Via Research Recognition Day 2024 VCOM-Carolinas

Clinical Case-Based Reports

Anatomical Variations of Aortic Arch Branches: A Rare case of Lusoria Artery with a Common Bicarotid Trunk Dustin Rizzieri, OMSII, David Jaynes, Ph.D. Edward Via College of Osteopathic Medicine - Carolina's campus, Spartanburg, SC.

Case Presentation

Abstract

I ntroduction : The right subclavian artery (RSA) typically branches from the brachiocephalic trunk; however, several variants have been described. One is a rare RSA variant that emerges from the proximal descending aorta (Lusoria artery). Resources: Lusoria artery was observed in an 84-year-old male cadaver who died of myocardial infarction Description: The Lusoria artery emerged from the proximal descending aorta and coursed right across the posterior mediastinum deep to the esophagus. A bicarotid trunk was also observed originating from the aortic arch; these variations are rarely observed together. Presence of the Lusoria artery is rare and 2/3 of these cases are asymptomatic. The presence of symptoms likely depends on other variants (e.g., bicarotid trunk). Several hypotheses have been proposed to explain why some people are asymptomatic, but later become symptomatic. One is increasing esophageal rigidity with advanced age, leading to dysphagia caused by the retroesophageal course of the artery. Another is that the bicarotid trunk gives rise to the right and left carotid arteries in close proximity, thus preventing the trachea and esophagus from bending forward where the Lusoria artery crosses. Calcification and aneurysm at the origin of Lusoria artery have been reported. We excised this region and found extensive calcification and a greatly thinned wall. This section of the artery appeared “folded upon itself”, possibly preventing noticeable blood loss. Significance: Patients with Lusoria artery may present with mild respiratory distress, dysphagia, and other less frequently observed symptoms. This anomaly is adequately common to demand the attention of vascular surgeons confronted with a superior mediastinal mass accompanied by symptoms of Lusoria artery. Awareness of diminished vascular wall thickness at the Lusoria artery origin (which could lead to a Kommerell Diverticulum) is an important consideration when proceeding with treatment. Normal anatomy appreciates 3 major branches from the aortic arch, the brachiocephalic trunk which branches into the right subclavian artery and the right common carotid artery, the left common carotid artery, and the left subclavian artery. Abnormalities in this vascular development are well documented but typically are of little consequence (2). However, the Lusoria artery is an abnormality in the branching of the right subclavian artery that requires increasing attention due to its increasing detection with advancing imaging techniques, such as ultrasonography. Its current incidence ranges from 0.2-1.7% of the population which makes it the most common congenital aortic arch anomaly and is predicted to be underreported (3) . This abnormality involves the right subclavian artery to originate in the proximal descending aorta instead of originating from the brachiocephalic trunk. This aberrant origin causes the artery to course abnormally with regard to nearby structures as it circulates blood to the right axilla. This abnormal path merits concern for not only the patency of the artery, but also complication risks for thoracic procedures Introduction

Calcification and aneurysm at the origin of Lusoria artery have also been reported (Kommerell diverticulum). The presence of an aneurysm in the proximal aorta increases the risk aortic dissections and should be completely removed if identified. Other medical management changes for these patients include the use of a transradial approach forcatheterization. In normal patients, transradial catheterization approach is viewed as the gold standard. However, the risk of dissection as a complication during catheterization in these patients is significantly increased and success rates are decreased to 60% (1,4). To raise success rates and reduce dissection risks, the femoral approach is the preferred method of catheterization in patients with aLusoria artery. The femoral approach to catheterization comes with increased infection risk, so it is important to maintain proper aseptic technique. It is therefore important to obtain confirmation of the malformation in suspect patients toprovide the correct medical care without subjecting the patient tosevere complications (dissection or infection).

An 84-year-old cadaver who died from a myocardial infarction was observed to have unique characteristics of the Lusoria artery abnormality. The Lusoria artery emerged from the proximal descending aorta and coursed transversely across the posterior mediastinum deep to the esophagus. A bicarotid trunk was also observed originating from the aortic arch; these variations are rarely observed together. We excised this region and found extensive calcification and a greatly thinned wall. This section of the artery appeared “folded upon itself”, possibly preventing noticeable blood loss. A persistent thyroglossal duct was also observed during the dissection which is another rare association seen in patients with a Lusoria artery, as shown in figure 3.

