What are the causes of pericardial effusion?

Causes of Pericardial Effusion

Pericardial effusion has numerous etiologies, with idiopathic causes accounting for up to 50% of cases in developed countries, while tuberculosis is the dominant cause (>60%) in developing countries where TB is endemic. 1

Major Etiological Categories

Infectious Causes (15-30%)

• Viral: Most common infectious cause in developed countries
  • Enteroviruses, echoviruses, adenoviruses, CMV, EBV, HSV, influenza, parvovirus B19, hepatitis C, HIV 2
• Bacterial:
  • Tuberculosis (leading cause worldwide, especially in developing countries)
  • Other bacteria: Staphylococcus aureus, Klebsiella pneumoniae 2
• Fungal and parasitic infections (less common)

Neoplastic (10-25%)

• Primary tumors (rare): Pericardial mesothelioma
• Secondary metastatic tumors: Lung cancer, breast cancer, lymphoma 2
• Most common cause of tamponade in medical patients 3

Autoimmune/Inflammatory (5-15%)

• Systemic lupus erythematosus
• Rheumatoid arthritis
• Scleroderma
• Systemic vasculitides
• Behçet syndrome
• Sarcoidosis 2

Iatrogenic/Traumatic (15-20%)

• Early onset:
  • Direct injury: Penetrating thoracic injury, esophageal perforation
  • Indirect injury: Non-penetrating thoracic injury, radiation injury
• Delayed onset:
  • Post-myocardial infarction syndrome
  • Post-pericardiotomy syndrome
  • Post-traumatic pericarditis
  • Iatrogenic trauma: Coronary percutaneous intervention, pacemaker insertion 2
• Anticoagulation therapy may be a risk factor for tamponade in iatrogenic effusions 1

Metabolic and Endocrine Disorders

• Hypothyroidism: Occurs in 5-30% of patients with hypothyroidism; effusions may be large but rarely cause tamponade 1
• Uremia
• Myxedema
• Anorexia nervosa 2

Drug-Induced

• Medications causing lupus-like syndrome: Procainamide, hydralazine, methyldopa, isoniazid
• Antineoplastic drugs: Doxorubicin, daunorubicin
• Others: Amiodarone, mesalazine, clozapine, anti-TNF agents 2

Pulmonary Arterial Hypertension

• Common (25-30%) but typically small effusions
• Related to right ventricular failure and increased right-sided filling pressures
• Even small effusions portend poor prognosis 1

Other Specific Types

• Chylopericardium: Effusion composed of chyle due to thoracic duct injury
  • Causes: Trauma, surgery, congenital lymphangiomatosis, radiotherapy, subclavian vein thrombosis, mediastinal neoplasms 1
• Cholesterol pericarditis: Clear fluid with high cholesterol content
  • Occurs in tuberculous pericarditis, rheumatoid pericarditis, trauma 1
• Pericardial cysts: Rare (1 in 100,000) mediastinal masses 1

Clinical Presentation and Diagnosis

The presentation varies based on:

1. Speed of fluid accumulation: Rapid accumulation (even small amounts) can cause tamponade, while slow accumulation allows large effusions to develop before symptoms appear 1
2. Size of effusion: Classified as mild (<10mm), moderate (10-20mm), or large (>20mm) 1
3. Presence of inflammation: Inflammatory signs suggest pericarditis 4

Diagnostic Approach

• Echocardiography: Primary diagnostic tool for detection, semiquantitative assessment, and evaluation of hemodynamic effects 1
• CT/MRI: Better for loculated effusions, pericardial thickening, and associated chest abnormalities 1
• Laboratory tests: Based on clinical suspicion of specific etiologies 4

Management Considerations

Management depends on:

• Hemodynamic impact (presence of tamponade)
• Size of effusion
• Presence of inflammation
• Underlying cause 5

Pericardiocentesis is mandatory for:

• Cardiac tamponade
• Suspected bacterial or neoplastic etiology
• Large chronic effusions (>3 months) due to risk of progression to tamponade 4

Pitfalls and Caveats

1. Asymptomatic large effusions: Up to one-third may progress to tamponade, requiring close monitoring 4

2. Diagnosing tamponade in PAH: Challenging because high right-sided pressures mask typical findings; look for left atrial early diastolic collapse instead 1

3. Recurrence after drainage: Common, especially with neoplastic effusions; consider pericardial window or pericardiectomy for recurrent cases 6

4. Chylopericardium vs. cholesterol pericarditis: Similar appearance but different management approaches 1

5. Idiopathic effusions: Remain common in developed countries despite extensive workup 1