What are the main causes of blood clots in legs. How can you recognize the symptoms of deep vein thrombosis. What are effective strategies for preventing blood clots during travel or prolonged inactivity. How is deep vein thrombosis treated and what are the long-term implications.

Understanding Deep Vein Thrombosis (DVT) and Its Implications

Deep vein thrombosis (DVT) is a serious medical condition that occurs when blood clots form in the deep veins of the legs. These clots can pose significant health risks, potentially leading to life-threatening complications such as pulmonary embolism (PE). In fact, PE claims more lives annually in the United States than breast cancer, highlighting the critical importance of understanding, recognizing, and preventing DVT.

DVT occurs when blood flow in the deep veins of the legs becomes sluggish or when an individual has a predisposition to blood clot formation. Dr. Sherry Scovell, a vascular surgeon specializing in venous disease at Harvard-affiliated Massachusetts General Hospital, explains, “If blood in the deep leg veins doesn’t move fast enough, or if you have a condition that makes you prone to blood clots, a blood clot can develop.”

The Relationship Between DVT and Pulmonary Embolism

Why is DVT so dangerous? The primary concern with DVT is the potential for a blood clot to break loose and travel through the bloodstream to the lungs, causing a pulmonary embolism. This can result in severe breathing difficulties, chest pain, and in some cases, can be fatal. Understanding this connection underscores the importance of early detection and prevention of DVT.

Common Causes and Risk Factors for Blood Clots in Legs

Several factors can contribute to the formation of blood clots in the legs. Some are related to lifestyle choices, while others are tied to medical conditions or genetic predispositions. Here are some of the most common causes and risk factors:

• Prolonged immobility (e.g., long flights, car rides, or bed rest)
• Recent surgery or injury
• Sedentary lifestyle
• Obesity
• Pregnancy and postpartum period
• Certain medications (e.g., birth control pills, hormone replacement therapy)
• Cancer and its treatments
• Advanced age
• Family history of DVT
• Smoking
• Certain medical conditions (e.g., heart failure, inflammatory bowel disease)

Can certain medical conditions increase the risk of DVT? Yes, several health conditions can elevate the risk of developing blood clots in the legs. These include heart failure, cancer, inflammatory bowel disease, and COVID-19. Additionally, genetic factors can play a role, with some individuals having inherited traits that make them more susceptible to clot formation.

Recognizing the Symptoms of DVT and Superficial Venous Thrombosis

Being able to identify the symptoms of blood clots in the legs is crucial for early detection and treatment. There are two main types of blood clots that can form in the legs: deep vein thrombosis (DVT) and superficial venous thrombosis (SVT). Each has distinct symptoms that individuals should be aware of.

Symptoms of Deep Vein Thrombosis (DVT)

DVT typically affects one leg and can cause the following symptoms:

• Sudden swelling in one leg
• Pain or tenderness in the affected leg
• Warmth in the area of the clot
• Redness or discoloration of the skin

Dr. Scovell notes, “When you get a blockage, the blood can’t leave your leg easily. That leg can become swollen rather suddenly, and painful. If your legs don’t normally get swollen, but one leg becomes swollen over a few days, that may be a sign of danger.”

Symptoms of Superficial Venous Thrombosis (SVT)

SVT, while generally less serious than DVT, can still cause discomfort and potentially progress to DVT. Symptoms of SVT include:

• Redness along the course of a vein
• Tenderness or pain over varicose veins
• Hardening of the vein
• Localized swelling

How can you differentiate between DVT and SVT? The main difference lies in the location and severity of symptoms. DVT typically causes more pronounced swelling and pain in the entire leg, while SVT is usually more localized and visible on the skin’s surface.

Prevention Strategies for Blood Clots During Travel and Prolonged Inactivity

Long periods of immobility, such as during air travel or extended bed rest, can significantly increase the risk of blood clot formation. However, there are several strategies individuals can employ to reduce this risk:

1. Stay hydrated: Drink plenty of water and avoid excessive alcohol intake.
2. Move regularly: Get up and walk around every hour or two when possible.
3. Exercise your legs: Even when seated, you can flex your ankles, rotate your feet, and stretch your calves.
4. Wear compression stockings: These can help prevent blood from pooling in your legs.
5. Choose an aisle seat: When traveling by plane, train, or bus, opt for an aisle seat to make it easier to get up and move around.
6. Avoid crossing your legs: This position can impede blood flow.

Dr. Scovell emphasizes the importance of calf muscle movement, stating, “The calf muscles act like pumps and propel blood through the veins.” By incorporating these strategies, individuals can significantly reduce their risk of developing blood clots during periods of prolonged inactivity.

