Pericardial Effusion

Pericardial effusion refers to an abnormal accumulation of fluid in the pericardial cavity. The pericardium comprises an outer fibrous connective membrane and an inner two-layered serous membrane, enclosing the pericardial cavity.

Normally, this cavity contains 15-50 mL of pericardial fluid, which provides lubrication, maintains the heart's position, and serves as a barrier against infections and inflammation.

Signs and Symptoms

Clinical presentation varies based on the size, acuity, and underlying cause of the effusion. Some individuals may be asymptomatic, while others with larger effusions could experience chest pressure or pain, dyspnea, malaise, and shortness of breath. In severe cases leading to cardiac tamponade, symptoms can include low blood pressure, restlessness, hyperventilation, discomfort when lying flat, dizziness, or even loss of consciousness. Non-cardiac symptoms might arise due to compression of adjacent structures, leading to nausea, abdominal fullness, dysphagia, and hiccups.

Causes

Pericardial effusion can arise from any process leading to injury or inflammation of the pericardium or inhibiting appropriate lymphatic drainage. Causes can be broadly categorised into inflammatory and non-inflammatory.

Inflammatory Causes

1. Infectious:
   • Viral: coxsackie A and B viruses, HIV, hepatitis viruses, parvovirus B19
   • Bacterial: Mycobacterium (tuberculosis), Streptococcus, Staphylococcus, Mycoplasma, Neisseria, Coxiella burnetii
   • Fungal: Histoplasma, Candida
   • Protozoal: Echinococcus, Trichinosis, Toxoplasma
2. Cardiac Injury Syndromes: Post-cardiac surgery, post-myocardial infarction (Dressler's syndrome), coronary interventions.
3. Cardiac Inflammation: Idiopathic pericarditis.
4. Autoimmune: Lupus, rheumatoid arthritis, Sjögren syndrome, scleroderma, Dressler's syndrome, sarcoidosis.
5. Drug Hypersensitivity/Side Effects: Chemotherapy drugs, Minoxidil.
6. Other: Kidney failure, uraemia.

Non-Inflammatory Causes

1. Neoplastic:
   • Primary Tumours: Mesothelioma, sarcoma, lymphoma.
   • Secondary Cancers: Metastases from breast and lung cancer.
2. Metabolic: Hypothyroidism, severe protein deficiency.
3. Traumatic: Penetrating or blunt chest trauma, aortic dissection.
4. Reduced Lymphatic Drainage: Congestive heart failure, nephrotic syndrome.

Pathophysiology

Fluid accumulation in the pericardial cavity results from an imbalance between production and reabsorption or structural abnormalities. Increased intrapericardial pressure due to fluid accumulation can compromise heart function, leading to cardiac tamponade. Acute effusions can cause tamponade with as little as 150 mL of fluid, whereas chronic effusions can accumulate up to 2L due to gradual pericardial stretching.

Diagnosis

Physical examination may reveal tachycardia, distant heart sounds, and tachypnea. Ewart's sign, characterised by dullness to percussion over the left scapula, can indicate pericardial effusion. Beck's triad (hypotension, jugular venous distension, distant heart sounds) and pulsus paradoxus are key findings in cardiac tamponade. Diagnostic tools include:

Imaging

• Chest X-ray: Can show the "water-bottle sign" in large effusions.
  

  Chest X-ray showing a massive pericardial effusion: Water bottle sign
• ECG: May show sinus tachycardia, low voltage QRS, and electrical alternans.
  

  EKG: sinus tachycardia with low QRS voltage and electrical alternans
• Echocardiogram (ultrasound): Confirms effusion, assesses size and hemodynamic impact.
  

  A large anechoic (black) pericardial effusion as seen on ultrasound. Closed arrow: the heart, open arrow: the effusion
• Cardiac CT and MRI: Useful for loculated effusions and assessing pericardial pathology.
  

  A CT scan showing a pericardial effusion

Pericardiocentesis

Fluid aspiration provides diagnostic analysis and symptomatic relief. Fluid analysis helps differentiate between transudative, exudative, and hemorrhagic effusions.

Treatment

Treatment depends on the underlying cause and severity. Asymptomatic small effusions may not require treatment. Viral infections usually resolve spontaneously. Severe cases causing cardiac tamponade necessitate immediate drainage via pericardiocentesis or surgical procedures like a pericardial window. Surgical drainage is often required for malignant or loculated effusions to prevent recurrence and manage chronic cases.

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Self-assessment MCQs (single best answer)

What is the normal amount of pericardial fluid in the pericardial cavity?

Which of the following is NOT a symptom of severe pericardial effusion leading to cardiac tamponade?

Which of the following is an inflammatory cause of pericardial effusion?

What term describes the dullness to percussion over the left scapula indicative of pericardial effusion?

Which imaging modality is most commonly used to confirm the presence of a pericardial effusion?

What is the characteristic ECG finding in cardiac tamponade due to pericardial effusion?

Which of the following conditions is a non-inflammatory cause of pericardial effusion?

What is the term for the clinical triad of hypotension, jugular venous distension, and distant heart sounds?

Which of the following symptoms is least likely to be directly caused by pericardial effusion?

What is the primary purpose of pericardiocentesis in the context of pericardial effusion?