Superior vena cava
Superior vena cava is a short thin-walled vein with a diameter of 20 to 25 mm, located in the anterior mediastinum. Its length on average varies from five to eight centimeters. The superior vena cava refers to the veins of the systemic circulation and is formed by the fusion of two (left and right) brachiocephalic veins. It collects venous blood from the head, upper chest, neck, and arms and flows into the right atrium. The only inflow of the superior vena cava is the azygos vein. Unlike many other veins, this vessel has no valves.
The superior vena cava is directed downward and enters the pericardial cavity at the level of the second rib, and slightly below flows into the right atrium.
The superior vena cava is surrounded by:
- Left - the aorta (ascending part);
- On the right is the mediastinal pleura;
- In front - the thymus (thymus gland) and the right lung (mediastinal part, covered with pleura);
- Behind - the root of the right lung (anterior surface).
Superior vena cava system
All vessels included in the superior vena cava system are located close enough to the heart, and during relaxation are under the influence of the suction action of its chambers. The chest also acts on them during breathing. Due to these factors, a fairly strong negative pressure is created in the superior vena cava system.
The main tributaries of the superior vena cava are the valveless brachiocephalic veins. They also always have very low pressure, so there is a risk of air getting in if they are injured.
The superior vena cava system is composed of veins:
- Neck and head areas;
- Chest wall, as well as some veins of the abdominal walls;
- Upper shoulder girdle and upper limbs.
Venous blood from the chest wall enters the inflow of the superior vena cava - the azygos vein, which draws blood from the intercostal veins. The azygos vein has two valves located in its mouths.
The external jugular vein is located at the level of the angle of the lower jaw under the auricle. This vein collects blood from tissues and organs located in the head and neck. The posterior ear, occipital, suprascapular and anterior jugular veins flow into the external jugular vein.
The internal jugular vein originates near the jugular foramen of the skull. This vein, together with the vagus nerve and the common carotid artery, forms a bundle of vessels and nerves in the neck, and also includes the veins of the brain, meningeal, ocular and diploic veins.
The vertebral venous plexuses, which are part of the superior vena cava system, are subdivided into internal (passing inside the spinal canal) and external (located on the surface of the vertebral bodies).
Compression syndrome of the superior vena cava
The syndrome of compression of the superior vena cava, manifested as a violation of its patency, can develop for several reasons:
- With the progression of the development of cancer. With lung cancer and lymphomas, the lymph nodes are often affected, in the immediate vicinity of which the superior vena cava passes. Also, metastases of breast cancer, soft tissue sarcomas, melanoma can lead to obstruction of patency;
- Against the background of cardiovascular failure;
- With the development of a retrosternal goiter against the background of thyroid pathology;
- With the progression of certain infectious diseases, such as syphilis, tuberculosis and histioplasmosis;
- In the presence of iatrogenic factors;
- With idiopathic fibrous mediastinitis.
The syndrome of compression of the superior vena cava, depending on the causes that caused it, can progress gradually or develop quickly enough. The main symptoms of the development of this syndrome include:
- Puffiness of the face;
- Cough;
- Convulsive syndrome;
- Headache;
- Nausea;
- Dizziness;
- Dysphagia;
- Change in facial features;
- Drowsiness;
- Shortness of breath;
- Fainting;
- Chest pain;
- Swelling of the veins of the chest, and in some cases of the neck and upper extremities;
- Cyanosis and congestion of the upper chest and face.
To diagnose the syndrome of compression of the superior vena cava, as a rule, an x-ray is performed, which allows to identify the pathological focus, as well as to determine the boundaries and extent of its distribution. In addition, in some cases, carry out:
- Computed tomography - to obtain more accurate data on the location of the mediastinal organs;
- Phlebography - to assess the length of the lesion focus and carry out differential diagnosis between vascular and extravascular lesions.
After the conducted studies, taking into account the rate of progression of the pathological process, the question of drug treatment, chemotherapy or radiation therapy or surgery is being decided.
In cases where the cause of vein changes is thrombosis, thrombolytic therapy is performed, followed by the appointment of anticoagulants (for example, sodium heparin or therapeutic doses of warfarin).
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