C. No Y descent on JVP – Explanation

In cardiac tamponade there is characteristically no Y descent on the JVP. The other four features
are seen in both cardiac tamponade and constrictive pericarditis
Cardiac tamponade
Features

• dyspnoea
• raised JVP, with an absent Y descent – this is due to the limited right ventricular filling
• tachycardia

• hypotension
• muffled heart sounds
• pulsus paradoxus
• Kussmaul’s sign (much debate about this)
• ECG: electrical alternans
• The key differences between constrictive pericarditis and cardiac tamponade are summarised in the
  table below:

  	Cardiac tamponade	Constrictive pericarditis
  JVP	Absent Y descent	X + Y present
  Pulsus paradoxus	Present	Absent
  Kussmaul’s sign	Rare	Present
  Characteristic features		Pericardial calcification on CXR

  A commonly used mnemonic to remember the absent Y descent in cardiac tamponade is
  TAMponade = TAMpaX