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Diagnosis of pericarditis
Last reviewed: 04.07.2025
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A presumptive diagnosis of pericarditis can be made based on ECG, chest radiography, and Doppler echocardiography, but cardiac catheterization and CT (or MRI) are used to confirm the diagnosis. Because ventricular filling is limited, ventricular pressure curves show a sudden drop followed by a plateau (resembling a square root sign) in early diastole. Sometimes a right ventricular biopsy is necessary to exclude restrictive cardiomyopathy.
ECG changes are nonspecific. QRS complex voltage is usually low. T waves are usually nonspecifically altered. Atrial fibrillation develops in approximately one third of patients. Atrial flutter is less common.
Lateral radiographs often show calcification, but the findings are nonspecific.
Echocardiographic changes are also nonspecific. When right and left ventricular filling pressures are equally elevated, Doppler echocardiography helps differentiate constrictive pericarditis from restrictive cardiomyopathy. During inspiration, mitral diastolic flow velocity falls by more than 25% in constrictive pericarditis but by less than 15% in restrictive cardiomyopathy. Tricuspid flow velocity increases more than normal during inspiration in constrictive pericarditis but does not increase in restrictive cardiomyopathy. Measurement of mitral annular velocities may be helpful when excessively high left atrial pressures obscure respiratory changes in transvalvular velocities.
If clinical and echocardiographic data indicate constrictive pericarditis, cardiac catheterization is performed. It helps to confirm and quantify the altered hemodynamics that are characteristic of constrictive pericarditis: the value of pulmonary artery wedge pressure (pulmonary capillary wedge pressure), pulmonary artery diastolic pressure, right ventricular pressure at the end of diastole, and right atrial pressure (all within 10-30 mm Hg). Systolic pressure in the pulmonary artery and right ventricle is normal or slightly elevated, so the pulse pressure is low. In the atrial pressure curve, x and y waves are typically enhanced; in the ventricular pressure curve, diastolic decrease occurs during the phase of rapid ventricular filling of the ventricles. These changes are almost always detected in severe constrictive pericarditis.
Right ventricular systolic pressure >50 mmHg is often found in restrictive cardiomyopathy but less commonly in constrictive pericarditis. When the pulmonary artery wedge pressure is equal to the mean right atrial pressure and the early diastolic pressure drop in the intraventricular pressure curve results in large x and y waves in the right atrial pressure curve, any of the above disorders may be present.
CT or MRI help identify pericardial thickening greater than 5 mm. Such findings with typical hemodynamic changes can confirm the diagnosis of constrictive pericarditis. When pericardial thickening or effusion is not detected, restrictive cardiomyopathy is diagnosed, but this is not proven.
Etiological diagnostics. After pericarditis is diagnosed, studies are conducted to identify the etiology and the effect on cardiac function. In young, previously healthy people who have had a viral infection and subsequently pericarditis, extensive diagnostic search is usually not advisable. Differential diagnostics of viral and idiopathic pericarditis is difficult, expensive, and of little practical value.
A pericardial biopsy or aspiration of pericardial effusion may be needed to establish the diagnosis. Acid staining and microbiologic examination of the pericardial fluid may help identify the causative agent. Samples are also examined for the presence of atypical cells.
However, complete removal of a newly identified pericardial effusion is usually not required to establish the diagnosis. Persistent (present for more than 3 months) or progressive effusion, especially when the etiology is unknown, is an indication for pericardiocentesis.
The choice between needle pericardiocentesis and surgical drainage depends on the physician's capabilities and experience, the etiology, the need for diagnostic tissue samples, and the prognosis. Needle pericardiocentesis is considered preferable when the etiology is known or the possibility of cardiac tamponade cannot be excluded. Surgical drainage becomes the method of choice when tamponade is proven but the etiology is unclear.
Laboratory findings on pericardial fluid other than culture and cytology are usually nonspecific. However, in certain cases, new imaging, cytology, and immunology techniques may be used on fluid obtained by pericardioscopy-guided biopsy.
Cardiac catheterization is used to assess the severity of pericarditis and to determine the cause of decreased cardiac function.
CT and MRI may be helpful in identifying metastases, although echocardiography is usually sufficient.
Other tests include a complete blood count, acute phase markers, blood chemistry, culture, and autoimmune tests. If necessary, HIV testing, complement fixation test for histoplasmosis (in endemic areas), streptolysin testing, and antibodies to Coxsackie, influenza, and ECHO viruses are performed. In some cases, anti-DNA, anti-RNA antibodies are determined, and a skin test for sarcoidosis is performed.
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