Internal Thoracic Vein

Your internal thoracic vein, formerly called the internal mammary vein, is a blood vessel in your chest (thorax). You have one on each side of your body. These are your:

• Left internal thoracic vein
• Right internal thoracic vein

Each internal thoracic vein runs alongside an internal thoracic artery. Blood in the artery flows from your heart. Blood in the vein runs back toward your heart.

What does the internal thoracic vein do?

Your internal thoracic vein helps oxygen-poor blood from different parts of your chest flow back to your heart and lungs. This supports the work of your circulatory system — the network of veins and arteries that keep blood moving throughout your body.

Your internal thoracic vein is responsible for draining blood from your:

• Pericardium (this is the sac that surrounds your heart)
• Breast
• Diaphragm
• Front of your chest wall (this is the medical term for the bones and muscles that surround and protect the organs in your chest)

Once this blood returns to your heart, it flows to your lungs. There, it gains oxygen and gets rid of waste products. This refreshed blood flows back to your heart and then out to your entire body.

Role in surgery

Like other veins, your internal thoracic vein supports healthy blood flow in your body. But it also has another role that sets it apart. Surgeons sometimes use the internal thoracic vein to help with breast reconstruction surgery.

One type of surgery, called flap reconstruction, involves taking tissue from somewhere else in your body (called a “flap”) and using it to form a breast. That tissue has blood vessels that need to connect with other vessels in your chest. This allows blood to flow normally through your chest after your surgery.

Surgeons may choose to use the internal thoracic vein as the linking vessel. This means they connect vessels in the flap to your internal thoracic vein to establish blood flow.

Research shows this vein is often ideal for this purpose because:

• It’s located in the middle of your chest.
• It’s often healthier than other nearby vessels.
• It has fairly predictable anatomy.

Where is it located?

Your internal thoracic veins run up and down (vertically) deep in your chest, close to your breastbone on either side. They start in your upper belly and extend all the way up to your collarbone.

The exact starting point for each internal thoracic vein is the point where two other veins join together. These are called your musculophrenic vein and superior epigastric vein. From there, the internal thoracic vein travels upward alongside your breastbone until it reaches your brachiocephalic vein.

Your right internal thoracic vein empties blood into your right brachiocephalic vein. And the same happens on your left side. Your brachiocephalic veins join together to form your superior vena cava. This large vein delivers blood directly into the upper right chamber of your heart.

Variant anatomy

Some people are born with internal thoracic veins that have a slightly different anatomy. For example, a vein may split into two (bifurcate) partway along its course. This means two internal thoracic veins continue traveling upward, with one on each side of the internal thoracic artery. This can happen on one or both sides of your body. These changes don’t harm the vein or affect its function.

Which veins drain into the internal thoracic vein?

Several veins from other areas of your chest send blood into your internal thoracic vein. These are called tributaries. You can think of them like tiny streams that flow into a river. Tributaries of the internal thoracic vein can vary from person to person but may include:

• Anterior intercostal veins: These small veins drain blood from the areas between your ribs, along the front of your body.
• Pericardiophrenic veins: These veins drain blood from structures in the middle of your chest, in the space known as your mediastinum.

What conditions can affect the internal thoracic vein?

Damage can occur to your internal thoracic vein from:

• Chest injuries: Trauma to your chest can harm tissues and blood vessels, including your internal thoracic vein.
• Medical procedure complications: Rarely, procedures like pericardiocentesis can damage your internal thoracic vein or artery. But healthcare providers use imaging, like ultrasound, to guide procedures like these and reduce the risk of any problems.