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Pulmonary Embolism & Deep Venous Thrombosis

Blood Clots in the Lungs and Legs

Doctor looking at the results of a lung scan.

What is Pulmonary Embolism?

Pulmonary embolism (PE) is a blockage in an artery in the lungs as a result of a blood clot (thrombus).

Pulmonary embolism is often caused by deep venous thrombosis (DVT), a condition where blood clots form in the deep veins of the legs. Deep venous thrombosis results in PE when the clots break off, travel up to the lungs and get stuck in the arteries, creating a blockage.

Venous thromboembolism, a term that includes both pulmonary embolism and deep venous thrombosis, can be provoked by a combination of hereditary and acquired risk factors. There are approximately 600,000 cases of venous thromboembolism in the U.S. every year.

Things that can increase your risk for PE and DVT:

  • Family history of blood clots or clotting disorders
  • Being overweight
  • Smoking
  • Cancer and cancer therapy
  • Age (older adults have a higher risk)
  • Medical conditions such as heart disease, hypertension, inflammatory bowel disease (IBD) and COPD
  • Childbirth (during and after pregnancy)
  • Severe injuries in the thigh or hip area
  • Brain, joint or bone surgery
  • Medications such as estrogen therapy and birth control pills
  • Enlarged veins in the legs
  • Hospitalization

Symptoms of Pulmonary Embolism (PE)

Shortness of breath is often the first warning sign of pulmonary embolism.

Since shortness of breath can be a result of many different lung problems, it’s important that you meet with a specialist who can provide an accurate diagnosis. ​bulletSee how we check lung function at UC San Diego.

Some people with pulmonary embolism may also experience chest pain that is:

  • Sharp and stabbing
  • Worse as you breathe deeply
  • On one side or underneath the breastbone
  • Dull, aching or burning
Other symptoms that may indicate pulmonary embolism include:
  • Fast heart rate
  • Sudden cough
  • Coughing up blood
  • Clammy skin, excessive sweating
  • Low blood pressure
  • Bluish skin
  • Fainting or dizziness
  • Anxiety

If you have any of these symptoms, don’t wait for an appointment with one of our pulmonary specialists – go to the ER!

Why is Treating Pulmonary Embolism Critical?

Acute pulmonary embolism can be life-threatening. It is the third most common cause of death from cardiovascular disease after heart attack and stroke. Acute pulmonary embolism requires immediate treatment with anticoagulant medications.

Despite treatment with anticoagulants, nearly a third of people with acute pulmonary embolism will have some amount of scarring in the lung arteries that can cause chronic problems. In a small portion of people, scarred lung arteries eventually develop into chronic thromboembolic pulmonary hypertension (CTEPH).

CTEPH refers to repeated blood clots in the pulmonary arteries that do not dissolve with medication. These clots become fibrotic and scarred and permanently attach to the blood vessel wall. Approximately 1-3 percent of people with pulmonary embolism will progress to CTEPH.

bulletLearn about our expertise in CTEPH.

Diagnosing Pulmonary Embolism

It can be difficult to diagnose pulmonary embolism (PE) as symptoms overlap with many other diseases and conditions (e.g., COPD, irregular heartbeat, asthma).

Often, diagnosis is made in the emergency room (by a doctor and radiologist) when symptoms demand immediate medical care.

There are three factors used to diagnose pulmonary embolism:

  1. Your medical history   
    The first step of diagnosis is determining how likely it is that you have pulmonary embolism. This involves ruling out other possible causes of your symptoms, as well as evaluating your risk factors for pulmonary embolism and deep vein thrombosis (DVT).
  2. Physical exam
    During the physical exam, the blood pressure of your heart and lungs will be checked, and your legs assessed for signs of deep venous thrombosis (e.g., swelling of leg or along a vein). bullet Learn more about the signs of deep vein thrombosis in our health library.
  3. Diagnostic tests
    Our team has advanced diagnostic tools to diagnose pulmonary embolism. Depending on your symptoms, one or several of these procedures may be performed during your exam.
  • Computed tomography (CT) scan of the chest and legs
  • Ultrasound
  • Ventilation perfusion scan (VQ scan)
  • Blood tests
  • Electrocardiogram (EKG)

Treatment of Pulmonary Embolism

A pulmonary embolism that does not resolve on its own can be life-threatening. For these cases, medication or surgery (rarely needed) is used to break up the clot.

There are two goals of pulmonary embolism treatment:

  1. Keep the existing blood clot from causing damage
  2. Prevent the formation of new clots

Anticoagulant Medicines

A pulmonary embolism is typically treated with anticoagulants, or “blood thinners.” Despite its nickname, anticoagulants don’t actually thin your blood – they stop your body’s ability to clot. This helps keep existing clots from getting bigger.

While anticoagulants do not break up clots that have already formed, your body can usually dissolve clots on its own over time.

