Pulmonary Embolism

The most common cause of pulmonary embolism (PE) is a condition known as deep vein thrombosis (DVT) where a blood clot forms in the deep veins of the legs, breaks loose, and travels through the bloodstream to the lungs, where it becomes lodged in a pulmonary artery. However, there are various risk factors and underlying conditions that can predispose individuals to developing DVT and subsequently PE. Primary causes and risk factors for pulmonary embolism include:

Deep Vein Thrombosis (DVT)

Prolonged Immobility

Prolonged periods of immobility, such as prolonged bed rest, long flights, or immobilization after surgery or injury, can increase the risk of developing blood clots in the legs, which may lead to PE.

Surgery

Major surgeries, particularly orthopedic procedures such as joint replacement surgery or hip fracture repair, carry an increased risk of developing DVT and subsequent PE due to immobility, tissue trauma, and alterations in blood flow.

Medical Conditions and Diseases

Medical conditions and diseases that can cause acute pulmonary emblism include:

• Cancer and cancer treatment
• Heart disease, particularly congestive heart failure and atrial fibrillation
• Inflammatory disorders such as lupus and inflammatory bowel disease, genetic or acquired thrombophilia (blood clotting disorders)
• Chronic kidney disease
• Obesity
• Pregnancy and postpartum period
• Hormone replacement therapy and oral contraceptives (particularly in women who smoke or have other risk factors)
• Paralysis or immobilization of a limb
• History of prior thromboembolism

Age

Advanced age is a significant risk factor, particularly in individuals over 60 years old.

Family History

A family history of blood clots or thromboembolic disorders may increase an individual's risk of developing DVT and PE.

Smoking and Tobacco Use

Smoking and tobacco use are associated with an increased risk of developing blood clots and pulmonary embolism.

Travel

Long-distance travel, particularly by air, car, or train, may increase the risk of developing blood clots and pulmonary embolism due to prolonged immobility and dehydration.

Hormonal Factors

Hormonal factors such as pregnancy, estrogen-containing medications (e.g., oral contraceptives, hormone therapy), and hormone-related conditions (e.g., polycystic ovary syndrome) can increase the risk of blood clots and pulmonary embolism.

Sudden Shortness of Breath

This is often the most prominent symptom and may range from mild to severe, depending on the size of the clot and the individual's overall health.

Chest Pain

Chest pain may be sharp and sudden, and it may worsen with deep breathing, coughing, or movement. The pain may also radiate to the shoulder, arm, neck, or jaw.

Rapid Heart Rate (Tachycardia)

The heart may beat faster than normal as it tries to compensate for decreased oxygen levels in the bloodstream.

Cough

A cough may be dry or produce bloody or bloody-tinged sputum.

Wheezing

Some individuals may experience wheezing or other respiratory symptoms.

Feeling Lightheaded or Dizzy

Reduced blood flow to the brain due to the blockage in the pulmonary arteries can cause feelings of lightheadedness or dizziness.

Fainting (Syncope)

In severe cases, reduced blood flow to the brain may lead to fainting spells.

Anxiety or Apprehension

Many people with pulmonary embolism experience a sense of impending doom or anxiety. 

Diagnosing acute pulmonary embolism (PE) can be challenging due to the varied and nonspecific nature of its symptoms. However, several diagnostic tools and tests can help confirm or rule out the presence of pulmonary embolism.

Clinical Assessment

A thorough medical history and physical examination are essential.

Blood Tests

Blood Gas Analysis

CT Pulmonary Angiography (CTPA)

Ventilation-Perfusion (V/Q) Scan

This nuclear medicine test evaluates airflow (ventilation) and blood flow (perfusion) in the lungs.

Echocardiography

Transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE) may be used to evaluate the heart's function and detect signs of right heart strain or dysfunction secondary to acute PE.

Venous Ultrasound

Doppler ultrasound of the lower extremities can help detect deep vein thrombosis (DVT), which is often associated with pulmonary embolism.

Pulmonary Angiography

Pulmonary angiography involves injecting contrast dye directly into the pulmonary arteries via a catheter inserted through a vein in the groin or arm. It provides detailed imaging of the pulmonary vasculature and can confirm the presence and location of pulmonary emboli.

Treating acute pulmonary embolism (PE) involves immediate management to stabilize the patient, prevent further clot formation, and minimize the risk of complications such as pulmonary infarction, right heart strain, and recurrent embolism. Treatment strategies for acute PE typically include:

Anticoagulation

Anticoagulant therapy is the cornerstone of treatment for acute PE. The goal is to prevent further clot propagation and thrombus extension while allowing the body's natural fibrinolytic mechanisms to dissolve existing clots.

