, an anomalous origin of the RVA from the RAA, with the LCCA as the first branch of the AA followed by RCCA, RSA, and LASA, has been presented only in the study by Tyczyński et al. An aberrant origin of the RVA directly from the arch may lead to an increased risk of spinal and right upper limb ischemia.,
Although this anomaly is found incidentally and mostly asymptomatic, preoperative evaluation using CTA is essential for planning endovascular intervention and surgical approach and avoidance of unexpected outcomes. Identification of this case report with the review of the literature has significant clinical implications in thoracic surgery and endovascular procedures.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]