What treatment procedures are involved in dealing with blood clots?

Treatment for a blood clot ranges from symptomatic care to more aggressive intervention, depending on the severity of a person’s condition and the location of the clot.

Typical treatment for venous blood clots

A superficial blood clot will be symptomatically treated and involve medications, such as ibuprofen or acetaminophen, which reduce inflammation and alleviate pain. These clots are low risk and typically do not embolise, causing more serious physical complications. The reason for this is because superficial veins connect with perforator veins, which have valves that act much like strainers. These normally block any clots from being able to travel through the system and enter the deeper veins. Risk of a clot embolising and travelling from a superficial origin is hence low.

Clots in the deep venous system may be treated as follows:

• Anticoagulant medications (blood thinners): Prescribed medications are likely to depend on a person’s current condition at the time of diagnosis. Has the clot embolised? Or is the clot immobile? Are there any signs of other medical conditions which could be underlying causes?
  
  Novel oral anticoagulants (NOACS) are often prescribed for instances of deep vein thrombosis or pulmonary embolism. These medications are also known as DOACS (direct oral anticoagulants) and work to block factors contributing to the clotting cascade. The medications fall into categories known as Factor Xa inhibitors and direct thrombin inhibitors. Heparin is one medication that has been frequently used in the treatment of blood clots, and is normally injected just beneath the surface of the skin with the aim of ‘thinning out’ the blood in the system. As an injectable medication, it reaches the system quickly and treats a person’s condition in a short space of time. This can be very efficient if the affected person is unstable, often as a result of another medical condition. Some low molecular weight heparin medications may be safe for use in pregnant women who develop clots.
  
  Another anticoagulant is Warfarin (administered in oral pill form), which works by blocking clotting factors II, VII, IX and X (all of which depend on vitamin K). It can take up to several days for the medication to reach and maintain a therapeutic effect in the system. In many instances, Heparin may be administered first for rapid effect and then Warfarin thereafter in order to maintain anticoagulation.
  
  Medication use will be carefully monitored by the treating medical team as it can have adverse interactions with certain foodstuffs and other medications. Newer medications (such as apixaban, dalteparin and dabigatran) have been developed with fewer known adverse reactions and can be prescribed as an alternative to Heparin or Warfarin. Blood thinners will be taken for at least 3 months following a diagnosis of a blood clot and the commencement of treatment¹¹. This is to treat an existing clot as well as prevent new clots from forming.

• Thrombolytic therapy: These medications may be preferred in instances where a person is severely ill and displays symptoms of shock or even heart strain. ⁽¹²⁾ They can also be used if other anticoagulant medications have not been as effective. Medications are classified as TPA (tissue plasminogen activators) which are usually injected into a peripheral vein (normally in the arm) for rapid anticoagulant effects. Known as ‘clot busting drugs’ the medication can be 'dripped' directly into a clot via a catheter (a long, thin and flexible tube) or IV line (intravenously) to alleviate discomfort. An interventional radiologist may administer this treatment. This therapy is usually used for arterial clots (e.g. coronary artery clots).

Medication use will be carefully managed by a treating team. All medications must be taken exactly as directed by a prescribing doctor as incorrect intake levels can have serious consequences (leading to possible side-effects or complications). A doctor will also carefully monitor the use of multiple medications (including supplements and herbal products) for potentially harmful interactions. No new substances should be taken without the prior knowledge of the treating doctor. A pregnant woman should also take extra precaution as certain medications can result in potential pregnancy complications, as well as birth defects.

