Deep Vein Thrombosis

Overview

When you hurt yourself and bleed, your body deploys certain inbuilt mechanisms to prevent excessive loss of blood and exposure to contamination. One of the most effective ways in which this is achieved in through the clotting or coagulation of blood. However, clots can form inside the body as well and these can be highly problematic. Clots that develop within arteries and veins can block the flow of blood. Worse, they can become detached only to be carried along by the blood until they get firmly lodged in an artery elsewhere. This is known as embolism and it can have severe, even fatal, consequences.

What Is Deep Vein Thrombosis?

A blood clot is also known as a ‘thrombus’. The process of formation of a blood clot is called ‘thrombosis’.  When thrombosis occurs within one of the deep veins in the body, this condition is referred to as deep vein thrombosis (DVT). One of the most common sites to be affected is the lower leg, although DVT can potentially appear in other areas such as the abdomen or the pelvis as well.

Sometimes the condition is silent and resolves spontaneously without causing any adverse effects. Otherwise, it can produce swelling in the affected area. Alternatively, the clot could become dislodged. This is what leads to complications such as pulmonary embolism. A particularly severe case of deep vein thrombosis could also leave the affected vein permanently damaged so that the patient might experience symptoms even after the clot itself has been resolved.

Why Does It Happen?

Generally speaking, any condition that makes your blood more likely to clot can increase your risk of developing deep vein thrombosis. This can occur in a few different ways:

• Hypercoagulability is the property that makes blood clot more willingly than usual. The causes for hypercoagulability of blood may be inherited or they may be acquired. The latter category includes pregnancy since blood has an increased likelihood to form clots during this time.
• Any condition that inflicts damage on the walls of your blood vessels, in this case, your veins, can also raise the risk of thrombosis.
• Alterations or impairment in the normal circulation of blood through the veins. Disturbances in blood flow can cause clot formation.

More specific risk factors are listed below:

• Damage to the walls of the veins. This can happen when you have a habit of smoking.
• Prolonged bed rest or immobility.
• Having a family history of blood clots.
• History of deep vein thrombosis or pulmonary embolism.
• Trauma. This can include surgical trauma as well.
• Hormone replacement therapy.
• Having a blood clotting disorder.
• Dehydration.
• Heart disease.
• Lung disease.
• Vasculitis.
• Hepatitis.
• Inflammatory bowel disease.
• Cancer.
• Hughes syndrome.
• Obesity.
• Taking oral contraceptives.
• Being pregnant.
• Having varicose veins.
• Taking chemotherapy or radiation therapy.

What Are The Symptoms Of Deep Vein Thrombosis?

It is quite possible to have deep vein thrombosis and not be aware of the fact. This happens when the condition is asymptomatic. In other words, the patient does not experience any symptoms indicating the presence of a blood clot in the deep veins. Usually, a significant blood clot will obstruct the flow of blood through the affected vein to an appreciable extent. In order to compensate for this, neighboring veins will enlarge and try to take on the load of the affected vein. When this happens, the body has managed to successfully adapt to the problem and the patient may not suffer from symptoms at all. In some cases, the symptoms may be only mild in severity.

When the condition is symptomatic, this may be because the bypass mechanism has not been able to relieve the load of the affected vein. In such cases, patients may experience the following indications:

• Pain in the affected area, often a leg.
• Swelling.
• Soreness.
• Tenderness.
• The affected area might be warmer than surrounding areas.

What Are Some Potential Complications?

When the blood clot becomes detached, there is a risk of it becoming lodged into an artery in an organ like the lungs. Such an occurrence is known as a pulmonary embolism. When this happens, the patient may start feeling breathless and may also complain of discomfort or pain in their chest. Soon they may start feeling lightheaded. The combination of deep vein thrombosis and pulmonary embolism is referred to as venous thromboembolism. It can be fatal.

Another possible complication is a condition known as post-thrombotic syndrome. As a result of the damage caused by thrombosis, the patient will continue to suffer from chronic pain in the affected area and may also experience cramps from time to time. The skin around that area may become hyperpigmented as well and the patient may feel a sense of fatigue or weakness. This is also known as a post-phlebitic syndrome.  

How Is Deep Vein Thrombosis Diagnosed?

The symptoms of deep vein thrombosis are rather vague and non-specific. It is difficult to arrive at a diagnosis on the basis of the symptoms alone. Imaging tests such as venography offer the best possibility for correct identification of the problem. The following procedures may be included in the process:

• Physical examination.
• Medical history.
• Blood tests.
• D-Dimer test.
• Ultrasound.
• Doppler ultrasound 
• Venography.
• Computerized tomography (CT).
• Magnetic resonance imaging (MRI).

What Treatments Are Available?

• Anticoagulants or blood thinners– These medications do not break the existing clots but prevent the new clots from forming. Heparin is a commonly used anticoagulant which can be administered either subcutaneously (under the skin) or intravenously (into the vein). Other similar drugs are dalteparin, fondaparinux, and enoxaparin. Oral anticoagulants such as warfarin are usually administered overlapping with heparin as the latter acts quickly; so, heparin makes up for the delay in action of the oral anticoagulant warfarin. Other oral anticoagulants are rivaroxaban, apixaban, edoxaban, dabigatran etc.
• Thrombolytics or clot dissolvers- These drugs are given intravenously or through a catheter which is directly positioned in the clot. They can break the clots formed in the veins. They are usually given only in life-threatening situations as they can cause severe bleeding owing to their clot-busting action.
• Vein filter– In this procedure, a filter is placed in the inferior vena cava (the main vein of the body) by means of a catheter. This vein carries blood from the lower half of the body to the right side of the heart (right atrium). These filters can prevent the blood clots from being carried to the lungs after breaking loose.
• Compression stockings– These are worn from the feet up to the knee level. These help to counter the swelling associated with DVT.

Prevention

Prevention of DVT is mainly by taking measures to improve blood circulation such as moving around often during long journeys, fidgeting in the seat whenever possible, tightening and releasing leg muscles, wearing loose clothes. Regular physical activity and maintenance of healthy body weight are very important.In case you are at risk for DVT, use graduated compression stockings and blood thinners (if prescribed by your doctor) to prevent DVT.

References