Superior vena cava syndrome

Definitions & Key takeaways

Superior vena cava syndrome is a condition caused by blood flow obstruction in the superior vena cava, most commonly from a tumor causing external compression, but it can also be from thrombosis. Symptoms of SVCS include swelling of the face, neck, and chest; difficulty breathing; and a bluish discoloration of the skin. Treatment involves removing the cause of the blockage, but in the meantime, it's important to ensure that a person's head is kept above the level of the heart because gravity can help drain fluid from the head and neck back towards the heart.

Chapters:

Watch video only

Introduction0:00–0:29

Superior vena cava syndrome occurs when blood flow through the superior vena cava is obstructed either from within due to a blood clot or from external compression.
The superior vena cava is a short and wide vein on the right side of the chest that drains blood from the head, upper body and both arms, and delivers all of that blood to the right atrium of the heart.

Causes0:29–1:54

The superior vena cava can get obstructed a few different ways, and the most common way is via a nearby tumor, through mass effect, where inflammation and swelling pushes up against the superior vena cava.
Alternatively, though, there can be direct tumor invasion into the superior vena cava which is when tumor cells penetrate and grow directly into the superior vena cava.
But this is only possible if the tumor is located on the right side near the superior vena cava. The most common type of cancer that does this is a lung cancer, and when it’s located in the apex of the right lung near the superior vena cava, it’s given the name Pancoast tumor - after Dr.
Henry Pancoast who first described them. Also in that area, though, you’ve got a bunch of lymph nodes, and another possible cause of SVC syndrome a tumor of the lymph nodes, which would could lead to compression of the SVC.
This could be lymphomas – or primary cancers of the lymph node - cause superior vena cava syndrome, or secondary and have spread from somewhere else, like the lungs.
Apart from tumors, the superior vena cava can also get obstructed if a blood clot or thrombosis forms within it. This most often develops in individuals who have a long-term device like an indwelling central venous catheter.

Pathology1:54–2:44

Regardless of the cause, when the superior vena cava gets obstructed, behind the obstruction you’ll get an increase in venous pressure.
When this happens, blood starts to get re-routed through different blood vessels, essentially draining into the inferior vena cava, which also drains into the right atrium.
These are now called collateral blood vessels, and are essentially alternate routes. If the blockage is low enough, it could be through the azygos system, but also other options are the internal mammary, lateral thoracic, and esophageal venous systems.
Over the course of a few weeks, these collateral veins dilate, after which point the venous pressure decreases a bit, but still remains higher than normal, even after the collaterals have dilated fully.

Symptoms2:44–4:11

Symptoms of superior vena cava syndrome relate to the blockage in venous blood blow. A decrease in venous return of blood to the heart, means that less blood is getting pumped to the lungs, leaving individuals feeling short of breath.
Meanwhile, the backup of venous blood and venous stasis gives individuals a flushed appearance and swollen neck and chest veins.
It also causes edema, where fluid leaks out of the blood vessels and into surrounding tissues, resulting in swelling of the face, neck and arms.
Sometimes the fluid build-up can cause compression of the trachea and other structures in the upper airway. This can cause shortness of breath as well as stridor, which is a harsh high pitched noise heard during inhalation.
Excess fluid can also compress the muscles of the voice box or larynx, causing a hoarse voice. Fluid around the esophagus, can cause dysphagia which is difficulty swallowing.
Most serious of all, though is cerebral edema, or excess fluid building up in the brain, which can cause symptoms like headaches and confusion.
Worse yet, if the cerebral edema is severe, the fluid in the tissues can compress the tiny blood vessels supplying the brain with blood, leading to cerebral ischemia.
If superior vena cava syndrome is suspected, diagnosis can be done by chest X-ray or CT scan can be helpful to look for tumors and visualize collateral vessels.

Diagnosis4:11–4:29

To look for obstruction within the superior vena cava, a radio-opaque dye can be injected into it, while a series of X-rays are taken to visualize how blood flows through it.

Treatment4:29–5:09

For treatment, one general key intervention is making sure that a person’s head is kept above the level of the heart, because gravity can help drain fluid from the head and neck back towards the heart.
Other treatments are dependent on the underlying cause - for example, a tumor is typically evaluated with a biopsy to determine it’s type and the how far it may have spread, and it may be treated with radiation and chemotherapy.
In addition, sometimes steroids can be used to reduce swelling around the tumor. If the cause is a blood clot within the superior vena cava, anticoagulants can be used to prevent it from getting larger.
Alright, as a quick recap - superior vena cava syndrome happens when blood flow in the superior vena cava is obstructed, most commonly from a tumor causing external compression, but it can also be from thrombosis.

Review5:09–6:22

The obstruction increases venous pressure and edema which can lead to a range of symptoms such as, stridor, voice changes, dysphagia, and even cerebral ischemia Thanks for watching, you can help support us by donating on patreon, or subscribing to our channel, or telling your friends about us on social media.