Thrombolytic Therapy

Thrombolytic therapy may be considered in hemodynamically unstable patients with massive or submassive PE, characterized by severe hypotension, shock, or evidence of right heart strain.

Thrombolytics rapidly dissolve blood clots and improve pulmonary blood flow, thereby reducing the risk of hemodynamic collapse and mortality.

Hemodynamic Support

Patients with hemodynamic instability or shock due to massive PE may require aggressive hemodynamic support, including fluid resuscitation, vasopressor therapy (e.g., norepinephrine), and inotropic agents (e.g., dobutamine) to maintain adequate tissue perfusion.

Extracorporeal Membrane Oxygenation (ECMO)

ECMO may be considered for refractory shock or cardiac arrest.

Oxygen Therapy and Supportive Measures

Supplemental oxygen therapy is provided to maintain adequate oxygenation and alleviate hypoxemia in patients with acute PE, particularly those with respiratory distress or hypoxemic respiratory failure.

Education about the signs and symptoms of recurrent thromboembolism, the importance of adherence to anticoagulant therapy, and follow-up arrangements for ongoing monitoring and management are the keys to living with this disease.

Close collaboration among healthcare providers, including emergency physicians, pulmonologists, cardiologists, and hematologists, is essential for coordinating care and ensuring the best possible outcomes for patients with acute PE.

Chronic pulmonary embolism occurs when blood clots fail to completely dissolve or if recurrent clots continue to obstruct pulmonary arteries, causing ongoing pulmonary vascular resistance and increased pressure in the pulmonary circulation.

Chronic pulmonary embolism can lead to a condition called chronic thromboembolic pulmonary hypertension. (CTEPH) is a unique form of pulmonary hypertension characterized by persistent obstruction of the pulmonary arteries due to organized blood clots (thromboemboli), elevated pulmonary artery pressures, and pulmonary vascular resistance. 

Chronic pulmonary embolism (CPE) – Chronic Thromboembolic Pulmonary Hypertension (CTEPH), can present with a variety of symptoms, which may overlap with those of other cardiopulmonary conditions. Symptoms are often nonspecific and can vary depending on the extent of vascular obstruction, the severity of pulmonary hypertension, and the presence of associated complications. Common symptoms include:

Dyspnea (Shortness of Breath)

Dyspnea, especially on exertion, is a common symptom. Patients may experience difficulty breathing during physical activity, which may progressively worsen over time. Dyspnea may also occur at rest in advanced cases.

Fatigue and Weakness

Fatigue, weakness, and decreased exercise tolerance are common complaints Patients may feel tired easily and may have difficulty performing routine activities.

Chest Pain

Some patients may experience chest pain or discomfort, which can vary in intensity and location. Chest pain may worsen with physical exertion or deep breathing.

Syncope (Fainting)

Syncope or near-syncope episodes may occur in advanced cases, particularly in patients with severe pulmonary hypertension and right heart strain. Syncope is typically related to decreased cardiac output and cerebral hypoperfusion.

Palpitations

Palpitations or awareness of an irregular heartbeat may occur in patients, especially those with right heart dysfunction or arrhythmias such as atrial fibrillation.

Peripheral Edema

Peripheral edema, characterized by swelling of the legs and ankles, may develop as a result of right heart failure and venous congestion.

Cough

Chronic cough, sometimes accompanied by hemoptysis (coughing up blood), may occur in patients, although it is less common than in acute pulmonary embolism.

Cyanosis

Cyanosis, a bluish discoloration of the lips, tongue, or extremities, may be present in patients with severe CPE and hypoxemia.

Dizziness and Lightheadedness

Patients may experience dizziness, lightheadedness, or feelings of faintness, particularly upon exertion or when changing positions.

Swelling in the Abdomen

Ascites, or fluid accumulation in the abdominal cavity, may occur in advanced cases of CPE, reflecting right heart dysfunction and venous congestion.

Diagnosing chronic pulmonary embolism and chronic thromboembolic pulmonary hypertension (CTEPH) can be challenging due to its varied clinical presentation and nonspecific symptoms. Diagnosing includes:

Clinical Evaluation

A thorough medical history and physical examination are essential. The presence of risk factors for venous thromboembolism (VTE), such as a history of deep vein thrombosis (DVT), pulmonary embolism (PE), recent surgery, immobilization, or hypercoagulable conditions, should be assessed.

Blood Tests

Ventilation-Perfusion (V/Q) Scan

A V/Q scan may be performed as an initial screening test for suspected chronic PE or CTEPH. Mismatched defects on the V/Q scan suggestive of chronic pulmonary thromboemboli can raise suspicion.

