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:
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
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
