Pericardial effusion and cardiac tamponade

Pericardial effusion is the acute or chronic accumulation of fluid in the pericardial space (between the parietal and the visceral pericardium) and is often associated with a variety of underlying disorders. The fluid can be either bloody (e.g., following aortic dissection) or serous (usually idiopathic). As the pericardium is rather stiff, the capacity of the pericardial space is limited. In chronic effusion, the pericardium can stretch to a certain degree, accommodating slightly more fluid. In the acute setting, however, the added volume quickly exceeds the maximum capacity of the pericardial space. In both cases, the end result is often cardiac tamponade: compression of the heart that can lead to a life-threatening reduction in cardiac output. Pericardial effusion is initially asymptomatic, but cardiac tamponade has a distinct clinical presentation, including hypotension, tachycardia, jugular venous congestion, and pulsus paradoxus. Echocardiography is the most important diagnostic procedure and usually reveals an anechoic pericardial space. Treatment depends on hemodynamic stability: unstable patients require quick pericardial fluid drainage, through either pericardiocentesis or surgery, whereas in stable patients, treatment focuses on the underlying disease.

• Hemopericardium
  • Cardiac wall rupture (e.g., complication of myocardial infarction)
  • Chest trauma
  • Aortic dissection
  • Cardiac surgery (e.g., heart valve surgery, coronary bypass surgery)
• Serous or serosanguinous pericardial effusion ^[2]
  • Idiopathic
  • Acute pericarditis (especially viral, but also fungal, tuberculous or bacterial)
  • Malignancy
  • Postpericardiotomy syndrome
  • Uremia
  • Autoimmune disorders
  • Hypothyroidism

Cardiac tamponade: pericardial fluid collection (e.g., bloody or serous) → ↑ pressure in the pericardial space → compression of the heart (especially of the right ventricle due to its thinner wall) → interventricular septum shift toward the left ventricle chamber → ↓ ventricular diastolic filling → ↓ stroke volume (and venous congestion) → ↓ cardiac output and equal end-diastolic pressures in all 4 chambers ^[3]

Pericardial effusion ^[4]

• Initially asymptomatic in most cases
• Shortness of breath, especially when lying down (orthopnea)
• Retrosternal chest pain
• Can cause compressive symptoms
  • Hoarseness
  • Nausea
  • Dysphagia
  • Hiccups
• Apical impulse is difficult to locate or nonpalpable.
• Ewart sign: percutory dullness at the base of the left lung with increased vocal fremitus and bronchial breathing due the compression of lung parenchyma by the pericardial effusion ^[5]

Tamponade ^[4]

• Beck triad
  • Hypotension
  • Muffled heart sounds
  • Distended neck veins
• Tachycardia, pulsus paradoxus
• Pallor, cold sweats
• Left ventricular failure
• Symptoms of right heart failure
• Obstructive shock, cardiac arrest (presenting as pulseless electrical activity) ^[1]

Approach

• Critically unstable patients and patients in cardiac arrest with suspected cardiac tamponade: start immediate treatment (i.e., pericardiocentesis).
• In all other patients, confirm the diagnosis with echocardiography. (either TTE or focus-assessed transthoracic echocardiography [FATE]).
• Laboratory studies and analysis of the pericardial fluid can be used in the investigation of the underlying etiology.

In unstable patients and those in cardiac arrest with suspected tamponade, pericardiocentesis should not be delayed for diagnostic confirmation.

Echocardiography

• Indication: all patients with suspected pericardial effusion
• Procedure: TTE (gold standard) or focused-assessed transthoracic echocardiography
• Allows for the detection of: ^[6]
  • Small effusions of 25–50 mL during ventricular systole
  • Effusions of > 50 mL throughout the cardiac cycle
  • Cardiac tamponade
• Findings supportive of pericardial effusion
  • Anechoic space between the pericardium and epicardium ^[7]
    • < 10 mm: small effusion ∼ 300 mL
    • 10–20 mm: moderate effusion ∼ 500 mL
    • > 20 mm: large effusion > 700 mL
  • Hemorrhagic or purulent effusions may be echogenic.
• Findings supportive of cardiac tamponade ^[7]
  • Chamber collapse
    • Early signs: collapse of the right atrium during systole, collapse of the right ventricle during early diastole
    • Later: collapse of the left atrium ^[7]
    • Rare: collapse of the left ventricle
  • Swinging motion of the heart
    • Inspiration: decrease in LV filling
    • Exhalation: increase in LV filling and decrease in RV filling
  • Blood flow changes during inspiration
    • Aortic valve and mitral valve: decrease
    • Pulmonary valve and tricuspid valve: increase
  • Hepatic vein and inferior vena cava plethora

Echocardiography is a quick and safe diagnostic tool for detecting pericardial effusions and pericardial tamponade.

ECG

• Indication
  • All patients with suspected pericardial effusion
  • Used to rule out an ischemic cause
• Findings in pericardial effusion
  • Normal in smaller effusions
  • Low voltage; complexes and electrical alternans in larger effusions
• Findings in cardiac tamponade ^[5]
  • Sinus tachycardia
  • Low voltage QRS complexes
  • Electrical alternans: consecutive QRS complexes that alternate in height due to the swinging motion of the heart when surrounded by large amounts of pericardial fluid
  • Pulseless electrical activity (PEA) in cardiac arrest ^[8]

