Pericarditis is inflammation of the pericardium and may be acute or chronic. Acute pericarditis is most commonly caused by a viral infection; however, a number of conditions can cause an inflammatory response in the pericardium. Acute pericarditis typically manifests with low-grade fever, pleuritic chest pain, and a pericardial friction rub on auscultation. The diagnosis is established based on clinical findings, although diffuse ST segment elevations on ECG and imaging may support the diagnosis. Acute pericarditis is usually self-limited, lasting days to weeks, and is therefore managed symptomatically. If pericarditis lasts longer than 3 months, it is described as chronic pericarditis. Chronic pericarditis is typically either constrictive or effusive-constrictive. Constrictive pericarditis is characterized by thickening and rigidity of the pericardium, resulting in both backward and forward failure. Patients typically present with fatigue, jugular vein distention, peripheral edema, and a characteristic pericardial knock on auscultation, which is caused by a sudden stop in ventricular diastolic filling. Effusive-constrictive pericarditis is characterized by a thickened pericardium with an effusion; this can lead to cardiac tamponade. It may manifest with symptoms similar to constrictive pericarditis, symptoms of pericardial effusion, or cardiac tamponade. In both constrictive and effusive-constrictive pericarditis, imaging is used to confirm the diagnosis. Management consists of treatment of heart failure (e.g., diuretics) and pericardiectomy.
- Acute pericarditis: inflammation of the pericardium that either occurs as an isolated process or with concurrent myocarditis (myopericarditis). 
- Relapsing/recurrent pericarditis: recurrence of symptoms after a symptom-free period of 4–6 weeks
- Transient constrictive pericarditis: constrictive pericarditis that lasts < 3 months
- Chronic pericarditis: inflammation of the pericardium that lasts > 3 months 
- Myocardial infarction
- Postoperative; (postpericardiotomy syndrome): due to blunt or sharp trauma to the pericardium
- Uremia: e.g., due to acute or chronic renal failure
- Neoplasms (e.g., Hodgkin lymphoma)
- Autoimmune connective tissue diseases (e.g., rheumatoid arthritis, systemic lupus, scleroderma)
- Pleuritic chest pain
- Improves on sitting and leaning forward
- Can radiate to the neck and shoulders (most commonly to the left side)
Pericardial friction rub: high-pitched scratching on auscultation
- Indicates friction between the visceral and parietal pericardial tissue 
- Best heard over the left sternal border during expiration while the patient is sitting up and leaning forward 
- Occurs in atrial and ventricular systole, as well as early diastole 
- Present in 85% of patients with acute pericarditis. 
- Low-grade intermittent fever, tachypnea, dyspnea, nonproductive cough
Constrictive pericarditis 
- Symptoms of fluid overload (i.e., backward failure)
- Symptoms of reduced cardiac output (i.e., forward failure)
Subtypes and variants
- Definition: infection of the pericardium with macroscopic or microscopic evidence of pus in the pericardial space
- Clinical features
- Pericardiocentesis to evacuate pericardial effusion; order cultures of pericardial fluid and blood
- Empiric intravenous antibiotic therapy (e.g., vancomycin, ceftriaxone, or meropenem) that is subsequently adjusted according to antibiogram
- In case of loculations: surgical drainage and/or intrapericardial fibrinolysis
- Check ECG, TTE to determine if diagnostic criteria are met.
- If TTE is inconclusive, consider CT or cardiac MRI to confirm pericardial inflammation/effusion.
- Determine whether any further diagnostic evaluation is indicated based on suspected etiology (see “Additional diagnostic evaluation” below).
Diagnostic criteria for acute pericarditis 
At least two of the following four criteria must be present for a diagnosis of acute pericarditis:
- Characteristic chest pain
- Pericardial friction rub
- Typical ECG changes (see below)
- New or worsening pericardial effusion
ECG features of pericarditis
- Stage 1: diffuse ST elevations; , ST depression in aVR and V1, PR segment depression
- Stage 2: ST segment normalizes in ∼ 1 week.
- Stage 3: inverted T waves
- Stage 4: ECG returns to normal baseline (as prior to onset of pericarditis) after weeks to months.