The Role of Lifestyle Modifications in Preventing DVT

Beyond situational prevention strategies, making long-term lifestyle changes can play a crucial role in reducing the risk of DVT. These modifications can improve overall cardiovascular health and promote better blood circulation:

• Maintain a healthy weight: Obesity is a significant risk factor for DVT. Losing excess weight can reduce pressure on veins and improve blood flow.
• Exercise regularly: Engaging in physical activity promotes better circulation and helps maintain a healthy weight.
• Quit smoking: Smoking damages blood vessels and increases the risk of clot formation.
• Manage underlying health conditions: Properly controlling conditions like diabetes and high blood pressure can reduce DVT risk.
• Stay hydrated: Adequate hydration helps maintain proper blood viscosity and flow.
• Avoid prolonged periods of sitting: If your job requires long hours of sitting, take regular breaks to stand and move around.

How does regular exercise help prevent DVT? Regular physical activity improves overall circulation, strengthens the muscles that help pump blood back to the heart, and can help maintain a healthy weight. All these factors contribute to reducing the risk of blood clot formation.

Diagnosis and Treatment Options for Deep Vein Thrombosis

If you suspect you may have DVT, it’s crucial to seek medical attention promptly. Diagnosis typically involves a combination of physical examination, medical history review, and diagnostic tests. The most common diagnostic procedures include:

• Duplex ultrasound: This non-invasive imaging test can visualize blood flow in the veins and detect clots.
• D-dimer blood test: This test measures a substance in the blood that’s present when a blood clot is breaking down.
• Venography: In some cases, a contrast dye may be injected into the veins to provide a clearer image of blood flow.

Once diagnosed, treatment for DVT typically involves:

1. Anticoagulant medications: These “blood thinners” help prevent existing clots from growing and new clots from forming.
2. Compression stockings: These help reduce swelling and prevent blood from pooling in the legs.
3. Lifestyle modifications: Patients are often advised to increase physical activity and make other lifestyle changes to reduce future risk.
4. In severe cases, more aggressive treatments such as thrombolytic therapy or placement of a vena cava filter may be necessary.

How long does DVT treatment typically last? Dr. Scovell explains, “Treatment typically involves taking a blood thinner for several months or longer. We also have to figure out why you got the blood clot. If we can’t find a reason, you may need to take a blood thinner for a longer time.”

Long-Term Implications and Follow-Up Care for DVT Patients

Experiencing DVT can have long-term implications for an individual’s health and lifestyle. After the initial treatment phase, patients often require ongoing care and monitoring:

• Regular follow-up appointments: These allow doctors to assess the effectiveness of treatment and adjust as necessary.
• Continued use of anticoagulants: Some patients may need to remain on blood thinners long-term to prevent future clots.
• Lifestyle adjustments: Patients are often advised to maintain an active lifestyle and avoid prolonged periods of immobility.
• Monitoring for post-thrombotic syndrome: This condition, characterized by chronic pain, swelling, and skin changes, can develop in some DVT patients.
• Genetic testing: In some cases, doctors may recommend genetic testing to identify any inherited clotting disorders.

What is post-thrombotic syndrome and how common is it after DVT? Post-thrombotic syndrome is a long-term complication that can occur in up to 50% of DVT patients. It results from damage to the valves in the veins, leading to chronic symptoms such as pain, swelling, and skin changes in the affected leg. Regular use of compression stockings and maintaining an active lifestyle can help reduce the risk of developing this condition.

Emerging Research and Future Directions in DVT Prevention and Treatment

The field of DVT research is continually evolving, with new studies shedding light on risk factors, prevention strategies, and treatment options. Some areas of current and future research include:

• Novel anticoagulants: Researchers are working on developing new blood thinners with improved efficacy and safety profiles.
• Personalized risk assessment: Advanced algorithms and genetic testing may allow for more accurate prediction of individual DVT risk.
• Improved diagnostic techniques: New imaging technologies could enable earlier and more accurate detection of blood clots.
• Targeted therapies: Research is ongoing into treatments that could dissolve clots more effectively with fewer side effects.
• Prevention strategies: Studies are exploring new approaches to prevent DVT in high-risk populations, such as hospitalized patients and long-distance travelers.

How might artificial intelligence contribute to DVT management in the future? AI could potentially play a significant role in DVT prevention and treatment. Machine learning algorithms could analyze vast amounts of patient data to identify subtle risk factors and predict DVT occurrence with greater accuracy. AI could also assist in interpreting diagnostic images, potentially leading to faster and more accurate diagnoses.

