Pulmonary Embolism: Causes, Symptoms and Treatment

According to the Centers for Disease Control, over 900,000 people in the United States are affected annually by a pulmonary embolism, with 1 in 4 cases resulting in sudden death. Many of these cases are unexpected, affecting people of all ages.

A pulmonary embolism (PE) occurs when a blood clot blocks one of the arteries in the lungs, cutting off blood flow and reducing oxygen supply. It is a leading cause of preventable hospital deaths and a significant concern in cardiovascular health.

This article comprehensively reviews pulmonary embolism, its causes, symptoms, diagnostic methods, treatment options, and ways to prevent it.

[signup]

What is Pulmonary Embolism?

Understanding pulmonary embolism starts with defining what it is and how it fits into the broader category of cardiovascular diseases.

Definition and Overview

A pulmonary embolism (PE) is a blockage in one of the pulmonary arteries in the lungs, most commonly caused by a blood clot. This clot typically forms in the deep veins of the body (deep vein thrombosis) and travels through the bloodstream to the lungs.

When the blood clot blocks an artery in the lung, it reduces blood flow to the lungs, depriving lung tissue of oxygen and increasing blood pressure in the pulmonary arteries. This may result in shortness of breath at rest, chest pain, and/or sudden collapse.

The severity of the PE depends on the artery that is blocked and the size of the clot:

Massive PE: Due to blockage of the main pulmonary artery or both of its major branches (right and left), leading to severe heart strain and potentially fatal outcomes.
Submassive or segmental PE: Results from a clot blocking one of the lung’s smaller arteries, often causing chest pain, shortness of breath, and low oxygen levels.
Subsegmental PE: Involves a tiny branch of the pulmonary (lung) artery and may cause mild or no symptoms.

How PE Fits into Cardiovascular Diseases

PE is a cardiovascular emergency related to conditions such as deep vein thrombosis (DVT), heart failure, and stroke. PE and DVT together are known as venous thromboembolism, a major cause of cardiovascular death.

Epidemiology of Pulmonary Embolism

Understanding the prevalence of PE and which populations are most affected can help identify at-risk individuals and promote early prevention strategies.

Demographics and Incidence

PE is more common than many people realize:

In the U.S., up to 900,000 people are affected by DVT and PE annually.
Between 60,000 and 100,000 deaths occur each year from PE.
About 1 in 3 patients with PE experience a recurrence within 10 years.
Many cases go undiagnosed, so the incidence rate may be higher than reported.

People who are older (>60 years), pregnant, obese, and/or have cancer are more likely to develop PE.

Causes and Risk Factors

Several medical and lifestyle factors can increase the risk of PE. Some causes are common, while others are less well-known but equally important to recognize.

Common Causes of Pulmonary Embolism

Most PE cases stem from conditions that promote blood clot formation, especially DVT.

Deep Vein Thrombosis (DVT) – A Primary Cause

DVT is the leading cause of pulmonary embolism. A DVT occurs when a blood clot forms in a deep vein, usually in the leg. If this clot breaks loose, it can travel through the veins to the lungs, causing a PE.

Common triggers for DVT include:

Long periods of immobility (e.g., long flights or bed rest).
Surgery, particularly joint replacement procedures.
Trauma or injury to the veins.

Surgical Procedures and Immobilization

Surgery and immobility increase the risk of PE, especially after:

Major surgeries: Orthopedic surgeries like hip and knee replacements significantly increase clot risk.
Prolonged bed rest: Slows blood flow, which can lead to clot formation.
Hospitalization: Patients who remain immobile for extended periods are at high risk.

Rare Causes of Pulmonary Embolism

Genetic Predispositions and Clotting Disorders

Certain inherited clotting conditions increase the likelihood of developing blood clots:

Factor V Leiden mutation: A genetic disorder that increases clotting tendencies.
Prothrombin gene mutation: Raises the risk of blood clots.
Antiphospholipid syndrome (APS): An autoimmune disorder that increases clot risk.

