Cardiac Tamponade

The heart is contained in a beautiful dual layered fibroserous elastic sac called the pericardium. The outer layer, the fibrous pericardium, is made of a tough connective tissue while the inner layer, the serous pericardium, is thin and consists of two parts, the parietal and visceral layers. The parietal layer lines the inner surface of the fibrous pericardium and the visceral layer adheres to the heart. The parietal and visceral layers are continuous at the roots of the great vessels creating a sealed sac, the pericardial cavity, which contains a very small amount of fluid allowing the heart to move with minimal friction.

Pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity.

The accumulating fluid can be transudative, exudative, hemorrhagic or metastatic in origin depending on the underlying cause. UptoDate.com provides a comprehensive list of causes of pericardial effusion, but states that the majority results from one of the following conditions:

      • Acute pericarditis (viral, bacterial, tuberculous, or idiopathic in origin)
      • Autoimmune disease
      • Postmyocardial infarction or cardiac surgery
      • Sharp or blunt chest trauma, including a cardiac diagnostic or interventional procedure
      • Malignancy, particularly metastatic spread of noncardiac primary tumors
      • Mediastinal radiation
      • Renal failure with uremia
      • Myxedema
      • Aortic dissection extending into the pericardium
      • Selected drugs

Since space is quite limited in the pericardium, accumulation of extra fluid can lead to an increase in intrapericardial pressure. Cardiac Tamponade is a clinical syndrome where the increase in intrapericardial pressure causes compression of the chambers of the heart resulting in reduced ventricular filling and ultimately decreased cardiac output. Clinical manifestations include cardiogenic shock and dyspnea which are represented by the lightning bolt and gasping puff of air in this Daily Doodle. Beck’s Triad is a classic collection of clinical signs of cardiac tamponade which includes distant heart sounds, increased JVP and hypotension. Other physical findings may include, reflex tachycardia, pulsus paradoxus, pericardial friction rub and tachypnea despite clear lungs.

Diagnostic studies, if available, should include ECG, chest x-ray and echocardiogram. ECG findings may include decreased voltage, electrical alternans and/or signs of pericarditis. On chest x-ray, cardiac silhouette may appear enlarged. Echocardiogram findings include a positive effusion +/- septal shift with inspiration and diastolic collapse of right atrium and/or right ventricle.

Treatment of pericardial effusions depends on the clinical presentation and hemodynamic stability of the patient. Cardiac Tamponade is a medical emergency and involves urgent drainage of the effusion. Volume resuscitation may be required for initially hypovolemic patients, however, caution must be taken because the tamponade may worsen with overfilling. Patients who are hemodynamically stable with no evidence of cardiac tamponade may not require immediate percutaneous or surgical drainage of the pericardial effusion. Instead, treatment is centered on the underlying condition with careful monitoring for progression of the effusion despite treatment and signs of cardiac tamponade.

 

Pop Quiz!

 

  1. What is the name of the beautiful dual layered fibroserous elastic sac that the heart is contained in?
  2. Define pericardial effusion.
  3. List five different causes of a pericardial effusion.
  4. Define cardiac tamponade.
  5. What is Beck’s Triad?
  6. What are some findings on ECG which may suggest cardiac tamponade?

 

 

References and Links

http://www.uptodate.com/contents/cardiac-tamponade

http://www.uptodate.com/contents/diagnosis-and-treatment-of-pericardial-effusion?detectedLanguage=en&source=search_result&search=pericardial+effusion&selectedTitle=1~150&provider=noProvider

R. Drake, W. Vogl, A. Mitchell. Gray’s Anatomy for Students. Canada: Elsevier. 2005. print

M. Sabatine. Pocket Medicine. Fourth Edition. Philadelphia: Lippincott. 2011. print

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