Venous thromboembolism (VTE) is a group of diseases characterized by the formation of a blood clot in a vein. Most of patient affected by VTE have a deep venous thrombosis of the lower limbs (DVT or phlebitis) or a pulmonary embolism (PE). In 2010, according to the Bulletin épidémiologique hebdomanaire, VTE affected 183/100,000 people annually, so this is a common pathology that can affect about 1 in 10,000 people. More rarely, the clot takes place in the veins of the upper limbs, the cerebral veins or the abdominal veins.
Risk factors
The risk of VTE increase in some situations, such as surgery with general anesthesia lasting more than 30 minutes, immobilization of a lower limb (plaster cast), hospitalization for acute illness, estrogen contraception, pregnancy and postpartum and cancer. VTE is also favored by patient-specific characteristics such as obesity, the presence of a genetic predisposition such as the factor V Leiden mutation, and certain autoimmune diseases like anti-phospholipid syndrome or hematological diseases.
Diagnosis
In most cases, the diagnosis of DVT is suspected upon the occurrence of clinical symptoms. Symptoms such as pain, edema, and redness of the lower limb (more rarely bilateral) are suggestive of DVT. PE is suspected when shortness of breath (dyspnea), chest pain, malaise, sensation of rapid heartbeat (palpitations), or the emission of blood through the mouth during a coughing effort (hemoptysis) occur. For venous thrombosis of atypical location (cerebral, abdominal, etc.), the symptomatology depends on the location of thrombus (headache, vomiting, abdominal pain, etc.).
The positive diagnosis of VTE is generally based on a radiological examination revealing the presence of one or more blood clots in the explored area. If DVT is suspected, a venous Doppler ultrasound is most often performed. It is a simple, non-irradiating procedure available in offices and hospitals. To diagnose PE, thoracic angioscan or ventilation-perfusion scintigraphy are used. Finally, to detect venous thrombosis in atypical locations, CT scans with injection of iodinated contrast or magnetic resonance imaging (MRI) may be useful. In some cases, the diagnosis of VTE can be excluded by a biological analysis performed on a simple blood test in your local laboratory: the measurement of the D-dimer levels in the plasma. However, if the D-dimer concentration is higher than a prespecified threshold, it is impossible to conclude and then, previously described imaging tests are necessary.
Treatment
The treatment of VTE is mainly based on anticoagulant therapy. These treatments help prevent the extension of the existing thrombosis or the occurrence of other thromboses at other location. The blood clot in place can be destroyed by the fibrinolytic system, specific to each patient, over a period of several months, but the patient can also keep a sequential, old clot. Different anticoagulant treatments are available. Some are administered orally, such as direct oral anticoagulants, and do not require systematic laboratory monitoring, while others, such as vitamin K antagonists, require regular measurement of the INR by means of a blood test in the laboratory to assess their effectiveness and safety. There are also injectable anticoagulant treatments. Low molecular weight heparins are administered subcutaneously in one or more daily injections and do not require systematic biological monitoring. Unfractionated heparin, on the other hand, is usually administered in hospital either subcutaneously or intravenously and requires regular biological monitoring of anti-Xa activity.
In some cases, the severity of the VTE requires the use of fibrinolytic agents. These are treatments aimed at destroying the blood clot. Because of their high risk of hemorrhagic complications, their use is limited to hospitalized patients presenting a critical clinical situation.
The use of venous compression socks, stockings or tights in the event of DVT is recommended for several months after the event.
The duration of the treatment is determined in agreement with your doctor and depends on a large number of factors such as, for example, the characteristics of the thrombotic event but also the presence of any factors favoring the occurrence of a venous thrombosis and whether they are permanent or transitory. During anticoagulant therapy, thrombosis risk decreases but there is a risk of bleeding (bruising, nosebleeds, heavy periods or hematomas when falling). It is this benefit-risk balance that allows the physician to evaluate the duration of anticoagulant treatment.
Prevention
Preventive measures for VTE exist. If you are exposed to a high-risk situation (please see above), your doctor may suggest that you wear compression stockings and/or take low-molecular-weight heparin at a preventive dose. The management of obesity and early mobilization after surgery are also important in the prevention of venous thromboembolic events.
