Purulent pericarditis

Purulent pericarditis or pericardial empyema isa serious form of a bacterial, fungal or parasitic infection of the pericardium associated with a neutrophilic pericardial effusion.

Epidemiology

Purulent pericarditis is rare nowadays and makes up for <1% of pericarditis cases.

Risk factors

Factors that increase the likelihood of developing purulent pericarditis include ^1-4:

• cardiac or thoracic surgery
• immunosuppression
• chronic kidney disease
• malignancy
• preexisting pericardial effusion

Associations

Clinical conditions with which purulent pericarditis has been associated with include ^1-3:

• pneumonia
• pleural empyema
• sepsis

Clinical presentation

Patients with purulent pericarditis are usually seriously ill and present with fever, fatigue and chest pain. On auscultation, there might be a pericardial friction rub ^1-4. An electrocardiogram might show abnormalities as PR segment depression and ST elevation in all leads ^2-5.

Complications

Complications of purulent pericarditis include the following ^1-4:

• pericardial tamponade
• persistent chronic pericarditis
• constrictive pericarditis
• septic shock
• cardiac arrest and death

Pathology

Purulent pericarditis is characterised by pus in the pericardial fluid which might show up frankly in pericardiocentesis, required for securing the diagnosis ¹. 

The following parameters are in favour of purulent pericarditis versus tuberculous or neoplastic pericarditis ¹:

• elevated pericardial white cell count (mean ≥2.8/µl) 
• a high percentage of neutrophils (≥92%)
• elevated pericardial versus serum glucose ratio (≈0.3)

The most common organisms in western countries are staphylococci streptococci and pneumococci. After thoracic surgery or in immunocompromised patients Staphylococcus aureus, fungi and anaerobes from the oropharynx are common pathogens ¹.

Radiographic features

On most imaging modalities purulent pericarditis manifests as pericardial effusion ².

Plain radiograph

Chest x-ray might show an abnormal cardiac silhouette and pleural effusions ³.

Echocardiography

Echocardiography is the first-line imaging modality in the diagnosis and monitoring of therapy in the setting of acute pericarditis. It can identify pericardial effusions as well as complications as cardiac tamponade or pericardial constriction ^3-5.

CT

CT will demonstrate pericardial effusion, pericardial thickening and enhancement. Additionally, it might demonstrate loculated collections and potential sources as pleural empyema or pneumonia.

MRI

MRI is an adjunctive imaging modality for pericarditis and is done if echocardiographic findings are ambiguous or if myocardial involvement is suspected. MR imaging findings include the following ⁵:

• pericardial thickening
• pericardial oedema
• heterogeneous pericardial effusion
• pericardial enhancement

Radiological report

The radiological report should contain a description of the following:

• pericardial effusion, pericardial thickening, pericardial enhancement
• cardiac volumes and measurements
• ventricular wall motion abnormalities
• myocardial involvement or signs of myocarditis

Treatment and prognosis

Purulent pericarditis is a serious and dangerous condition and requires fast and aggressive treatment. Even then, the mortality rate is approximately 15%. Management includes immediate empiric antibiotic therapy until the causative microbiological agent is available on one hand and pericardial drainage on the other hand. Intrapericardial thrombolysis is an option for loculated fluids. More invasive surgical options include subxiphoid pericardiotomy with rinsing the pericardial cavity, pericardial windowing or pericardiectomy ^1-3.

History and etymology

Pericardiocentesis had been already advocated by Riolanus almost 400 years ago ⁶.

Differential diagnosis

Conditions mimicking the radiological appearance of purulent pericarditis include ¹:

• tuberculous pericarditis
• neoplastic pericarditis