Pericarditis: Aetiology and Anatomy

• Pericarditis involves inflammation of the pericardium, the fibrous sac surrounding the heart.

Prevalence & Impact

• Pericarditis is more common in men and young adults.
• It is the most common pericardial disease seen clinically.
• Pericarditis accounts for 0.1% of hospital admissions and 5% of emergency department chest pain cases.

Aetiology of Pericarditis

• Most cases are idiopathic.
• Potential causes include infections (viral, bacterial, fungal).
• It can develop 1-3 days post-myocardial infarction in transmural infarctions; this is due to the interaction of healing necrotic tissue interacting with the pericardium.
• Weeks to months post-infarction, Dressler’s syndrome (autoimmune response) can occur.
• Other causes include cancer, autoimmune disorders, drug-induced, and uraemia.

Anatomy of the Pericardium

• The pericardium has an outer fibrous and inner serous part.
• The fibrous pericardium is a connective tissue layer around the heart.
• The serous pericardium has parietal (outer) and visceral (inner) layers.
• The visceral layer forms the epicardium.
• The pericardial cavity between these layers contains fluid to reduce friction and allow heart movement.

Risk Factors

• Age (41-60 years for acute pericarditis, advanced age for bacterial pericarditis).
• Male sex.
• Spring and fall seasons (idiopathic pericarditis).
• Steroid treatment.
• Additional risk factors for bacterial pericarditis: diabetes, burns, systemic infections, immunosuppression, heart surgery, chest trauma, pre-existing pericardial effusion.

Clinical features: History

• Chest pain (>90%) is a typical symptom, retrosternal, may radiate, pleuritic, and worsens when lying down and improves when sitting or leaning forward.
• Dyspnoea.
• Systems review (infective symptoms, autoimmune disorders).
• Drug history (chemotherapy).
• Travel history (endemic infectious diseases).

Clinical features: Examination

• Pericardial rub (friction between layers, loudest at the left lower sternal border while leaning forward).
• Pericardial effusion (soft heart sounds, tubular breath sounds due to bronchial compression, obscured apex beat)
• Beck’s triad for cardiac tamponade: hypotension, muffled heart sounds, raised JVP.

Cardiac Tamponade

• Features signs of decreased cardiac output and shock.
• Look for hypotension, tachycardia, cool peripheries, diaphoresis, and cyanosis.
• Absent y descent of JVP and pulsus paradoxus (drop in systolic BP during inspiration).

Differential Diagnoses

• Acute coronary syndrome.
• Pneumonia with pleurisy.
• Pulmonary embolism.
• Gastro-oesophageal reflux disease.
• Costochondritis
• Less common: aortic dissection, intra-abdominal pathology, pneumothorax.
• Cardiac tamponade can mimic decompensated heart failure. conditions causing pulmonary hypertension, and right ventricular myocardial infarction.

Investigations: Bedside

• Check vital signs.
• ECG findings: widespread ST-elevation, PR depression, low voltage QRS complexes (effusion).

Investigations: Laboratory

• FBC: raised white blood cell count.
• Inflammatory markers: raised CRP/ESR.
• Troponin: may be elevated if co-existent myocarditis.
• Urea and electrolytes: check renal function.
• LFTs: check liver function.
• Additional tests based on suspected underlying cause.

Investigations: Imaging

• Chest X-ray: may show cardiothoracic ratio and globular heart (effusion).
• Transthoracic echocardiography: checks for effusion and haemodynamic compromise.
• Cardiac CT or MRI: used in atypical cases to look for pericardial thickening/inflammation or suspected myopericarditis.

Management

• Treatment aims to alleviate symptoms, as acute idiopathic pericarditis is often self-limiting (70-90%).
• Treat the underlying cause if identified.
• Restrict physical activity until symptoms resolve.
• Athletes: return to sports only after three months, with full resolution and normal investigations recommended.

Symptomatic Management

• NSAIDs (e.g., ibuprofen) are first-line, with gastroprotection.
• Colchicine is an adjunct for three months to improve therapy response and reduce recurrence by approximately 50%.
• Corticosteroids are second-line, used at low doses with colchicine.

Predictors of Poor Prognosis

• Fever >38oC.
• Subacute onset.
• Large pericardial effusion.
• Cardiac tamponade.
• Failure to respond to NSAIDs after a week.

Complications: Pericardial Effusion & Cardiac Tamponade

• Pericardial effusion is due to inflammation, infection, neoplasm, or reduced reabsorption from venous pressure.
• Cardiac tamponade occurs when effusion impairs heart filling and reduces cardiac output.
• Treatment involves pericardiocentesis (drainage of fluid).

Complications: Recurrent/Chronic Pericarditis

• Recurrence in 15-30% of patients; can be incessant (4-6 weeks) or chronic (>3 months).
• Recurrence is less likely with colchicine.
• Novel treatments for refractory cases: immunosuppressants, IVIG, IL-1 antagonists.
• Pericardiectomy is an alternative.

Complications: Constrictive Pericarditis

• It is the final stage of pericardial inflammation.
• Fibrosis and calcification of the pericardium lead to adhesions.
• Scarring hinders diastolic filling, resulting in constrictive pericarditis.
• Surgical pericardiectomy is definitive treatment.