Inferior Vena Cava: The inferior vena cava is a large vein that carries deoxygenated blood from the feet, legs, thighs, pelvis, abdomen and delivers into the right atrium of the heart. It runs alongside the abdominal aorta, It enters the right atrium at the lower right, the back side of the heart. The inferior vena cavas walls are rigid and has valves so the blood does not flow down via gravity.
The inferior vena cava is the two extended veins that carry deoxygenated blood from the body. It is formed by the joining of the right and the left common iliac veins, habitually the iliac veins have merged at the level of the fifth lumbar vertebra. It is a large retroperitoneal vein that rests posterior to the abdominal cavity and runs along the right side of the vertebral column. The inferior vena cava takes blood from the lower half of the body whilst the superior vena cava transports blood from the upper half of the body.
Structure of the Inferior Vena Cava
The inferior vena cava is formed by the joining of the left and right common iliac veins. The inferior vena cava begins as the left and right common iliac veins behind the abdomen unite, at about the level of L5. It also joins with the azygos vein and venous plexuses next to the spinal cord.
It passes through the thoracic diaphragm at the caval opening at the level of T8.
Tributaries of the Inferior Vena Cava
At the T8 level hepatic veins, inferior phrenic vein
At the L1 level right suprarenal vein, renal veins
At the L2 level right gonadal vein
At the L1–L5 level lumbar veins
At the L5 level common iliac veins
All the lumbar veins and hepatic veins usually drain directly into the inferior vena cava.On the left, they drain into the renal vein which in turn drains into the inferior vena cava.On the right, the gonadal veins and suprarenal veins drain into the inferior vena cava directly.
Development of the Inferior Vena Cava
In the fetus, the inferior vena cava and right atrium are isolated by the valve of the inferior vena cava. In the adult, this valve typically has completely regressed or remains as a small fold of endocardium.
Clinical significance of the Inferior Vena Cava
Health problems attributed to the inferior vena cava are most often associated with it being compressed. Typical sources of external pressure are an enlarged abdominal aorta (an aneurysm), the gravid uterus, known as the aortocaval compression syndrome and abdominal malignancies, such as colorectal cancer, renal cell carcinoma, and ovarian cancer. In rare cases, straining associated with defecation can lead to restricted blood flow through the inferior vena cava and result in syncope (fainting).
Blockage of the inferior vena cava is exceptional and is treated necessarily as a life-threatening condition. It is linked to deep vein thrombosis, inferior vena cava filters, liver transplantation and surgical procedures such as the infusion of a catheter in the femoral vein in the groin.
Trauma to the vena cava is ordinarily fatal as unstoppable excessive blood loss occurs.