Pulmonary Embolism - Symptoms, Causes, Diagnosis, and Treatments

Introduction

Embolism means a plug or stopper in Greek. A blockage in the artery (pulmonary artery) that supplies blood to the lungs is known as pulmonary embolism (PE). It is estimated that around one in 1,000 people in the United States are affected by this condition, and it is one of the most common risks for cardiovascular diseases. It is fatal, as it prevents oxygen supply to the lung tissues.

The block or embolus can most commonly be a blood clot. An embolus can form in any part of the body, travel through the bloodstream, and block blood flow to other parts, causing an embolism. A thrombus (a form of clot), unlike an embolus, develops and remains in the same place. Prompt treatment intervention can prevent complications and reduce death rates.

What Is a Pulmonary Embolism?

Pulmonary embolism is either formed in the pulmonary blood vessel or is carried in the bloodstream, which is formed somewhere else in the body (embolus). The significant symptom of pulmonary embolism is shortness of breath. Pulmonary arteries are blood vessels that transport blood from the heart to the lungs, and the exchange of gases takes place (inside the lungs), and the blood returns its oxygen to the heart. From the heart, the blood containing oxygen is pumped to different parts of the body, thus providing oxygen to all the tissues in the body.

When this pulmonary artery is blocked or obstructed because of a blood clot (thrombus) or embolus, tissues will not receive sufficient amounts of oxygen. A large embolus can cause so much blockage that the heart is unable to pump enough blood through the pulmonary arteries, and this leads to a decrease in blood pressure. Also, large embolisms can obstruct the blood flow to the lungs, leading to the death of lung tissues, and this condition is called pulmonary infarction. Pulmonary infarction is a fatal condition, but it can be reversed.

Usually, the body splits up smaller clots quickly compared to larger ones, so the damage can be minimal. Large clots take too much time to disintegrate, leading to scar formation on the blood vessel and raising blood pressure in the lungs’ blood vessels. This condition is known as pulmonary hypertension, and it causes permanent damage to the lungs.

What Are the Stages of Pulmonary Embolism?

Pulmonary embolism (PE) is not categorized in stages as cancer would be. Physicians perform PE depending on the clot size, whether it has affected blood circulation, and the patient's stability. The main categories are:

Low-risk PE (mild):

• Small clot, limited blockage.

• The patient is stable with normal blood pressure and heart rate.

Submassive PE (intermediate-risk):

• Moderate clot burden.

• Patient with normal blood pressure but with evidence of heart strain on the right (as observed in an echocardiogram or blood analysis).

Massive PE (high-risk):

• Clot severe, huge in size.

• Patients experience low blood pressure (hypotension), shock, or even cardiac arrest.

• This is a life-threatening stage that needs immediate intervention.

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What Are the Symptoms and Warning Signs of Pulmonary Embolism?

The clinical manifestations of pulmonary embolism depend on the amount of lung tissue involved, the embolus size, and the existing comorbid conditions. The common symptoms are:

• Difficulty in breathing worsens with exertion.

• Chest pain increases with a deep breath, cough, or exertion.

• Cough (presence or absence of bloody and blood-stained sputum).

• Calf pain or leg swelling.

• Cyanosis (bluish discoloration of the skin).

• Clammy and cold skin, especially in the hands and legs.

• Fever (low grade or intermittent).

• Profuse or excessive sweating.

• Irregular heartbeats.

• Dizziness.

• Restlessness.

These are also signs of a heart attack, so immediate medical intervention is required if any symptom persists.

What Causes a Pulmonary Embolism in the Body?

Pulmonary embolisms are generally caused by the development of blood clots that obstruct the deep veins in the body, known as deep vein thrombosis. These blood clots normally start in the leg or pelvic arteries and are caused by:

• Bone fractures or muscle injuries can cause damage to blood vessels.

• Long periods of inactivity lead to blood clots as the blood settles in the lowest parts of the body because of gravity.

