First of all, we need to understand the concept of “superior vena cava”. The blood in our body is pumped from the left ventricle, through the aorta, and to the arterial branches. The arterial blood is exchanged for oxygen, carbon dioxide and other substances in the capillary network of tissues throughout the body and becomes venous blood. The peripheral venous blood gradually pools to larger veins, and finally all the venous blood in the upper half of the body pools into one large vein. This vein is the superior vena cava, and correspondingly, the large vein that collects venous blood from the lower half of the body is the inferior vena cava. The superior and inferior vena cava are connected to the right atrium, which sends venous blood to the right atrium. The blood then completes the entire circulation in the heart and lungs. The superior vena cava is the main artery of venous blood in the body, so to speak, and all the venous blood in the upper part of the body on all the “paths” eventually passes through this main artery to reach its destination, the right atrium, and if this main artery is “blocked” for any reason If this main artery is “blocked” for various reasons, there is no way for blood to flow back to the right atrium smoothly. A small portion of the blood can return to the right atrium indirectly through various “pathways”, creating a collateral circulation. Superior vena cava syndrome is a group of syndromes in which the main clinical manifestation is the obstruction of blood return to the superior vena cava system and the formation of collateral circulation due to the complete or partial obstruction of the superior vena cava for various reasons. There are many causes of superior vena cava “blockage”, basically it can be divided into two categories: malignant and non-malignant, of which malignant accounts for about 80%-90%, the most common cause is bronchial lung cancer. The superior vena cava travels between the left lung and the right lung, and the left lung and the right lung are like the “high mountains” on both sides of the “big river” of the superior vena cava. If lung cancer occurs, the ground of the high mountains will be enlarged, which will naturally narrow the river, and the upstream water will not pass smoothly. Non-malignant causes mainly refer to thrombosis in the superior vena cava. Due to the increased clinical use of devices such as central venous catheters and pacemakers, the number of superior vena cava syndromes caused by thrombosis is gradually increasing. Devices placed in the superior vena cava for long periods of time can damage the lining of the vessel and lead to thrombosis; thrombosis is like having a large number of cars blocking the main road, so other cars cannot pass. So, what kind of patients may have superior vena cava syndrome? Due to the obstruction of venous return in the upper body, blood pools in the head and neck, which often manifests as edema and venous filling and expansion in the face, neck or upper chest. Blood return is reduced, oxygen supply is inadequate, and the patient may also have difficulty breathing. Some patients may also experience cough, hoarseness, and headache. Superior vena cava syndrome due to causes such as malignancy or rapidly progressing thrombosis often becomes a very aggressive emergency due to rapidly progressing respiratory distress and cerebral edema in a short period of time. Enhanced CT of the chest has a very important role in the diagnosis of this disease, not only to understand its etiology, but also to observe the site and extent of obstruction and the collateral circulation, and is now widely used in clinical practice. If the cause is suspected to be malignant, a biopsy is also needed to obtain a pathological diagnosis. Biopsy methods include fiberoptic bronchoscopy, CT-guided puncture biopsy or mediastinoscopy. The treatment of superior vena cava syndrome depends on the severity of its symptoms and its etiology. Currently, with the rapid development of endovascular stents, endovascular stenting of the superior vena cava has become the treatment of choice for the symptomatic treatment of superior vena cava syndrome. In simple terms, this intervention involves entering the vein through a small incision in the skin, which in turn reaches the obstructed superior vena cava and places a stent after dilating the vein, which then supports the vein and allows blood to flow back smoothly. In other words, the stent is used to widen the main artery of the blockage, and the vehicle is naturally cleared. This interventional treatment means can rapidly relieve the symptoms of venous obstruction compared with radiotherapy and chemotherapy, and has the characteristics of less trauma and fewer complications compared with conventional surgery, so it is widely used for superior vena cava syndrome caused by benign and malignant diseases with acute onset, poor radiotherapy or no indication for surgery. After the interventional treatment, appropriate treatment such as radiotherapy, chemotherapy and surgery can be performed according to the specific cause. In conclusion, superior vena cava syndrome is a critical emergency due to malignancy or thrombosis, and endovascular stenting can safely and rapidly relieve its symptoms and is the first choice for symptomatic treatment.