Deep Vein Thrombosis (DVT)
What is deep vein thrombosis?
Deep vein thrombosis (DVT, also called venous thrombosis) is a blood clot that develops in a vein deep in the body. The clot may partially or completely block blood flow through the vein. Most DVTs occur in the lower leg, thigh or pelvis, although they also can occur in other parts of the body including the arm, brain, intestines, liver or kidney.
What is the danger of DVT?
Even though DVT itself is not life-threatening, the blood clot has the potential to break free and travel through the bloodstream, where it can become lodged in the blood vessels of the lung (known as a pulmonary embolism). This can be a life- threatening condition. Therefore, prompt diagnosis and treatment are necessary.
DVT can also lead to complications in the legs referred to as chronic venous insufficiency or the post-thrombotic syndrome. This condition is characterized by pooling of blood, chronic leg swelling, increased pressure, increased pigmentation or discoloration of the skin, and leg ulcers known as venous stasis ulcers.
What is the difference between DVT and a superficial venous thrombosis?
A superficial venous thrombosis (also called phlebitis or superficial thrombophlebitis) is a blood clot that develops in a vein close to the surface of the skin. These types of blood clots do not usually travel to the lungs unless they move from the superficial system into the deep venous system first.
What are the symptoms of DVT?
DVT most commonly occurs in just one leg or one arm. Not everyone with DVT will experience symptoms, although when present, they may include:
- Swelling of the leg or arm (sometimes it occurs suddenly)
- Pain or tenderness in the leg that may only be present when standing or walking
- Feeling of increased warmth in the area of the leg or arm that is swollen or that hurts
- Redness or discoloration of the skin
- Enlargement of the superficial veins in the affected leg or arm
Symptoms of a pulmonary embolism include:
- (Sudden) shortness of breath
- Sharp chest pain, often aggravated by coughing or movement
- Pain in the back
- Cough with or without bloody sputum
- Excessive sweating
- Rapid pulse or breathing
- Lightheadedness or passing out
Some people only find out they have DVT after the clot has moved from the leg or arm and traveled to the lung.
It is important to notify your doctor immediately or go to the emergency room if you have symptoms of a pulmonary embolism or DVT. Do not wait to see if the symptoms will "go away." Get treatment right away to prevent serious complications.
What are the potential risk factors?
The following conditions may increase your risk of developing DVT:
- An inherited (family) condition that increases the risk of blood clotting
- Cancer and some of its treatments (chemotherapy)
- Limited blood flow in a deep vein, due to injury, surgery, or immobilization
- Long periods of inactivity that decrease blood flow, such as:
- Sitting for a long period of time on long trips in a car, truck, bus, train, or an airplane
- Immobility after surgery or a serious injury
- Pregnancy, and the first 6 weeks after giving birth
- Being over age 40 (although deep vein thrombosis can occur in any age group)
- Being overweight
- Taking birth control pills or hormone therapy, including for postmenopausal symptoms
- Placement of a central venous catheter or pacemaker
How is DVT diagnosed?
Your doctor will ask you questions about your medical history and perform a physical exam as part of your diagnostic evaluation. Several tests will also be performed.
A duplex venous ultrasound is the most common test used to diagnose deep vein clots. It is used to evaluate the blood flow in the veins and to detect the presence and specific location of blood clots. During a venous ultrasound, the technologist applies pressure when scanning your arm or leg. If the vein does not compress with pressure, it may indicate a blood clot is present.
Venography is an X-ray procedure used to examine the deep veins. During the procedure, a contrast material (dye) is injected into the veins before the X-rays are taken. Venography may be performed if the Duplex ultrasound does not provide a clear diagnosis. The dye makes the vein and the blood clot visible on the x-ray. If the blood flow in the vein is blocked, it may also show on the x-ray.
Other tests that may be performed to detect a blood clot include:
- Magnetic Resonance Imaging (MRI) or Magnetic Resonance Venography (MRV): MRI shows pictures of organs and structures inside the body, while MRV shows pictures of the blood vessels in the body. Radio waves are used in MRI and MRV to create the images. In many cases, MRI and MRV can provide information that may not show up on an x-ray. However, MRV is a more expensive technology and not always readily available.
