In hemodialysis patients, stenosis or obstruction of central veins including subclavian vein, cephalobrachial vein and superior vena cava can cause serious clinical symptoms and affect the use of hemodialysis access and its lifespan, which is a difficult problem in clinical practice. From July 2006 to July 2008, 13 cases were admitted to our department, and the experience and treatment effects are reported as follows. 1. Data and Methods 1.1 General Data In this group, there were 9 male and 4 female cases with an average age of 60.31±10.42 years (43~73 years). The average time of hemodialysis access establishment was 27.15±23.42 months (8 months~96 months), 7 cases in the right upper limb, 6 cases in the left upper limb, 1 case of artificial vascular loop endovascular fistula in the forearm brachial artery-median vein, 10 cases of cephalic vein-radial artery end lateral autogenous arteriovenous access in the wrist, and 2 cases of brachial artery or proximal radial artery-median vein autogenous arteriovenous access in the elbow. 13 cases had previous history of ipsilateral internal jugular vein or Among the 13 cases, 8 cases (61.54%) had previous history of intubation of the ipsilateral internal jugular or subclavian vein, and 5 cases (38.46%) had no history of intubation. 1.2 Clinical manifestations The average duration of disease was 5.90~6.39 months (10 days~2 years). 13 cases had different degrees of swelling of the affected upper limbs, including 4 cases of subcutaneous soft tissue thickening, 4 cases of orange peel-like skin changes, 2 cases of forearm skin ulcers, 12 cases of superficial venous dilatation and varicosities in the chest wall, scapula, axilla or neck, and 1 case of ipsilateral facial swelling; all cases had the function of arteriovenous access, access In all cases, varicose veins and tumor-like dilatation in the access area were present in 8 cases, and the venous pressure was increased during hemodialysis in 9 cases. 1.3 Diagnosis and treatment All cases in this group were clearly diagnosed by venography. Firstly, the superficial vein of upper limb is punctured for imaging, and in case of suspicious stenotic lesion, the vein is cannulated to the lesion site through your vein, cephalic vein or transfemoral vein, and the pressure gradient before and after the stenotic lesion can be measured to clarify the nature, location and scope of the lesion. Conservative or surgical treatment is chosen according to the symptoms and imaging results. 2.1 Results 2.1 Venography results showed 1 case of bilateral lesion of right cephalobrachial vein and left subclavian vein stenosis; 12 cases of unilateral lesion, including 4 cases of occlusive lesion, 2 cases each of subclavian vein and cephalobrachial vein occlusion; 8 cases of stenotic lesion, all of which were short segmental stenosis of 1~3 cm, 3 cases of cephalobrachial vein stenosis, 5 cases of subclavian vein stenosis, and 2 cases of unilateral 2 stenotic lesions. At the distal end of the stenotic or occlusive lesions there were varying degrees of anomalous collateral venous opening, either through the internal jugular vein, contralateral subclavian vein reflux, or through collateral branch compensation. The mean venous pressure gradient before and after the stenosis site was 12 cmH2O. 2.2 Treatment results Two cases were treated conservatively. Hemodialysis access closure with removal of the arteriovenous access anastomosis and reconstruction of the artery was performed in 6 cases. Balloon catheter dilation (PTA) was performed in 5 cases (see Table 1 for details) and was successful in 3 cases, with the appropriate balloon (Cordis, 2 balloons of 10*40mm and 1 balloon of 15*40mm) selected according to the length of the lesion and the diameter of the distal and proximal veins, and the dilation pressure was 10-14 atm (Figure 3). 2 cases failed PTA, with the guidewire unable to pass through the occluded segment and the technical operation failed. The three successful PTA cases were followed up for an average of 8.33 months, of which two were patulous and one recurred 4 months after the operation, so an ipsilateral subclavian vein-contralateral subclavian vein artificial vessel (6mm*20cm) bypass was performed. two cases were patulous after artificial vessel diversion. The time (until the follow-up date) was 6 and 7 months, respectively. In all treated cases, the swelling of the limb was significantly relieved and the ulcer healed. 3. Discussion 3.1 Incidence and etiology The incidence of central venous stenosis (CVS) has been inconsistently reported, with Chemla reporting a 1.6% incidence of CVS in 640 hospitalized hemodialysis patients [1]; Mickley reporting a 2.2% incidence (9/401) [2], while others have reported an incidence of CVS of up to 22% to 29% [3,4]. Central venous cannulation is the most important cause of CVS, and Forauer [5] observed proliferation of venous smooth muscle cells at the cannulation site (90 days), thickening of the venous wall, and adhesion of the catheter to the wall. It is now believed that mechanical injury from cannulation results in a series of lesions such as endothelial damage, secondary inflammatory reaction, endothelial proliferation, and fibrosis, leading to local stenosis of the central vein. The incidence of stenosis after subclavian vein cannulation is high, and the left jugular vein converges into the right atrium at a greater angle than the right, so the left side of the cannula is more prone to CVS. infection, repeated cannulation, and prolonged retention are all factors that increase CVS, and the diameter, material, and location of the cannula are also influential factors [6]. In our data 61.54% of the patients had a history of internal jugular vein cannulation. Therefore, hemodialysis via central venous cannulation, especially subclavian vein cannulation, should be avoided and minimized. The literature reports about 5-10% of CVS cases in hemodialysis patients without a history of central venous cannulation [7], which was 38.46% in our data. The patient did not have a history of clavicle fracture or local mass compression, and it is thought that the onset of the disease may be related to the following factors: (1) anatomical factors: the cephalic brachial vein is located between the sternum and the aortic arch and its bifurcation, and