eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology

Pericarditis, Bacterial: Differential Diagnoses & Workup

Author: John Berger, MD, Departments of Critical Care Medicine and Pediatric Cardiology, Assistant Professor, George Washington University and Children's National Medical Center
Contributor Information and Disclosures

Updated: Jul 15, 2008

Differential Diagnoses

Other Problems to Be Considered

Diseases associated with pericardial effusion and tamponade
Infectious pericarditis (fungal pericarditis)
Malignancy
Autoimmune disorders
Connective tissue diseases (see Mixed Connective Tissue Disease, Undifferentiated Connective Tissue Disease)
End-stage renal disease (uremic pericarditis)
Chest trauma (see Penetrating Chest Trauma, Blunt Chest Trauma)
Extravasation from central venous catheter

Workup

Laboratory Studies

• CBC count
  • The CBC count usually reveals leukocytosis with predominance of immature polymorphonuclear leukocytes.
  • Lymphocytosis suggests viral or idiopathic etiology.
• Blood culture: Results are positive in more than one half of patients with bacterial pericarditis.
• Other tests: Erythrocyte sedimentation rate (ESR) and other acute phase reactant levels are elevated in purulent pericarditis.

Imaging Studies

• Chest radiography
  • A rapidly enlarging cardiac silhouette with a water-bottle appearance without accompanying increase in pulmonary vascular markings strongly suggests a pericardial effusion.
  • Consider purulent pericarditis in an infant or child with sepsis and cardiomegaly.
• Echocardiography
  • Echocardiography is the imaging modality of choice for rapid accurate identification of a pericardial effusion and its size and distribution.¹
  • Using 2-dimensional echocardiography, pericardial fluid appears as an "echo-free" space. With small effusions, fluid first appears posteriorly in the dependent portion of the pericardial sack. With larger effusions, fluid is found both anterior and posterior to the heart.
  • Echogenic material may be observed in the pericardial fluid and may represent adhesions, clots, or fibrinous material.
  • Multiple echocardiographic indicators of cardiac tamponade are recognized, but none are completely sensitive or specific. Echocardiography findings must be considered in relation to the clinical picture when making the diagnosis of tamponade.
  • Common criteria of tamponade on echocardiography include right atrium (RA) collapse at end diastole that continues into systole, right ventricle (RV) compression during diastole (especially with expiration), and marked respiratory variation in transvalvular flow velocities by Doppler echocardiogram. Reversal of systemic venous return flow can occur during diastole.
  • Echocardiography is useful in guiding pericardiocentesis. Visualizing the tip of the needle is helpful because echographic artifacts arising from the shaft of the needle may mislead the operator to the actual location of the needle tip. If needle position is uncertain, 5 mL (or less) of agitated saline may be injected for a contrast echocardiography.

Other Tests

Most patients exhibit at least 1 ECG abnormality. ECG abnormalities depend on the amount of effusion and the presence of superficial myocardial injury. Normal ECG findings do not exclude the diagnosis of acute pericarditis. Typical findings include ST segment elevation and low voltage QRS complexes.

• Pericardial fluid can produce low voltage QRS complexes because of a dampening effect of the fluid between the chest wall and myocardium.
• Most patients have ST elevation (usually in leads I, II, V5, and V6).
• Electrical alternans (ie, changes in the P, QRS, and T wave voltages) is very specific, although not sensitive for large pericardial effusions. Electrical alternans results from the heart swinging in a large effusion.
• Four classic stages of ECG changes are described in acute pericarditis; however, many patients do not exhibit all 4 stages. The stages are as follows:
  1. ST segment elevation and PR segment may be depressed.
  2. ST segment is still elevated but returns to baseline with decreased T-wave amplitude. PR segment is depressed.
  3. ST segment returns to normal with T-wave inversion (may be incomplete in some cases).
  4. ECG normalization occurs. T-wave changes may persist and do not necessarily indicate active disease.

Procedures

Definitive diagnosis of purulent pericarditis requires direct examination of pericardial fluid.

• Pericardiocentesis is safest when performed in a controlled environment, such as the catheterization laboratory or ICU.
• ECG, blood pressure, and oximetry monitoring is necessary.
• The procedure is associated with morbidity and should be performed or supervised by an experienced physician.
• Sedation is desirable unless the patient is unconscious or extremely unstable. Pericardiocentesis in a struggling patient is dangerous.
• Some operators prefer to use ECG monitoring of needle advancement by clipping the V₁ lead to the needle. This technique is cumbersome and is not often used. If visualization is desired, echocardiography or fluoroscopy guidance is preferred.
• A pericardial pigtail catheter may be placed using a modified Seldinger technique. The use of a pigtail catheter reduces the risk of dislodgment and myocardial puncture. Additionally, the pigtail catheter may be left in place to provide continuous and potentially definitive pericardial drainage.
• During pericardiocentesis, bloody fluid is often obtained that may be blood from a myocardial puncture or bloody pericardial fluid. Pericardial fluid fails to clot and has a hematocrit level that is much lower than the patient's hematocrit.
• Potential complications of pericardiocentesis include arrhythmias, laceration of coronary arteries with subsequent hemopericardium and tamponade, pneumothorax, and myocardial perforation.
• Careful handling of pericardial fluid is required to properly identify etiologic agents for pericardial effusion.
• Culture fluid for aerobic and anaerobic organisms, fungi, miliary tuberculosis, and viruses.
• Approximately 50-60% of patients with purulent pericarditis have positive pericardial fluid cultures.
• Antigen detection tests can be helpful in patients who have received antibiotics.
• If malignancy is suspected, other studies include cell count and differential, Gram stain, and cytology.
• The effusion of purulent pericarditis usually has a high WBC count with predominately polymorphonuclear cells.
• Viral pericarditis produces a lymphocytic picture. Protein and lactate dehydrogenase (LDH) levels are often obtained, although both are usually elevated in most types of pericarditis.

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