Deep Vein Thrombosis (DVT)

Definition

Deep vein thrombosis (DVT) is a medical condition characterized by blood clot formation in a vein or veins lying deep within the body. It most commonly affects the leg veins. Symptoms of DVT are pain, redness and swelling of the affected part of the body usually the leg although about half of the patients of DVT may not have any symptoms. DVT may be life-threatening due to its complication (pulmonary embolism).

Damaged walls of the vessels, long-standing stagnant blood flow and increased clotting tendency are the three factors responsible for DVT. Breaking of the clot (anticoagulant therapy) is the principal therapeutic approach. Use of compression stockings and exercise are used commonly to prevent DVT.

Symptoms

DVT patients may present with :

  • Swelling of affected legs (usually leg veins are most commonly affected)
  • Pain, redness and increased temperature (warmth) of the legs
  • The skin overlying the affected part may show change in color (pale, red even blue), become stretched and shiny (sue to swelling).

It is important to remember that the abovementioned symptoms are seen in only half of the DVT patients andin the remaining half there may be no noticeable symptom until complications of DVT occur.

Complications are mainly of two types :

  • Pulmonary embolism marked by sudden breathlessness with chest pain, profuse sweating, palpitation even blackout. There may be blood tinged sputum production with a sense of apprehension.
  • Post phlebitis syndrome (post thrombotic syndrome) due to damage of the vessel walls characterized by similar symptoms as DVT (swelling, pain and change in skin color)

Causes

Interplay among three following factors is responsible for DVT. These are :

  • Long-term stagnation of blood flow (due to prolonged sitting or immobility) especially after major surgery commonly orthopedic surgery.
  • Increased tendency of blood clotting due to some genetic or acquired factors.
  • Genetic factors:
    – Deficiency of three common blood factors (protein C, protein S and antithrombin) preventing blood clot.
    – Mutation (sudden, unexpected permanent change in gene) of factor V and prothrombin genes ( both favor clotting)
    – Blood group other than O.

Acquired factors occurring secondary to any disease, drug intake or physiological condition :

  • Cancer and chemotherapy
  • Pregnancy, immediately after delivery of baby
  • Oral contraceptive pill intake
  • Hormone replacement therapy in post menopausal females
  • Old age
  • Obesity
  • Damage to the inner smooth lining of the blood vessels
  • Physical trauma
  • Surgery
  • Infection
  • Catheter in the central vein

DVT usually starts in the veins of the calf and gradually progress to the direction of venous blood flow (towards the knee) affecting the thigh and knee veins. Sometimes a clot can break away and travel through the bloodstream to other sites in the body. Complications arise when the thrombus is dislodged from the vein (embolus) and reach via blood the lung (pulmonary) veins causing pulmonary embolism (life-threatening).

Risk factors

  • Prolonged immobilization (during surgery, long distant flying, bed rest after major surgery)
  • Genetic defect in blood clotting
  • Pregnancy
  • Heart failure
  • Smoking
  • Obesity
  • Advanced age
  • Pacemaker
  • Family or personal history of prior DVT

Treatment

Anticoagulation therapy is the main therapy for DVT. Drugs used are oral (warfarin) and parenteral (low molecular weight heparin) anticoagulant. This prevents the formation of a clot but in some cases clot busting drugs are needed to remove an already established drug. Prevention of DVT is done by using compression stockings, leg exercise and early mobilization after surgery. Lifestyle measures along with these drugs can ensure that complications are avoided or at the very least minimized.

 

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