- Computed tomography (CT) scan is a type of x-ray that can provide pictures of structures inside the body. A CT scan may be used to diagnose deep vein thrombosis in the abdomen or pelvis, as well as blood clots in the lung to diagnose pulmonary embolism.
If your doctor suspects that an inherited disorder could be causing the clots, he or she may conduct a series of blood tests. This may be important if:
- You have repeated blood clots that cannot be linked to any other cause
- You have a blood clot in a vein at an unusual location, such as in a vein from the intestines, liver, kidney or brain
- You have a strong family history of blood clots
How is DVT treated?
Depending on your condition, you may be admitted to the hospital for DVT treatment, or you may receive treatment on an outpatient basis.
Treatments include medications, compression stockings, elevation of the affected leg, and if the blood clot is extensive, more invasive diagnostic and treatment procedures. The main goals in treating deep vein thrombosis are to:
- Stop the clot from getting bigger;
- Prevent the clot from breaking off in your vein and moving to your lungs;
- Reduce the risk of another blood clot;
- Prevent long-term complications from the blood clot (chronic venous insufficiency or the post-thrombotic syndrome or, if in the lungs, a condition known as chronic thromboembolic pulmonary hypertension).
There are several medications used to treat and/or prevent DVT:
Anticoagulants (sometimes called blood thinners) decrease your blood's ability to clot. They are used to stop clots from getting bigger and to prevent a blood clot from moving. They are also often used in patients who are hospitalized to prevent clots from forming. Anticoagulants do not break up blood clots that have already formed. Your body's natural system may help dissolve the clot. In some cases, however, the clot will not completely dissolve.
Anticoagulants can either come as a pill, such as warfarin (Coumadin) or as an injection or shot, such as heparin or low molecular weight heparin (including enoxaparin sodium [Lovenox] or dalteparin sodium [Fragmin]). Another medication called fondaparinux sodium (Arixtra) can also be used and is given as an injection. There are several new medications that are all given orally (by mouth). They include rivaroxaban (Xarelto) and dabigatran (Pradaxa). These newer anticoagulants do not require monitoring.
Heparin, the low molecular weight heparin, fondaparinux, and warfarin may be given at the same time. Heparin and fondaparinux will act quickly, while the warfarin will take 4 to 5 days before it starts to work. Once the warfarin is working, the other anticoagulants will be stopped, but usually only after a minimum of 5 days of combined therapy. Pregnant women cannot take warfarin and will be treated with heparin or low molecular weight heparin only.
Heparin, low molecular weight heparin, or fondaparinux can also be given with the new anticoagulant, dabigatran, over a five-day overlap. Once the five days are completed, dabigatran can be used alone.
The other new anticoagulant, rivaroxaban, does not need an overlap and can be used alone and long-term for the treatment of patients with DVT and/or pulmonary embolism. Pregnant women cannot take warfarin and will need to be treated with heparin or low molecular weight heparin only.Treatment for DVT with anticoagulants usually lasts for 3 to 6 months. The following situations may change the length of treatment:
- If your blood clot occurred after a short-term risk like surgery or trauma, your treatment with anticoagulants may be shorter(3 months).
- If you have had clots before, you may need longer treatment
- If you are being treated for another illness (such as cancer), you may need to take an anticoagulant as long as the risk factor(cancer) is present
The most common side effect of anticoagulants is bleeding. You should call your doctor right away if you are taking warfarin, heparin, low molecular weight heparin, fondaparinux, dabigatran, or rivaroxaban and experience easy bruising or bleeding.
Thrombolytics are medications given to quickly dissolve the blood clot. These medications are delivered through a catheter that is directed into the area of the clot. They are used to treat large clots causing severe symptoms. Because they increase the risk of bleeding, they are only used in special situations determined by your physician. These situations may include massive swelling of an arm or leg or in situations where a blood clot in the lungs (pulmonary embolism) has left the patient very short of breath or with low blood pressure.
Direct thrombin inhibitors are medications that interfere with the clotting process. They are used to treat some types of clots and may be prescribed for patients who cannot take heparin or low molecular weight heparins.
Your doctor should prescribe graduated compression stockings to reduce the chronic swelling that can occur in the leg after a blood clot has developed. The swelling often occurs because the valves in the leg veins have become damaged or the vein remains blocked from the blood clot.
Most compression stockings are worn just below the knee. These stockings are tight at the ankle and become more loose as they go up the leg. This causes gentle external compression (or pressure) on your leg.
