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.

• Pericardial effusion: an accumulation of fluid in the pericardial space between the parietal and visceral pericardium. May be acute or chronic.
• Cardiac tamponade: a pathophysiological process whereby elevated intrapericardial pressure from a pericardial effusion causes compression of the heart (especially the right ventricle) ^[1]

• Hemopericardium: accumulation of blood in pericardial space
  • Cardiac wall rupture (e.g., complication of myocardial infarction)
  • Chest trauma (traumatic cardiac tamponade)
  • 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
  • Right heart failure

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 → ↓ systemic venous return (preload) → ↓ ventricular diastolic filling → ↓ stroke volume (and venous congestion) → ↓ cardiac output and equal end-diastolic pressures in all 4 chambers

Pericardial effusion ^[3]

• 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: dullness to percussion at the base of the left lung with increased vocal fremitus and bronchial breathing due the compression of lung parenchyma by the pericardial effusion ^[4]

Tamponade ^[3]

• 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

• Unstable patients with suspected tamponade: Do not delay treatment for extensive diagnostic workup; proceed directly with management of cardiac tamponade.
• In all other patients, confirm the diagnosis with echocardiography (either TTE or FAST).
• 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: diagnosis and monitoring of all patients with suspected pericardial effusion and/or tamponade ^[5]
• 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: Can be identified using POCUS (See “Subxiphoid view" of the “FAST scan.”)
  • 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.
• Echocardiographic findings supportive of cardiac tamponade ^[7][8]
  • 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 (See “IVC ultrasound.”)

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

Epicardial fat can be mistaken for pericardial fluid on echocardiography. However, unlike fluid, it tends to be brighter, moves along with the myocardium, and does not collect in dependent regions. ^[8]

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 ^[4]
  • 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 ^[9]

Imaging

• Chest x-ray: not required to diagnose pericardial effusion but often performed to exclude other causes of dyspnea ^[10][11]
  • PA view findings
    • Normal in small effusions ^[12]
    • 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 ^[13]
    • 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 ^[10]
• Further imaging ^[7]
  • Indications: consider if small or loculated effusions are suspected or visualization via TTE is difficult
  • Modalities include: TEE, CMR, CT

∼ 250 mL of pericardial fluid must be present before an effusion is visible on chest x-ray!

Investigation of the underlying etiology

Pericardial fluid analysis ^[14][15]

• Indication: pericardial effusion of unclear etiology ^[15]
• Procedure: Pericardial fluid is obtained via diagnostic pericardiocentesis.
• Analysis ^[15]
  • 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 ^[14]
  • There are no established biochemical thresholds for the classification of pericardial effusions.
  • Light criteria can be used for interpretation.

Laboratory studies and specific investigations ^[11]

• 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

Approach

• Unstable patients: Identify and treat cardiac tamponade urgently, if present.
• Stable patients
  • Small pericardial effusion: Conservative management focusing on treating the underlying cause is usually sufficient.
  • Large pericardial effusion causing symptoms or of uncertain etiology: Consider pericardial fluid drainage.
• All patients
  • Treat the underlying cause, e.g., manage acute heart failure, treat pericarditis.
  • Provide supportive care, e.g., pain management
• Disposition
  • Consult cardiology urgently if cardiac tamponade is suspected (See “Management of cardiac tamponade”).
  • Consult cardiothoracic surgery if surgical pericardial fluid drainage is indicated.
  • If pericardiocentesis is performed, admit patients to hospital ward or observation unit for postprocedure monitoring, serial examination, and pericardial fluid analysis.

Surgical pericardial fluid drainage (e.g., pericardiotomy and pericardiectomy) is commonly performed for patients with traumatic, purulent, loculated, rapidly reaccumulating, or malignant effusions. ^[11]

Pericardial fluid drainage ^[11][19]

• Therapeutic pericardiocentesis
  • Performed as a temporizing measure for hemodynamically unstable patients with cardiac tamponade
  • Can relieve symptoms for large chronic or recurrent effusions
  • Consider specialist referral for patients at high risk of reaccumulating pericardial fluid, e.g., for indwelling catheter or pericardiectomy
  • See “Pericardiocentesis” for details.
• Pericardiotomy: the creation of an opening in the pericardium to allow continuous drainage of pericardial fluid (externally or into the pleural space) ^[20]
  • Surgical pericardiotomy (pericardial window): A surgical incision is made in the pericardium. ^[21]
    • Subxiphoid approach: can be done under local anesthesia at the bedside (e.g., emergency department or ICU) and allows external fluid drainage
    • Thoracotomy approach: needs to be done in the operating room and allows drainage into the pleural cavity
  • Percutaneous balloon pericardiotomy: A transthoracic needle introduces a balloon-tipped catheter into the pericardial space which is progressively dilated to create an opening wide enough for continuous drainage.
  • Complications: The mortality rate varies from 8–19%, depending on the underlying etiology. ^[22]
• Pericardiectomy: performed as definitive management for refractory pericardial effusion, effusion due to constrictive pericarditis, or purulent pericarditis ^[12]

