OBJECTIVE: To investigate the value of endoluminal treatment of subclavian aneurysm. METHODS: Eight cases of subclavian aneurysm were treated intraluminally from January 2012 to March 2014, including six cases of true aneurysm and two cases of pseudoaneurysm. five cases were treated with overmolded stents, one case with overmolded stents + bare stents, one case with descending aortic stents plus spring embolization, and one case with multilayer bare stents. RESULTS: All 8 cases completed the procedure successfully without serious complications, with an average operative time of 69 min and an average bleeding volume of 30 ml. 8 cases were followed up for 6 to 26 months, with an average of 15 months. 7 cases had complete thrombosis of the aneurysm lumen, and 1 case with multilayer bare stent was followed up for 12 months, with endoleaks in the aneurysm lumen but no increase in the aneurysm diameter. Conclusion: Endoluminal technique is a feasible method for treating subclavian aneurysm, and the procedure should be selected based on the size of the aneurysm and the spatial location with the aorta, carotid artery, and vertebral artery. Subclavian artery aneurysm (SAA) is rare clinically, and the treatment is mostly chosen from traditional open surgery. However, due to the obstruction of the clavicle, the arteries and veins and nerves on the aortic arch are crisscrossed, making the surgery difficult and the surgical risks and complication rates are high. In recent years, with the development of endoluminal techniques and materials, more and more SAA cases are choosing endoluminal treatment. From January 2012 to March 2014, 11 cases of SAA were admitted to our department, among which 8 cases chose intracavitary treatment because of the risk of traditional open surgery, which are reported below. 1. Methods Six cases were selected for luminal repair with a laminated stent because of sufficient riveting distance between the proximal and distal ends of the tumor. The right femoral artery was punctured and a guidewire and catheter sheath were implanted. Intravenous 5000 U of heparin was administered systemically. The guidewire and catheter were used in conjunction with a carotid artery guiding catheter to access the aortic arch, with access to the subclavian artery selected. Case 1 was difficult to select the distal end of the aneurysm lumen because of the twisted vessel and large lumen, so the brachial artery was punctured and the guidewire was captured with a captive device to establish working access. In case 2, a ball expansion stent (Biotronic 8×38 mm) was reimplanted due to residual stenosis within the stent. Postoperatively, enteric aspirin 100 mg and clopidogrel sulfate tablets (Bolivar) 75 mg were given as antiplatelet therapy, which was changed to aspirin after 6 months to continue antiplatelet therapy. In one case, thoracic aortic stenting combined with embolization of the left subclavian artery was chosen because the aneurysm was adjacent to the aorta. The right femoral artery was dissected and the left brachial artery was punctured. After intravenous heparinization, a thoracic aortogram was performed, the openings of the left carotid and left subclavian arteries were identified, the diameter of the thoracic aorta at the opening of the carotid artery was measured, and a suitable overlapping stent was selected. The anterior edge of the stent overlay was positioned at the left edge of the left carotid artery, and the overlay stent was released. Two 8 mm diameter spring plugs were placed distal to the aneurysm. Postoperatively, aspirin 100 mg antiplatelet therapy was given. In one case, because the dominant vertebral artery originated from the lumen of the aneurysm, a multilayer bare stent was chosen to avoid symptoms of posterior circulation ischemia due to closure of the vertebral artery. Intravenous 5000 U heparin was used for systemic heparinization. The guidewire and catheter were used with a carotid artery guiding catheter to enter the aortic arch and selected to enter the subclavian artery. Imaging was performed to assess the aneurysm and proximal and distal artery diameters, and a stent (Smartcontrol 8-80 mm × 2) was selected for overlapping release. Postoperative antiplatelet therapy with enteric aspirin 100 mg and Bolivar 75 mg was administered, which was changed to aspirin for continued antiplatelet therapy after 6 months. 