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Paget Schroetter Syndrome, a subset of TOS

What is Paget-Schroetter Syndrome?
This is the name given to the clotting of the subclavian vein (beneath the collarbone) which results in pain, swelling, blue discoloration, and congestion of the arm. It is most commonly caused by compression of the vein between the collarbone and the first rib, and is considered one of the venous manifestations of TOS.

What causes Paget-Schroetter Syndrome in TOS?
Some persons may have congenital (from birth) abnormalities in the development of the bones and muscles of the shoulder and neck. In these situations, the subclavian vein is compressed by an extra rib, or is compressed by an abnormal ligament, and this results in the syndrome.

The most common cause is overexertion and over development of the muscles of the neck and upper extremities. In such instances, the anterior scalene muscles grow and enlarge to the point where they compress the subclavian vein and results in the syndrome.

How is this condition diagnosed?
It usually will come to attention by causing dramatic swelling, blue discoloration, congestion and pain in the affected arm. The diagnosis is then made by testing the vein to see if it is clotted or narrowed.

Ultrasound machines can determine if the vein is clotted in the upper arm. Occasionally they may miss a clot in the area beneath the collarbone or inside the chest cavity.

Venograms are tests where dye is injected into the veins and then X-rays are developed to show the flow of blood within the vein. The venograms are more accurate than ultrasound in showing the condition of the veins inside the chest and under the collarbone. These tests are considered the "gold standard" in testing because they are the most accurate.

CT scans and MRA scans can also show the condition of the veins within the chest and under the collarbone, but are more expensive and a little less reliable.

How is Paget-Schroetter Syndrome in TOS treated?
There are two principal avenues of treatment: (1) anticoagulation with thrombolysis, and (2) decompression. Anticoagulation serves to prevent further clotting from happening; thrombolysis serves to dissolve the clot. Decompression is required to release the compression of the vein, which caused the vein to clot in the first place.

The anticoagulation is usually started with intravenous Heparin. More recently, Heparin injections have been tried for this same purpose. Most patients will require anticoagulation for several months. In this instance, patients are given Coumadin, which comes in a tablet, and can be taken by mouth. It is important to understand that anticoagulation will thin the blood and reduce the clotting of the blood. This means that there is an increased tendency to bleed. For this reason, patients are restricted from activities where they may be bruised or injured while on these medications.

Thrombolysis refers to dissolving the clot with intravenous medication. The most widely know medications for this purpose include Urokinase, Streptokinase and TPA (also known as Redivase).

Urokinase, which was the preferred medication, has recently been removed from the marked by the FDA. Streptokinase, one of the older medications, is not preferred because of technical issues in its administration.

TPA is a naturally occurring enzyme inside the human body. It has recently been genetically cloned and is now available as an intravenously administered medication. In this instance, an intravenous catheter is placed inside or just next to the blood clot and the medication is allowed to dissolve the clot.

Once the clot is dissolved then X-ray images will be able to show if the vein is compressed by the collar bone, scalene muscle, and rib. In this instance, the next step of treatment is to remove the rib and divide the scalene muscle. This then allows the vein to decompress and re-expand.

Occasionally there will be a buildup of scar tissue around and inside the vein, which will prevent the vein from re-expanding. In these instances, a balloon angioplasty is performed to stretch the scar tissue and re-expand the vein. We usually will delay this last step for at least two weeks to allow time for recovery from the operation. Accordingly, two weeks following surgery we will ask patients to undergo a repeat venogram to see if there is any residual narrowing of the vein. If there is residual narrowing then the angioplasty is done at the same time.

What is the outcome of treatment for Paget-Schroetter?
Most of our patients are able to resume their pre-injury activities without limitation. Occasionally patients may find that they note some blue discoloration and mild congestion, but it is rarely as severe as at the time of the initial blood clot. At such times, patients may worry about the possibility of a blood clot forming again. We have so far not seen this in any of our patients.

What if the blood clot can not be dissolved?
Some patients arrive too late for the medicine to be able to dissolve the blood clot. In these cases we will usually recommend decompressing the subclavian vein for several reasons: the vein may occasionally clear the clot by itself and having the vein decompressed will reduce the chance of another clot forming; removing the compression may allow more space for the development of collateral veins for drainage of the arm; some patients will have compression of the other structures (nerves, or the subclavian artery) and decompression may help these avoid further injury.

In these patients whose blood clot can not be dissolved, it is more common to experience the intermittent congestion and blue discoloration in the affected arm. Competitive athletes may find this restricting.

Can surgery be avoided by using angioplasty and stenting?
Angioplasty refers to the use of a small balloon to stretch the narrowed portion of the vein back to normal size. Angioplasty is not effective until the rib is removed since the rib is a principal element in compressing the vein, and angioplasty can not overcome the compression produced by the rib.

Stenting refers to use of small wire mesh scaffolds inside the vein to help support it and keep it from re-compressing. These wire scaffolds do not have sufficient strength to overcome the compression caused by the rib. In the instances where this has been tried, it has invariably resulted in crushing of the stent and irreparable damage to the vein. For this reason, we strongly advise all patients and physicians to avoid use of stenting before the rib is removed. Additionally, our experience has shown that once the rib is removed, stenting is not needed. If there is a persistent narrowing of the vein after the rib is removed, then angioplasty alone has been sufficient.

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