Cardiac tamponade

Overview

•Beck's triad - hypotension + raised JVP + muffled heart sounds (all three present in <40% of cases)

•Tachycardia - compensatory as stroke volume falls

•Pulsus paradoxus - exaggerated fall in systolic BP (>10 mmHg) on inspiration

•Dyspnoea, tachypnoea, anxiety - low cardiac output and cerebral hypoperfusion

•Kussmaul's sign typically absent - JVP does not rise further on inspiration (distinguishes tamponade from constrictive pericarditis where it does rise)

🎯

Maintain high suspicion in the right context (malignancy, trauma, recent cardiac procedure) even if Beck's triad is incomplete. Kussmaul's sign negative = tamponade; Kussmaul's sign positive = constrictive pericarditis.

Investigations

🏆 Gold standard

•echocardiogram (transthoracic) - demonstrates pericardial effusion, right atrial and right ventricular diastolic collapse; bedside, immediate

•ECG - sinus tachycardia, low-voltage QRS, electrical alternans (alternating QRS height = heart swinging in effusion), PR depression

•Chest X-ray - enlarged 'water bottle' cardiac silhouette; may be normal with rapid accumulation

•Bloods - FBC, CRP, U&Es (uraemia), coagulation screen before pericardiocentesis, troponin, group and save

💡

Electrical alternans is highly specific for cardiac tamponade when present - caused by the heart physically swinging in the effusion, changing its electrical axis beat-to-beat. Absence does not exclude tamponade.

Differential diagnosis

Tamponade vs constrictive pericarditis

Feature	Cardiac tamponade	Constrictive pericarditis
Kussmaul's sign	Absent (JVP unchanged with inspiration)	Present (JVP rises on inspiration)
Pulsus paradoxus	Present (>10 mmHg drop)	Usually absent
Heart sounds	Muffled	Pericardial knock
Echo	Pericardial effusion, RV diastolic collapse	No effusion, pericardial thickening
Causes	Malignancy, trauma, post-procedure	Post-cardiac surgery/catheterisation, TB

•Tension pneumothorax - also obstructive shock + raised JVP; distinguished by tracheal deviation, hyperresonance, absent unilateral breath sounds

•Pulmonary embolism - dyspnoea + hypotension; distinguished by CTPA and echo (no pericardial fluid)

Management

•Immediate: call for help - alert cardiology and critical care simultaneously; prepare for pericardiocentesis while supporting haemodynamics

•Definitive - pericardiocentesis - needle aspiration of pericardial fluid; echo-guided reduces risk of cardiac perforation

•Neoplastic tamponade - percutaneous balloon pericardiotomy preferred when caused by malignancy

•Pericardial fluid analysis - send for cytology (malignant), culture (infective), biochemistry

⚠️

Avoid positive-pressure ventilation where possible - positive intrathoracic pressure reduces venous return, removing the last compensatory mechanism for right heart filling. If intubation is unavoidable, perform pericardiocentesis immediately post-induction.

Key causes

Common causes of cardiac tamponade

Malignancy - lung, breast, haematological (pericardial metastases)

Penetrating chest trauma - haemopericardium

Viral/bacterial/tuberculous pericarditis

Uraemic pericarditis

Aortic dissection extending into pericardium

Iatrogenic - post-cardiac catheterisation, post-cardiac surgery

Post-MI / Dressler's syndrome