• Medical conditions that lead to blood clots easily.

Other than blood clots, the blood vessels may at times be obstructed by:

• Collagen.

• A piece of a tumor.

• Air bubbles.

• Fat that has been dislodged from a broken bone.

Who Is at Risk of Pulmonary Embolism?

A pulmonary embolism (PE) can occur in anyone. Still, risk increases with the presence of one or more components of Virchow's triad: blood stasis (reduced flow), hypercoagulability (clotting tendency), or vessel damage. Here is a detailed, physician-quality breakdown of who's at increased risk and why:

• Highest-risk groups-

  • Previous DVT (deep vein thrombosis or PE (pulmonary embolism), or a strong family history.

  • Inherited or acquired thrombophilia.

  • Major surgery or trauma.

  • Active malignancy or cancer therapy.

• Situational/transient risks (typically stacked together)-

  • Immobility.

  • Pregnancy and the postpartum.

  • Exposure to estrogen.

  • Severe medical illness: Recent stroke (particularly with paralysis), heart failure, recent myocardial infarction, serious infections (such as COVID-19), COPD (chronic obstructive pulmonary disorder) exacerbation, nephrotic syndrome, inflammatory bowel disease, systemic lupus, and renal failure.

  • Central venous access devices.

• Baseline factors-

  • Older age.

  • Obesity and sedentary lifestyle.

  • Smoking.

  • Dehydration and prolonged sitting.

  • Varicose veins and chronic venous insufficiency.

  • Blood disorders.

What Are the Possible Complications of Pulmonary Embolism?

Pulmonary embolism (PE) may be fatal if it is not diagnosed and treated promptly. Given below are the major complications elaborated in detail:

• Sudden death:

Big clots can block the total flow of blood to the lungs, leading to heart and lung failure. It is the most extreme complication and may arise if PE is massive.

• Pulmonary hypertension:

Recurring or massive clots harm the lung arteries, causing them to become stiff and narrowed. This increases pressure in the lungs (pulmonary hypertension), causing the heart's right side to work harder.

• Right-sided heart failure (cor pulmonale):

Because the right ventricle must pump blood through high-pressure in injured lung arteries, it can become enlarged and ultimately fail. This leads to leg swelling, liver congestion, and fatigue.

• Chronic thromboembolic pulmonary hypertension (CTEPH):

In a few patients, clots do not entirely break down even after therapy. These residual clots clog blood vessels and induce permanent pulmonary hypertension, resulting in chronic shortness of breath and exercise intolerance.

• Recurrent VTE (venous thromboembolism) (DVT/PE):

After you have had a PE, you are more likely to get another clot, particularly if you have risk factors such as thrombophilia, cancer, or long-term immobility. Long-term preventive anticoagulation might be required.

• Lung tissue damage (pulmonary infarction):

In a few instances, the clot occludes blood to a section of lung, leading to tissue death (infarction). It may cause pain in the chest, fever, spitting blood, and the inability to recover for a long while.

How Is Pulmonary Embolism Diagnosed?

Pulmonary embolism (PE) is difficult to diagnose since its symptoms overlap with those of other lung and heart diseases. Physicians base their diagnosis on a systematic, step-by-step approach that includes history, laboratory tests, and imaging.

1. Medical history and physical examination:

Physicians inquire about chest pain, shortness of breath, tachypnea, or hemoptysis and look for risk factors such as recent surgery, immobility, cancer, or familial history.

2. Imaging studies:

• CT pulmonary angiography (CTPA): Gold standard test. Utilizes contrast dye to visualize lung artery blood clots directly.

• Ventilation-perfusion (V/Q) scan: This scan tests airflow vs. blood flow in the lungs. It is useful in patients who cannot have CT scans.

• Doppler ultrasound: To detect DVT in the legs. If DVT is detected, it strongly suggests a PE.

3. Blood tests:

• D-dimer test: A sensitive blood test that measures clot fragments. Raised results indicate clotting but are not specific for PE.