Uncommon Medical Conditions Leading to PE

Less common medical events that cause PE include:

Fat embolism: This occurs when fat particles enter the bloodstream, usually after trauma, such as a fracture of a large bone.
Air embolism: Results from air bubbles entering the veins during certain medical procedures.
Amniotic fluid embolism: A rare but serious condition that happens when amniotic fluid, which surrounds the baby in the womb, enters the mother's bloodstream during childbirth or soon after delivery.

Risk Factors Associated with Pulmonary Embolism

In addition to medical causes, certain lifestyle habits and pre-existing conditions increase the risk of developing PE.

Lifestyle Factors

Lifestyle factors associated with clot formation include:

Smoking: Damages blood vessels and increases clotting risk.
Obesity: Puts extra pressure on veins, increasing the risk of DVT.
Sedentary Lifestyle: Lack of movement slows blood flow, increasing clot risk.

Medical History and Comorbidities

Pre-existing medical conditions that increase the risk of PE are:

History of blood clots: Previous DVT or PE significantly increases the risk of recurrence.
Cancer: Certain cancers and treatments increase clotting risks.
Hormone therapy: Including birth control pills and hormone replacement therapy.

Symptoms and Diagnosis

Recognizing the symptoms of PE and receiving a prompt diagnosis can be life-saving. PE symptoms can range from mild to life-threatening.

Recognizing the Symptoms of Pulmonary Embolism

PE symptoms can appear suddenly and vary in severity, making early recognition critical.

Common Symptoms

Common symptoms of PE:

Shortness of breath (dyspnea): Sudden difficulty breathing during rest or activity.
Chest pain: Sharp, stabbing pain that worsens with deep breaths (pleuritic pain).
Coughing: May produce bloody sputum (hemoptysis).
Rapid heart rate (tachycardia): The heart beats faster to compensate for reduced oxygen.

Rare and Atypical Symptoms

Less common symptoms:

Fainting (syncope): Especially in large or sudden clots.
Flu-like symptoms: Fever, chills, and body aches, often mistaken for pneumonia.
Leg swelling and pain: A sign of an underlying DVT.

If you experience these symptoms, seek urgent medical care. Do not attempt to self-diagnose or delay treatment. Symptom presentation varies among individuals; consult a healthcare provider for evaluation.

Diagnostic Procedures for Pulmonary Embolism

When PE is suspected, healthcare providers use imaging and blood tests to confirm the diagnosis.

Imaging Tests

Imaging is key for detecting clots and assessing lung function:

CT Pulmonary Angiography (CTPA): The gold standard test for diagnosing PE, providing clear images of lung blood vessels.
Ventilation/Perfusion (V/Q) Scan: This scan measures air and blood flow in the lungs and is often used if CTPA is not suitable.

Blood Tests and Clinical Assessments

Blood tests and heart evaluations can help confirm or rule out PE:

D-dimer blood test: Measures a substance released when blood clots break down.
Echocardiogram: Assesses heart function and right-sided heart failure, which may indicate a PE.

Differential Diagnosis

Distinguishing PE from other conditions is essential for effective treatment.

Distinguishing PE from Other Respiratory Conditions

PE shares symptoms with many other illnesses, but there are key differences:

Pneumonia: Both cause fever and chest pain, but PE pain is sudden and worsens with breathing.
Heart Attack: Heart attack pain may spread to the arm or jaw, while PE pain worsens with deep breaths.

Misdiagnosing PE can be fatal. Accurate diagnosis by a healthcare provider ensures that patients receive prompt and effective treatment, reducing the risk of complications or death.

Treatment Options

The treatment for PE focuses on removing the clot, preventing new clots, and managing complications. Treatment strategies depend on the severity of the embolism.

Emergency Treatment for Acute PE

For severe PE, immediate interventions are necessary to dissolve clots and restore blood flow.

