Acute Pericardial Effusion

Accumulation of fluid in the pericardial sac over hours to days (normal volume 15 to 50 mL). The pericardium is stiff, so as little as 100 to 200 mL appearing rapidly can cause tamponade, whereas a slow accumulation can hold 1 to 2 L without haemodynamic effect.

• Size on echocardiography (echo free space in diastole): small less than 10 mm, moderate 10 to 20 mm, large greater than 20 mm.
• Causes: viral and idiopathic pericarditis (commonest in high income settings), tuberculosis (commonest cause of large effusion in endemic areas and in HIV), bacterial infection, malignancy (lung, breast, lymphoma), uraemia, post-myocardial infarction, post-cardiac surgery, aortic dissection, chest trauma, iatrogenic perforation (catheter, pacemaker lead, ablation), autoimmune disease (lupus, rheumatoid arthritis), hypothyroidism, and drugs (hydralazine, procainamide, isoniazid, minoxidil, doxorubicin).
• About 60% of patients with acute pericarditis have a small effusion. Large effusions are more often non-viral, and about one third of large idiopathic effusions progress to tamponade over years.
• Haemopericardium (blood in the sac) follows dissection, rupture, trauma, anticoagulation or malignancy and progresses faster.

• Pleuritic or positional chest pain relieved by sitting forward, dyspnoea, cough, hiccups, dysphagia, hoarseness, nausea, fever, malaise. Small effusions are often asymptomatic.
• Signs: tachycardia, muffled heart sounds, pericardial friction rub, Ewart sign (dullness and bronchial breathing at the left lung base from compression), raised jugular venous pressure and pulsus paradoxus (inspiratory fall in systolic pressure greater than 10 mmHg) when tamponade is developing.
• Differential diagnosis: pleural effusion, dilated cardiomyopathy with cardiomegaly, epicardial fat, acute coronary syndrome, pulmonary embolism, pneumonia, heart failure, constrictive pericarditis.
• Complications: cardiac tamponade, recurrence, constrictive pericarditis, effusive constrictive disease, purulent pericarditis, and arrhythmia (atrial fibrillation).

• Echocardiography (first test): size and distribution, loculation, fibrin strands, right atrial collapse lasting more than one third of the cardiac cycle, right ventricular diastolic collapse, plethoric inferior vena cava, respiratory variation of mitral inflow greater than 25% and tricuspid inflow greater than 40%.
• ECG: low voltage, electrical alternans (specific for large effusion), diffuse concave ST elevation with PR depression in pericarditis. Chest X-ray: "water bottle" cardiac silhouette when more than 250 mL; look for pulmonary tuberculosis, mass or pleural effusion.
• CT or cardiac MRI for loculated fluid, haemopericardium, pericardial thickening or mass, or suspected malignancy.
• Blood tests: full blood count, CRP, ESR, troponin, urea, creatinine, thyroid stimulating hormone, HIV test, antinuclear antibody, blood cultures if febrile, sputum or other samples for tuberculosis (Xpert MTB/RIF).
• Pericardial fluid (when drained): cell count, protein (exudate if protein greater than 30 g/L or fluid to serum ratio greater than 0.5, or fluid to serum LDH ratio greater than 0.6), glucose, Gram stain and culture, acid fast smear, Xpert MTB/RIF and mycobacterial culture, adenosine deaminase (greater than 40 U/L suggests tuberculosis), cytology (positive in about 60 to 90% of malignant effusions), and haematocrit if bloody.

• Treat the cause. Small asymptomatic effusions need observation and repeat echocardiography at 1 to 4 weeks. Avoid anticoagulants unless needed (haemopericardium risk).
• Inflammatory pericarditis with effusion (after excluding tuberculosis, bacterial infection and malignancy):
  • Ibuprofen 600 mg orally 8-hourly (maximum 2400 mg/day) or aspirin 750 to 1000 mg 8-hourly for 1 to 2 weeks, then taper by 200 mg (ibuprofen) or 250 to 500 mg (aspirin) every 1 to 2 weeks once symptoms and CRP settle. Give omeprazole 20 mg daily for gastric protection.
  • Colchicine 0.5 mg twice daily (0.5 mg once daily if weight less than 70 kg or intolerant of diarrhoea) for 3 months. Reduce the dose in renal impairment and avoid with strong CYP3A4 or P-glycoprotein inhibitors.
  • Prednisolone 0.25 to 0.5 mg/kg/day only when NSAIDs and colchicine are contraindicated or have failed, tapered slowly over weeks, because steroids increase recurrence.
• Indications for pericardiocentesis: tamponade, suspected purulent or tuberculous effusion, suspected malignancy needing diagnosis, or a large effusion (greater than 20 mm) persisting more than 3 weeks.
• Technique: echo guided subxiphoid or apical approach with a 16 to 18 gauge needle, then a 6 to 8 French pigtail catheter left in place. Correct coagulopathy where time allows. Remove the catheter when drainage is less than 25 mL in 24 hours (usually 2 to 5 days).
• Cause specific therapy:
  • Purulent: urgent drainage with a large bore catheter or surgical window, irrigation, and IV vancomycin 15 to 20 mg/kg 8 to 12-hourly plus ceftriaxone 2 g IV daily, adjusted to culture, for 4 to 6 weeks.
  • Tuberculous: rifampicin 10 mg/kg (maximum 600 mg), isoniazid 5 mg/kg (maximum 300 mg), pyrazinamide 25 mg/kg (maximum 2 g) and ethambutol 15 mg/kg (maximum 1.2 g) daily for 2 months, then rifampicin and isoniazid for 4 months, with pyridoxine 25 to 50 mg daily. Prednisolone may lower the risk of constriction, but in HIV it has been linked to excess HIV-related cancers, so avoid it unless the patient is on antiretroviral therapy; evidence is limited.
  • Uraemic: intensify dialysis (5 to 7 sessions weekly with minimal or no heparin); drain only for tamponade or failure to resolve.
  • Malignant: drainage with extended catheter placement, systemic cancer therapy, and pericardial window if recurrent. Intrapericardial cisplatin or bleomycin has limited evidence.
  • Haemopericardium after dissection or rupture: urgent surgery; limit drainage to what restores pressure.
  • Hypothyroidism: levothyroxine, starting at 25 to 50 micrograms daily in older patients and those with heart disease.
  • Autoimmune: prednisolone 0.5 to 1 mg/kg/day with specialist input.
• Special groups:
  • Pregnancy: aspirin or ibuprofen up to 20 weeks, then avoid NSAIDs; low dose prednisolone if needed; colchicine data are limited.
  • Children: ibuprofen 30 to 40 mg/kg/day in 3 divided doses.
  • Renal impairment: avoid NSAIDs when eGFR is less than 30.
  • Immunosuppressed: lower threshold for pericardiocentesis and fluid culture.
• Red flags: hypotension, rising jugular venous pressure, pulsus paradoxus, fever, rapid enlargement on echo, haemopericardium.
• Follow up: echocardiography at 1 week for large effusions, then at 1 and 3 months; CRP monitoring to guide tapering; specialist referral for recurrence or failure to resolve.