Lower vena cava

The lower vena cava – the wide vessel formed by merge of the left and right ileal veins at the level of the fourth or fifth vertebrae of lumbar department. Diameter of the lower vena cava varies ranging from 20 to 34 mm. Length of a chest part – 2-4 cm, belly 17-18 cm.

Structure of the lower vena cava

Vienna will be stirred in retroperitoneal space, behind internals, to the right of an aorta. It passes behind the upper site of a duodenum, behind a root of a mesentery and a head (top) of a pancreas and gets to a hepatic furrow, incorporating liver veins.

Passing through the opening of tendinous area of the same name of a diaphragm, the vein falls into the back area of a chest cavity. At the same time elastic, collagenic and muscle fibers of a wall of a vein are interwoven into a diaphragm wall.

Having reached a pericardium cavity, the vein gets into the right auricle. On the site of an entrance to the right auricle the vena cava is a little thickened. This vein has no valves.

Diameter of the lower vena cava changes during a respiratory cycle. At an exhalation the vein extends, and at a breath clenches. Change of diameter of the lower vena cava facilitates its recognition and differentiation from other large veins.

System of the lower vena cava

The system of the lower vena cava belongs to the most powerful system in a human body. About 70% of the general venous blood-groove fall to its share.

The system of the lower vena cava is created by the vessels collecting blood from an abdominal cavity, walls and bodies of a basin, the lower extremities.

This vein has parietal (pristenochny) and splanchnic (visceral) inflows.

Carry to pristenochny inflows:

• lumbar veins (on three-four from each party) – collect blood from muscles and skin of a back, from stomach walls, and also from area of a vertebral texture;
• phrenic veins – originate from the lower surface of a diaphragm;
• iliolumbar, lateral sacral, lower and upper buttock veins – collect blood from muscles of a stomach, a hip and a basin.

Carry to visceral inflows:

• gonadal veins – the ovarian and yaichkovy veins collecting blood from an ovary (small egg);
• renal veins - connect at the level of a cartilage to the lower vena cava between lumbar vertebrae (first and second). The left renal vein is much longer than the right renal vein. It crosses an aorta in front.
• veins of adrenal glands - the right vein gets into the lower vena cava, and the left vein connects to a renal vein.
• hepatic veins – bear blood from a liver.

All veins (except the largest) form numerous textures in and outside of bodies for blood redistribution. In case of injury of any vein the blood flow goes on collaterals (bypass ways).

Thrombosis of the lower vena cava

About 11% of total number of vein thromboses of a basin and the lower extremities are the share of thrombosis of the lower vena cava. The vein thrombosis can be primary and secondary (depending on the development reason).

Primary thrombosis develops owing to a malignant or benign tumor, inborn defects, a vein injury. The reasons of secondary thrombosis can be germination of a vein a tumor or its prelum. Quite often secondary thrombosis of the lower vena cava extends in the ascending way from other veins (smaller).

In medicine allocate thrombosis of the distal site of a vein, and also renal and hepatic sites. Thrombosis of the distal site of a vein is shown in cyanosis and hypostasis of the lower extremities, the lower half of a stomach, lumbar area. Sometimes hypostasis extends prior to the beginning of a thorax. The upper bound of cyanosis and a cutaneous dropsy depends on extent of spread of thrombosis.

At fibrinferment of a renal segment of a vein there are heavy general disturbances which can lead to a lethal outcome.

Development of thrombosis of a hepatic segment of a vein most often is followed by disturbance of the main functions of a liver and the subsequent thrombosis of a portal vein. Abdominal pains, increase in a spleen, liver, ascites, dispepsichesky frustration, change of a xanthopathy belong to symptoms of thrombosis of the hepatic site.

Prelum of the lower vena cava

The prelum of the lower vena cava can arise owing to a hyperadenosis, and also at retroperitoneal fibrosis and tumors of a liver.

The prelum of the lower vena cava and aorta the increased uterus at pregnant women serves as the reason of development of a syndrome of arterial hypotonia and emergence of disturbances of uteroplacental blood circulation (in a dorsal decubitus).

The vein prelum during pregnancy can lead to development of phlebitis, emergence of hypostasis of the lower extremities and venous stagnation.