part of the cephalic brachial vein crosses in front of the innominate artery and is vulnerable to local stenosis due to compression by the dilated artery [7,8]. When the subclavian vein crosses the thoracic outlet from the axilla into the chest, it can be compressed by the surrounding bones, muscles, tendons, ligaments and other tissues and cause stenosis, such as cervical ribs, excessive length of the transverse process of the 7th cervical vertebra, malformation of the 1st rib or bifurcation of the clavicle, exophytic warts, spasm and fibrosis of the oblique muscles, sagging shoulder girdle and excessive abduction of the upper limbs can cause narrowing of the thoracic outlet, resulting in thoracic outlet syndrome [9]. (ii) The arteriovenous hemodialysis access exposes the veins to continuous high flow, which increases shear stress, platelet aggregation, and leads to endothelial proliferation, especially at the site of venous bifurcation, and turbulent flow at the valve site adds to the hemodynamic changes. oguzkurt [7] found a high flow condition in the hemodialysis access with CVS, with a flow rate of 1440 ml/min in the arteriovenous access at the wrist, much higher than The flow rate of the arteriovenous access at the wrist was 1440 ml/min, much higher than the normal 650 ml/min, and the flow rate of the arteriovenous access at the elbow was more than 2000 ml/min, which also indirectly proves that high flow rate is one of the causes of CVS. 3.2 Clinical manifestations and diagnosis In normal population, chronic central venous obstruction can be compensated by a large number of collateral branches in chest wall, neck and mediastinum, but for hemodialysis patients, due to the presence of hemodialysis access, the blood flow in their limbs is more than 10 times of normal, so even stenotic lesions can produce obvious venous hypertension, unbearable swelling sensation in upper limbs, skin pigmentation, even ulceration and necrosis; chest wall, In case of cephalic or superior vena cava lesions, the swelling can involve the face and neck, breast, chest wall; the forearm hemodialysis pathway is distorted and tumor-like dilated. At the same time, swelling and venous hypertension increase the difficulty of hemodialysis puncture, easily cause bleeding and hematoma, increase the chance of infection, increase the chance of hemodialysis access thrombosis, and affect the use and life of hemodialysis access. Patients with venous hypertension in the upper extremities should be given early attention. Since the central veins are located behind the chest and clavicle, especially the cephalobrachial vein and the subclavian vein in the proximal 1/3 section, which are not easily displayed clearly by color ultrasound, venography is the preferred diagnostic method to diagnose venous stenosis and occlusion. Compression of the arteriovenous access anastomosis and superficial venipuncture angiography of the upper extremity initially screens for the cause of limb swelling, and if there is stenosis or occlusion of the central vein, imaging changes of interruption of the central venous trunk and opening of the surrounding collateral branches are seen. Trans-stenosis trunk venography provides a clearer picture of the site, degree and extent of stenosis and can help in the diagnosis by changes in the pressure gradient distal and proximal to the stenosis. In addition, CTV and MRV help to show the tissue structure around the vein and can exclude other factors such as exogenous compression, but further exploration of the imaging conditions is needed for more accurate visualization. 3.3 Treatment The ideal treatment for CVS lies in both relieving the symptoms and keeping the hemodialysis access open. In 1984, Glanz [10] pioneered the use of PTA to treat CVS and dilate stenotic lesions, which is less invasive and provides both symptomatic relief and maintains patency of the hemodialysis access, but has poor long-term efficacy due to postoperative restenosis, with a one-year patency rate of less than 40%, requiring repeated PTA. For asymptomatic CVS, PTA instead accelerates the progression of stenotic lesions, and therefore PTA treatment is not advocated [11]. This is also true for the treatment experience of our three PTA cases, where the stenotic segment was severely fibrotic and difficult to dilate, requiring higher pressure, and one case was restenosed after 4 months with recurrence of symptoms. Therefore, a part of scholars advocate the simultaneous placement of stents to prevent restenosis after PTA, and most reports show that the one-year primary patency rate of stent implantation is better than that of balloon dilation alone, 49%-71%. However, restenosis still exists, and 2-year primary and secondary patency rates are unsatisfactory [2,12]. Therefore, another part of scholars suggested stenting only for cases with elastic retraction after PTA and still existing severe stenosis or recurrent restenosis. Surgical reconstruction has a higher patency rate than endoluminal treatment, with a one-year patency rate of 80% to 90% [2], but it is highly invasive, especially for reconstructive venous or venous patch surgery into the chest, with high postoperative complications and mortality. Extra-anatomic bypass surgery such as subclavian vein- internal jugular vein bypass [13], subclavian vein-contralateral subclavian vein bypass, and subclavian-saphenous vein bypass is an alternative procedure to reduce surgical trauma, but the other central vein as an outflow tract may be affected in the long term due to proliferation of the anastomotic lining, and the long-term patency rate of surgical treatment is subject to bulk clinical follow-up. Hemodialysis access ligation is an effective negative method for symptom relief. In patients requiring long-term hemodialysis, hemodialysis access is equivalent to their lifeline and should be preserved rather than closed when possible. In conclusion, the clinical symptoms of central venous stenosis in hemodialysis patients are severe and affect the use and longevity of hemodialysis access, phlebography remains the preferred diagnostic method, while the long-term efficacy of treatment remains to be further explored, and minimizing hemodialysis cannulation via central veins, especially subclavian veins, is an effective preventive method.