Pulmonary embolism, a blockage in the lung artery, is a life-threatening medical emergency that requires quick intervention and treatment. With symptoms that resemble many other medical conditions, including heart attack and pneumonia, it can be difficult to diagnose. 

The condition is most commonly associated with pregnancy, and medical conditions including cancer, and is also commonly seen in those with sedentary lifestyles and following long periods of inactivity. If you have any symptoms that suggest pulmonary embolism, such as coughing, chest pain and shortness of breath, it's important to seek emergency medical care immediately.

Yale Medicine provides extraordinary expertise in the diagnosis and treatment of pulmonary embolism. We represent one of the few medical institutions that has a dedicated team of specialists focused on treating pulmonary embolism and who are also involved in cutting-edge research to help advance the management of this condition.

Pulmonary embolism is usually caused by a blood clot that has broken loose from a deep vein in the leg or pelvis before it travels up to the lungs. This condition is called deep vein thrombosis (DVT). Common symptoms of a DVT include pain, swelling, redness, or weakness of the involved leg. 

Once detached, the clot may travel up the bloodstream into a lung artery, blocking it and resulting in pulmonary embolism. (The blood flow from the veins of the pelvis or leg directly travels to the pulmonary artery of the lungs through the right side of the heart.)

Although uncommon, pulmonary embolism may also be caused by dislodged fat or air bubbles that obstruct the pulmonary arteries of the lung. 

Pulmonary embolism has similar symptoms to conditions like heart attack, aortic dissection, and pneumonia. Symptoms may vary greatly depending on a range of factors, including the size of the clot and the patient’s overall health. The most common symptoms include:

• Coughing (in rare cases, accompanied by blood)
• Chest pain (sometimes accompanied by pressure)
• Shortness of breath
• Dizziness

Chest pain, shortness of breath, dizziness, or a combination of those symptoms is cause for concern—especially if DVT symptoms are present. In rare cases, patients may also experience stomach pain, back pain, or heart palpitations.

Generally, people who are susceptible to blood clots and those with a prior history of pulmonary embolism are at higher risk of developing pulmonary embolism. As pulmonary embolism is most often a consequence of DVT, the two conditions share the following major risk factors:

Cancer. Patients with an active diagnosis of cancer are more likely to develop pulmonary embolism. It is worth noting that in several cases, DVT or pulmonary embolism can be the initial manifestation of cancer.

Pregnancy. The enlargement of the uterus slows the circulation of blood from the legs to the heart, increasing the likelihood of clots developing. Pregnant women also have higher levels of circulating clotting factors in their blood compared to those who are not pregnant, predisposing them to clot development.

Trauma to the legs. Injuries to the legs, or surgeries such as hip and knee replacements, increase the likelihood of clotting in the deep veins.

History of heart failure.Heart failure patients usually have complications with blood flow, which increase the likelihood of clotting.

Other common risk factors for pulmonary embolism include the following:

• Aging
• Obesity
• Smoking
• Pregnancy
• History of connective tissue diseases such as rheumatoid arthritis or lupus
• Extended periods of immobility (prolonged air travel or recovery following surgery)
• Hormone-related therapies, such as oral contraception or testosterone
• Family history of inborn clotting-related diseases, such as Factor V Leiden

People at risk for pulmonary embolism are encouraged to increase limb mobility (especially during long stretches of immobility, such as during prolonged air travel), use medication to prevent blood coagulation, and wear compression socks to aid in blood flow.

In 10 percent to 15 percent of pulmonary embolism patients, the condition causes low blood pressure or shock (the inability of the heart and lungs to provide oxygen to the organs of the body). These complications define the condition as a high-risk pulmonary embolism.

Such complications usually develop if the clot is large enough to obstruct blood flow from the heart or if the patient has a heart or lung condition. They may arise immediately after the blockage of the artery or over a period of time.

Such patients require immediate attention to avert the possibility of sudden death, but Inderjit Singh, MD, director of the Yale Medicine Pulmonary Vascular Disease Program, emphasizes that if patients are diagnosed early enough, these complications can be prevented.

Various tests are often needed to diagnose pulmonary embolism because it shares a presentation similar to other conditions. Those tests are meant to rule out other conditions and to understand the complexity of the pulmonary embolism.

Diagnosis usually begins with an assessment of the patient’s medical history and a physical. Patients who are not regarded as high-risk may also undergo the following:

Electrocardiogram (EKG): Patches are placed on the skin to evaluate the electrical activity of the heart in order to rule out a heart attack. It is fast and fairly easy to interpret.

