What is internal thoracic veins?

Internal thoracic veins (ITV) are a pair of large veins that are located on either side of the chest and run parallel to the internal thoracic arteries. The ITV drain blood from the anterior chest wall and the adjacent muscles, skin, and bones, and eventually return it to the right atrium of the heart.

The internal thoracic vein arises at the level of the sixth rib and descends along the sternum, eventually joining the brachiocephalic vein near the clavicle. Along its course, the ITV gives off numerous tributaries that drain the intercostal spaces, the mammary gland, and the muscles of the anterior chest wall.

The internal thoracic veins play an important role in cardiac surgery, as they are often used as a conduit for bypassing blocked coronary arteries. This procedure, called an internal mammary artery coronary artery bypass graft (CABG), involves removing a segment of the internal thoracic artery, which runs alongside the ITV, and using it to create a new blood supply to the heart.

Although the internal thoracic veins are not typically prone to disease or blockage, there are certain medical conditions that can affect them, such as thrombosis (clotting) or compression by nearby structures. In rare cases, a congenital anomaly may cause the ITV to drain into the left atrium of the heart, a condition known as persistent left superior vena cava.