As research progresses, our understanding of DVT continues to improve, leading to better prevention strategies and treatment options. However, awareness and proactive measures remain key in reducing the impact of this potentially life-threatening condition. By staying informed about the causes, symptoms, and prevention strategies for DVT, individuals can take an active role in protecting their vascular health and overall well-being.

Top causes of blood clots in the legs and how to avoid them

Don’t let a plane ride or an extended couch potato session put you at risk. Here’s what to do to keep your blood flowing.

Blood clots that form in the deep veins of the legs (deep-vein thrombosis, or DVT) can cause leg symptoms. Worse, the clots can break loose and travel through the blood to the heart and then to the lungs, causing a pulmonary embolism (PE).

More people die from PE each year in the United States than from breast cancer. What causes DVT and PE, what are the symptoms, and how can you prevent them?

Causes and triggers

After your arteries bring oxygen-rich blood to your legs, your veins send the blood back up to your heart and lungs (for more oxygen).

“If blood in the deep leg veins doesn’t move fast enough, or if you have a condition that makes you prone to blood clots, a blood clot can develop,” explains Dr. Sherry Scovell, a vascular surgeon who specializes in venous disease at Harvard-affiliated Massachusetts General Hospital.

Common blood clot triggers include

• being bedridden for long periods because of surgery or illness
• sitting for long periods — even three to four hours — in a car, plane, or train
• getting too little activity and sitting too much
• having blood pool in your legs because valves in a superficial vein don’t work properly (a varicose vein)
• taking a medication that promotes blood clotting.

Your risk for blood clots also increases with older age, a family history of DVT, a previous DVT, cancer, certain genes, COVID-19, heart failure, obesity, pregnancy, sickle cell disease, smoking, spinal cord injury, stroke, untreated varicose veins, and use of birth control pills or hormone replacement therapy.

Symptoms and risks

Be on the lookout for symptoms of two types of blood clots that can form in the legs.

A blood clot in the superficial veins. This is called a superficial venous thrombosis (SVT). “It causes redness, tenderness, or pain over varicose veins,” Dr. Scovell says. “Sometimes, an SVT can grow and become a deep-vein thrombosis.”

A blood clot in the deep leg veins. A DVT usually begins in one leg. “When you get a blockage, the blood can’t leave your leg easily. That leg can become swollen rather suddenly, and painful,” Dr. Scovell says. If your legs don’t normally get swollen, but one leg becomes swollen over a few days, that may be a sign of danger.

If part of that deep-vein clot breaks off and travels to the lungs, a PE occurs. “The clot gets stuck in blood vessels in the lung, you stop getting enough blood flow there, and that part of the lung dies. You have shortness of breath and chest pain when you take in a deep breath,” Dr. Scovell says.

Avoiding blood clots

There are apps available to help you determine your risk for getting a DVT. Dr. Scovell recommends an app called “Caprini DVT Risk,” available on iOS devices, such as an iPhone.

How can you avoid getting a clot when you’re stuck in situations that increase your risk, such as a long car ride? Keep the following tips in mind.

Stay hydrated. Avoid excessive alcohol intake, and drink lots of water.

Stretch your legs. Get up every hour or two and stretch your calves or move your ankles back and forth repeatedly. “The calf muscles act like pumps and propel blood through the veins,” Dr. Scovell says.

Move your legs while you’re lying down. Bend your knees, or point and flex your feet.

Wear compression stockings. They’ll help prevent swelling and keep blood from pooling in the legs.

Pay attention to your position. Avoid crossing your legs, and periodically change your position while seated.

Get an aisle seat when traveling. On a plane, train, or bus, sit in an aisle seat so you can easily get up and move around every few hours.

What if you have symptoms?

If you have new symptoms indicating the possibility of a DVT or a PE, and if you can’t speak immediately to your doctor or nurse, go to the emergency room. “It’s an emergency, not something to check out on Monday if it’s Friday,” Dr. Scovell says.

Treatment typically involves taking a blood thinner for several months or longer. “We also have to figure out why you got the blood clot. If we can’t find a reason, you may need to take a blood thinner for a longer time,” Dr. Scovell says. “And we don’t want you to ever get a blood clot again, so you’ll need to be proactive about avoiding future risks.”

Image: © gradyreese/Getty Images

How to Spot and Prevent Deep Vein Thrombosis

January 2017

Print this issue

When the Clot Thickens

En españolSend us your comments

Lots of things can cause pain and swelling in your leg. But if your symptoms stem from a blood clot deep in your leg, it can be dangerous. Blood clots can happen to anyone, anytime. But some people are at increased risk. Taking steps to reduce your chances of a blood clot forming in your veins can help you avoid potentially serious problems.

