What are the management options for rare disorders causing pulmonary embolism (PE)?

Management Options for Rare Disorders Causing Pulmonary Embolism

Management of rare disorders causing pulmonary embolism (PE) should be tailored to the specific etiology, with treatment primarily consisting of supportive care and addressing the underlying cause, while anticoagulation remains the cornerstone for most cases. 1

Types of Non-Thrombotic Pulmonary Embolism and Their Management

Venous Air Embolism

• Principal management goals include:
  • Prevention of further air entry
  • Reduction in volume of air entrained when possible
  • Hemodynamic support 1
• Position patients in left lateral decubitus head-down position to trap air in the right atrium and prevent it from entering the pulmonary outflow tract 1
• Intraoperative needle aspiration may occasionally be performed to relieve large air bubbles 1

Septic Embolism

• Most commonly associated with tricuspid valve endocarditis, particularly in:
  • Intravenous drug users
  • Patients with infected indwelling catheters or pacemaker wires
  • Patients with peripheral septic thrombophlebitis
  • Organ transplant recipients 1
• Typical presentation includes fever, cough, and hemoptysis 1
• Management:
  • Antibiotic treatment is generally successful
  • Surgical removal of the embolic source may occasionally be necessary 1

Amniotic Fluid Embolism

• Rare but catastrophic complication unique to pregnancy (1/8,000-1/80,000 pregnancies) 1
• Associated with high maternal and fetal mortality rates (80% and 40%, respectively) 1
• Management:
  • Thrombolysis or surgical embolectomy should be considered for pregnant women with high-risk PE 1
  • Consider amniotic fluid embolism in pregnant or post-partum women with unexplained hemodynamic instability, respiratory deterioration, and disseminated intravascular coagulation 1

Tumor Embolism

• Present in up to 26% of autopsies but rarely identified before death 1
• Most commonly associated with carcinomas of the prostate gland and breast, followed by hepatoma, stomach, and pancreas 1
• Radiologically mimics pneumonia, tuberculosis, or interstitial lung disease 1
• Management:
  • Limited success with chemotherapy has been reported 1
  • Treatment is often not initiated until post-mortem diagnosis 1

Talc Embolism

• Associated with intravenous injection of ground oral medications containing fillers (talc, starch, cellulose) 1
• Common drugs involved: amphetamines, methylphenidate, hydromorphone, dextropropoxyphene 1
• Filler particles become entrapped in pulmonary vasculature causing thrombosis and intravascular granulomas 1
• Management is primarily supportive 1

Other Rare Causes

• Cotton embolism, hydatid embolism, iodinated oil embolism, metallic mercury embolism, cement (polymethylmethacrylate) embolism 1
• Clinical presentation varies widely, making diagnosis difficult 1
• Hemodynamic consequences are usually mild except in severe air and fat embolism 1
• Management is mostly supportive but varies according to embolic material and clinical severity 1

General Management Principles

Diagnostic Approach

• Stratify patients with suspected PE based on hemodynamic stability to identify those at high risk of early mortality 1
• In suspected high-risk PE:
  • Perform bedside echocardiography or emergency CTPA depending on availability and clinical circumstances 1
  • Initiate intravenous anticoagulation with unfractionated heparin without delay 1

Treatment Strategies

• For hemodynamically unstable patients:

  • Administer systemic thrombolytic therapy 1
  • Consider surgical pulmonary embolectomy when thrombolysis is contraindicated or has failed 1
  • ECMO may be considered in combination with surgical embolectomy or catheter-directed treatment in refractory circulatory collapse or cardiac arrest 1

• For stable patients:

  • When oral anticoagulation is initiated, prefer NOACs (apixaban, dabigatran, edoxaban, or rivaroxaban) if eligible 1, 2, 3
  • As an alternative, administer a vitamin K antagonist (VKA), overlapping with parenteral anticoagulation until an INR of 2.5 (range 2.0-3.0) is reached 1

Special Considerations

Antiphospholipid Syndrome (APS)

• Continue oral anticoagulant treatment with a VKA indefinitely 1
• Do not use NOACs in patients with APS 1
• Risk factors for APS in PE patients include: male gender, decreased platelets, slightly increased D-dimer, and prolonged APTT 4

Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

• Pulmonary endarterectomy provides excellent results and should be considered as first-line treatment when feasible 1
• Surgical removal requires true endarterectomy (not simple embolectomy) performed on cardiopulmonary bypass with deep hypothermia and complete circulatory arrest 1
• Refer symptomatic patients with mismatched perfusion defects on V/Q scan >3 months after acute PE to a pulmonary hypertension/CTEPH expert center 1

Follow-up Care

• Routinely re-evaluate patients 3-6 months after acute PE 1
• Implement an integrated model of care after acute PE to ensure optimal transition from hospital to ambulatory care 1
• For patients receiving extended anticoagulation, regularly reassess drug tolerance, adherence, hepatic and renal function, and bleeding risk 1

Clinical Pitfalls and Caveats

• Non-thrombotic PE does not represent a distinct clinical syndrome and may present with a wide spectrum of clinical manifestations 1
• Diagnosis is often challenging due to variable presentations 1
• With the exception of severe air and fat embolism, hemodynamic consequences of non-thrombotic emboli are usually mild 1
• Avoid NOACs during pregnancy or lactation 1
• Do not routinely use inferior vena cava filters 1