Pericardial Effusion and Cardiac Tamponade

Pericardial effusion is the accumulation of excess fluid in the pericardial space around the heart. The pericardium does not easily expand; thus, rapid fluid accumulation leads to increased pressure around the heart. The increase in pressure restricts cardiac filling, resulting in decreased cardiac output and cardiac tamponade. Signs and symptoms usually occur in the setting of cardiac tamponade and include dyspnea, hypotension, muffled heart sounds, jugular venous distension, and pulsus paradoxus. The diagnosis of pericardial effusion is confirmed with echocardiography. Small effusions in stable patients are treated medically. Larger effusions and cardiac tamponade may require pericardiocentesis or pericardiotomy.

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Epidemiology and Etiology


Pericardial effusion is the accumulation of fluid in the pericardial space.

Cardiac tamponade is the accumulation of pericardial fluid sufficient to impair cardiac filling and cause hemodynamic compromise. The rate of fluid accumulation, and not necessarily the amount, is most important.


Pericardial effusion:

  • The incidence is unknown.
  • Has been observed in approximately 3% of autopsy subjects in studies
  • Age:
    • Can occur in all age groups
    • Mean: 50–60 years

Cardiac tamponade: 

  • Incidence: 2 cases per 10,000 people in the United States
  • Occurs in approximately 2% of penetrating injuries
  • More common in boys and men


Many conditions are associated with pericardial effusion, including:

  • Infection:
    • Viral (most common):
      • Coxsackievirus group B
      • Influenza
      • Echovirus
      • HIV
      • EBV
      • CMV
      • Parvovirus B19
      • Varicella
    • Bacterial:
      • Staphylococcus aureus
      • Streptococcus
      • Neisseria
      • Legionella
      • Treponema pallidum
      • Mycobacterium tuberculosis
    • Fungal:
      • Candida
      • Histoplasmosis
      • Coccidioidomycosis
  • Malignancy:
    • Primary cardiac tumors
    • Metastatic disease
  • Trauma
  • Post-procedural occurrence:
    • Cardiac surgery (postpericardiotomy syndrome)
    • Radiation
  • Autoimmune and connective tissue disease:
    • Systemic lupus erythematosus
    • Rheumatoid arthritis
    • Ankylosing spondylitis
    • Scleroderma
    • Sarcoidosis
    • Sjögren syndrome
    • Vasculitis
  • Other medical conditions:
    • Post-myocardial infarction (Dressler syndrome)
    • Heart failure
    • Aortic dissection (type A)
    • Uremia (chronic renal failure)
    • Myxedema
    • Amyloidosis
  • Can be induced by drugs:
    • Procainamide
    • Hydralazine
    • Isoniazid
    • Minoxidil
    • Phenytoin
    • Anticoagulants
  • Idiopathic


Normal physiology

  • The pericardial space normally contains a small volume of serous fluid. 
  • Under normal circumstances, the pericardial fluid cushions the heart, provides a low-friction environment, and allows the heart to move easily.

Pericardial effusion and cardiac tamponade

  • The pericardium has limited elasticity.
  • Accumulation of pericardial fluid → ↑ pressure in the pericardial sac
  • As pericardial effusion continues to increase → ↑ compression of the heart:
    • ↓ Diastolic filling → venous congestion
    • ↓ Stroke volume
    • ↓ Cardiac output → hypotension and obstructive (cardiogenic) shock
    • ↑ HR to maintain cardiac output as a compensatory mechanism
  • The rate of fluid accumulation is important:
    • If fluid were to fill the pericardial space rapidly (e.g., chest trauma), as little as 150 mL could lead to tamponade. 
    • If fluid accumulates slowly, the pericardial sac can stretch to accommodate approximately 2 L of fluid.

Clinical Presentation


Without cardiac tamponade:

  • Usually no symptoms specific to effusion
  • Symptoms may be related to the underlying condition (e.g., infection, uremia, autoimmune disease).