Take your medications exactly as prescribed and at the same time every day.
Have blood tests as directed by your doctor and keep all scheduled laboratory appointments so that your response to the medication can be monitored. If you are taking warfarin, the blood test will evaluate how well your medicine is working.
A blood test called a Protime or PT/INR measures how fast or slow your blood clots. The PT test results are reported as an international normalized ratio (INR). Your medications may be changed or adjusted based on the results of this test.
If you are prescribed one of the newer medications such as rivaroxaban or dabigatran, you will not need routine monitoring. However, most physicians advocate checking the patient’s renal (kidney) function from time to time with these newer anticoagulants.
Talk to your doctor before taking any other medications, especially over-the-counter medications.
Talk to your doctor about your diet, because certain foods affect how well your warfarin medication works. The newer anticoagulants (rivaroxaban and dabigatran) are not affected by your food intake.
Once DVT occurs, getting around may become more difficult at first. You should gradually return to your normal activities. If your legs feel swollen or heavy, lie in bed with your heels elevated 5 to 6 inches. This will help improve circulation and decrease your leg swelling.
- Exercise your lower leg muscles if you are sitting still for long periods of time.
- Stand up and walk for a few minutes every hour while awake.
- Don't wear tight-fitting clothing that could decrease the circulation in your legs.
- Wear compression stockings as recommended by your doctor.
- Avoid activities that may cause a serious injury.
DVT Treatment Procedures
Catheter-directed thrombolytic therapy is a nonsurgical treatment for DVT that dissolves blood clots. It is performed in a catheterization laboratory by a specially-trained physician and a team of nurses and technicians. The doctor and his team will use clot-dissolving medications referred to as thrombolytics.
First, the patient receives medication for relaxation. The doctor numbs the area where the procedure is to be performed. A guide wire followed by a sheath (thin, plastic tube) is inserted into the vein. A long, slender tube called a catheter is inserted through the sheath and guided through the vein to the segment where the blood clot is located. A clot-dissolving drug is infused through the catheter into the clot.
The clot usually dissolves in a matter of hours to a few days. The physician often uses a venogram or duplex ultrasound to evaluate the progress of the medication. At times, the narrowed area of the vein will need to be treated with angioplasty and/or a stent to prevent further clots from forming.
Angioplasty is a nonsurgical treatment for DVT that is used to widen the vein after the blood clot has been dissolved. During angioplasty, a small balloon at the tip of the catheter is inflated to stretch the vein open and increase blood flow. A stent may be necessary at times and is placed during the angioplasty procedure to keep the vein open.
A stent is a small, metal mesh tube that acts as a scaffold and provides support inside the vein. A balloon catheter, placed over a guide wire, is used to insert the stent into the narrowed vein. Once in place, the balloon is inflated and the stent expanded to the size of the vein holding it open. The balloon is deflated and removed, and the stent stays in place permanently.
Inferior vena cava filters are used when you cannot take any of the blood thinners, or if you are taking blood thinners and continue to develop clots. The filter can prevent blood clots from moving from the vein in your legs to the lung (pulmonary embolism). During a small surgical procedure, the filter is inserted through a catheter (thin tube) into a large vein in the groin or neck, then into the vena cava (the largest vein in the body). It can catch clots as they move through the body to the lungs. This treatment will help prevent a pulmonary embolism, but will not prevent the development of more clots.
Can DVT be prevented?
If you have had DVT, then you will need to prevent further clots from developing by:
- Taking your medications to prevent or treat blood clots as prescribed by your doctor.
- Keeping your follow-up appointments with your doctor and, if taking warfarin, with the laboratory so that your response to medications and other treatments can be evaluated.
If you have never had a deep vein clot, but have an increased risk for developing one, be sure to:
- Exercise your lower leg muscles if you will be sitting still for long periods of time. Stand up and walk at least every half hour if you are on a long flight. Or get out of the car every hour if you are on a long road trip.
- Get out of bed and move around as soon as you are able after surgery or being ill. The sooner you move around, the less chance you have to develop a clot.
- Take medications or use intermittent compression garments to prevent clots after some types of surgery, as directed by your doctor.
- Follow-up with your doctor as recommended to evaluate your risk and follow your doctor's recommendations for reducing your risk.
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