What is a pulmonary embolism?
A pulmonary embolism (PE) occurs when a blood clot gets lodged in an artery in the lung, blocking blood flow to part of the lung. The blood clots usually begin in the large veins of the legs or pelvis, then break away and travel to the lungs. A PE can be life-threatening if a large blood clot blocks the main artery of the lung or arteries in both lungs. Even small PEs can lead to long-term complications like pulmonary hypertension or right-sided heart failure if untreated.
Symptoms of a PE may include:
- Sudden shortness of breath
- Sharp chest pain, often made worse by deep breaths
- Coughing up blood
- Rapid heart rate
- Lightheadedness or passing out
Some PEs have no symptoms at all and are discovered incidentally on imaging tests done for other reasons.
What is a small pulmonary embolism?
Pulmonary emboli are classified as massive, submassive, or small (nonmassive).
A massive PE blocks the main pulmonary artery or arteries to both lungs, causing severe symptoms like cardiac arrest or shock. Only about 5% of PEs are massive.
A submassive PE blocks at least 30-50% of the pulmonary vasculature. It often causes strain on the right ventricle of the heart but not complete cardiovascular collapse. About 15% of PEs are submassive.
A small PE blocks less than 30% of the pulmonary arteries and usually has milder symptoms or none at all. About 80% of PEs are small. Some small PEs are found incidentally on scans looking for other issues.
Can you live with a small pulmonary embolism?
Yes, most people can live with a small PE. The prognosis is generally good if properly diagnosed and treated.
Without treatment, about 30% of submassive PEs worsen or have recurrences. Only 2-8% of small PEs recur if anticoagulation treatment is given.
The recurrence risk depends on the underlying cause. Temporary risk factors like recent surgery, injury, or long travel increase risk of blood clots but the risk decreases once the trigger resolves. Chronic conditions like cancer, clotting disorders, heart or lung disease increase lifelong recurrence risk.
Risks of living with an untreated small PE
Potential complications of leaving even a small PE untreated include:
- The clot dislodging and blocking a larger artery
- Development of pulmonary hypertension
- Strain on the right heart leading to right-sided heart failure
- Recurrence of blood clots, including potentially fatal ones like DVTs or strokes
- Chronic thromboembolic pulmonary hypertension (CTEPH), scarring of the pulmonary arteries
- Death, though rare with isolated small PEs
Up to 4% of small PEs eventually cause CTEPH if left untreated.
Benefits of treating small PEs
Treatment for PEs focuses on preventing the clot from getting larger and preventing recurrence.
Anticoagulant medications like heparin and warfarin thin the blood to prevent clots from forming and existing ones from enlarging. They do not break up existing clots.
Treatment significantly lowers the risks of complications and recurrence. Caught early, most small PEs resolve completely within 1-2 weeks with anticoagulation treatment and do not cause long-term damage.
Diagnosing a small PE
Since small PEs often have no symptoms, they may only be discovered during medical testing for other issues. Imaging tests that can detect small PEs include:
- CT pulmonary angiography – CT scan with contrast dye that highlights blood vessels in the lungs
- Ventilation-perfusion (V/Q) scan – Nuclear imaging test looking at airflow and blood flow in the lungs
- Pulmonary angiography – Direct imaging of pulmonary arteries by injecting dye into the lungs
- Echocardiogram – Uses ultrasound to look at the heart and pulmonary artery pressures
- Leg ultrasound – Looks for deep vein thrombosis (DVT) which can cause PEs
Blood tests like D-dimer may be done to look for evidence of blot clot formation. However, they are nonspecific and can be elevated due to other reasons.
Once a small PE is found, your doctor will do more tests to determine the cause and look for additional clots. This helps determine treatment approach and duration.
Treatment for small PEs
Treatment guidelines are similar for small PEs versus larger ones:
- Anticoagulant medications are given, usually for 3-6 months. Low molecular weight heparin, followed by warfarin or direct oral anticoagulants like Xarelto or Eliquis are commonly used.
- Elastic compression stockings help prevent leg DVTs from forming.
- For larger PEs or hemodynamic instability, thrombolytics like tPA may be given to try to break up the clot sooner.
- In rare cases, surgical embolectomy is done to remove large clots.
- Treatment of any underlying causes or risk factors for blood clots.
The duration of treatment depends on the cause and individual recurrence risk. If the PE was due to a temporary risk like surgery, 3 months of treatment may be sufficient. With ongoing risk factors like active cancer or clotting disorders, indefinite treatment is often needed.
Home care
Along with medications, your doctor may recommend:
- Getting adequate hydration and avoiding long periods of immobility.
- Walking regularly to promote blood flow in the legs.
- Breathing exercises to maximize lung capacity.
- Eating a heart healthy diet and maintaining a healthy weight.
- Avoiding smoking and vaping.
- Wearing compression stockings.
Seek prompt medical attention if you experience symptoms like sudden shortness of breath, chest pain, coughing blood, racing heart rate, or feeling faint, as these could signal a recurrent clot.
Prognosis and outlook
With early diagnosis and proper anticoagulant treatment, most people with small PEs recover fully. The overall risk of death from small PEs is very low, under 1-2%.
Lingering symptoms like shortness of breath, fatigue, chest pain, or reduced exercise tolerance are more common with submassive PEs involving larger clots. Symptoms usually resolve within 1-2 months but may persist longer.
Only about 1-5% of properly treated PEs cause chronic thromboembolic pulmonary hypertension (CTEPH). This can happen even months or years later due to blood vessel scarring. Screening echocardiograms are sometimes done to monitor for pulmonary hypertension after a PE.
Recurrence risk depends on the underlying cause but is generally low with adequate treatment duration. Analyzing blood for clotting disorders or genetic factors can sometimes help determine if lifelong anticoagulation is needed after an unprovoked PE.
With the right treatment, most people can live a long and active life after a small PE. Following doctor’s orders for medications, compression stockings, and lifestyle changes is key to preventing complications and recurrences. Prompt attention to any new symptoms can help catch recurrent clots early.
References
- Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society. European Heart Journal. 2019;41(4):543-603. doi:10.1093/eurheartj/ehz405.
- Fesmire FM, Brown MD, Espinosa JA, et al. Critical issues in the evaluation and management of adult patients presenting to the emergency department with suspected pulmonary embolism. Annals of Emergency Medicine. 2011;57(6):628-652.e75. doi:10.1016/j.annemergmed.2011.01.020
- Cohen AT, Agnelli G, Anderson FA, et al. Venous thromboembolism (VTE) in Europe. The number of VTE events and associated morbidity and mortality. Thrombosis and Haemostasis. 2007;98(4):756-764. doi:10.1160/TH07-03-0212
- Klok FA, van Kralingen KW, van Dijk APJ, Heyning FH, Vliegen HW, Huisman MV. Prospective cardiopulmonary screening program to detect chronic thromboembolic pulmonary hypertension in patients after acute pulmonary embolism. Haematologica. 2010;95(6):970-975. doi:10.3324/haematol.2009.018390
- Fasullo S, Scalzo S, Maringhini G, et al. Six-month echocardiographic study in patients with submassive pulmonary embolism and right ventricle dilation: implications for the timing of echo follow-up. Internal and Emergency Medicine. 2011;6(2):153-159. doi:10.1007/s11739-010-0440-0