The goal of imaging is to identify any new pericardial effusion and rule out alternative etiologies.
- Cardiac MRI
- CT scan with IV contrast
- Chest x-ray: usually normal; may show an enlarged cardiac silhouette
Elevation of inflammatory markers may support the diagnosis of pericarditis but are not considered to be a part of the diagnostic criteria. 
Additional diagnostic evaluation
- Pericardiocentesis with pericardial fluid analysis 
- Additional workup based on suspected etiology
- Additional laboratory studies
- Investigation of the underlying cause: See “Additional diagnostic evaluation” above.
Constrictive pericarditis 
- ↑ Pericardial thickness
- Abnormal ventricular filling with sudden halt during early diastole
- Variation in ventricular filling with inspiration
- Moderate biatrial enlargement 
- Excludes and
- Indications: if noninvasive methods have failed to provide a definitive diagnosis 
- Findings 
- Similar pressures in the left and right atria and right ventricle at the end of diastole (e.g., “equalization of pressures”)
- Normal pulmonary artery systolic pressure < 40 mm Hg
- Mean right arterial pressure > 15 mm Hg
- Square root sign 
The diagnostic findings of effusive-constrictive pericarditis are similar to those of pericardial effusion, with the exception that in addition to pericardial effusion, pericardial thickening may also be seen. Elevation of right atrial pressures despite pericardiocentesis is strongly suggestive of effusive-constrictive. 
- Echocardiography, CT, and/or cardiac MRI: pericardial effusion ; pericardial thickening may also be present 
- Pericardiocentesis with cardiac catheterization: right atrial pressure remains persistently elevated after pericardiocentesis. 
- Other findings consistent with pericardial effusion
The mainstays of therapy include anti-inflammatories to control pain and prevent a recurrence, and treatment of the underlying cause (if found).
Acute pericarditis is often self-limited but NSAIDs can alleviate symptoms and prevent a recurrence. Consider anti-inflammatory therapy also for chronic pericarditis (transient constrictive pericarditis may respond). 
- NSAID therapy
- Consider colchicine in combination with NSAIDs or as a monotherapy. 
- Only consider prednisone in severe cases or in pericarditis caused by uremia, connective tissue disease, or autoreactivity.
- Consider gastroprotective therapy (e.g., omeprazole ) in patients at risk for GI bleeding
- Treat any known underlying causes.
- Restrict physical activity in patients with acute pericarditis. 
- Initiate if present. 
Special circumstances 
- : Avoid NSAIDs other than aspirin. 
- Perimyocarditis: Consider lower doses of NSAIDs , adding a beta blocker , and the avoidance of strenuous physical activity for 6 months. 
- Constrictive pericarditis with effusion: Use caution when sedating patients or initiating positive pressure ventilation. 
Administration of sedatives and/or the initiation of positive pressure ventilation may precipitate hemodynamic collapse in patients with constrictive pericarditis or effusive-constrictive pericarditis. 
- Pericardiocentesis: indicated for cardiac tamponade, large pericardial effusion, acute management of effusive-constrictive pericarditis 
- Pericardiectomy: complete removal of the pericardium 
- Most well patients with no indicators of poor prognosis can be managed on an outpatient basis.
- Consider inpatient admission for the following:
- Indicators of poor prognosis in acute pericarditis are present. 
- Suspicion of specific etiologies (e.g., tuberculosis, malignancy, or bacterial infection)
- Chronic pericarditis: Consider admission in patients who have symptoms of congestive heart failure, or in whom further diagnostic evaluation is necessary.
- Perform ABCDE assessment.
- Check ECG and TTE.
- Rule out life-threatening .
- Perform immediate pericardiocentesis in unstable patients if there is evidence of tamponade (see “Acute management checklist for cardiac tamponade”)
- Consider advanced imaging if the diagnosis is uncertain.
- Start NSAIDs (if there are no ).
- Consider colchicine, prednisone, and/or gastroprotective therapy.
Identify and treat the underlying cause.
- Advise patients to limit strenuous exercise.
- Consider cardiology consult for severe cases.
- Consider indications for admission.
- If the patient is discharged, arrange for a follow-up in 1 week.
We list the most important complications. The selection is not exhaustive.