Treat hemopericardium due to penetrating chest injury surgically, e.g., with pericardial window, as soon as possible. Only consider pericardiocentesis as a temporizing measure if surgery is unavailable. ^[23]

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

Rapid evaluation of unstable patients

Cardiac tamponade is a clinical diagnosis, however, clinical features are poorly sensitive and the diagnosis is often confirmed retrospectively. ^[24]

• Use POCUS to confirm the presence of a pericardial effusion (see the “Subxiphoid view” of the “FAST scan” for the technique).
• Suspect tamponade in patients with suggestive clinical features and/or bedside imaging findings.
  • ≥ 70% of patients have ≥ 1 of the following: ^[24]
    • Shortness of breath
    • ↑ Heart rate
    • ↑ JVP
    • Pulsus paradoxus (> 10–12 mm Hg)
    • Cardiac enlargement on CXR
  • Beck's triad is poorly sensitive for tamponade and it is very rare for all elements to be present ^[25]
  • < 50% of patients have low voltage QRS complexes on ECG. ^[24]
• Obtain an urgent bedside echocardiogram to evaluate for echocardiographic findings supportive of cardiac tamponade.
• Evaluate the need for immediate pericardial fluid drainage.
• Consult a cardiologist and/or cardiothoracic surgeon and consider using a scoring system to help determine when urgent pericardiocentesis is advised and when it can safely be deferred. ^[26][27]

The most common underlying causes of cardiac tamponade are cardiac interventions (e.g., PCI, pacemaker implantation), malignancy, infectious or inflammatory pericarditis, mechanical complications of MI, and aortic dissection. ^[28]

Cardiac arrest due to suspected cardiac tamponade

See also “Cardiac arrest and cardiopulmonary resuscitation.”

• Nontraumatic cardiac arrest ^[29]
  • Consider POCUS during CPR to confirm pericardial effusion.
  • Pause CPR to perform immediate pericardiocentesis as soon as possible if cardiac tamponade is the suspected etiology. ^[30][31]
  • Blind pericardiocentesis can be performed using landmarks if no ultrasound guidance is available. . ^[23][32]
• Traumatic cardiac arrest
  • Assume pericardial fluid seen on FAST scan is traumatic hemopericardium.
  • Perform emergency thoracotomy with vertical pericardiotomy. ^[23]

Urgent pericardial fluid drainage

• Perform pericardiocentesis under echocardiographic (or fluoroscopic) guidance without delay in unstable patients unless indications for immediate surgery are present. ^[11]
• Do not delay immediate surgical management in patients with a low likelihood of successful pericardiocentesis due to immediate reaccumulation of pericardial fluid, for example in: ^[1][26][33]
  • Type A aortic dissection
  • Ventricular free wall rupture
  • Severe blunt chest trauma or penetrating chest injury
  • Iatrogenic hemopericardium refractory to percutaneous hemostatic control
• Refer for surgical management if pericardiocentesis is unsuccessful, e.g., due to difficult conditions ^[1][8][33]

Hemodynamic support

Manage as obstructive shock.

• Establish IV access with two large-bore IV lines (peripheral or central).
• Cautious fluid resuscitation (only in hypovolemic patients) ^[34]
• Inotropic support: dobutamine ^[33]
• Avoid anesthetic agents and positive pressure ventilation. ^[35]
• See “Hemodynamic compromise in mechanically ventilated patients” for the management approach if mechanical ventilation is unavoidable.

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

Subsequent management

• Identify and treat the underlying cause: See “Investigation of underlying etiology” in “Diagnostics.”
• Monitor for complications and reaccumulation.
  • ICU admission recommended ^[12]
  • Continuous telemetry
  • Regular BP monitoring
  • Serial pulsus paradoxus measurement

• Consult cardiology immediately.
• Confirm the diagnosis with echocardiography if the patient is stable (proceed directly to pericardiocentesis if not).
• Urgent pericardiocentesis in patients with cardiac tamponade
  • Cardiac arrest or peri-arrest patient and no bedside imaging (e.g, POCUS) available: Consider blind technique.
  • All other patients: Use POCUS guidance for unstable patients; consider CT or fluoroscopy guidance for stable patients.
• Continuous telemetry
• If the patient is hypotensive, consider cautious IV fluid use.
• Consult cardiothoracic surgery for surgical drainage if pericardiocentesis is unsuccessful or if hemopericardium or purulent effusion are suspected.
• Serial pulsus paradoxus measurement
• Transfer to ICU/CCU.
• Avoid anesthetic agents and positive pressure ventilation.