Proximal right subclavian artery aneurysms: A case report and review of the literature

Introduction

Among all peripheral arterial ¹ aneurysms, isolated genuine aneurysms of the subclavian artery are among the least common. When these aneurysms are large enough to elicit compressive symptoms or when traditional aneurysm consequences like rupture, thrombosis, or distal embolisms have occurred, they are automatically treated surgically. Asymptomatic aneurysms in the middle or distal part of the subclavian artery are regarded to have malignant potential or other concerns, and surgical treatment is advised. However, the natural history of these aneurysms is not well understood due to their rarity. Small, asymptomatic intrathoracic subclavian aneurysms, however, have an undetermined course. Here, we describe a patient who underwent conservative treatment for a tiny, asymptomatic aneurysm in his right proximal subclavian. We will closely monitor the condition for a full year and anticipate finding no growth or indications of problems. Review and discussion of English literature are presented.

Case report

Our hospital’s right subclavian artery aneurysm was discovered during the examination, prompting the admission of a 68-year-old male patient to the vascular surgery unit. He came to our department for additional assessment at the doctor’s recommendation. Throughout the entire process, the patient had no symptoms or indicators that interfered with normal living. The patient has had hypertension for almost 20 years, and their highest recorded systolic blood pressure was 160 mmHg. Amlodipine and other antihypertensive medications often allow for blood pressure regulation at a level of about 140 mmHg. The patient has had a coronary artery stent implanted and has a history of coronary heart disease dating back more than 10 years. After surgery, continue taking atorvastatin 20 mg/d and 100 mg of aspirin every day. The patient has already undergone endovascular aneurysm repair (EVAR) surgery for “abdominal aortic aneurysm.” The patient has taken Ezemeb 10 mg/d orally for a long time and has a history of hyperlipidemia dating back more than 10 years. The patient has been drinking for more than 40 years and has smoked for more than 30 years, averaging more than 20 cigarettes per day. The patient further stressed his history of leek, onion, and garlic allergies as well as the abdominal aortic aneurysms that his parents and two younger siblings had experienced in the past. The routine physical examination after admission did not find a mass in the right supraclavicular region, nor did it show neurological symptoms and dyspnea due to aneurysm compression. The patient underwent a Doppler ultrasound examination. During the Doppler procedure, the bilateral carotid intima thickening and multiple calcified plaques were found, but on a view of the subclavian artery, a proximal right subclavian artery aneurysm was noted. The patient subsequently underwent Computed tomography (CT) and Computed tomography angiography (CTA). The CTA scan verified the findings of a 1.95-cm proximal right subclavian artery aneurysm (Figure 1). Other views of a three-dimensional reconstruction from the CTA confirmed the findings of a fusiform proximal right subclavian artery aneurysm, excluding a stenosis at the initial segment of the subclavian artery, no other obvious arterial abnormalities were detected (Figure 2(a)–(c)). The reconstruction of CTA in Multi-planar reconstruction (MPR) mode showed the aneurysm more intuitively (Figures 3 and 4). The patient was subsequently determined to be hospitalized and resolved without further treatment or accepted a surgery. After admission, we took the necessary steps to get the patient ready for surgery. The patient has been taking antiplatelet medications for a long time, so we did not administer the pre-operative load dose or substitute other medications. In addition to the tests mentioned above, tolerance assessment tests such as echocardiography and magnetic resonance imaging of the head did not reveal any contraindications to surgery. In comparison to their pre-admission symptoms, the patients’ clinical symptoms did not significantly change. We therefore limited our action to controlling the patients’ blood pressure, blood sugar, and blood lipid levels. After communicating with the patients and their families about the surgical plan, the patient decided not to consider surgery, and the plan for conservative treatment and very close observation was outlined. We told patient that he should be observed clinically every 3 months, with a CT scan performed every 6 months for a year; thereafter, clinical follow-up every 6 months with yearly CT. Currently, we have conducted the patient’s first telephone follow-up 3 months after the operation and the first carotid ultrasound examination following discharge. The findings revealed that the aneurysm was free of any symptoms, such as enlargement or thrombosis. After the patient is checked on for the second time in 3 months, a CT scan will be done to provide a more thorough assessment.OPEN IN VIEWER

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Figure 2.

(a) CTA three-dimensional reconstruction in a right sagittal position view reveals a fusiform proximal right subclavian artery aneurysm, the right vertebral artery originates from the posterior wall of the aneurysm(white arrow shows the aneurysm, and the black arrow shows a stenosis at the beginning of the subclavian artery). (b) CTA three-dimensional reconstruction in a right/posterior position view reveals a fusiform proximal right subclavian artery aneurysm. (c) CTA three-dimensional reconstruction in a right/anterior position view reveals a fusiform proximal right subclavian artery aneurysm.

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Figure 3.

Sagittal reconstruction view of the CTA scan delineating the right subclavian artery aneurysm.

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Figure 4.

Coronary reconstruction view of the CTA scan delineating the right subclavian artery aneurysm.

