Cardiac tamponade is characterized by the accumulation of pericardial fluid under pressure.

Clinical features

Classical features - Beck's triad:
  • Hypotension
  • Raised JVP
  • Muffled heart sounds

Other features:
  • Dyspnoea
  • Tachycardia
  • An absent Y descent on the JVP - this is due to the limited right ventricular filling
  • Pulsus paradoxus - an abnormally large drop in BP during inspiration
  • Kussmaul's sign - much debate about this
  • ECG: electrical alternans

Differential diagnosis

The key differences between constrictive pericarditis and cardiac tamponade are summarised in the table below:

Cardiac tamponadeConstrictive pericarditis
JVPAbsent Y descentX + Y present
Pulsus paradoxusPresentAbsent
Kussmaul's signRarePresent
Characteristic featuresPericardial calcification on CXR