Key Facts

Cardiac tamponade occurs when fluid accumulation in the pericardial space reaches a pressure that impairs cardiac filling, leading to haemodynamic compromise. It is a medical emergency requiring urgent drainage.

Epidemiology

• Incidence depends on underlying cause; occurs in ~2% of penetrating chest trauma
• Malignancy is the most common cause of large pericardial effusion/tamponade in developed countries
• Can occur with any cause of pericardial effusion

Aetiology

• Malignancy: lung, breast, lymphoma, melanoma (most common in chronic effusions)
• Pericarditis: viral, bacterial (purulent), tuberculous
• Uraemia: end-stage renal disease
• Post-MI: free wall rupture (acute), Dressler syndrome (subacute)
• Aortic dissection (type A): haemopericardium
• Post-cardiac surgery/intervention: post-CABG, post-PCI, post-pacemaker
• Trauma: penetrating or blunt chest injury
• Iatrogenic: central line insertion, cardiac catheterisation
• Connective tissue disease: SLE, RA
• Hypothyroidism: myxoedema pericarditis (usually slow, large effusion)

Pathophysiology

• Pericardial fluid accumulation increases intrapericardial pressure
• When intrapericardial pressure exceeds cardiac chamber filling pressures, diastolic filling is impaired
• Right-sided chambers (lower pressure) compress first → reduced RV filling → reduced LV preload → reduced cardiac output
• Rate of accumulation is critical: rapid (100-200 mL) causes tamponade; slow allows pericardial stretch (up to 1-2 L)
• Compensatory tachycardia and vasoconstriction maintain BP initially → then decompensation → PEA arrest

Beck Triad (Classic)

1. Hypotension (low cardiac output)
2. Raised JVP (impaired venous return)
3. Muffled/distant heart sounds (fluid around heart)

• Found in only ~30% of cases; more common in acute surgical tamponade

Other Clinical Features

• Pulsus paradoxus: >10 mmHg drop in SBP during inspiration (exaggeration of normal ~5 mmHg variation)
• Tachycardia (compensatory)
• Dyspnoea, tachypnoea
• Cool peripheries, oliguria
• Kussmaul sign: paradoxical rise in JVP during inspiration (impaired RA filling)
• Electrical alternans on ECG

Red Flags

• Haemodynamic collapse/PEA arrest
• Tamponade post-cardiac surgery (rapid re-accumulation)
• Suspected aortic dissection with tamponade
• Penetrating chest trauma with shock

Bedside

• ECG: sinus tachycardia, low-voltage QRS, electrical alternans (alternating QRS amplitude)
• Observations: tachycardia, hypotension, pulsus paradoxus measurement
• JVP: elevated, non-pulsatile

Bloods

• FBC, U&Es, coagulation: baseline
• Group and save/crossmatch: if surgical intervention planned
• Troponin: if MI/myocarditis suspected
• BNP: may be elevated

Imaging

• Echocardiography (URGENT): diagnostic gold standard
  • Pericardial effusion (circumferential in large effusions)
  • RA collapse in late diastole (earliest sign)
  • RV diastolic collapse (highly specific)
  • IVC plethora (>21 mm with <50% respiratory variation)
  • Respiratory variation in mitral/tricuspid inflow velocities
  • Swinging heart motion
• CXR: enlarged globular cardiac silhouette (flask-shaped) — insensitive for small effusions
• CT chest: characterise effusion, identify cause (malignancy, dissection)

Pericardial Fluid Analysis (post-drainage)

• Biochemistry: protein, LDH, glucose (exudate vs transudate)
• Cytology: malignant cells
• Microbiology: Gram stain, culture, TB PCR, adenosine deaminase
• BNP level in fluid: may differentiate aetiologies

Non-pharmacological

• Emergency pericardiocentesis: definitive treatment
  • Subxiphoid (subcostal) approach under echo guidance
  • Aspirate as little as 50-100 mL can produce dramatic haemodynamic improvement
  • Leave pericardial drain in situ if ongoing accumulation
• IV fluid resuscitation: maintain preload — 500-1000 mL normal saline bolus
• Avoid diuretics, nitrates, and other vasodilators (reduce preload further)
• Position: sit patient upright (effusion pools inferiorly, away from apex)

Pharmacological

• IV fluids: normal saline to maintain preload
• Inotropes (dobutamine, noradrenaline): if persistent hypotension post-drainage
• Treat underlying cause: antibiotics for purulent, anti-TB therapy, chemotherapy for malignant
• Avoid: diuretics, ACEi, GTN, beta-blockers — all reduce preload/cardiac output

Surgical/Interventional

• Echo-guided pericardiocentesis: standard approach; Seldinger technique
• Surgical pericardial window: for recurrent effusions (creates communication with pleural space)
• Pericardiectomy: for recurrent tamponade or constrictive pericarditis
• Emergency thoracotomy: for traumatic tamponade or post-surgical tamponade

Referral Criteria

• All cardiac tamponade: emergency admission and immediate pericardiocentesis
• Recurrent effusions: cardiothoracic surgical assessment for pericardial window
• Malignant effusions: oncology input for systemic and local (intrapericardial) therapy

• Untreated tamponade: rapidly fatal (PEA arrest)
• With prompt pericardiocentesis: immediate haemodynamic improvement in >90%
• Prognosis depends on underlying cause:
  • Viral pericarditis with tamponade: excellent after drainage
  • Malignant: median survival ~3-6 months (depends on cancer type)
  • Post-MI free wall rupture: high mortality even with surgery
  • Aortic dissection with tamponade: emergency surgery required; high mortality
• Recurrence: ~15-30% for malignant effusions; pericardial window reduces recurrence

Beck Triad vs Kussmaul Sign

Echo Features of Tamponade