Blood clots can arise anywhere in your body. They develop when blood thickens and clumps together. When a clot forms in a vein deep in the body, it’s called deep vein thrombosis. Deep vein blood clots typically occur in the lower leg or thigh.

“Deep vein thrombosis has classic symptoms—for example swelling, pain, warmth, and redness on the leg,” says Dr. Andrei Kindzelski, an NIH blood disease expert. “But about 30–40% of cases go unnoticed, since they don’t have typical symptoms.” In fact, some people don’t realize they have a deep vein clot until it causes a more serious condition.

Deep vein clots—especially those in the thigh—can break off and travel through the bloodstream. If a clot lodges in an artery in the lungs, it can block blood flow and lead to a sometimes-deadly condition called pulmonary embolism. This disorder can damage the lungs and reduce blood oxygen levels, which can harm other organs as well.

Some people are more at risk for deep vein thrombosis than others. “Usually people who develop deep vein thrombosis have some level of thrombophilia, which means their blood clots more rapidly or easily,” Kindzelski says. Getting a blood clot is usually the first sign of this condition because it’s hard to notice otherwise. In these cases, lifestyle can contribute to a blood clot forming—if you don’t move enough, for example. Your risk is higher if you’ve recently had surgery or broken a bone, if you’re ill and in bed for a long time, or if you’re traveling for a long time (such as during long car or airplane rides).

Having other diseases or conditions can also raise your chances of a blood clot. These include a stroke, paralysis (an inability to move), chronic heart disease, high blood pressure, surgical procedure, or having been recently treated for cancer. Women who take hormone therapy pills or birth control pills, are pregnant, or within the first 6 weeks after giving birth are also at higher risk. So are those who smoke or who are older than 60. But deep vein thrombosis can happen at any age.

You can take simple steps to lower your chances for a blood clot. Exercise your lower leg muscles if you’re sitting for a long time while traveling. Get out of bed and move around as soon as you’re able after having surgery or being ill. The more active you are, the better your chance of avoiding a blood clot. Take any medicines your doctor prescribes to prevent clots after some types of surgery.

A prompt diagnosis and proper treatment can help prevent the complications of blood clots. See your doctor immediately if you have any signs or symptoms of deep vein thrombosis or pulmonary embolism (see the Wise Choices box). A physical exam and other tests can help doctors determine whether you’ve got a blood clot.

There are many ways to treat deep vein thrombosis. Therapies aim to stop the blood clot from getting bigger, prevent the clot from breaking off and moving to your lungs, or reduce your chance of having another blood clot. NIH scientists continue to research new medicines and better treatment options.

If you think you may be at risk for deep vein thrombosis, talk with your doctor.

NIH Office of Communications and Public Liaison
Building 31, Room 5B52
Bethesda, MD 20892-2094
[email protected]
Tel: 301-451-8224

Editor: Harrison Wein, Ph.D.
Managing Editor: Tianna Hicklin, Ph.D.
Illustrator: Alan Defibaugh

Attention Editors: Reprint our articles and illustrations in your own publication. Our material is not copyrighted. Please acknowledge NIH News in Health as the source and send us a copy.

For more consumer health news and information, visit health.nih.gov.

For wellness toolkits, visit www.nih.gov/wellnesstoolkits.

Signs and symptoms of deep vein thrombosis

• July 13, 2021

Deep vein thrombosis (DVT) occurs when a blood clot (thrombus) forms in one or more deep veins in your body, usually in your legs. Deep vein thrombosis can cause leg pain or swelling, but may be asymptomatic.

• Symptoms of deep vein thrombosis
• Causes of deep vein thrombosis
• Risk factors
• DVT complications
• Prevention of thrombosis

DVT may be associated with diseases that affect the blood clotting process. A blood clot in your legs can also form if you don’t move for a long time, such as after surgery or an accident. But walking extremely long distances can lead to blood clots.

Deep vein thrombosis is a serious condition because blood clots in your veins can travel through your bloodstream and get stuck in your lungs, blocking blood flow (pulmonary embolism). However, pulmonary embolism may occur without evidence of DVT.

When DVT and pulmonary embolism occur at the same time, it is called venous thromboembolism (VTE).

Symptoms

Signs and symptoms of DVT:

• Swelling of the affected leg. In rare cases, swelling appears on both legs.
• Pain in the leg. The pain often starts in the calf and may feel like spasms or soreness.
• Red or discolored skin on the leg.
• Sensation of warmth in the affected leg.