CT Pulmonary Angiography (CTPA)

CTPA provides detailed imaging of the pulmonary vasculature and can identify chronic thromboembolic obstructions in the pulmonary arteries, as well as associated findings such as vascular pruning, mosaic perfusion, and pulmonary hypertension.

Magnetic Resonance Imaging (MRI)

MRI with contrast may be used as an alternative imaging modality in patients with contraindications to CTPA or in cases where additional information is needed.

Right Heart Catheterization (RHC)

RHC assesses pulmonary hemodynamics. This invasive procedure involves inserting a catheter into the right side of the heart and pulmonary arteries to directly measure pulmonary artery pressures, cardiac output, and pulmonary vascular resistance.

Pulmonary Angiography

Pulmonary angiography may be performed as part of RHC or as a standalone procedure to directly visualize chronic thromboembolic obstructions in the pulmonary arteries. It allows for precise assessment of the location, extent, and severity of pulmonary vascular lesions.

Multidisciplinary Evaluation

Given the complexity of chronic PE/CTEPH diagnosis and management, a multidisciplinary team involving pulmonologists, cardiologists, radiologists, and thoracic surgeons review diagnostic findings and coordinate treatment strategies.

Early diagnosis and intervention are crucial for optimizing outcomes in patients with chronic PE/CTEPH. Treatment options may include medical therapy, pulmonary endarterectomy (PEA) surgery, balloon pulmonary angioplasty (BPA), and other interventions aimed at improving pulmonary hemodynamics and reducing pulmonary hypertension.

Treating CTEPH involves a comprehensive approach aimed at improving symptoms, reducing pulmonary hypertension, and addressing the underlying cause of persistent pulmonary vascular obstruction. Treatment includes medical therapy, surgical intervention, and interventional procedures that are patient-specific, including:

Medical Therapy

• Anticoagulation: Anticoagulant therapy with medications such as warfarin or direct oral anticoagulants (DOACs) is typically initiated to prevent further thrombus formation and reduce the risk of recurrent thromboembolic events.
• Pulmonary vasodilators: Medications such as endothelin receptor antagonists, phosphodiesterase-5 inhibitors, and soluble guanylate cyclase stimulators may be used to reduce pulmonary vascular resistance and improve symptoms of pulmonary hypertension.

Pulmonary Endarterectomy (PEA)

PEA surgery is the treatment of choice for eligible patients. It involves removing chronic thromboembolic material and fibrotic lesions from the pulmonary arteries, thereby restoring pulmonary blood flow and reducing pulmonary artery pressure.

PEA is performed in specialized centers by experienced cardiothoracic surgeons. It can lead to significant improvements in symptoms, exercise capacity, and long-term survival in appropriately selected patients with CTEPH.

Balloon Pulmonary Angioplasty (BPA)

BPA is a minimally invasive procedure that may be considered for patients who are not candidates for PEA or have residual or inaccessible thromboembolic lesions after surgery.

During BPA, catheters with balloons are inserted into the pulmonary arteries under fluoroscopic guidance, and the balloons are inflated to dilate stenotic or obstructed segments. This helps improve pulmonary blood flow and reduce pulmonary artery pressures.

BPA is typically performed in multiple sessions over several weeks to months to gradually address multiple areas of pulmonary vascular obstruction.

Medical Therapy for Inoperable Patients

For patients who are not candidates for PEA surgery or BPA, medical therapy with pulmonary vasodilators and anticoagulants may be used to manage symptoms and slow disease progression.

Oxygen Therapy

Supplemental oxygen therapy may be prescribed to improve oxygenation and alleviate symptoms such as dyspnea and fatigue, particularly those with advanced disease or hypoxemic respiratory failure.

Multidisciplinary Care

The treatment of chronic thromboembolic disease and CTEPH requires a multidisciplinary approach involving pulmonologists, cardiologists, cardiothoracic surgeons, interventional radiologists, and specialized nurses. Close collaboration among healthcare providers is essential for optimizing treatment and addressing the complex needs of patients.

Clinical Trials

Participation in clinical trials investigating new treatments and therapies for CTEPH may be an option for some individuals. Clinical trials offer access to cutting-edge treatments and contribute to advancing medical knowledge and treatment options for CTEPH.

Overall, the management of chronic thromboembolic disease/CTEPH requires a coordinated and individualized approach by a multidisciplinary team of healthcare professionals

Regular follow-up and monitoring are essential to management to assess treatment response, adjust medications as needed, and monitor disease progression. Treatment decisions should be individualized based on the specific characteristics of the patient, disease severity, comorbidities, and patient preferences. Early diagnosis and timely initiation of appropriate therapy are crucial for improving outcomes and quality of life.