Cardiac tamponade

Cardiac tamponade occurs when fluid accumulates in the pericardium and exerts a pressure that exceeds intracardiac pressures, leading to impaired cardiac output. 

Normally the pericardial space contains 15-50mls of fluid. If fluid accumulates slowly it can accommodate up to 2l without causing tamponade; however, if it accumulates rapidly 150-200mls can result in tamponade. 

Possible causes of tamponade are any cause of a pericardial effusion. 

The classic clinical triad is Becks (present in 10 to 40% of cases): 

• falling BP 
• rising JVP 
• muffled heart sounds

Other clinical signs and symptoms include:

• Shortness of breath 
• Chest pain 
• Palpitations
• Tachycardia
• Pulsus paradoxus = increased fall in BP during inspiration >10mmHg - present in 98%
• Raised JVP with decreased y descent 
• Kussmaul’s sign = rising JVP on inspiration (more common in constrictive pericarditis than tamponade) 
• Ewart’s sign = area of dullness and bronchial breathing below left scapular due to pericardial collection

Investigations 

• ECG 
• Low voltages complexes 
• Electrical alternans (present in 10 to 20%) 
• CXR
• 'flask-like’ cardiac shadow if slow accumulation\
• may be normal if rapid 
• Echo 
• RA+/-RV collapse during diastole 

Treatment: 

Pericardiocentesis or cardiothoracic surgery 

References:

Ariyarajah, V. and Spodick, D. Cardiac tamponade revisited: a postmortem look at a cautionary case. Tex Heart Inst J. 2007; 34(3): 347-351. 

Ball, J. and Morrison, W. Cardiac tamponade. Postgrad Med J. 1997; 73(857):141-145.

Bandinelli, G., Lagi, A. and Modesti, P. Pulsus paradoxus: an underused tool. Intern Emerg Med. 2007; 2(1): 33-35.
European Society of Cardiology. Guidelines on the Diagnosis and Mnaagement of Pericardial Diseases. Available at http://www.escardio.org/guidelines-surveys/esc-guidelines/Pages/pericardial-diseases.aspx  

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