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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Tamponade = pericardial fluid accumulation compressing the heart → impaired diastolic filling → reduced cardiac output → obstructive shock
- Beck triad: hypotension, raised JVP, muffled heart sounds (classic but not always complete)
- Pulsus paradoxus: SBP drop >10 mmHg on inspiration (exaggerated normal response)
- Echo: pericardial effusion + RA/RV diastolic collapse + IVC plethora (no inspiratory collapse)
- Treatment: emergency pericardiocentesis (needle aspiration under echo guidance). IV fluids to maintain preload. Definitive surgery if recurrent
Overview
Cardiac tamponade occurs when fluid accumulates in the pericardial space faster than the pericardium can stretch, raising intrapericardial pressure to the point where it compresses the cardiac chambers and prevents adequate diastolic filling. The rate of accumulation is more important than the volume — rapid accumulation of even 200 mL (e.g. trauma, aortic dissection) can cause tamponade, whereas slow accumulation (e.g. malignancy) may allow 1–2 L before symptoms develop. Common causes include malignancy (most common cause of large effusions), uraemia, viral pericarditis, post-cardiac surgery, aortic dissection (Type A), trauma, and autoimmune conditions.
Epidemiology
The incidence of tamponade depends on the underlying cause. Malignancy (lung, breast, lymphoma, leukaemia) is the most common cause of large pericardial effusions causing tamponade. Post-cardiac surgery and catheter-related perforation are important iatrogenic causes. Tamponade complicates approximately 10–15% of Type A aortic dissections. Traumatic tamponade from penetrating chest injury is a surgical emergency. The mortality of untreated tamponade approaches 100%.
Clinical Features
Symptoms
Dyspnoea (the most common symptom)
Chest pain or tightness
Lightheadedness, presyncope, or syncope
Symptoms of underlying cause (fever, weight loss, recent surgery/trauma)
Signs
Beck triad: hypotension, raised JVP, muffled (quiet) heart sounds
Pulsus paradoxus (SBP drop >10 mmHg on inspiration) — measure with manual sphygmomanometer
Tachycardia (compensatory)
Kussmaul sign (paradoxical rise in JVP on inspiration) — more common in constrictive pericarditis but may be seen
Reduced cardiac output: cool peripheries, oliguria, altered consciousness
Ewart sign: dullness to percussion below left scapula (compressed left lung by large effusion)
Investigations
First-line
Echocardiography (bedside — emergency)Pericardial effusion (echofree space), RA diastolic collapse, RV diastolic collapse, IVC plethora (>2.1 cm, <50% inspiratory collapse), swinging heart. Confirms diagnosis and guides pericardiocentesis
ECGLow voltage QRS complexes, electrical alternans (alternating QRS amplitude — swinging heart), sinus tachycardia
Second-line
Chest X-rayGlobular (water-bottle) cardiac silhouette if large effusion. May be normal with acute small-volume tamponade
BloodsFBC, U&Es, coagulation, group and save, troponin, inflammatory markers
Specialist
Pericardial fluid analysisSend for: cytology (malignancy), culture and sensitivity (infection), TB (culture, PCR, ADA), protein/LDH (exudate vs transudate), glucose
CT chestDefine underlying cause — mediastinal mass, aortic dissection, loculated effusion
Management
ESC 2015 Pericardial diseases guidelines1
Emergency pericardiocentesis
- Echo-guided percutaneous needle aspiration — subxiphoid approach
- Even removing 50–100 mL can produce dramatic haemodynamic improvement
- Leave pigtail catheter for ongoing drainage if needed
- Send fluid for cytology, culture, biochemistry
2
Supportive measures
- IV fluid resuscitation to maintain preload (do NOT use diuretics — will worsen filling)
- Avoid positive pressure ventilation if possible (reduces venous return)
- Inotropes (dobutamine) may temporarily support cardiac output
3
Definitive management
- Treat underlying cause (chemotherapy for malignancy, dialysis for uraemia, antibiotics for infection)
- Surgical pericardial window for recurrent effusions (video-assisted thoracoscopic or open)
- Pericardiectomy for constrictive pericarditis or recurrent tamponade
- Type A aortic dissection with tamponade → emergency cardiac surgery (NOT pericardiocentesis alone — may worsen haemorrhage)
Complications
- Cardiogenic/obstructive shock: Untreated tamponade is rapidly fatal
- Cardiac arrest: PEA arrest from tamponade — potentially reversible (4Ts)
- Organ failure: From prolonged hypoperfusion
- Recurrence: Especially malignant effusions — may require pericardial window
UKMLA Exam Tips
- 1Beck triad: hypotension + raised JVP + muffled heart sounds = cardiac tamponade
- 2Electrical alternans on ECG is almost pathognomonic for large pericardial effusion with tamponade
- 3Pulsus paradoxus >10 mmHg — but also seen in severe asthma and tension pneumothorax
- 4Tamponade is one of the reversible 4Ts in cardiac arrest (PEA) — consider echo in PEA arrest
- 5Do NOT give diuretics in tamponade (reduces preload → worsens filling). Give IV fluids
- 6Type A dissection + tamponade → surgery, NOT pericardiocentesis (removing blood may precipitate full rupture)
practicetest your knowledge on cardiac tamponadeApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — cardiovascular and beyond.
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