2. Results Six cases of intraluminal repair with overlapping stents (one of them was overlapping stent + bare stent), one case of thoracic aortic stent combined with spring embolization, and one case of multilayer bare stent. There was no perioperative death, acute arterial thrombosis or cardiovascular accidents. No pseudoaneurysm, arteriovenous fistula or large hematoma occurred at the puncture site. In seven cases, intraoperative imaging showed complete thrombosis of the aneurysm lumen, and in one case, an endoleak was seen in the aneurysm lumen of a multilayer bare stent. eight cases were followed up, and no aneurysm rupture or surgery-related death or disability occurred, and all stents were patent. one case had decreased mobility of the left upper extremity after thoracic aortic stenting with spring embolization, and the symptoms were largely relieved after 6 months. The CTA of the patient with multilayer bare stent showed that the aneurysm lumen was still not completely thrombosed at 6 and 12 months after surgery, but the aneurysm did not expand further. It may be related to atherosclerosis, thoracic outlet syndrome, aortitis, degenerative necrosis of the middle layer of the artery, infection, trauma and other causes, with atherosclerosis being more common. Patients with subclavian aneurysms may have no obvious symptoms and may be unintentionally detected by other examinations. Some patients visit the clinic for a mass in the neck or supraclavicular fossa, and may have symptoms such as difficulty swallowing, numbness and weakness of the upper limbs. If a thrombus forms and dislodges and obstructs the distal artery, it may cause ischemia in the upper limbs; if the tumor ruptures, hemorrhagic shock may be life-threatening. Color Doppler ultrasound is useful for screening of SAA, but this test is not exact due to the obstruction of the sternoclavicular joint. Arteriography can show the condition of the aneurysm and branch arteries, but it is limited by the presence of a wall clot in the aneurysm, which can only show the blood flow in the aneurysm lumen. MRA and CTA can not only clearly show the intraluminal flow, but also accurately show the extent of the aneurysm and its relationship with the surrounding tissues, which can guide the treatment plan. The classic surgical treatment strategy for SAA is lumpectomy, in situ or bypass arterial reconstruction. However, due to the obstruction of the clavicle and the complex anatomical relationship with adjacent tissues, there are many adhesions between the aneurysm and the surrounding tissues, which makes it very difficult to separate and reveal the SAA, and the local operation space is narrow, making the surgery very difficult. Endoluminal treatment has the advantages of simple operation and small trauma, and has advantages that cannot be matched by surgery. However, the choice of endoluminal treatment requires consideration of the spatial adjacency between the SAA and the vertebral artery, carotid artery and aorta. In our group, six cases were treated with endoluminal repair using a laminated stent. This procedure was chosen because the proximal aneurysm neck of the SAA was in adequate condition and the distal end had sufficient riveting distance. In all cases, the proximal end of the aneurysm was more than 1 cm from the aortic arch or the opening of the right common carotid artery, and in four cases, the ipsilateral vertebral artery was closed in order to extend the distal riveting area. Intraoperatively, it should be noted that SAA often occurs at the beginning of the subclavian artery, where the artery is often tortuous, and a flexible overmolded stent should be selected as much as possible. If a stent with high support but poor flexibility is chosen, there is a risk of stent fracture, resulting in treatment failure. Because of the limited proximal aneurysm neck, precise intraoperative positioning is critical to successful treatment. The tumor is brought to the center of the display, the most suitable projection angle is sought, the local image is magnified, and the location of the subclavian artery opening is clearly marked. Second, the affected vertebral artery should be preserved as much as possible intraoperatively. If the vertebral artery must be closed, a preoperative subclavian and vertebral arteriogram must be performed to carefully evaluate the artery. The incidence of neurological complications from closure of the relatively healthy vertebral artery on one side is 8%, and the incidence is higher if the contralateral vertebral artery is slender or diseased. Therefore, if closure of one vertebral artery is required, a vertebral artery balloon block test must be completed to avoid blocking the affected vertebral artery and causing inadequate blood supply to the vertebrobasilar artery. Endoluminal treatment of the SAA at the beginning of the right subclavian artery should be performed with caution to avoid blockage of the right carotid artery flow by the proximal end of the stent. Such stent delivery systems usually require sheaths above F8, and brachial artery access is prone to puncture-related complications; therefore, femoral