Imaging

• Chest x-ray: not required to diagnose pericardial effusion but often performed to exclude other causes of dyspnea ^[9][10]
  • PA view findings
    • Normal in small effusions ^[9][10]
    • Enlarged cardiac silhouette and clear lungs may be seen in moderate effusions.
    • Water bottle sign: the radiographic sign of a large pericardial effusion in which the cardiac silhouette resembles a bottle
  • Lateral view findings
    • Posterior inferior bulge sign: a change in the silhouette of the heart due to a pericardial effusion that collects in the posterior-inferior pericardiac recess and expands the pericardium ^[11]
    • Pericardiac fat pad sign: a > 2 mm soft-tissue stripe between the epicardiac fat and the anterior mediastinal fat that may be visible anterior to the heart ^[9]
• Further imaging ^[7]
  • Indications: consider if small or loculated effusions are suspected or visualization via TTE is difficult
  • Modalities include: TEE, CMR, CT

Investigation of the underlying etiology

Pericardiocentesis with pericardial fluid analysis ^[12][13]

• Indication: etiology of the effusion is unclear ^[13]
• Analysis ^[13]
  • Cell count
    • ↑ WBC in infection
    • ↑ RBC in hemorrhagic effusions
  • Gram stain and culture
  • Cytology
  • Acid-fast bacilli
  • Glucose level: < 60–80 mg/dL suggestive of malignant, parapneumonic, or tuberculous effusions, or connective tissue disease.
  • Protein level: > 6.0 g/dL is associated with purulent, parapneumonic, and tuberculous effusions.
  • LDH: Isolated pericardial fluid LDH elevation of > 300 units/dL suggests malignant effusion.
• Interpretation ^[12]
  • There are no established biochemical thresholds for the classification of pericardial effusions.
  • Light criteria can be used for interpretation.

Interpretation of pericardial fluid samples
Fluid type	Appearance	Etiology [12]
Transudate	Clear	Heart failure Renal failure Hypoalbuminemia Postradiotherapy
Exudate	Cloudy, chylous	Viral infection Inflammation Malignancy Autoimmune disease Chylopericardium
Blood	Hemorrhagic	Postcardiac surgery Cardiac rupture Aortic dissection Tuberculosis [14] Malignancy [15][14]
Purulent [16]	Thick, yellowish-white, cloudy	Tuberculosis Bacterial infection

Laboratory studies and specific investigations ^[10]

• CBC: leukocytosis if infection or inflammation
• CRP, ESR: elevated in infection or inflammation
• Troponin
  • Can be slightly elevated in pericarditis
  • Significantly elevated if there is associated myocarditis
• Creatinine kinase: elevated in myocarditis, rhabdomyolysis
• BMP: elevated BUN in uremic pericarditis

Investigation of underlying etiology in pericardial effusion
Suspected etiology	Additional investigations to consider
Acute pericarditis	Blood cultures If tuberculosis is suspected: Quanti-FERON TB assay HIV test Chest x-ray
Uremic pericardial effusion	Renal ultrasound
Autoimmune disease	ANA Rheumatoid factor ACPA ANCA Ferritin Imaging of other affected systems guided by reported symptoms
Malignancy	Serum calcium CT PET scan
Hypothyroidism	Thyroid function tests Thyroid ultrasound
Aortic dissection	D-dimer CT angiography
Postpericardiotomy syndrome	Blood cultures Chest x-ray
Trauma	FAST scan Trauma CT Additional x-rays as required

In cardiac tamponade, the mainstay of treatment is urgent decompression of the heart. In pericardial effusion, treatment is focused on management of the underlying cause with a more limited role for pericardial fluid drainage.

Cardiac tamponade

• Urgent pericardiocentesis
  • Hemodynamically unstable: without imaging guidance ^[17][18][19]
  • Hemodynamically stable: ultrasound, CT, or fluoroscopy guidance ^[10]
• Hemodynamic support
  • Cautious fluid resuscitation (only in hypovolemic patients) ^[20]
  • Inotropic support: dobutamine ^[21]
  • Avoid anesthetic agents and positive pressure ventilation. ^[22]
• Subsequent management
  • Surgical management if the tamponade immediately reaccumulates, pericardiocentesis is unsuccessful, or conditions make pericardiocentesis difficult ^[1][21]
  • Identify and treat the underlying cause.
• Monitoring: : Serial pulsus paradoxus measurement

Acute pericardial effusion with pericardial tamponade is a life-threatening condition that requires immediate pericardial decompression.

Positive pressure ventilation can lead to hemodynamic decompensation in patients with cardiac tamponade.

Pericardial effusion

Small pericardial effusions may resolve with treatment of the underlying cause. In an uncertain diagnosis or with larger effusions that are causing symptoms, pericardial fluid drainage should be performed.

Pericardial fluid drainage

Pericardiocentesis

• Indications ^[23]
  • Hemodynamically unstable patients with cardiac tamponade (generally as a temporizing measure prior to surgery)
  • Large effusions
  • For pericardial fluid analysis in effusions of unknown etiology
  • If there has been no resolution with treatment of the underlying condition
• Procedure: ultrasound, CT, or fluoroscopy guidance recommended for planned pericardiocentesis ^[10][24]
• Complications
  • Perforation of the lung, liver, internal thoracic artery, colon, stomach, ventricle, or left anterior descending artery ^[17][18][19]
  • Pericardial decompression syndrome ^[25]

Pericardial window

• Description: : a pericardial incision for continual drainage from the pericardial space into the pleural cavity
• Indications: : commonly used for reaccumulating effusions and in a palliative setting for effusions due to underlying malignancy ^[10]

Pericardiotomy ^[10]

• Description: surgical or percutaneous opening is made in the pericardial sac to drain pericardial fluid
• Indications
  • Loculated effusions
  • Purulent effusion
• Complications: The mortality rate varies from 8–19%, depending on the underlying etiology. ^[26]