Anticoagulants come in the following forms:

Newer oral anticoagulants (e.g., apixiban, rivaroxabin, dagibatran) that do not require monitoring are available for some patients in whom the risk of bleeding is deemed to be low.

The most common side effect of warfarin is excessive bleeding, which can be fatal. To prevent this, routine blood tests PT (prothrombin time) and PTT (partial thromboplastin time) will be performed. These tests measure the blood’s ability to clot.

Other Types of Therapy

Other forms of treatment may be necessary in cases where:
  1. Pulmonary embolism is causing critical illness
  2. Patient is unable to take anticoagulant medicines

In these situations, the following therapies may be recommended:

  • Tissue plasminogen activator (tPA): A clot-dissolving medication.
  • Ultrasonic catheter: Administered by interventional radiologist. Helps break up clot with ultrasonic waves. Often used jointly with tPA.
  • Surgical embolectomy: Blood clot is removed with surgery.
  • Vacuum catheter: A tiny vacuum is threaded through the veins and used to draw out blood clots.
  • Inferior vena cava (IVC) filter: A small, cone-shaped device designed to catch blood clots is implanted by an interventional radiologist in the inferior vena cava, the large vein that carries blood back to the heart, using a catheter. This minimally invasive procedure is done while the patient is awake. An IVC filter can be permanently or temporarily implanted.

While an IVC filter cannot prevent new blood clots from forming, it can help prevent deep venous thrombosis from moving into your lungs.

bulletLearn more about vena cava filter implantation in our Health Library.

​Deep Venous Thrombosis (Deep Vein Thrombosis)

About Blood Clotting

Blood clotting is a normal and important process that helps stop excessive bleeding. However, slow-moving blood flow, blood vessel wall injuries, or a defect in clot forming can cause abnormal clotting in the arteries and veins. Our pulmonologists work closely with the anticoagulation clinic to determine length and level of therapy. Learn more about bleeding disorders and how we treat them.

Deep venous thrombosis (DVT) refers to blood clots that form in the deep veins in the legs.

Deep venous thrombosis is the most common cause of pulmonary embolism.

Some people have no symptoms when clots form in their legs, while others have severe, debilitating symptoms. Deep venous thrombosis usually affects deep veins in the thigh, lower leg and pelvis, and less commonly, the arm.

People with deep venous thrombosis may experience one or several of the following symptoms in the affected area:

  • Tenderness
  • Leg pain
  • Redness and changes in skin color
  • Skin that is warm to the touch
  • Leg swelling

Illustration of deep vein thrombosis. 

    Long-Term Management after Pulmonary Embolism

    bulletSee a Specialist

    Meeting with a specialist who can determine your risk for more blood clots and diagnose the cause of your shortness of breath may reduce your need for invasive surgeries later.

    The pulmonary embolism experts at UC San Diego:

    • Pinpoint the cause of your blood clot
    • Ensure you have completely recovered from the blood clot
    • Select the best therapy for you
    • Determine length of therapy
    • Assess your risk of recurrence
    • Manage your anticoagulants around future operations
    • Perform diagnostic testing (in the event you have shortness of breath)

    The most important aspect of long-term care after a pulmonary embolism is reducing the risk for a recurrent pulmonary embolism.

    bulletBlood Clot Risk

    To fully assess your risk of blood clot recurrence, our team may:

    1. Develop a thorough history in order to determine the risk of future blood clots.
    2. Do blood tests to see if you have hypercoagulability (a tendency to form clots).
    3. Perform additional imaging tests.

    After calculating your risk, we will work with you to determine a personalized preventive plan that includes recommendations for medication and length of treatment.

    bulletShortness of Breath

    After pulmonary embolism, some people continue to experience shortness of breath. If you are having symptoms of breathlessness, it's important that you follow up with a specialist who can properly evaluate your condition and rule out recurrent pulmonary embolism.

    Our pulmonary experts assess shortness of breath with:

    • Cardiopulmonary exercise testing
    • VQ SPECT
    • Echocardiogram

    In many cases, further analysis may be needed in order to identify the cause. We provide comprehensive diagnostic testing in our Pulmonary Function & Exercise Lab.

    bulletOther Prevention Tips

    You can help prevent deep venous thrombosis by:

    • Limiting the amount of time you spend in bed when ill or recovering from surgery.
    • Taking medicines that help prevent blood clots (e.g., anticoagulants).
    • Regularly participating in physical activity.
    • Exercise/move leg muscles when forced to sit for long periods of time.
    • Wearing compression stockings that promote blood flow in your legs.

    Clinical Research

    Our physician-scientists are active in clinical research including clinical trials investigating:
    • Prevention of blood clots following hospitalization (APEX study).
    • The link between acute pulmonary embolism and CTEPH.

    We also participate in registry studies for pulmonary embolism. These studies allow us to gather data from multiple accredited medical centers to help provide a clearer understanding of the disease progression of pulmonary embolism and outcomes for different therapies.

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