Thrombolytic Therapy (Clot-Busting Drugs)

Thrombolytic drugs quickly dissolve clots in severe cases:

Alteplase (tPA): A powerful clot-dissolving drug used during life-threatening PE.
Risk: Thrombolytics carry a high risk of bleeding, so they are only used for severe PE.

Anticoagulant Medications (Blood Thinners)

Anticoagulants prevent the formation of new clots and stop existing ones from growing:

Heparin: An immediate-acting blood thinner, usually given intravenously in hospitals.
Direct Oral Anticoagulants (DOACs): Examples include apixaban (Eliquis) and rivaroxaban (Xarelto), which are usually suitable for long-term clot prevention.

Long-Term Management and Prevention

Long-term management aims to prevent future clots and support recovery.

Lifestyle Modifications and Physical Therapy

Lifestyle changes reduce recurrence risk:

Regular exercise: Promotes blood circulation and reduces clot risk.
Quitting smoking: Reduces damage to blood vessels.
Maintaining a healthy weight: Reduces strain on veins.

Use of Compression Stockings and Preventive Medications

Compression stockings and medications help prevent clot formation:

Compression stockings: Improve blood circulation in the legs and may reduce the risk of DVT and PE.
Preventive anticoagulants: These are often prescribed by a healthcare provider for patients who have atrial fibrillation, after surgery, or during extended periods of immobility.

Integrative and Functional Approaches

Some people may benefit from holistic approaches alongside standard treatments.

Holistic Treatments and Complementary Therapies

Complementary therapies that can support recovery and improve well-being include:

Nutritional counseling: Focuses on anti-inflammatory foods and vascular health.
Yoga and acupuncture: May help reduce stress and improve circulation.

Treatment options should be discussed with a healthcare provider, as individual risks and benefits vary.

Complications and Prognosis

Understanding potential PE complications and recovery expectations is essential for patients and healthcare providers.

Potential Complications from PE

If PE is not properly treated, it may cause long-term damage to the lungs and heart.

Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but serious complication that can develop after a pulmonary embolism:

In CTEPH, blood clots cause scarring in the lung’s arteries, leading to increased pressure in the pulmonary arteries.
Symptoms: Patients may experience persistent shortness of breath, chest pain, and fatigue, even months after the initial PE.
Long-Term Impact: If untreated, CTEPH can lead to right-sided heart failure.
Treatment Options: CTEPH may require pulmonary thromboendarterectomy (PTE), a surgical procedure to remove clots from lung arteries. Patients may benefit from medications like riociguat (Adempas) to lower pulmonary artery pressure.

Pulmonary Infarction

A PE can cause a pulmonary infarction by blocking blood flow to part of the lung. Without enough oxygen-rich blood, the lung tissue starts to die, leading to chest pain, coughing blood, and breathing problems.

Recurrent Embolisms and Long-Term Health Impacts

Patients with a blood clot are more likely to have another one. Studies have shown without proper treatment, up to 30% of PE patients experience another clot within 10 years. Repeated PEs can cause lung damage, reduced lung function, and chronic shortness of breath.

Additionally, some patients develop persistent symptoms after treatment, including chronic fatigue, chest discomfort, and exercise intolerance. Long-term anticoagulant therapy, regular follow-ups, and lifestyle changes reduce the risk of recurrence.

Prognosis and Recovery

The outlook for patients with PE depends on how quickly they receive treatment and their overall health condition.

Factors Influencing Recovery Outcomes

Recovery outcomes after PE depend on several factors:

Severity of the embolism: Large or multiple clots increase the risk of long-term complications.
Speed of diagnosis and treatment: Early detection and prompt treatment significantly improve survival rates.
Patient’s age and overall health: Older patients or those with underlying health conditions may experience slower recovery.
Comorbidities: Conditions such as heart failure, cancer, or chronic obstructive pulmonary disease (COPD) can complicate or lengthen recovery time.
Adherence to treatment plan: Patients who take prescribed anticoagulants and attend follow-up appointments have better outcomes.