Deep vein thrombosis may occur without noticeable symptoms.

When to see a doctor

If you have signs or symptoms of DVT, see your doctor.

If you have signs or symptoms of pulmonary embolism (PE), a life-threatening complication of deep vein thrombosis, seek emergency medical attention.

Call 103

Warning signs and symptoms of pulmonary embolism include:

• Sudden shortness of breath
• Chest pain or discomfort that is aggravated by taking a deep breath or coughing.
• Feeling dizzy or dizzy or fainting
• Rapid pulse
• Fast breathing
• Cough with blood

Suspect deep vein thrombosis? Contact the professionals.

Causes

Anything that interferes with the normal flow or clotting of blood can cause blood clots.

The main causes of DVT are damage to the vein from surgery or trauma, and inflammation from infection or trauma.

Risk factors

Many factors can increase the risk of developing DVT, which include:

• Age. The risk of DVT increases at age 60, although it can occur at any age.
• Sitting for long periods of time, such as while driving or flying. When your legs remain motionless for several hours, your calf muscles do not contract. Muscle contractions promote blood circulation.
• Prolonged bed rest, such as during a long hospital stay or paralysis. Blood clots can form in the calves if the calf muscles are not used for a long time.
• Injury or surgery. Injury to the veins or surgery may increase the risk of blood clots.
• Pregnancy. Pregnancy increases pressure in the veins of the pelvis and legs. Women with an inherited bleeding disorder are at particular risk. The risk of blood clots as a result of pregnancy may remain up to six weeks after the baby is born.
• Contraceptive pills (oral contraceptives) or hormone replacement therapy. Both factors can increase the ability of the blood to clot.
• Exposure to drugs or chemicals. Certain drugs can cause blood clots. Before use, consult your doctor.
• Overweight or obese. Excess weight increases pressure in the veins of the pelvis and legs.
• Smoking. Smoking affects clotting and circulation, which may increase the risk of DVT.
• Cancer. Some forms of cancer increase blood levels of substances that cause blood clotting. Some forms of cancer treatment also increase the risk of blood clots.
• Heart failure. Increases the risk of deep vein thrombosis and pulmonary embolism. Because people with heart failure have limited heart and lung function, symptoms caused by even a small pulmonary embolism are more noticeable.
• Inflammatory bowel disease. Bowel disease such as Crohn’s disease or ulcerative colitis increases the risk of DVT.
• Personal or family history of DVT or PE. If you or someone in your family has had one or both of these, you may be at greater risk of developing DVT.
• Genetics. Some people inherit genetic risk factors or disorders, such as factor V Leiden, that make their blood clot more easily. The hereditary disease itself may not cause blood clots unless it is combined with one or more other risk factors.
• Risk factor unknown. Sometimes a blood clot in a vein can occur without an obvious underlying risk factor. This is called unprovoked VTE.

Complications

Complications of DVT may include:

• Pulmonary embolism (PE). PE is a potentially life-threatening complication associated with DVT. This happens when a blood vessel in your lung is blocked by a clot that travels to your lung from another part of your body, usually your leg.
  If you have signs and symptoms of PE, it is important to seek immediate medical attention. Sudden shortness of breath, chest pain when inhaling or coughing, rapid breathing, rapid pulse, feeling weak or faint, and coughing up blood can occur with PE.
• Post-phlebitic syndrome. Damage to a vein by a thrombus reduces blood flow to the affected areas, causing leg pain and swelling, skin discoloration, and skin ulcers.
• Complications of treatment. Complications may arise from blood thinners used to treat DVT. Bleeding is a side effect of anticoagulants. It is important to have regular blood tests while taking these medications.

Prophylaxis

Measures to prevent deep vein thrombosis include the following:

• Don’t sit still. If you have had surgery or otherwise been on bed rest, try to get back to work as soon as possible. If you are sitting for a while, do not cross your legs as this can block blood flow. If you are traveling long distances by car, stop about every hour and take a walk.
  If you are on an airplane, stand or walk from time to time. If you can’t do this, stretch your shins. Do some exercises. Try raising and lowering your heels while keeping your toes on the floor, then lift your toes while resting your heels on the floor.
• Do not smoke. Smoking increases the risk of developing DVT.
• Exercise and control your weight. Obesity is a risk factor for DVT. Regular exercise reduces the risk of blood clots, which is especially important for people who sit a lot or travel frequently.

16 Department of Vascular Surgery

Updated by experts. Last edited: July 13, 2021

Thrombosis of limbs | Symptoms, Treatment

Deep vein thrombosis, along with subcutaneous vein thrombophlebitis and pulmonary embolism, are combined into a single concept – venous thromboembolic complications (VTEC).

