The vena cava are two large veins that carry venous blood from the body back to the right atrium .
There are the
- Upper vena cava ( superior vena cava , referred to in animals as the anterior vena cava cranialis ), which drains the blood of most of the structures above the diaphragm (except for the pulmonary circulation and the heart) as well as the
- Inferior vena cava ( inferior vena cava , referred to in animals as the posterior vena cava caudalis ), which drains the blood from the body sections below the diaphragm.
In humans, the vena cava have a varying cross-section, depending on the body position, intravascular fluid volume, breathing, cardiac activity and function, and are approximately 2-3 cm wide at the level of the liver. The venous blood pressure within the vena cava is around 0–15 mmHg (0–20 mbar , see central venous pressure ). An extension of more than 2.5 cm in the ultrasound diagnosis without breathing variability is an indirect indication of increased central venous pressure.
During embryonic development, the inferior vena cava arises from the fusion of the paired subcardinal veins (to the right and left of the spine). Accordingly, standard variants are possible. The most common is the inferior vena cava located on the left, which often opens into the hemiazygos vein . Agenesia or partial agenesis of the inferior vena cava are rare and are associated with an increased tendency to leg vein thrombosis .
The vena cava can be probed well with catheters . They can also be well represented and assessed with various imaging methods such as ultrasound , venography or computed tomography .
The vena cava can be thrombotic or tumorous , or compressed from the outside (for example by tumor or pregnancy).
- ↑ Seitz / Schuler / Rettenmaier (eds.): Clinical sonography and sonographic ultrasound diagnostics . 2nd Edition. Thieme, Stuttgart 2008, p. I-456 .