Fig. 3. Anterior view of the lower neck. Presence of alarge asymmetric right persistent thyroglossal duct. PTD= persistent thyroglossal duct, TG = thyroid gland.

PTD

Conclusion

Although rare, the prevalence of a Lusoria artery is increasing with advancements in imaging techniques. Therefore, physicians should practice a high index of suspicion in patients with aortic variations, progressive dysphagia, aneurysms, and/or a persistent thyroglossal duct. Early diagnosis can improve long term health outcomes for patients and potentially reduce serious complications of invasive procedures such as thoracic surgery or catheterization during minimally invasive procedures. Lastly, any mediastinal mass has the ability to compress weak points in the artery which could lead to further complications during thoracic procedures.

TG

Fig. 4. Anterior view of the mediastinum showing abicarotid trunk emerging near the apex of the aortic arch; the trunk gives rise to both common carotid aa. (the right common carotid a. has been cut near its’ origin). AA = arch of aorta, BCT = bicarotid trunk, LCC = left common carotid a.

BCT

AA

References

1. Huang IL, Hwang HR, Li SC, Chen CK, Liu CP, Wu MT. Dissection of arteria lusoria by transradial coronary catheterization: a rare complication evaluated by multidetector CT. J Chin Med Assoc 2009;72:379-81. 2.Layfield DM, Nikolaidis N, Harden SP , et al Aneurysm of aberrant right subclavian artery (arteria lusoria) presenting as cardiac dyspnea Thorax 2011; 66: 456. 3.Myers PO, Fasel JH, Kalangos A, Gailloud P. Arteria lusoria: developmental anatomy, clinical, radiological and surgical aspects. Ann Cardiol Angeiol (Paris) 2010;59:147-54 4.Valsecchi O, Vassileva A, Musumeci G, Rossini R, Tespili M, Guagliumi G, Mihalcsik L, Gavazzi A, Ferrazzi P. Failure of transradial approach during coronary interventions: anatomic considerations. Catheter Cardiovasc Interv 2006;67:870-8 5.Yiu KH, Chan WS, Jim MH, Chow WH. Arteria lusoria diagnosed by transradial coronary catheterization. JACC Cardiovasc Interv 2010;3:880-1 The authors would like to thank the person who donated their body to further the education of medical school students and allowed for this research to be conducted. The authors would like to extend their gratitude to the family of the donor for supporting their loved ones' decision to become a donor. Acknowledgements

It is reported that 2/3 of the population having Lusoria artery are asymptomatic (2,5). Females seem to be affected by the mutation more than men with 69% of incidences being female. Some known associations with the vascular mutation are aneurysms, persistent thyroglossal duct, heart or vascular abnormalities like a bicarotid trunk, and progressive dysphagia. Some signs of the abnormality may be persistent dysphagia or right radial pulses diminished during swallowing due to the arteries' retroesophageal path. The presence of symptoms likely depends on other variants (e.g., bicarotid trunk, persistent thyroglossal duct, aneurysms). Several Hypotheses have been proposed to explain why some people are asymptomatic, but later become symptomatic. One is increasing esophageal rigidity with advanced age, leading to dysphagia caused by the retroesophageal course of the artery. Another is that the bicarotid trunk gives rise to the right and left carotid arteries in close proximity, thus preventing the trachea and esophagus from bending forward where the Lusoria artery crosses. In either event, there is pressure on the artery from surrounding structures. This suggests that any mediastinal mass may provide a sufficient obstacle to the patency of the Lusoria artery and should be taken into consideration during any procedures that could increase thoracic pressures on the aorta. Discussion

Fig. 2. Arterial section excised as describedin Figure 1. The upper image is provided so the section can be clearly seen. On thelower image, the yellow circle delineates the cut (distal) edge of descending aorta-ARSA junction and a possible weak point.The red arrows indicate a few of the many thick calcifications at the origin of ARSA. Few ARSA. The blue circleshows the

A A

LA

ARSA

E

Fig. 1. Yellow lines delineate arterial section excised. AA = arch of aorta, LA = ligamentum arteriosum. E = esophagus .

calcifications were observed beyond theexcised tissue.

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