Long-Term Monitoring and Follow-Up Care

After a PE, ongoing and follow-up care is essential to prevent complications and monitor recovery:

Follow-Up Appointments: Patients should regularly visit their healthcare provider for check-ups and monitoring.
Imaging Tests: Repeat CT or V/Q scans may be performed to monitor for new or persistent clots.
Echocardiogram: Helps detect heart strain, especially in patients at risk of CTEPH.
Medication Management: Patients may need long-term anticoagulant therapy depending on their risk factors.
Pulmonary Rehabilitation: This program includes breathing exercises and physical therapy to help patients regain strength and improve lung function.

Prevention Strategies

Medical strategies and lifestyle habits can help reduce the risk of PE.

Primary Prevention of Pulmonary Embolism

Primary prevention focuses on identifying and reducing risks before a PE occurs, especially in high-risk patients.

Risk Assessment and Management in High-Risk Populations

Identifying high-risk patients and implementing preventive measures can significantly reduce PE incidence. This may be achieved by:

Screening for risk factors:

Healthcare providers should assess patients with the following:

History of blood clots or venous thromboembolism.
Genetic clotting disorders (e.g., Factor V Leiden).
Cancer or undergoing chemotherapy.

Blood tests for clotting disorders:

D-dimer and thrombophilia screening help detect clotting tendencies.

Personalized prevention plans:

High-risk patients may receive preventive treatments, including:

Low-dose aspirin for patients with moderate risk.
Anticoagulants (e.g., apixaban or rivaroxaban) for high-risk individuals.

Patient Education:

High-risk individuals should be educated about the warning signs of DVT and PE.

Preventive Measures During Hospitalization and Surgery

Patients undergoing surgery or long-term hospitalization are at high risk for PE, making preventive measures essential:

Early post-operative ambulation:

Encouraging patients to walk soon after surgery improves circulation and reduces clot formation.

Mechanical devices:

Devices that help prevent clot formation include:
- Intermittent pneumatic compression (IPC) devices inflate and deflate to improve leg blood flow.
- Compression stockings help prevent DVT.

Medication:

Prophylactic anticoagulants are often given to prevent clots:
- Heparin or low-molecular-weight heparin
- DOACs such as apixaban or rivaroxaban

Post-operative care:

Special care after orthopedic surgeries (e.g., hip or knee replacement) may include:
- Anticoagulant therapy for 10–35 days post-surgery.
- Regular leg movement exercises.

Lifestyle and Home-Based Prevention

In addition to medical prevention, making simple changes in daily life can help lower the risk of PE.

Importance of Regular Exercise and Maintaining a Healthy Weight

A healthy lifestyle improves circulation and reduces clotting risks:

Exercise:
- Aim for at least 150 minutes of moderate activity per week, such as brisk walking, swimming, or cycling.
- Include strength training exercises twice a week to improve overall fitness.
Weight management:
- Maintain a healthy weight to reduce pressure on veins and lower the risk of DVT.
- Follow a heart-healthy diet rich in fruits, vegetables, and whole grains.
Smoking cessation: Smoking increases clotting risk, so quitting significantly reduces the chance of PE.

Avoiding Prolonged Immobility and Staying Active

Avoiding long periods of inactivity also helps prevent blood clots, especially during travel or after surgery:

During Travel:
- Take breaks every 1–2 hours on long flights or car trips to walk or stretch.
- While seated, perform simple leg exercises, such as ankle circles and foot pumps.
After surgery and during recovery:
- Start moving as soon as your surgeon permits to promote circulation.
- Use compression stockings if prescribed.
Workplace habits:
- Take short breaks every hour to stand, stretch, or walk.
- If working at a desk, use a footrest to elevate your legs.
Stay hydrated: Proper hydration keeps blood thinner and reduces the chance of clotting.

Consult your healthcare provider before altering diet, exercise, and other lifestyle choices to determine the best plan for your needs.

This article is for educational purposes only and is not a substitute for medical advice. Consult a licensed healthcare provider for diagnosis and treatment. Individual results may vary.