II. Venous Thromboembolism (VTE)


Definition of VTE

Venous thromboembolism is defined by the presence of a thrombosis (a blood clot) that prevents the blood from circulating well in the veins.  Deep vein thrombosis (also known as phlebitis or thrombophlebitis) usually occurs in the deep veins of the leg.  The obstruction to the passage of blood in the leg causes swelling and pain.  The most serious complication of deep vein thrombosis is pulmonary embolism.  In pulmonary embolism, the clot that has formed in the leg breaks off and travels to the lungs.  The clot (called an embolus) in turn blocks the arteries of the lungs and compromises the exchange of oxygen, which can cause shortness of breath and chest pain.

Although venous thrombosis most often affects the deep veins of the leg, it can also occur in the surface veins (superficial vein thrombosis).  These two phenomena can also occur in the arm. 




Risk factors and symptoms of VTE

Who is at risk of developing venous thromboembolism?  It affects about 1 in 1000 people and 3 in 1000 people in patients over 80 years old.  A hereditary factor is sometimes present and is associated with a bleeding disorder, which increases the likelihood that a clot will form.


In the general population, the following risk factors are sometimes associated:


  • Pregnancy
  • Obesity
  • Smoking
  • Hormone therapy or the contraceptive pill
  • A sedentary lifestyle or prolonged immobilization (bed rest, long journey)
  • Certain surgical interventions
  • Cancers and chemotherapy treatments
  • Heart failure
  • Advanced age
  • History of venous thrombosis or pulmonary embolism




The symptoms of venous thromboembolism vary according to the pathology:


  • Superficial vein thrombosis: pain, hardening, redness and heat in the vein path
  • Deep vein thrombosis: pain (often in the calf), swelling, heat, redness
  • Pulmonary embolism: shortness of breath, palpitations, chest pain


In certain cases, patients will not necessarily have these symptoms.




Preventing VTE

Several measures can be taken to prevent venous thromboembolism:

  • Get regular physical exercise;
  • Avoid becoming overweight;
  • Avoid prolonged downtime (for example, in the case of an extended trip by plane, it is recommended to get up and walk around every 1-2 hours and stay well hydrated).




Medical treatment of VTE

If the patient’s medical history and a physical examination suggest venous thromboembolism, further exams should be ordered to confirm the diagnosis. For venous thrombosis, a doppler ultrasound is performed.  It will confirm the presence of a clot in the vein. For pulmonary embolism, a tomography scan with injection of a contrast medium (angiogram) or a nuclear medicine examination, ventilation-perfusion scintigraphy can confirm the diagnosis.


Medical and non-surgical treatment of VTE

When a diagnosis of venous thromboembolism is made, treatment consists of thinning the blood using an anticoagulant to prevent the spreading and travelling of the clot.

The following anticoagulant medications are used:

  • Unfractionated Heparin (Heparin IV)
  • Low molecular weight heparin (LMWH, such as Enoxaparin (Lovenox), Dalteparin (Fragmin), Tinzaparin (Innohep) or Nadroparin (Fraxiparin*)
  • Warfarin (Coumadin)
  • Direct oral anticoagulants (DOA, such as Apixaban (Eliquis), Rivaroxaban (Xarelto), Dabigatran (Pradaxa), Edoxaban (Lixiana*)


*The availability of these anticoagulants may vary from one Canadian province to another.


The duration of treatment varies according to the location of thrombosis and the associated risk factors. Do not hesitate to discuss various treatments and preventive measures with your healthcare professional as they may vary depending on your medical conditions.