Chest X-ray: An X-ray is done of the chest to determine whether symptoms can be explained by other diseases, such as pneumonia or fluid in the lungs.

Computerized tomography (CT scan): Dye is injected into the veins so that the lung arteries are highlighted, and then three-dimensional scans of the chest and lung are performed to look for the presence of blood clots. This is usually the main diagnostic test for pulmonary embolism and it takes 15 to 30 minutes. If a patient has symptoms of DVT, the following tests are often performed before the CT scan.

Ventilation-perfusion scan (VQ scan): This test is usually recommended instead of the CT scan for pregnant women or patients with kidney disease. A lung VQ scan is an imaging test that uses a ventilation (V) scan to measure air flow in your lungs and a perfusion scan (Q) that evaluates how well blood circulates within your lungs. This test can help diagnose or rule out pulmonary embolism.

D-dimer test: A sample of the patient's blood is drawn and analyzed to measure the degree of clotting in the patient’s blood.

Ultrasound: A wand-shaped device called a transducer is used to direct sound waves to the leg veins to test for blood clots. These waves are then reflected back to the transducer and translated into a moving image by a computer.

Diagnosis can be made within 30 minutes but may take longer depending on a number of tests.

After diagnosis, an echocardiogram, or ultrasound of the heart, will evaluate the effect of the pulmonary embolism on the heart’s function. But in cases when a CT scan is not immediately available, an echocardiogram may also be done before a CT scan, since it provides valuable information.

There are a range of therapies currently available, including:

Anticoagulants (blood thinners). As a first line of treatment, most patients are put on blood thinners (medications that gradually break up blood clots) such as Coumadin (warfarin sodium), low molecular weight heparin or newer oral anti-coagulants. Patients with a high risk of bleeding (for example, patients with peptic ulcer disease) will not receive this treatment, as it increases the risk of bleeding.

Systemic thrombolysis. This aggressive treatment, reserved for high-risk patients, consists of the intravenous administration of medication called tissue plasminogen activator (tPA) over several hours. The medication is administered through an intravenous line placed typically in the arm.

Nonsurgical pulmonary thrombectomy. Through a tiny incision in the skin, an interventional radiologist guides a catheter (tube) into the pulmonary artery to first identify the exact location of clots. As the catheter is retracted, a suction device (vacuum) sucks the clots out of the artery—and removes them through the small incision in the skin.

Surgical thrombectomy. This approach is primarily used for high-risk patients who cannot receive thrombolysis or blood thinners. It involves the surgical removal of the blood clot during open heart surgery. Following the successful completion of the procedure, patients are then placed on a treatment of blood thinners to prevent other clots from forming.

Catheter-directed thrombolysis. This minimally invasive approach is also used for high risk patients with large clots. A catheter (small tube) is inserted through an incision in the leg or neck using real-time X-ray imaging. The doctor then injects small doses of thrombolytics directly into the clot through the tube while at the same time using ultrasound waves to help break them up.

Lifestyle changes. Patients are also asked to quit smoking, increase mobility and wear compression socks in order to minimize the risk of clots redeveloping.

At Yale Medicine, we involve various specialists at different points of treatment. The emergency room doctor, radiologist, cardiologist, cardiothoracic surgeon, pharmacist, hematologist, and pulmonologist may all play a role in effectively treating a patient with pulmonary embolism.

Most patients can maintain a good quality of life after treatment. Depending on the underlying cause of the pulmonary embolism, patients remain on anticoagulation medication for several weeks to months after treatment to prevent clots from redeveloping, with periodic checkups for incidence of bleeding.

In some cases, this may result in some dietary adjustments (for example, cutting out leafy green vegetables, as they may interfere with the efficacy of some blood-thinning medications such as Coumadin).

Yale Medicine is one of a handful of health care providers that offer the full spectrum of interventions currently available pulmonary embolism.

We are one of the few centers in the country with a dedicated pulmonary embolism response team (PERT) designed specifically to manage and treat high-risk pulmonary embolism cases, says Dr. Singh. “We created this team to make sure that individual patients are attended to promptly and to ensure that they receive the best treatment available,” Dr. Singh says.

Yale Medicine is also deeply invested in pulmonary embolism and deep vein thrombosis research. We encourage participation of patients in ongoing clinical trials to help further advance current diagnostic and treatment strategies of pulmonary embolism.