**4. Clinical characteristics**

**Figure 4.** Three-dimensional computed tomography reconstruction of the arteries (CT-64-row MDCT scanner, Light-Speed VCT, GE, Waukesha, Wisconsin, USA). Ao—arch of the aorta, AL—arteria lusoria, KD—Kommerell's diverticu-

78 Epidemiology of Communicable and Non-Communicable Diseases - Attributes of Lifestyle and Nature on Humankind

Arteria lusoria results from abnormal embryologic development of the aortic arch. In the normal situation, between the 4th and 5th weeks of embryonic life, blood leaves the heart by a common trunk called the "truncus arteriosus", which divides into two branches termed the ventral aortae. These branches are connected with the paired dorsal aortae by six aortic arches. The carotid system is formed by segments of the first three arches. The right fourth arch, a segment of the right ventral aorta, and a portion of the right dorsal aorta develop into the right subclavian artery. The left fourth arch persists as the adult aortic arch with the anlagen of the seventh dorsal intersegmental artery, and this forms the left subclavian artery. The fifth arches are both resorbed, and the sixth arches form the pulmonary artery and the ductus arteriosus

The aberrant origin of the right subclavian artery is caused by the involution of the right fourth vascular arch and proximal right dorsal aorta and the persistence of the seventh intersegmental artery originating from the proximal descending thoracic aorta, resulting in

the arteria lusoria following an abnormal course [5, 6].

lum, LSA—left subclavian artery, LCCA—left common carotid artery, RCCA—right common carotid artery.

**2. Embryology**

[5, 6].

An aberrant right subclavian artery is usually asymptomatic, while about 8–10% of adult patients develop symptoms [16]. The anomaly does not cause symptoms in most patients and can be discovered incidentally during life or found at autopsy [17, 18].

When present, symptoms usually occur at the two extremes of life [19]. In children, respiratory symptoms are prevalent, mainly dyspnea or chronic coughing. They can also present with repetitive respiratory infections. Infant patients may demonstrate an increased frequency of pulmonary infections, which is thought to be due to absence of tracheal rigidity in combination with dysphagia and aspiration [19, 20]. As noted above, a rare cause of dysphagia observed in adults is compression of the esophagus by an abnormal course of the aberrant right subclavian artery, which is classically termed "dysphagia lusoria" [3].

Although dysphagia may be the most frequent symptom demonstrated by adults, children demonstrate a different respiratory symptomatology attributed to lack of the tracheal rigidity associated with dysphagia and false routes [21]. In addition, the arteria lusoria can also be revealed by the extension of aortic dissection or by peripheral arterial embolism.

A meta-analysis by Polguj et al. found the most commonly reported symptoms related to compression of adjacent structures by an aberrant right subclavian artery to be dysphagia (71.2%), dyspnea (18.7%), retrosternal pain (17.0%), cough (7.6%), and weight loss greater than 10 kg over a six-month period (5.9%) [15]. Among the less common symptoms, stomachache, back pain, and numbness of the right upper limb were reported. The mean age of the onset of symptoms was 49.9 ± 19.4 years for the whole group (data shown as mean ± standard deviation). However, the mean age according to gender was 44.9 ± 18.1 years for males and 54.0 ± 19.6 years for females. This difference was statistically significant [15].

Dysphagia also frequently occurs in elderly patients, for which four mechanisms have been proposed: increased rigidity of the trachea leading to easy compression of esophagus, aneurysm formation, presence of Kommerell's diverticulum, elongation of the aorta, the coexistence of an aberrant artery with a truncus bicaroticus, or a close origin of common carotid arteries from the arch of the aorta [22–25].

To the angiographer who uses the right axillary, brachial or radial approach to the ascending thoracic aorta, the arteria lusoria is also a clinically important element. The presence of an ARSA is suspected in cases in which catheterization of the ascending aorta proves difficult. Using the right radial approach, access to the ascending aorta is usually easy [11]. Previous studies indicate that only 60% of such cases were successfully performed by transradial approach in the setting of AL [26]. This variant makes the right transradial route difficult to approach the ascending aorta, as it requires the catheter to curve back to reach the aortic root [26, 27]. However, the repeated entry of the guide wire from the right subclavian artery to the descending aorta rather than the ascending aorta should indicate this possibility. Thus, angiography can prove to be very challenging in the presence of an arteria lusoria [11, 26, 27].

Finally, the inferior right recurrent laryngeal nerve is an asymptomatic variation anomaly, which can be an important obstacle and be seriously damaged during cervicotomy, thyroid, and parathyroid surgery. In such cases, the inferior right recurrent laryngeal nerve is a classic risk and must be eliminated by location and routine dissection of the nerve [28–30]. This is of particular importance when the diagnosis concerns an asymptomatic neural anomaly discovered by dissection or a vascular anomaly whose symptoms are very variable [30].