artery access is generally preferred. Conformal angiography is also beneficial for superior arch artery as well as intracranial arteriography to assess intracranial anterior and posterior circulation compensation. In some cases with severe distortion or large aneurysmal space where the guidewire is difficult to select to the distal end of the aneurysm, a dual approach can be used, where the guidewire is directed to the brachial artery through a captive device and superrigid guidewire access is established to support the delivery system of the stent. In cases where the aneurysm is close to the aortic arch, the proximal aneurysm neck is not long enough to use a conventional overmolded stent, which not only has incomplete isolation but also has an unstable anchorage, which can easily cause displacement and lead to treatment failure. In this case, a thoracic aortic overmolded stent can be chosen to cover the beginning of the subclavian artery, while spring bolus embolization prevents the reverse blood flow from entering the aneurysm lumen to achieve the purpose of closing the aneurysm lumen. It should be noted that intraoperative closure of the subclavian artery opening may cause acute ischemia of the vertebral artery, and preoperative evaluation of the posterior circulation is also required. According to Gu Yongquan et al, if the vertebral artery on one side is not the dominant artery, the subclavian artery on that side can be directly blocked; if it is the dominant artery, it can also be directly blocked if the basilar artery loop can be assessed to be patent preoperatively. In practice, we completed a preoperative subclavian artery balloon block experiment to avoid the occurrence of ischemic symptoms in the posterior circulation as much as possible. Due to the large number of branch vessels compensating in the neck and shoulder, clinical cases of acute upper limb arterial ischemia after subclavian artery closure are not rare, and most of them only have upper limb weakness and pulse disappearance, and acute necrosis is rare. With the passage of time, the compensatory capacity is increasing and the limb strength can be gradually restored. Case 3 was treated with thoracic aortic overmold stenting with spring embolization, and postoperative decreased activity tolerance of the affected upper extremity was observed, and the symptoms were basically relieved after six months of follow-up. Case 5 was treated with a multilayer bare stent technique. In this patient, the vertebral artery originated from the aneurysmal cavity and was relatively dominant. Because of the concern for posterior circulation ischemia due to closure of the affected vertebral artery, we applied the concept of multilayer bare stenting and gave overlapping placement of two bare stents to complete the endoluminal treatment. Multi-layered bare stents are an emerging technique, and clinical work has shown that when an aneurysm is isolated by several layers of bare stents, the blood flow within the aneurysm lumen slows down significantly, and most aneurysms thrombose and shrink during follow-up. Multilayer bare stents were first used in visceral aneurysms, and have achieved relatively good results in the treatment of aneurysms involving or immediately adjacent to visceral arteries, and have been applied to subclavian aneurysms with good results. Multi-layer bare stents induce luminal thrombosis by reducing the blood flow into the aneurysm lumen, while maintaining laminar flow within the stent, allowing luminal thrombosis on the basis of maintaining patency in the stent and branch vessels. In practice, the number of layers of bare stents is not strictly defined, and the mesh density is considered to have been achieved when there is a significant decrease in intraluminal flow velocity under DSA. The time to thrombosis may be related to the morphology of the lumen, the collateral vessels within the lumen, and the individual coagulation status. It is generally accepted that if there is still blood flow in the tumor cavity after 6 months, the treatment is considered to have failed. Currently, there are finished stents (Cardiatis multilayer bare stents) available internationally, but they are not yet available in China. In this case, we overlapped and released 2 bare stents, and intraoperatively we found that the blood flow rate in the tumor cavity decreased significantly. Since this technique is not yet available, the study of its mechanism is still superficial, and the long-term results need to be followed up. In conclusion, endoluminal treatment of subclavian aneurysms is an option, and the choice of the specific modality needs to take into account the size of the aneurysm and its spatial location in relation to the aorta, carotid artery, and vertebral artery.