What is Pericardial Effusion?
Pericardial effusion is an abnormal accumulation of fluid in the pericardial space that exceeds the normal physiological amount (typically 15-50 mL), which can result from inflammatory, infectious, neoplastic, metabolic, traumatic, or idiopathic causes. 1, 2
Definition and Pathophysiology
Pericardial effusion represents an increase beyond the normal volume of fluid within the pericardial cavity. 2 The fluid can manifest as different types depending on the underlying cause:
- Transudate (hydropericardium) - typically from heart failure or metabolic causes 1, 3
- Exudate - from inflammatory or infectious processes 1
- Pyopericardium - purulent fluid from bacterial infection 1
- Hemopericardium - blood accumulation from trauma, malignancy, or aortic dissection 1, 4
The hemodynamic impact depends critically on the rate of fluid accumulation rather than absolute volume. 1, 5 Rapid accumulation of even 100-200 mL over minutes to hours can cause cardiac tamponade, while slow accumulation over days to weeks allows the pericardium to stretch and accommodate large volumes (sometimes >1000 mL) before symptoms develop. 5, 6
Major Etiologies
Geographic Variation in Causes
The etiology varies dramatically by geographic region and healthcare setting:
- Developing countries: Tuberculosis dominates, accounting for >60% of cases, especially in HIV-endemic areas 7, 8
- Developed countries: Idiopathic causes account for up to 50% despite comprehensive evaluation, with malignancy (10-25%), infections, iatrogenic causes, and autoimmune diseases comprising other major etiologies 7, 8
Specific Causes by Category
Infectious 7:
- Viral infections (most common in developed countries): enteroviruses, echoviruses, adenoviruses, CMV, EBV, HSV, influenza, parvovirus B19, hepatitis C, HIV
- Tuberculosis (leading cause worldwide and in endemic regions)
- Fungal infections (particularly in immunocompromised patients)
Neoplastic 7:
- Secondary metastatic tumors (40 times more common than primary): lung cancer, breast cancer, lymphoma, melanoma, leukemia
- Primary pericardial tumors (rare): mesothelioma most common
- Critical caveat: In almost two-thirds of patients with documented malignancy, the pericardial effusion is actually caused by non-malignant diseases such as radiation pericarditis or opportunistic infections 7
Autoimmune/Inflammatory 7:
- Systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis, scleroderma, systemic vasculitides (account for 5-15% of cases)
- Post-cardiac injury syndromes: post-MI pericarditis, post-pericardiotomy syndrome, post-traumatic pericarditis
- Sarcoidosis
Metabolic/Endocrine 7:
- Hypothyroidism (occurs in 5-30% of hypothyroid patients; effusions may be large but tamponade is rare)
- Uremia in renal failure
- Heart failure (causes transudative effusion through increased systemic venous pressure and decreased pericardial fluid reabsorption)
- Pulmonary arterial hypertension (25-30% of cases have effusion, typically small and rarely causing hemodynamic compromise)
- Aortic dissection with hemopericardium (occurs in 17-45% of ascending aortic dissections)
Iatrogenic/Traumatic 7:
- Cardiac surgery, percutaneous coronary intervention, pacemaker insertion, radiofrequency ablation
- Penetrating or non-penetrating thoracic trauma
- Radiation therapy (causes effusion/constriction in 6-30% of patients)
- Chemotherapy agents: anthracyclines, cyclophosphamide, cytarabine, imatinib, dasatinib, interferon-α, arsenic trioxide, docetaxel, 5-fluorouracil, osimertinib
Drug-Related 7:
- Lupus-like syndrome: procainamide, hydralazine, methyldopa, isoniazid, phenytoin
- Other medications: amiodarone, methysergide, mesalazine, clozapine, minoxidil, anti-TNF agents
Clinical Presentation
Symptoms
The clinical presentation varies based on the speed of accumulation and size of effusion:
Slowly developing effusions can be remarkably asymptomatic even when large, while rapidly accumulating smaller effusions present with tamponade. 1, 5
Common symptoms include 5:
- Dyspnea on exertion progressing to orthopnea (hallmark presentation)
- Chest pain or chest fullness
- Nausea, dysphagia, hoarseness, hiccups (from compression of adjacent structures)
- Non-specific symptoms: cough, weakness, fatigue, anorexia, palpitations, fever
Physical Examination
Physical examination may be completely normal in patients without hemodynamic compromise. 5 When cardiac tamponade develops, classic findings include 1, 5:
- Neck vein distension with elevated jugular venous pressure
- Pulsus paradoxus
- Diminished/distant heart sounds
- Pericardial friction rubs (rarely heard, but may be present with concomitant pericarditis)
Insidiously developing tamponade may present with complications such as renal failure, abdominal plethora, shock liver, and mesenteric ischemia. 1
Clinical Pearls for Etiology Assessment
Cardiac tamponade without inflammatory signs is associated with higher risk of neoplastic etiology (likelihood ratio 2.9). 7
Severe effusion without cardiac tamponade and without inflammatory signs is usually associated with chronic idiopathic etiology (likelihood ratio 20). 7
If inflammatory signs are present (chest pain, fever, pericardial friction rub, elevated CRP), clinical management should follow that of pericarditis. 7
In 60% of patients, the cause of pericardial effusion may be a known medical condition. 1, 7
Serosanguinous or hemorrhagic fluid can be found in malignant, post-pericardiotomy, rheumatologic, traumatic, and iatrogenic effusions, but also in idiopathic and viral forms, so fluid appearance alone cannot determine etiology. 7
Risk of Progression
Large chronic pericardial effusions are rare (2-3.5% of all large effusions). 1 However, up to one-third of patients with asymptomatic large chronic pericardial effusion develop unexpected cardiac tamponade. 1, 8, 9 Triggers for tamponade include hypovolemia, paroxysmal tachyarrhythmias, and intercurrent acute pericarditis. 1