Venous thrombosis is an acute disease characterized by the formation of a thrombus in the lumen of a vein with a more or less pronounced inflammatory process and impaired blood flow. The presence of an inflammatory component in the thrombosis zone determines another name for this disease – thrombophlebitis.

Most phlebologists, understanding the conditionality of such a division of venous thrombosis, use the term “thrombophlebitis” to refer to damage to the saphenous veins (in which symptoms of inflammation are pronounced), and the term “thrombosis”, “deep vein thrombosis”, “phlebothrombosis” – to refer to damage to the deep veins.

Deep vein thrombosis (DVT) is a disease that negatively affects not only the venous and lymphatic return system, but also worsens the function of the cardiovascular system as a whole.

If you do not take active steps to eliminate this pathology, the further course of the pathological process becomes persistent, prone to self-development and irreversible.

The disease does not have strictly characteristic symptoms and has many risk factors and trigger factors, which requires additional involvement in clarifying its presence and type of course of additional high-precision modern instrumental diagnostic tools, the main of which in modern clinical conditions is the method of ultrasonic angioscanning with color mapping.

• According to the International Consensus Statement, the incidence of deep vein thrombosis in the general population is about 160 cases per 100,000 population, with a fatal pulmonary embolism rate of 60 per 100,000 population.
• In Russia, 240,000 people fall ill with venous thrombosis every year, and pulmonary embolism, including fatal, develops in 100,000 of them, which significantly exceeds the incidence of tuberculosis, viral hepatitis, and HIV infection.
• Approximately 200,000 people are hospitalized each year for deep vein thrombosis in the United States. At the same time, 1/3 falls on repeated thrombosis. Among the inhabitants of Italy, who are in the most active working age (from 20 to 55 years), deep vein thrombosis is diagnosed within 1%.
• Venous thrombosis occurs in a wide variety of clinical situations and complicates the course of many diseases. The incidence of postoperative thrombosis, according to different authors, is 20-59%.

The history of the study of phlebothrombosis

The study of phlebothrombosis of deep veins has more than 400 years.

Occlusion of the main veins as a cause of gangrene was first described by F. Hildanus in 1593. The first mention of ileofemoral phlebothrombosis appeared in the medical literature 300 years ago, it was made by Mauriceau.

The concept of “thrombophlebitis” was first introduced into medicine by the English surgeon John Hunter (1728-1793), who operated a lot on gunshot and other wounds and noted the frequency of inflammatory processes, combined with the formation of blood clots in the veins.

Interest in deep vein phlebothrombosis increased significantly after the creation of the theory of venous thromboembolism by the eminent German pathologist R. Virchow. Opening in 1844 the corpse of a young man who died suddenly after he developed pain in the thigh, Virchow found a blood clot in the right femoral vein and a twisted clot in the pulmonary artery. After that, he introduced the concepts of “thrombus” and “embolus” into medical terminology. In 1845, having found venous thrombi in 18 cases out of 76 autopsies, in 11 cases revealing the presence of thromboembolism in the pulmonary artery, he came to the conclusion that blood clots form in the veins and are transferred with the blood flow to the pulmonary artery. He also formulated the classical triad, which is still the most complete reflection of the links in the pathogenesis of local vascular thrombosis.

The first Russian-language monograph devoted to this problem was the work of I.F. Klein “On thrombosis, embolism and ichorremia”, published in 1863.

Despite the fact that acute deep phlebothrombosis in different types of localization and clinical course differ significantly from each other, they are united by the commonality of the main etiopathogenetic processes. The idea of ​​phlebothrombosis as a nosological group is based on the classical Virchow triad.

More than 150 years ago, Rudolf Virchow described the main mechanisms of intravascular thrombosis. Its classic triad includes hypercoagulability, damage to the vessel wall, and slowing of blood flow. Sometimes, for the occurrence of this pathology, a pathological change in only one of these factors is sufficient.

Despite the fact that the thrombotic process can develop at any level of the main veins, in more than half of the cases, the starting point of its development in the centripetal direction is the veins of the leg.
In the vast majority of cases, thrombosis is primarily localized in the veins of the leg, and then grows in the proximal direction into the popliteal, femoral and iliac veins.

It is this type of development that is very often embologenic, since the growth of a thrombus occurs in the direction of veins with an increasing inner diameter, where thrombus masses are not always fixed along the entire perimeter of the vein. Such thrombi are called floating.