Cardiac tamponade:

  • Dyspnea
  • Chest pain (pericarditis):
    • Worse when lying flat
    • Improves when sitting up
  • Lightheadedness
  • Syncope
  • Palpitations
  • Hoarseness
  • Anxiety or confusion
  • Fatigue
  • Hiccups

Physical exam

The following may be seen with large pericardial effusions and cardiac tamponade:

Vital signs:

  • Hypotension
  • Tachycardia


  • Pericardial friction rub (pericarditis)
  • Muffled heart sounds
  • Jugular venous distension
  • Hepatojugular reflux
  • Weakened peripheral pulses
  • Pulsus paradoxus: a drop in systolic blood pressure of > 10 mm Hg during inspiration


  • Ewart’s sign: 
    • Dullness to percussion beneath the angle of the left scapula
    • Tubular breath sounds
    • Egophony
  • Diminished breath sounds (if pleural effusion is present)


  • Edema
  • Cyanosis

Beck’s triad

The triad describes the classic findings in cardiac tamponade:

  • Hypotension
  • Jugular venous distension
  • Muffled heart sounds on auscultation 




  • Sinus tachycardia
  • Low voltage of QRS complexes
  • Diffuse ST elevation with PR depression (pericarditis)
  • Electrical alternans: 
    • Consecutive QRS complexes that alternate in height
    • A motion artifact due to the pendular swinging of the heart within the pericardial space
    • Seen in large pericardial effusion or cardiac tamponade
Electrical alternans pericardial effusion

Electrical alternans on an ECG in a patient with a large pericardial effusion:
The arrows point to the alternating amplitude of the QRS complex.

Image: “Electrical alternans” by Eric Williams Medical Sciences Complex, The University of the West Indies, Champs Fleurs, Trinidad and Tobago. License: CC BY 4.0

Chest X-ray: 

  • Might appear normal in conditions with low fluid accumulation
  • Enlargement of the cardiac silhouette:
    • Occurs when > 250 mL of fluid has accumulated
    • Takes on a “water bottle” shape
  • Lung fields are typically clear.
Cardiomegaly due to pericardial effusion before and after drainage

Cardiomegaly due to pericardial effusion before and after drainage:
(a) Chest X-ray demonstrating cardiomegaly due to the accumulation of pericardial effusion
(b) There is resolution of this cardiomegaly after drainage of the fluid.

Image: “CXR” by Division of Cardiology, Saint Luke’s University Health Network, Bethlehem, PA 18015, USA. License: CC BY 3.0


  • Diagnostic test of choice 
  • High sensitivity and specificity
  • Provides hemodynamic information
  • Pericardial effusion appears as an echolucent space in the pericardial sac.
  • Cardiac tamponade findings:
    • Right atrial free-wall collapse during systole
    • Right ventricle collapse during diastole
    • Septal bowing
    • Inferior vena cava dilation without respiratory variation
Echocardiogram showing pericardial effusion

Transthoracic echocardiography showing pericardial effusion (echolucent region around the heart)

Image: “Transthoracic echocardiography” by Department of Internal Medicine, The University of New Mexico, Albuquerque, NM 87106, USA. License: CC BY 4.0

CT and MRI:

  • Not the diagnostic modalities of choice
  • May be used if echo imaging is not diagnostic
  • Can evaluate for pericardial pathology
  • May be more sensitive for identifying loculated effusions
CT pulmonary embolus showing pericardial effusion

A CT scan demonstrating pericardial effusion, measuring 19.27 mm

Image: “CT pulmonary embolus” by Stanford Hospital and Clinics, Stanford, California. License: CC BY 2.0

Pericardial fluid analysis and pericardial biopsy

Pericardial fluid analysis and pericardial biopsy may be performed to determine the cause of the pericardial effusion. The following tests may be conducted on the pericardial fluid:

  • Gram stain and cultures (including fungal)
  • Cell count with differential
  • Cytology
  • Acid-fast bacillus stain and culture
  • Viral PCR panel

Laboratory evaluation

The following tests may be performed to ascertain the etiology of a pericardial effusion:

  • CBC with differential
  • BUN and creatinine
  • Erythrocyte sedimentation rate and CRP
  • Troponin
  • Thyroid-stimulating hormone (TSH)
  • Rheumatoid factor levels
  • ANA
  • Complement levels
  • Quantiferon-TB assay
  • HIV serology


