Deep Vein Thrombosis Treatments and Medications

Blood clots are the body’s first step in healing injuries. Sometimes, however, unnecessary blood clots form inside the bloodstream and cause problems such as a pulmonary embolism, heart attack, or stroke, all of which may result in death. Deep vein thrombosis happens when a blood clot forms inside a deep vein. Although not immediately hazardous, a deep vein blood clot can develop into a serious condition if it breaks loose. If it’s diagnosed in time, treatment can keep the hazard in check while the blood clot slowly breaks apart.

What is deep vein thrombosis (DVT)?

Deep vein thrombosis (DVT) is a blood clot (thrombus) that forms on the inner tissue of a deep vein. Deep vein blood clots most commonly form in the calf, thigh, or pelvis, but can also form in the arms, intestinal area, or head.

Many deep vein clots resolve without complications. However, the deep vein blood clot could detach from the vein, travel through the heart, and block arteries in the lungs, a potentially fatal condition called pulmonary embolism (PE). Also, about 20% to 50% of deep vein blood clots advance to post-thrombotic syndrome, a potentially debilitating condition marked by intense pain, swelling, and ulcers.

Deep vein thrombosis is caused by a combination of one or more factors: blood pooling in a vein, damage to a vein, or increased blood coagulation, called hypercoagulation. Blood pooling can result from immobility, bed rest, long-distance travel, or vein problems, such as varicose veins. Injury, surgery, or catheters can cause vein damage. Finally, hypercoagulation can be triggered by dehydration, older age, excessive salt intake, illness, medications, or genetics.

It often takes a combination of these factors to induce a deep vein blood clot. For instance, surgery puts people at risk for DVT because surgery can damage veins and several days of bed rest causes blood to pool in the legs.

Deep vein thrombosis strikes about one out of every 1,000 people every year. Fortunately, DVT can be successfully treated with anticoagulants, medications that help to thin the blood and reduce the body’s ability to form future blood clots. Early diagnosis, however, is critical in preventing potentially fatal complications.

How is deep vein thrombosis diagnosed?

Deep vein thrombosis is diagnosed based on risk factors, symptoms, a D-dimer test, and ultrasonography.

History and physical examination

A healthcare professional can’t diagnose DVT with certainty by just taking a medical history and performing a physical exam—both are only able to contribute to the likelihood of DVT.

The history will help the physician identify risk factors such as:

• Immobility (bed rest, operations, long flights)

• Injury to the vein (injury, intravenous drug use, surgery, history of DVT)

• Blood thickening (dehydration or thrombocytosis)

• Conditions that increase coagulation (genetics, cancer, sepsis, heart failure, estrogen birth control pills, burns, irritable bowel syndrome, smoking, high blood pressure, or diabetes

• Conditions that increase the risk of blood clots (surgery, cancer, pregnancy, or obesity)

In the exam, the physician is also looking for symptoms of DVT, such as:

• Localized pain, swelling with tenderness, and/or redness over the site in question

The healthcare provider will use a scoring method to determine the clinical probability of DVT. The initial exam can be performed by a general practitioner or urgent care doctor, but they might refer the patient to a hematologist (an internist who specializes in blood conditions) or even a vascular surgeon for further assessment and management.

D-dimer test

A D-dimer test alone cannot be used to confirm a DVT but can help rule out a DVT in patients who are at low to intermediate risk based on the history and physical. D-dimer is a left-over product of the blood clotting process, so a D-dimer test can determine if blood clots are forming in a person’s body. If the test comes back negative in a low risk patient, there is a very minimal chance the patient has a DVT. If the test comes back positive, the doctor will order an ultrasound for confirmation.

Ultrasonography

An ultrasound is a fairly accurate test for DVT. It cannot only determine the presence of a blood clot, it can determine the size of the blood clot and how much of the vein is blocked. It is the first test given for patients with a high probability of DVT or to any patient with a positive D-dimer test.

Venography

Venography is an expensive and more invasive procedure that is only performed when an ultrasound is uncertain, which may happen if the clot is in the calf. A contrast dye is injected into the bloodstream and the nearby veins are imaged by X-ray to assess blood flow through the veins.

Deep vein thrombosis treatment options

DVT treatment focuses on preventing complications such as pulmonary embolism or post-thrombotic syndrome using anticoagulant medications to prevent further blood clotting. For severe cases or patients who cannot take anticoagulants, a small blood clot filter can be implanted in the vein that runs to the heart.

Anticoagulant medications

Anticoagulants are the central pillar of DVT treatment. Depending on whether the DVT episode requires hospitalization, treatment may begin in a hospital setting with injectable anticoagulants versus oral anticoagulants due to their fast onset of action and predictable duration of action. Once the patient is stabilized, patients can be treated on an outpatient basis withusually oral anticoagulants. Patients who do not require hospitalization may avoid injectable anticoagulants altogether and be initiated on an oral anticoagulant with close monitoring. The usual duration of therapy is at least three to six months. Patients with recurrent DVTs and/or other underlying conditions, such as cancer, will receive therapy for longer.