One of the main causes of blood flow slowdown is immobilization. Under normal conditions, the outflow of blood from the lower extremities is carried out by contraction of the calf muscles, which act as a peripheral pump, pushing blood in the proximal direction, assisted by the function of the valves. Restriction of physical activity significantly disrupts this mechanism. In this case, the blood lingers in the venous sinuses of the lower leg.

The question of the significance of risk factors and triggering factors of thrombosis has been studied in sufficient detail:

• Congenital thrombophilias (deficiencies of various factors of the hemostasis system or their pathological changes)
• Activation of coagulation factors and fibrinolysis disorders (trauma, surgery, neoplasms, pregnancy, childbirth, etc. ).
• Pathology of platelets.
• Slowdown and / or disturbance of blood flow (age over 40 – 45 years, immobilization, pathology of the central circulatory mechanisms, obesity, etc.).
• Changes in the rheological properties of blood.
• Damage to the endothelium and vascular wall (contrast agents, intravascular devices, venous catheters, vein dilatation, etc.).
• Drug therapy (anesthetics, muscle relaxants, chemotherapy, contraceptives, contrast agents). For example, the incidence of postoperative thrombosis after various surgical interventions can reach 20-59%.

Symptoms of thrombosis

Symptoms of acute deep vein thrombosis include:

• edema,
• bursting pains,
• cyanosis of limb,
• dilatation of the saphenous veins,
• local increase in skin temperature,
• pain along the vascular bundle.

However, local hyperthermia and pain are more characteristic of superficial thrombophlebitis. The latter should be attributed rather to risk factors for the development of deep vein thrombosis.

Classic DVT symptoms:

• pain,
• soreness,
• puffiness,
• hyperemia,
• Homans symptom.

The overall sensitivity/specificity of these symptoms is 3 to 91%.
The presence of symptoms does not confirm DVT. The absence of symptoms does not rule out DVT (up to 50% of patients have no clinical symptoms).

Thrombosis Probability Calculation

In 1997, Wells et al developed and tested a clinical DVT probability model

The presence of each sign is estimated at 1 point:

The primary development of thrombosis in the deep veins of the leg is most common. This is facilitated by the conditions under which such an important hemodynamic factor as the contraction of the calf muscles is turned off. Such localization occurs in more than half of the observations.

Physical examination reveals positive symptoms:

• Moses – pain when pressing the lower leg in the anteroposterior direction,
• Homansa – pain in the calf muscles with dorsal flexion of the foot,
• Lowenberg – pain in the calf muscles at a pressure of up to 150 mm Hg. Art., created by the cuff of the sphygmomanometer.

However, the same symptoms will be positive in any other inflammatory process in the limb under study.

When the femoral vein is involved in the process, patients notice aching pains along the medial surface of the limb, according to the projection of the Gunter’s canal.

Thrombosis of the common femoral vein is manifested by a more pronounced increase in the volume of the lower leg and even the thigh, cyanosis of the skin, the intensity of which increases towards the periphery. There is an expansion of the saphenous veins in the distal part of the thigh and lower leg. If thrombosis extends to the mouth of the great saphenous vein of the thigh, then the hypertension developing in the superficial venous system leads to the exclusion of anastomoses crossing with the contralateral limb. At the same time, there is an increase in the pattern of saphenous veins in the pubic and groin area. On palpation, the vascular bundle is painful throughout the thigh. The period of pronounced venous stasis lasts 3-4 days, after which a slow decrease in edema occurs. This phenomenon is due to the inclusion of collateral systems in the circulation. Thus, a reduction in pain and less swelling can create illusory well-being and often result in a late referral to a specialist. In addition, phlebothrombosis can occur without any complaints from the patient (asymptomatically), especially in postoperative patients.

More or less characteristic symptoms:

• bursting pains,
• edema (increased leg circumference),
• skin cyanosis.

Edema is of the greatest importance in terms of making a preliminary diagnosis. However, none of the listed clinical symptoms can be considered absolutely reliable in the diagnosis of this nosology. Any, even the most minimal patient complaints (for example: simple discomfort in the distal segments of the lower limb), especially in combination with the presence of risk factors, require an additional examination of the patient for the presence of phlebothrombosis.

Thus, we can conclude that the presence of phlebothrombosis on the basis of anamnesis, patient complaints and clinical symptoms can only be suspected in order to confirm or exclude its existence during further examination, to determine the localization and embologenic danger. The absence of pathognomonic symptoms and the presence of a period of imaginary improvement are the cause of late hospitalization of patients, which in many cases limits the possibility of effective surgical treatment.

Diagnostic tests in patients with suspected DVT

• Assessment of the clinical likelihood of DVT,
• D-Dimer,
• Ultrasound examination of veins,
• MRI phlebography,
• MSCT.