Management of pericardial effusion

  • Depends on the patient’s stability and the underlying cause of effusion
  • Identify and treat the underlying conditions.
  • Medical therapy for inflammatory effusions or associated pericarditis:
    • NSAIDs
    • Colchicine
  • Small effusions in a stable patient are usually self resolving → no need for any intervention
  • Pericardial drainage can be considered in:
    • Large symptomatic effusions
    • Uncertain etiology

Management of cardiac tamponade

General considerations:

  • Administer oxygen.
  • Measures to ↑ cardiac output:
    • IV fluid resuscitation 
    • Inotropic support (e.g., dobutamine)


  • A needle is inserted into the pericardial space.
  • Fluid is removed to relieve pressure on the heart.
  • A catheter can be placed for periodic drainage.
Subxiphoid approach for pericardiocentesis

Subxiphoid approach for pericardiocentesis:
This approach allows the drainage of pericardial fluid.

Image by Lecturio.

Surgical management:

  • Allows for pericardial biopsy
  • Preferred in traumatic pericardial effusions
  • Options:
    • Pericardiotomy
    • Pericardial window

Differential Diagnosis

  • Pericarditis: an inflammation of the pericardium resulting from infection, autoimmune disease, radiation, surgery, myocardial infarction, or cardiac surgery. Patients may have fever, pleuritic chest pain, and a pericardial rub on cardiac auscultation. The diagnosis is confirmed based on diffuse ST elevation on ECG, and findings of pericardial thickening and effusion on echocardiography. Management may include NSAIDs, colchicine, and steroids.
  • Myocarditis: an inflammatory disease of the myocardium. Myocarditis most often leads to signs and symptoms of heart failure. The course of myocarditis may vary based on the etiology and the timeline of symptom progression. The diagnosis is supported by clinical findings, laboratory evaluation, and cardiac imaging. A definitive diagnosis using endomyocardial biopsy is rarely required. Management is supportive and aimed at addressing complications.
  • Pulmonary embolism: an obstruction of the pulmonary arteries, most often due to thrombus migration from the deep venous system. Signs and symptoms include pleuritic chest pain, dyspnea, tachypnea, and tachycardia. Severe cases can result in hemodynamic instability or cardiopulmonary arrest. A chest CT with angiography is the primary method of diagnosis. Management includes oxygenation, anticoagulation, and thrombolytic therapy for unstable patients.
  • Pneumothorax: a life-threatening condition in which air collects in the pleural space, causing a partial or complete collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. A large or tension pneumothorax can result in cardiopulmonary collapse. The diagnosis is made based on imaging findings. Management includes needle decompression and placement of a chest tube (thoracostomy).


  1. Hoit, B.D. (2020). Etiology of pericardial disease. In Yeon, S.B. (Ed.), UpToDate. Retrieved April 8, 2021, from
  2. Hoit, B.D. (2020). Diagnosis and treatment of pericardial effusion. In Yeon, S.B. (Ed.), UpToDate. Retrieved April 8, 2021, from
  3. Hoit, B.D. (2019). Cardiac tamponade. In Yeon, S.B. (Ed.), UpToDate. Retrieved April 8, 2021, from
  4. Spodick, D.H. (2003). Acute cardiac tamponade. N Engl J Med. 349(7):684–690.
  5. Sagristà-Sauleda, J., Angel, J., Sambola, A., Permanyer-Miralda, G. (2008). Hemodynamic effects of volume expansion in patients with cardiac tamponade. Circulation. 117:1545–1549.
  6. Strimel, W.J., Ayub, B., Contractor, T. (2018). Pericardial effusion. In O’Brien, T.X. (Ed.), Medscape. Retrieved April 8, 2021, from
  7. Yarlagadda, C. (2018). Cardiac tamponade. In O’Brien, T.X. (Ed.), Medscape. Retrieved April 8, 2021, from
  8. Weiser, T.G. (2020). Cardiac tamponade. [Online] MSD Manual Professional Version. Retrieved April 8, 2021, from
  9. Willner, D.A., Goyal, A., Grigorova, Y., Kiel, J. (2020). Pericardial effusion. [Online] StatPearls. Retrieved April 8, 2021, from
  10. Stashko, E., Meer, J.M. (2020). Cardiac tamponade. [Online] StatPearls. Retrieved April 8, 2021, from

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