Catheter-directed thrombolysis (CDT)

For severe DVT, a vascular surgeon will insert a catheter into a vein and inject a clot-breaking medication directly on to the blood clot - called a thrombolytic. Clot-breaking medications have a high risk of causing internal bleeding, so CDT allows for a very small dose to be used. This approach has demonstrated a reduction in progression to PTS by preventing venous scarring.

Mechanical devices

Mechanical devices are often used to improve blood flow as a preventative measure. These include compression stockings, intermittent pneumatic compression (IPC), and the venous foot pump.

Surgery

In severe cases or for patients who cannot safely take anticoagulants, surgery may be used to remove the blood clot via thrombectomy. Patients who cannot be put on anticoagulants will most likely have a filter implanted in the inferior vena cava (IVC), the large vein in the middle of the body that carries blood from the lower body to the heart. The inferior vena cava filter is implanted with a catheter and catches any blood clot that comes loose, preventing that blood clot from reaching the lungs and causing a pulmonary embolism. Depending on the patient’s risk of forming blood clots, the IVC filter may be installed permanently or removed after a few months.

Deep vein thrombosis medications

Deep vein thrombosis is treated with anticoagulants, drugs that suppress the formation or function of various clotting factors normally present in the blood. In severe cases, deep vein thrombosis will also be treated with medications that dissolve blood clots.

How do anticoagulants work?

Blood clot formation is a complex process. To make a blood clot, platelets—small, disk-shaped cells in the bloodstream—clump and glue themselves together in a web made out of a protein called fibrin.

The process involves activating a series of proteins one after another, known as the coagulation cascade. These proteins are known as blood clotting factors, each one having an inactive state and an active state. Each active blood clotting factor activates the next clotting factor in line with the cascade. At the end of this line is factor X (“factor 10”) which is activated into factor Xa (“activated factor 10”). Activated factor X converts an inert protein called prothrombin into thrombin, the last switch in the process. Thrombin activates fibrinogen to form fibrin, the “glue” that catches platelets circulating within the bloodstream to form the clot.

The formation of many of these active clotting factors requires a reserve of vitamin K. In addition, the human body produces proteins that function to shut down the coagulation cascade as a form of checks and balances. The most important of these is antithrombin, a protein that attaches to thrombin and prevents that crucial last step, the activation of fibrinogen into fibrin.

The whole process, then, is like a factory line that can be shut down at any step. That is what anticoagulants do. Some push antithrombin into action (called antithrombin activators), some shut down the formation of vitamin K (called vitamin K antagonists), and some just flip the off switch on factor Xa or thrombin (called direct factor Xa inhibitors and direct thrombin inhibitors).

Antithrombin activators

Antithrombin activators are fast-acting blood thinners and a first-line therapy for DVT. They are intended to quickly slow down and stabilize blood clotting. The most commonly prescribed are low molecular weight heparins (LMWH) such as enoxaparin, but unfractionated heparin (UFH) may be used in certain patients, such as those with kidney failure. Heparins, however, can have serious side effects, which if arise doctors may prescribe a similar acting drug called fondaparinux.

Vitamin K antagonists (VKAs)

Vitamin K antagonists prevent cells from converting vitamin K into a version that can be used to form active blood clotting factors. Warfarin has historically been the first-line anticoagulant prescribed after a patient has been treated with enoxaparin or fondaparinux. Warfarin, however, has a narrow therapeutic range, so patients require close monitoring of the drug through regular blood work.

Direct oral anticoagulants (DOACs)

Direct oral anticoagulants block proteins involved in blood clot formation. For DVT, the most commonly prescribed oral anticoagulant is Pradaxa (dabigatran), a direct thrombin inhibitor. Factor Xa inhibitors include Xarelto (rivaroxaban), Eliquis (apixaban), and Savaysa (edoxaban). All have similar efficacy to warfarin, but have a wider therapeutic range and do not require continual blood work monitoring.

Thrombolytics

Thrombolytic (“clot-dissolving”) medications break up blood clots and are most commonly prescribed for patients immediately after a stroke or heart attack due to a clot. Alteplase is one thrombolytic used in DVT patients, but only in very small doses injected directly on to the blood clot using catheter-directed thrombolysis (CDT).

What is the best medication for deep vein thrombosis?

Anticoagulant treatment of DVT follows well-researched protocols and is closely monitored. The “best” medication may vary depending on pre-existing conditions and side effects.

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Best medications for deep vein thrombosis