• Arterial blood gas (ABG): It can show low levels of oxygen, but it is not diagnostic by itself.

4. Cardiac and supportive tests:

• Echocardiogram: Detects strain on the right heart, particularly in high-risk or massive cases of PE.

• Chest X-ray: Nonspecific for PE, but excludes pneumonia, collapse of the lung, or pleural fluid.

5. Diagnostic approach in emergency situations:

If the patient is highly suspected to have PE and is unstable, physicians may initiate anticoagulant treatment before confirmation with final tests. The probability of PE is often estimated by a clinical scoring system such as the Wells Score or Geneva Score prior to requesting tests.

How Is Pulmonary Embolism Treated?

Treatment of pulmonary embolism (PE) varies based on the size of the clot, the patient's overall health, and the likelihood of developing clots in the future. The primary objectives are to prevent the clot from enlarging, prevent new clots from being created, and increase blood flow in the lungs.

1. Anticoagulant medications (blood thinners): Initial treatment for most patients.

• Common medications: Heparin, Warfarin, and direct oral anticoagulants (DOACs) such as Rivaroxaban or Apixaban. These do not break up the clot but stop it from enlarging and lower the chance for new clots to form.

• Length of treatment: Typically three to six months, occasionally longer in higher-risk situations.

2. Thrombolytic therapy (clot-busting medications):

Employed in life-threatening or large PE when the clot is obstructing major blood flow and resulting in low blood pressure or shock. Drugs such as Alteplase (tPA) rapidly dissolve clots. High risk of severe bleeding, and hence reserved for emergencies.

3. Interventions through surgery or catheter:

• Catheter-directed thrombolysis/thrombectomy: A catheter is advanced into the lung arteries to infuse clot-dissolving medication directly or manually extract the clot.

• Surgical embolectomy: Open surgery to remove large clots if other methods fail or cannot be used.

4. Inferior vena cava (IVC) filter:

A small tube is inserted into the large vein (vena cava) that stops blood clots before they get to the lungs. Recommended for patients who cannot take blood thinners because of the risk of bleeding. Typically temporary and taken out when safe.

5. Supportive therapies:

• Oxygen therapy: Assists patients with low oxygen levels to breathe more easily.

• IV fluids and medications: Keep blood pressure stable in serious cases.

• Pain relief: To relieve chest pain and discomfort.

6. Long-term management and prevention:

Patients with recurring clots, inherited clotting disorders, or malignancies might require lifelong anticoagulation.

• Lifestyle changes: Exercise, avoiding immobility, keeping a healthy weight, smoking cessation, and using compression stockings can lower recurrence risk.

How Can Pulmonary Embolism Be Prevented?

• Pulmonary embolism is prevented through decreased clot risk.

• Be active, do not sit or lie down too much, and get up from sitting or lying down for an extended period during long travel.

• Be at a healthy weight, drink plenty of fluids, and quit smoking.

• Physicians can prescribe anticoagulants or compression stockings following surgery or hospital stays if the patient is high-risk.

• Early detection and treatment of DVT (deep vein thrombosis).

Conclusion

Pulmonary embolism is a condition that causes a blood clot, leading to obstruction and cessation of the blood flow to the lungs. In most cases, the blood clot usually develops in a deep vein in the lower leg and then moves to the lung. The underlying cause needs to be detected and treated after managing pulmonary embolism. The physician will prescribe blood thinners to prevent more blood clots. If left untreated, pulmonary embolism could result in serious medical complications and could even cause death.

Key Takeaway From iCliniq

Pulmonary embolism (PE) occurs when a blood clot, usually developed in the legs, obstructs blood flow in the lungs.

More serious cases require more potent medicine or effective procedures. Healthcare providers say that the most important thing is to prevent risks in the future.

Whether you have had a PE or are concerned about your risks, experts at iCliniq can help you learn more about your health status and provide preventive steps towards combating pulmonary embolism.