DEFINITION

Acute pericarditis is a symptomatic inflammation of the pericardium of sudden onset with symptoms of less than 2 weeks’ duration. Acute pericarditis may result in fibrinous secretions or the development of a pericardial effusion.

PREVALENCE AND EPIDEMIOLOGY

The true prevalence of acute pericarditis is unknown, but it may account for 1% of all emergency department visits for chest pain.¹

ETIOLOGY AND PATHOPHYSIOLOGY

There are many causes of acute pericarditis (Table 69-1).^2–6 The specific etiology is often unknown, thereby resulting in the diagnosis of idiopathic pericarditis. The use of a systematic approach to the diagnosis of the cause of acute pericarditis, including a detailed history, blood cultures, antibody testing, and viral testing, can reduce the number of “idiopathic” diagnoses.⁷ Viral infection is the most common cause of acute pericarditis in the United States, and is probably the etiology in patients with idiopathic pericarditis.^8,9 The most common viral agents causing acute pericarditis are coxsackievirus group B and echovirus.⁸ Viral pericarditis is usually preceded by upper respiratory infection symptoms, and typically is a self-limited disease that can be diagnosed by serologic testing of antiviral titers. Numerous systemic diseases can also result in acute pericarditis and pericardial effusion. These diseases are discussed in Chapter 70. It is difficult to distinguish cases of acute pericarditis from cases of pericardial effusion in the literature because the presence of pericardial fluid is sometimes seen as an indicator of the presence of pericarditis.

TABLE 69-1 Etiology of Acute Pericarditis

MANIFESTATIONS OF DISEASE

Imaging Techniques and Findings

Radiography

Typically, because of the acute onset of symptoms, the chest radiograph is normal in appearance. Depending on the amount of pericardial fluid, there may be an increase in the size of the cardiac silhouette. The chest radiograph can also be assessed for absence of findings associated with other disease entities that result in chest pain, such as pneumonia or pneumothorax.

Ultrasonography

Echocardiography may be performed to assess for the presence of pericardial effusion, to assess for evidence of cardiac tamponade, or to establish a baseline appearance of the pericardial space. The echocardiographic findings of acute pericarditis include a normal examination, pericardial thickening with or without pericardial effusion, and pericardial effusion without pericardial thickening.¹¹ Depending on the echocardiographic findings, assessment can be made for tamponade or constrictive physiology.

Computed Tomography

Contrast-enhanced CT scans may be performed in patients in whom the clinical presentation is unclear or to exclude other potential causes of chest pain. Typical findings of acute pericarditis on CT scans include enhancement of smooth, uniformly thickened pericardium and pericardial effusion (Fig. 69-1).¹²

FIGURE 69-1 A 19-year-old man presented with a 3-week history of chest pain. The chest pain was sharp in nature and radiated to his throat and left trapezius muscle. The pain worsened when lying flat and relieved on sitting upright and leaning forward. A and B, Contrast-enhanced CT scan of the chest was performed and shows a small to moderate-sized pericardial effusion with smoothly thickened, enhancing pericardium (arrowheads). The patient was initially thought to have viral pericarditis. On further testing, the diagnosis of adult-onset Still disease was made.

Magnetic Resonance Imaging

Although not frequently performed for the evaluation of acute pericarditis, MRI can show a pericardial effusion, thickening, and enhancement.

Nuclear Medicine

Nuclear medicine studies are usually not performed for assessment of patients with acute pericarditis.

Angiography

Angiography is usually not performed for assessment of patients with acute pericarditis.

DIFFERENTIAL DIAGNOSIS

TREATMENT OPTIONS

Surgical/Interventional

If cardiac tamponade is present, if the infectious agent is bacterial (Fig. 69-2), or if neoplastic involvement is suspected, pericardiotomy is indicated.^2,10,13 In cases of neoplasm or granulomatous disease, pericardial biopsy may be necessary to establish the diagnosis.

FIGURE 69-2 A 61-year-old man presented with a 2-month history of progressive soft tissue infection involving the right shoulder that had not been treated. CT scan was performed to evaluate the extent of the infection and to assess for involvement of the chest and mediastinum. Contrast-enhanced CT scan shows a moderate-sized pericardial effusion with enhancement of the visceral and parietal pericardium (arrowheads) consistent with acute pericarditis. Pericardial window was performed, and Staphylococcus aureus was cultured from the pericardial fluid.

INFORMATION FOR THE REFERRING PHYSICIAN

Chest radiograph and CT scan should be assessed for associated findings such as pleural effusion or any other findings that may provide clues as to the etiology. If there are erosive changes at the distal ends of the clavicle, consideration can be given to rheumatoid arthritis as the possible etiology.

KEY POINTS

Acute pericarditis is a clinical diagnosis.

Characteristic imaging findings may be present in patients undergoing CT to evaluate for pulmonary emboli, aortic dissection, or coronary artery disease.

Idiopathic pericarditis is usually caused by a virus. Because the pericarditis usually occurs 1 to 3 weeks after initial viral infection, the virus is often not recovered.