The right and left brachiocephalic (or innominate) veins are a pair of large veins deep in the upper chest. Each brachiocephalic vein returns blood to the heart from the head, neck, arm, and chest.
These two veins take a downward course, meeting each other to form a large vein called the superior vena cava (SVC), which leads directly into the heart.
On each side of your upper chest, the subclavian vein, bringing blood from your upper chest and arm, joins with the internal jugular vein, which brings blood from your head and neck. The large vein that results is called the brachiocephalic vein, and you have one on each side. Incidentally, they are among the few veins in the body that do not have valves, which regulate blood flow.
Roughly, each brachiocephalic vein originates behind the point where your clavicle (collarbone) meets your sternum (breastbone). The left brachiocephalic vein is longer than the right, and courses down and toward the right. It joins the right brachiocephalic vein to form the superior vena cava (SVC), which carries blood directly to the right atrium of the heart.
Other than the subclavian and internal jugular veins, smaller tributaries of the brachiocephalic veins include the vertebral, internal thoracic, and inferior thyroid veins, which bring blood from the head, chest wall, and thyroid gland, respectively. The left superior intercostal vein also brings blood from the posterior chest to the left brachiocephalic vein.
Usually, the left brachiocephalic vein passes above and in front of the aortic arch, the large artery of the chest. Rarely, the left brachiocephalic vein can take a different course, passing behind and under the aortic arch, a condition called a subaortic or retro-aortic brachiocephalic vein.
The left brachiocephalic vein can sometimes take an abnormal course, passing behind and under the aortic arch, rather than above and in front of it. By itself, this usually doesn’t cause problems, but it is associated with more significant congenital defects such as tetralogy of fallot, right aortic arch, or total anomalous pulmonary venous return.
Also, when doctors plan pacemaker placement or cardiac surgery, it is useful to know about the presence of an abnormal brachiocephalic vein course, as it can affect the surgical approach.
The primary function of the brachiocephalic veins is to carry deoxygenated blood from the head, neck, arms, and chest back to the heart for oxygenation.
Blood from the head drains via the internal jugular veins, while blood from the upper extremities drains via the subclavian veins. Other vessels that empty into the brachiocephalic veins include the inferior thyroid veins, internal thoracic veins, and the left superior intercostal vein.
Upper Extremity DVT
The brachiocephalic veins may be involved in deep vein thrombosis (DVT), a blood clot that forms in a vein deep inside your body. “Upper extremity DVT” refers to clots affecting the brachiocephalic, internal jugular, subclavian, or other deep veins of the arms, and is less common than DVT of the legs.
The subclavian vein is the most commonly involved upper extremity vessel. In venous thoracic outlet syndrome, anatomic abnormalities of the bones, muscles, or tendons of the upper chest may cause chronic irritation of the vessels, resulting in thrombosis.
Other causes of upper extremity DVT include:
- Certain drugs
- Other medical conditions that place people at increased risk of blood clot formation
Central Venous Catheters
Central venous catheters (CVCs) are commonly used in medicine to administer certain drugs (like chemotherapy) or total parenteral nutrition (TPN). The internal jugular and subclavian veins are frequent sites of catheter access, and central venous catheters often pass through one of the brachiocephalic veins.
Although CVC placement is generally a safe procedure, on rare occasions a catheter may perforate the wall of the brachiocephalic vein, leading to bleeding in the chest. Repeat or long-term catheter placement puts people at risk for injury to the brachiocephalic vein (or other veins), resulting in chronic narrowing or thrombosis.
The brachiocephalic veins can be affected by diseases that affect the chest generally. The brachiocephalic veins can be compressed by tumors in the chest, obstructing venous flow and leading to swelling of the face or arms. Also, the brachiocephalic veins can be injured in blunt chest trauma, causing bleeding.
Very rarely, an aneurysm, or abnormal ballooning, of the brachiocephalic vein may develop. This may be congenital or due to trauma or inflammation. Usually, aneurysms of the brachiocephalic veins do not cause symptoms. Occasionally, they may bleed, form clots, or become obstructed, and require surgical repair.