Other treatment measures can include:

• Vena cava filter: An IVC filter (vena cava filter) may sometimes be recommended in the event that a person cannot (or is unable to) be effectively treated with blood thinning medication. A small cone-shaped filter will then be surgically placed inside a large abdominal vein, known as the inferior vena cava vein. This is designed to 'catch a clot' and prevent it from embolising in the system. Blood flow is not, however, restricted and can move freely through the filter normally and safely.
• Venous thrombectomy: In the case of severe thrombosis or embolism, a clot may be required to be surgically removed. A doctor will discuss all necessary risks with a person (should an individual be in a state to make the decision for surgery along with the medical professional).
• Medical / graduated compression stockings: These are specially designed to help treat deep vein thrombosis and can significantly reduce swelling in the legs, as well as aid in reducing the likelihood of new clots forming in the veins. Stockings (without a covered toe portion) are worn over the feet and stretch up towards the knee. The stockings are normally tightest at the ankles and gradually become a little looser towards the end (just beneath or just over the knee). This is to stimulate normal compression (which would naturally take place in the calf) and encourage blood flow back up the leg (eventually returning to the heart). Stockings can be worn for extended periods of time, significantly reducing symptoms of DVT (clotting and blood pooling) in the lower extremities.

Typical treatment for arterial blood clots

Treatment is often more aggressive when it comes to a blood clot in the arterial system. Medication will be administered for quick action and absorption into the system (via the peripheral arteries), targeting the clot and thereby helping to restore blood supply. Medications can help to dissolve a clot (these are known as tissue plasminogen activators / TPA).

Treatment may also involve cardiac catheterisation (to locate the blockage in a blood vessel), as well as the surgical placement of a tiny balloon at the tip of a catheter (which is inflated with a salt water solution or X-ray dye once placed to open the blocked blood vessel) and a stent (to keep the blood vessel open this is known as an angioplasty). A stent is essentially a mesh tube which a doctor will place inside an affected blood vessel, most often in the coronary arteries (supplying the heart). The entire procedure will be guided by X-ray imagery to determine the exact location of the clot and perform the angioplasty.

An angioplasty, which mechanically opens up arteries in danger of closing completely, is usually performed within 60 to 90 minutes of the diagnosis of a myocardial infarction / heart attack being made, making it a time-sensitive surgical procedure. ⁽¹³⁾ It helps to restore blood flow quickly, along with intravenously administered medications – TPA or tenecteplase (TNK). The procedure does carry some potential risks including the formation or more blood clots and rupturing of the blood vessels. It has been noted that stents have caused additional blood clots in some individuals. This is due to the fact that a foreign object in the body is in constant contact with blood and can lead to the formation of clots at the location in which it is placed. Modern procedures use stents which are coated with medications to try and alleviate risk of this taking place, instead of the previous versions which were bare-metal.

Risk versus benefit will always be carefully assessed by the treating medical team. Surgery is generally more successful if a stent is left in the artery, as narrowing (known as restenosis) can occur down the line following the procedure. A fabric stent may be used for larger arteries.

Treatment of this kind is also often used for those having a heart attack and helps to dissolve the blood clot, and just as importantly, minimise potential damage to the heart. In severe instances, heart bypass surgery may be necessary for extensive blood supply restriction due to damage caused by the clot.

Following any surgery, especially one where a stent was placed, a doctor will advise the following in order to minimise risk of future blood clots:

• Maintain a healthy blood pressure
• Maintain a healthy weight
• Ensure healthy cholesterol levels
• Get in regular exercise
• Quit or do not smoke

Anticoagulant medication will also be prescribed following surgery, along with regular medical check-ups and blood tests to monitor overall health condition, as well as effects of the drugs used for treatment.

An embolism which results in a stroke is also often treated with TPA. An interventional radiologist or neurologist can also operate to surgically remove the clot from the brain by threading a catheter into the blocked artery, locating the thrombus and removing it (a similar technique to the removal of clots from the peripheral artery).

References:

^{11. AHRQ (Agency for Healthcare Research and Quality). August 2017. Your Guide to Preventing and Treating Blood Clots: https://www.ahrq.gov/patients-consumers/prevention/disease/bloodclots.html#treatment [Accessed 28.08.2018]}

^{12. European Respiratory Review. 2015. Developments in the management and treatment of pulmonary embolism: http://err.ersjournals.com/content/24/137/484 [Accessed 28.08.2018]}

^{13. University of Maryland Medical Center. July 2016. Heart attack and acute coronary syndrome: https://www.umms.org/ummc/patients-visitors/health-library/in-depth-patient-education-reports/articles/heart-attack-and-acute-coronary-syndrome [Accessed 28.08.2018]}