Treatment of thrombosis

The tasks or goals of the treatment being carried out are formulated very specifically for today:

1. Stop the spread of thrombosis.

2. Prevent pulmonary embolism.

3. Prevent progression of edema and prevent venous gangrene.

4. Restore the patency of the veins and the functions of the valvular apparatus in order to avoid the development of post-thrombophlebitic disease in the future.

5. Prevent recurrence of thrombosis.

Conventionally, modern approaches to the treatment of patients with acute phlebothrombosis in the basin of the inferior vena cava can be divided into three main ones:

1. Conservative.

2. Minimally invasive.

3. Surgical aggression.

Conservative therapy

This approach includes:

• early activation with elastic compression,
• anticoagulant,
• non-specific anti-inflammatory therapy,
• hemorheological therapy,
• intermittent pneumocompression.

With the timely application of the above methods, it is possible to restore the patency of the veins and minimize the manifestations of post-thrombotic disease.

Minimally invasive methods

To date, this is the most common group of methods in clinical use, designed to solve all of the above tasks or goals of treating patients with deep phlebothrombosis.

Here it is necessary to distinguish three subgroups of methods:

1. Installation of cava filters and partial cavaplication.

2. Regional and systemic thrombolysis.

3. Catheter thrombectomy and pharmacomechanical thrombectomy.

Installation of cava filters and partial cavaplication

At the beginning of the formation of phlebology as a separate scientific specialty, one of the main issues that needed to be addressed immediately was the issue of preventing pulmonary embolism in phlebothrombosis. After the development in 1959 of the method of external plication of the vena cava with mattress sutures and external plication with clamps, it was possible to determine the further direction of solving the problem of acute deep phlebothrombosis and their complications – PE. Until 1967, the method in combination with conservative therapy remained the only clinical approach to this problem. Despite the fact that the implementation of the technology of external partial clipping with clamps is associated with the need for a traumatic surgical approach and is practically impossible in seriously ill patients, this approach has been used and improved to date in limited situations (for example, using endovideoscopic technique, plication from a mini-access).

The Mobin-Addin intraluminal umbrella cava filter developed and applied clinically, which required the study of methods for delivering the device to the object, was the first experience of intraluminal catheter intervention and, in fact, served as the beginning of the development of a new branch of angiology – interventional radiology. Further development of this direction was carried out mainly along the path of improving the design of cava filters and studying their influence on hemodynamics and the clinical course of the main process.

Temporary cava filters are currently preferred. The temporary cava filter is removed no later than the third week.

In the vast majority of cases, the installation of a cava filter is not required at all.

Why is it not advisable to install a permanent cava filter?

Always remember that a permanent cava filter is a lifelong intake of anticoagulant drugs and a lifetime risk of filter thrombosis (foreign body in the lumen of the vein is often complicated by thrombosis).

It has been repeatedly noted that as a result of the installation of cava filters in the near future, PE may occur with a frequency of 1.5-8%, and in terms of up to 3 years, thrombosis of the inferior vena cava occurs with a frequency of 12-25%.

In thrombosis below the inguinal ligament, the installation of a cava filter is not advisable, since there are other methods for preventing PE.

Regional and systemic thrombolysis, catheter thrombectomy, rheolytic thrombectomy

Thrombolytic therapy. The method is based on the introduction of drugs that activate endogenous fibrinolysis (streptokinase, urokinase, tPA, etc.).

Probably because the agents used in this method for influencing a blood clot can be effective only in relatively fresh areas of a blood clot (up to 3-5 days), so its effectiveness is low. Meanwhile, the use of regional catheter thrombolysis in 44% of cases allowed some authors to preserve valvular function and thereby prevent the development of post-thrombotic disease.

Catheter thrombus extraction . It should immediately be clarified that this method is applied only to the high segments of the inferior vena cava basin, since the technology itself does not allow it to be used in the infrainguinal position due to the obstacles formed by the valve apparatus of the veins at this and lower levels. The method is based on capturing thrombus masses from accessible segments of the inferior vena cava and iliac veins into a special bag-container and removing them by removing them through the phlebotomy opening.

Pharmaco-mechanical thrombectomy . The newest of all interventional and surgical technologies. While in the literature there are descriptions of individual cases. The method is based on the Bernoulli effect, where the velocity of a hydrodynamic jet creates areas of negative pressure in the environment. The method has the same scope as catheter thrombectomy.

Surgical interventions for femoral-popliteal phlebothrombosis

It is known that the most effective thrombectomy is possible only with thrombi not older than 3-7 days.