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Pericardial effusion CT scan

Image: “A coronal CT showing a pericardial effusion identified by a white arrow” by James Heilmann, MD. License: CC BY-SA 3.0


Definitions

Pericardial effusion is defined as the accumulation of fluid in the pericardial space that surrounds the heart, between the parietal and visceral membranes of the pericardium. If this effusion is too acute, severe in volume, or allowed to progress over time, the fluid can accumulate to the point that it creates pressure on the heart itself.

Cardiac tamponade develops when the elevation of intrapericardial pressure from a pericardial effusion causes compression of the heart, leading to a disruption in ventricular diastolic filling and a reduction in cardiac output.

Epidemiology of Pericardial Effusion

Asymptomatic pericardial effusions have been reported in about 3 % of patients at autopsy. The groups at greatest risk of developing pericardial effusion include patients with cancer and patients with HIV and AIDS. Tamponade, requiring a large effusion, is less common and, when present, is usually due to trauma rather than a chronic illness.

Etiology of Pericardial Effusion

The causes of pericardial effusion can be divided into conditions that cause the accumulation of blood within the pericardium and conditions that cause a serous or serosanguinous effusion. Hemopericardium is usually caused by the weakening and rupture of the ventricular wall (e.g. post-myocardial infarction), trauma (e.g. car accidents, blunt force chest trauma, penetrating injury), and even during cardiac surgery.

Serous effusions occur as a result of pericarditis. Malignancy, especially lung and breast cancer, is the most common cause of effusion and tamponade followed by uremia and infectious disease. Autoimmune disorders are also known to cause pericardial effusion.

Causes of pericardial effusion and cardiac tamponade:

  • Neoplasm (e.g. breast and lung cancer)
  • Post-myocardial infarction
  • Postpericardiotomy syndrome
  • Hypothyroidism
  • Viral infections (e.g. coxsackie group B, influenza, echoviruses)
  • Bacterial infection
  • Connective tissue disease (e.g. lupus)
  • Trauma, blunt or penetrating
  • Uremia
  • Drug-induced

Pathology and Pathophysiology of Pericardial Effusion

Cardiac Tamponade

Image: “Cardiac Tamponade.” by BruceBlaus. License: CC BY 3.0

The pericardial space normally contains a small volume of serous fluid. Under normal circumstances, it cushions the heart and allows for a low friction environment so the heart can move easily. If fluid were to fill the pericardial space rapidly, as in a penetrating chest trauma, as little as 150 ml could lead to tamponade. If fluid were to slowly accumulate, then the pericardial sac could stretch to accommodate about 2 L of fluid without symptoms.

Pericardial effusions can be serous, hemorrhagic, or serosanguinous.

As the pericardial effusion continues to grow, the diastolic filling will be affected. The physiologic response is to increase the heart rate in order to maintain cardiac output. Venous return is also hampered by the gathering fluid around the heart, resulting in an intravascular buildup in the superior and inferior vena cava and a collapse of the right atrium and ventricle. Then, the left ventricle is last to collapse, leading to a significant drop in cardiac output. Insufficient cardiac output eventually leads to shock, cardiac arrest, and death.

Symptoms of Pericardial Effusion and Tamponade

Symptoms of a cardiac effusion include the following:

  • Chest pain or pressure
  • Palpitations
  • Cough
  • Additionally, the patient may present symptoms related to the underlying cause of the effusion.

As the effusion grows into a tamponade other symptoms can develop, including:

Upon physical examination, look for Beck’s Triad:

  • Low blood pressure
  • Distended neck veins
  • Muffled heart sounds on auscultation

Also look for pulsus paradoxus, an abnormally large drop in systolic blood pressure (normal drop is < 10 mm Hg) during inspiration with a lack of palatable radial pulse and Kussmaul’s sign, a paradoxical increase in venous pressure during inspiration.

On an X-Ray, the pericardial silhouette is enlarged and takes on a “water-bottle” shape.

Water bottle chest

Image: “Water bottle” by Jer5150. License: CC BY-SA 3.0

Diagnosis of Pericardial Effusion

Small effusions that are found incidentally are usually worked up to determine their etiology. An echocardiogram is used to verify the size of the effusion. It presents as an anechoic space between the layers of the serous pericardium. This will appear black. Remember: bone appears white, while fluid appears dark gray/black on ultrasound and echocardiogram.

If the effusion is small and the patient is asymptomatic, then the underlying condition is treated and the effusion is monitored. A large effusion may cause the pericardium to “swing” on echo, as the motion of the heart is transmitted through the fluid to the pericardium.

The effusion becomes a cardiac tamponade when sufficient fluid has accumulated in the pericardial space to inhibit proper heart function. Cardiac tamponade is a clinical diagnosis, an enlarged pericardial silhouette on a chest X-Ray is insufficient to make the diagnosis. If tamponade is suspected, the patient should be evaluated for Beck’s triad, pulsus paradoxus, echocardiograph, and ECG.

On an echocardiogram, the tamponade will show the following:

  • Large pericardial effusion
  • Collapse of the right ventricle during diastole
  • Dilation of the inferior vena cava
  • Compression of the left atrium and ventricle

This will result in poor left heart filling with a drop in cardiac output and venous stasis in the superior and inferior vena cava.

Pericardial effusion with tamponade

Image: “Pericardial effusion with tamponade” by Jer5150. License: CC BY-SA 3.0

Signs of tamponade on ECG include sinus tachycardia, low-voltage QRS complexes, and electrical alternans (consecutive QRS complexes that alternate in height).

Pericardial effusion with tamponade

Image: “Pericardial effusion with tamponade” by Jer5150. License: CC BY-SA 3.0

Differential Diagnoses of Pericardial Effusion

Management of Pericardial Effusion

Cardiac effusion will focus on removing the effusion, preventing further effusions, and treating the underlying cause. Medical treatment depends on the cause and includes:

  • NSAIDs, first-line therapy
  • Colchicine
  • Antibiotics, if caused by infection

Small effusions are monitored by echocardiography. Larger effusions are removed via pericardiocentesis. If recurrence is a concern, a pericardial window may be installed (a permanent catheter that drains any pericardial fluid into the peritoneal cavity).

Cardiac tamponade is a medical emergency and is treated with oxygen, volume expansion with IV fluids to increase cardiac output, inotropic drugs (e.g. dobutamine) to increase cardiac output, and elevating the legs to improve venous return. Pericardiocentesis should be performed as soon as the patient is stable.

Treatment of Pericardial Effusion

“Treatment of Pericardial Effusion” Image created by Lecturio

Progression and Prognosis of Pericardial Effusion

The prognosis of pericardial effusion depends on the etiology. Treating the underlying cause may be curative. Small effusions are simply monitored. However, untreated cardiac tamponade is rapidly fatal. Long term survival depends on etiology. Tamponade induced by malignancy has the worst long term prognosis.

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