Discussion

Over nearly a century, there were only 400 reported cases of subclavian aneurysms, which are clinically uncommon and mostly affect the right side. ¹ This reveals how subclavian aneurysms are rare among all the aneurysms. Zhang, ² Nicholas, ³ and their colleagues found that right subclavian artery aneurysms (SAAs) were more common than left and were found more often in males, atherosclerotic etiology seems to be more closely related to the occurrence of aneurysms. Besides, the proximal portion of the subclavian artery has the majority (39%) of aneurysms, whereas the intermediate and distal segments contain 25% and 24%, respectively. ¹

True aneurysms (excluding pseudoaneurysm caused by Truman and dissecting aneurysms) have multiple etiologies. Atherosclerosis and Thoracic outlet syndrome (TOS) are by far the most common reported cause of these aneurysms in modern medicine.^4–6 Other causes include cystic medical necrosis, Marfan’s syndrome, Ehlers-Danlos syndrome, Turner’s syndrome, mycotic infection, neurofibromatosis, Behcet disease, syphilis, and tuberculosis.^1,4,7–11 Recently, there have been reports of Larsen syndrome and tumor-related hypermetabolic subclavian aneurysms.^12,13 In our case, excluding an obvious family genetic history, we were not able to find other etiology of this isolated right subclavian aneurysm. However, the diagnosis of congenital aneurysm cannot be made because the only conclusive evidence can come from the histologic investigation of the aneurysm itself. The symptoms may include aneurysm rupture-related pain, hoarseness from right aneurysm-compressed recurrent laryngeal nerve, dysphagia from esophageal compression, and stroke from thrombosis. Proximal subclavian aneurysms have a significant chance of rupturing, which could cause fatal bleeding.^14–16 However, this patient had no overt symptoms or warning signals, and the subclavian aneurysm was discovered by mistake during the examination.

The specific surgical approach used to treat a subclavian artery aneurysm depends on where it is located. These anatomical positions can be classified as extrathoracic and intrathoracic.^4,16 Here, we will focus on Intrathoracic ones.

Traditional treatment for intrathoracic SAAs within the anterior scalene muscle (the first and second segments of the subclavian artery) includes a high posterolateral thoracotomy on the left side or a median sternotomy on the right. After the aneurysm is removed, repair using an artificial blood artery is required ¹⁵ or when the proximal end of subclavian artery aneurysm is closed while descending aorta replacement is performed, subclavian artery revascularization is not required. ¹⁷ If the aneurysm is located on the left side and the aortic wall accumulates, we also need routine protection of the aortic arch. ⁴

Now, the open bypass surgery combined with intravascular stent hybridization technology has become the mainstream treatment, and the success rate and efficiency of this technology are significantly higher than traditional surgery.^1,2,15,18,19 If SAAs builds up in the vertebral artery in the right chest, the common carotid and vertebral arteries can each receive a stent so that they all open into the innominate artery, and then an axillary artery bypass can be performed. For left proximal SAAs, the left subclavian artery is often covered by an aortic stent on the left side of the chest, embolized with a coil, and subsequently bypass surgery using the axillary or carotid subclavian arteries is carried out. In 10 years, Wooster and his colleagues treated 10 cases of subclavian aneurysms, with nine patients receiving stent implants covering the subclavian artery to the proximal end of the descending branch of the thoracic aorta. One patient also received an aortic dissection stent that covered the entire descending branch of the thoracic aorta. PTFE and autologous subclavian artery transposition are used in the bypass surgery. To reduce the risk of leakage, all patients had distal vertebral artery embolization (Amplatzer II plug or ligation). ²⁰ Treatment of intrathoracic SAAs with the hybridization approach or endovascular stent in conjunction with coil embolization has also produced positive outcomes, according to Kochupura, Zhang and Li et al.^2,21,22

Conclusion

Two surgical techniques were developed for patients. The first involves performing a common carotid subclavian artery bypass while using a hybridized technique. In this minimally invasive approach, embolization with coils or a vascular plug of a proximal subclavian artery aneurysm (not involving the origin) is combined with subclavian artery transposition or carotid–subclavian bypass, avoiding placement of an endograft. ²³ The benefit of hybrid technology is that it lessens patient harm from catheter systems. Nervous system complications and the resulting signs of limb exhaustion and numbness pose the biggest risk following surgery. ²⁴ The second involves using only an endovascular procedure, using a large stent to completely cover the subclavian artery before using a small stent for splicing to complete the reconstruction of the vertebral artery. We used the flow-diverter stent principle because the patient’s vertebral artery comes from the aneurysm’s posterior wall, ensuring cerebral blood flow. Currently, it has been effectively used to treat subclavian aneurysms; Euringer et al. ²⁵ reported the outcomes of using a shunt stent in a case of bilateral subclavian aneurysms, and the stent was clear after 18 months of follow-up. According to the meta-analysis, flow-diverter stents had a satisfactory therapeutic impact on aneurysms. ²⁶ The high rate of internal leakage and susceptibility to fracture and deformation, in our opinion, are the major drawbacks of flow-diverter stents. The patient ultimately decided against surgery and went with conservative treatment, which is likewise a strategy but necessitates stringent and prolonged testing and follow-up. Since subclavian aneurysms are uncommon, the etiology, pathophysiology, clinical symptoms, and available technology all need to be taken into account when treating them. Although there is growing evidence for the benefits of hybridization technology, open surgery can occasionally produce results that are good. In any case, we should assess the viability of intravascular technology.