Deep vein thrombosis (DVT) is a disease characterized by the formation of thrombus (blood clots), capable of completely or partially occluding blood vessels.
Thrombi can form in the bloodstream anywhere in the body, although the deep veins in the legs and pelvis are certainly the most affected areas. Blood clots inside the veins obstruct normal blood circulation causing pressure to rise in that swollen and painful area. Sometimes, however, no disturbance may be present.
DVT is a disease with an annual incidence of about 800,000 cases and, although it can strike at any age, it is more frequent in the elderly population. It can occur in elderly patients bedridden due to chronic diseases, in those suffering from certain diseases that impair blood clotting or in someone who is forced to sit for a long time, for example during a long-haul trip by plane or car.
DVT is a serious disease and can lead to a potentially fatal complication such as pulmonary embolism. In this case the thrombus (or a fragment of it) detaches from its site of origin forming an embolus (obstruction) which, through the circulation venous, reaches the heart and can reach an arterial branch of the pulmonary circulation, obstructing it.Symptoms
Deep vein thrombosis in many cases can give no sign of its presence (asymptomatic). Often the disorders caused by the disease are not specific and can be represented by:
- calf cramps
- pain and tension in one leg, which can become red and hotter than the other
Deep vein thrombosis, if neglected and not treated immediately, can be the cause of a "pulmonary embolism, a very serious complication that causes:
- difficulty in breathing
- wheezing (dyspnoea)
- chest pain which gets worse when breathing
- sudden collapse
Therefore, in the presence of pain, swelling in the legs, dyspnea and chest pain, it is necessary to seek immediate medical attention.Causes
Deep vein thrombosis is caused by the presence of thrombi within the bloodstream. It can occur anywhere in the body but more often in the veins of the lower limbs and pelvic region (part of the body between the abdomen and lower limbs. ).
Although sometimes it occurs for no apparent reason, it is the consequence of one or more risk factors including:
- old age
- long periods of inactivity and prolonged immobility, such as a long journey by plane or by car. In this case it is important to get up from time to time, straighten and move your legs
- pregnancy, hormone replacement therapy. Blood tends to clot more than normal during pregnancy or the use of hormonal therapies such as birth control pills, hormone replacement therapy in menopause, hormonal therapies for the treatment of some types of cancer
- trauma, especially fractures of the pelvis, hip or leg
- tumors / chemotherapy
- chronic inflammatory diseases
- coagulation defects, hereditary thrombophilic syndromes, antiphospholipid antibody syndrome, hyperhomocysteinemia and hereditary predisposition
- surgical interventions, especially in the abdomen and orthopedics, such as hip replacement surgery
Deep vein thrombosis often not manifesting itself with specific and evident disorders (symptoms) is difficult to ascertain (diagnose). The medical examination and the history of the person's state of health (anamnesis) do not allow to identify with certainty the DVT which must therefore be confirmed with instrumental and laboratory tests.
The ecocolordoppler is the most widely used instrumental examination to identify the localization and conformation of the thrombus. It is neither invasive nor painful or dangerous. It is based on ultrasound technology and is a valuable aid for the doctor to check for any slowdown or blockage of blood flow due to the presence of thrombi.
Another important exam is the dosage of D-dimer, protein fragment detectable in the blood in the event of degradation of fibrin, a component of the thrombus.
To check for changes in blood clotting, laboratory tests may also be necessary, such as:
- blood count
- genetic testing, to reveal the presence of mutations favoring thrombosis
- antithrombin III
- antiphospholipid antibodies, lupus anticoagulants
- homocysteine dosage
The goals of deep vein thrombosis treatment are to prevent thrombus enlargement and the departure of emboli, to promote and accelerate thrombus degradation (fibrinolysis), and to prevent long-term complications.
Usually, drug treatment begins with the administration of heparin which is able to immediately prevent thrombus formation. There are two different types of heparin:
- standard heparin (unfractionated), administered both subcutaneously and intravenously (injection and infusion) with a dose that varies from person to person
- low molecular weight heparin, administered subcutaneously
Both types of heparin can cause mild unwanted effects (side effects) such as allergies, rashes, bleeding and, if taken for a long time, weakening of the bones.
After treatment with heparin, we generally continue with oral anticoagulant therapy (OTA): warfarin is certainly the most widely used drug and can be administered for a period of time ranging from three to six months or, sometimes, for life. People on warfarin must, however, periodically undergo a blood test to evaluate the so-called prothrombin time (a measure of some clotting factors); the INR value (International Normalized Ratio) is then determined, useful for establishing the right dosage of the drug. In addition, warfarin can interfere with many medicines and with different foods such as vegetables and foods rich in vitamin K.
The arrival of the new oral anticoagulants (NAOs) has opened interesting perspectives in the therapy of DVT: they are direct inhibitors of thrombin or activated factor X (FXa) of the coagulation cascade that appear effective, safe, with a short half-life (the time required to reduce its availability by 50%) and reduced interference with other drugs or foods, without having to force the patient to frequent laboratory tests. Currently, the NAOs available in clinical practice (DVT, stroke prevention) are: rivaroxaban, apixaban and dabigatran. However, it must be considered that they are contraindicated in patients with mechanical heart valves and in those with high renal insufficiency and severe liver disease.
However, in some cases, anticoagulant therapy may not be effective or contraindicated, or may need to be stopped for other reasons. As an alternative, a mechanical protection technique is used which consists in the insertion of filters in the inferior vena cava. Filters are small devices that, inserted in place, are able to retain large fragments of clots in the blood and block their path towards the heart and lungs.
The filters used can be of two types:
- temporary, temporary filters are inserted and then removed later
People with DVT in the lower limbs are advised to wear special graduated compression stockings that can reduce the risk of complications.Prevention
The prevention of deep vein thrombosis is mainly based on the observance of certain lifestyles:
- walk 4-5 kilometers every day at a fast pace, cycling and / or swimming regularly
- get up and move your legs on the go, if you have to face a long journey by plane or by car it is advisable to get up frequently to take a few steps and / or stretch the legs, calves and ankles at regular intervals
- maintain a healthy weight, obese or overweight people should eat a balanced diet
- not smoking
- do not expose your legs to the sun during the hottest hours, during the summer
- keep your legs raised, when resting on the bed it is a good idea to raise the legs by at least 10-15 centimeters in order to facilitate the return of blood to the heart
- wear elastic stockings graduated compression, especially those who do a job that forces them to stand for a long time
Most episodes of DVT occur as a complication of surgery or the presence of a tumor. To prevent these episodes, people are treated with low molecular weight heparin both in the hospital and at home after being discharged.