Pericarditis

Acute pericarditis is a common inflammatory condition affecting the fibro-serous sac surrounding the heart. In developed countries, the majority of cases (80-90%) are idiopathic, likely following a viral infection (e.g., Coxsackie, Echo, or Adenovirus). Other causes include post-MI (early or late Dressler’s syndrome), uraemia, malignancy (lung/breast), and connective tissue diseases (SLE). The clinical hallmark is retrosternal chest pain that is pleuritic (worse on inspiration) and positional (worse lying flat, better leaning forward). A pericardial friction rub on auscultation is pathognomonic. The diagnosis is clinical, supported by ECG changes and potentially an elevated CRP. Pericarditis can lead to pericardial effusion and, in severe cases, cardiac tamponade. Management is usually medical with high-dose NSAIDs and colchicine to prevent recurrence. Complications like chronic constrictive pericarditis are rare but can lead to right heart failure.

The pericardium consists of an outer fibrous layer and an inner serous layer (parietal and visceral). The space between contains 15-50ml of serous fluid. Inflammation leads to the infiltration of the pericardium with polymorphonucleocytes and fibrin deposition ('bread and butter' pericarditis). This inflammation irritates the phrenic nerve (causing pain referred to the trapezius ridge) and the underlying epicardium. The involvement of the epicardium is what causes the characteristic ECG changes (ST elevation). If the inflammation causes significant exudation, a pericardial effusion develops. The speed of fluid accumulation determines whether cardiac tamponade occurs: a slowly accumulating large effusion can be tolerated, whereas a rapid 100ml effusion can cause collapse by restricting ventricular filling.

Presentation: Sudden onset sharp, central chest pain. It is differentiated from MI by its pleuritic nature and the fact that it improves when leaning forward. On examination, a pericardial friction rub may be heard (superficial, scratchy sound, usually best at the left sternal edge). If a large effusion develops, heart sounds may become muffled, and the friction rub may disappear. Watch for Cardiac Tamponade (Emergency): Beck's Triad—1. Hypotension, 2. Muffled heart sounds, 3. Raised JVP (distended neck veins). Another sign of tamponade is Pulsus Paradoxus (a fall in systolic BP >10mmHg during inspiration). Complications: Recurrence (up to 30%), Constrictive Pericarditis (leading to Kussmaul’s sign - JVP rising on inspiration).

1. Bedside: 12-lead ECG. Stage 1: Widespread (concave/saddle-shaped) ST elevation with PR segment depression (specific). Stage 2: Normalisation. Stage 3: T-wave inversion. Stage 4: Resolution.
2. Bloods: FBC, CRP/ESR (usually elevated), Troponin (may be raised if 'myopericarditis'), U&Es (uraemic cause?), Coagulation (pre-NSAID).
3. Imaging: Chest X-ray (usually normal; 'globular' heart if large effusion). Echocardiogram (Essential if effusion/tamponade suspected; shows fluid in pericardial sac).
4. Special: Viral serology is NOT routinely recommended unless specific suspicion.

1. Medical (First-line): High-dose NSAIDs (e.g., Ibuprofen 600mg TDS) or Aspirin (600-900mg TDS) for 1-2 weeks plus Colchicine (500mcg OD/BD) for 3 months. Colchicine significantly reduces the risk of recurrence.
2. Secondary: If post-MI, Aspirin is preferred over Ibuprofen (which may interfere with healing). PPI cover for gastric protection while on high-dose NSAIDs.
3. Steroids: Only if NSAIDs are contraindicated or for auto-immune causes (SLE).
4. Emergency: Pericardiocentesis (ultrasound-guided) if cardiac tamponade is present.
5. Follow-up: Advise avoidance of strenuous exercise until symptoms and CRP normalize.