What is Effort Thombosis or Subclavian Thrombosis??

As promised, here is a short (well somewhat short!) explanation of the injury I sustained.

The condition/injury goes under a few names, most commonly effort thrombosis, subclavian vein thrombosis and Paget-Schroetter syndrome, and also falls into a sub-classification of Thoracic Outlet Syndrome (TOS). To be explain the condition I believe some basic anatomy is quite helpful and this is where we will begin.

The thoracic outlet refers to the region or space directly above and below your clavicle (collarbone) in which several nerves, arteries and veins pass. The main anatomic structures that form your outlet are the clavicle, first rib, subclavius muscle and the scalene muscles. With movement of your shoulder girdle (shoulder blade and arm) this space can be increased and decreased in size with certain positions of your shoulder girdle being associated with significant narrowing of this space. Prolonged postures (particularly slouching), hypertrophy (increase in size) of muscles and bone abnormalities can over time cause either the nerves, artery or vein to become compressed and subsequently injured. This process of compression of these structures is called Thoracic Outlet Syndrome.

In my particular case it appears that the narrowing of the thoracic outlet has caused compression of the subclavian vein (the vein that passes under your clavicle) and subsequently triggered an inflammatory process to be initiated within the vein itself. The damaged vein then attempts to heal the injured area. This includes clotting around the damaged tissue to prevent further injury. If the compression of the vein continues to occur this clotting process can get amplified to the point at which significant narrowing or even complete blockage of the vein due to the thrombosis (clot) may happen. It is quite difficult to pin-point the exact time at which this process begins as usually symptoms such as swelling and discolouration usually only occur when there is almost complete blockage of the vein.

Once the vein becomes significantly blocked, the blood within the arm begins to pool in the veins. When exercising the upper body (eg. Swimming) this pooling or swelling within the arm becomes more noticeable as the muscles of the arms are working harder and therefore are requiring more blood. Once this process begins symptoms such as arm swelling, tightness and arm pain generally start to occur. When my arm began to swell quite noticeably after swimming, alarm bells started to go off in my head and this is what initially prompted me to get the injury examined further.

Diagnosis of subclavian vein thrombosis is usually made by examination of the vascular structures around the shoulder by ultrasound. This technique is recognised as being one of the most valuable for identifying the condition as it is low cost, non–invasive and quite sensitive. Other investigations including CT and MRI with contrast are sometimes also used to confirm the diagnosis and rule out any other concurrent conditions.

Once the diagnosis is confirmed there are several treatment options available depending on several factors, most importantly time. If the clot is identified early enough there is the possibility that break down of the clot via catheter directed thrombolytics (ie. Putting a catheter into the vein and injecting medication directly onto the clot) can be performed. This would allow the vein to be essentially unblocked and allow blood to return from the arm. If however the clot is not identified within two-three weeks of developing, it will harden and this procedure will not be effective. In this case the first line of treatment is starting an anti-coagulant medication that will prevent the clot from increasing in size and allow the body to begin the process of breaking the clot down. Generally this medication is Warfarin, however there are some newer anti-coagulant medications now available.

Surgical invention in some cases is also indicated. Most procedures are directed at increasing the space around the vein to prevent any further compression form occurring. Generally the first rib and surrounding soft tissue are removed. Furthermore the vein itself is normally exposed and the clot removed. As with all surgeries there are risks involved.

In my case the clot was not diagnosed early enough and therefore the treatment option that best suited me was to commence anti-coagulant mediation (Warfarin). The general guidelines for treatment of a deep vein thrombosis (DVT) with anti-coagulants recommend taking the medication for a period of 6 months. This allows time for the body to dissolve the clot and for the vein to return to normal. In this time it is recommended that you avoid any dangerous sports/activities as a side effect of anti-coagulant medication is the risk of increased bleeding. Once 6 months has passed a follow-up ultrasound is preformed to ensure the clot has dissolved.

To ensure that the condition does not return upon return to normal sporting activities, treatments including physiotherapy and strength/conditioning exercises are usually performed. Treatments are aimed at increasing the thoracic outlet space and addressing abnormal movement patterns that may be causing compression of the vein. Most athletes make a full recovery and return to normal sporting activities.

I have been on the anti-coagulant mediation for 2 months and the signs are promising. This is minimal swelling in my arm and I have commenced some light training with no issues. The major part of the rehabilitation process will be addressing my shoulder biomechanics when swimming as this was the activity that I believe triggered the condition initially. Also, I will be examining my bike position to ensure it is was not contributing.

I hope this little overview has given you a bit of information about subclavian vein thrombosis. It is worth nothing that most people think that clots or DVTs only occur in the elderly population. I, for one, certainly did not expect this type of injury to happen to me and consider myself lucky that I had it diagnosed and addresses quite quickly. I will post another quick blog about why athletes are at a higher risk of clots developing then the average person and what they should be on the lookout for to ensure they minimise their risks.


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