Pericardial effusion is a relatively common finding in everyday clinical practice. Sometimes the clinical picture of the patient leads directly to the search for pericardial effusion, as occurs in patients with chest pain of pericarditic characteristics or in patients with underlying diseases that can cause pericardial involvement (renal failure, chest irradiation) and thoracic complaints. Other patients, without previous known diseases, seek medical attention because of dyspnea or nonspecific chest discomfort and the thoracic X-ray shows the presence of an enlarged cardiac silhouette with clear lungs. Finally, an unexpected cardiomegaly can be fortuitously found in asymptomatic patients during routine medical control for job or insurance purposes or for unrelated complaints. In any case, the finding of cardiomegaly with clear lungs should raise the suspicion of a pericardial effusion. The echocardiogram is the most available and reliable technique in order to verify the presence and the amount of a pericardial effusion; in addition, the echocardiogram offers valuable data for evaluation of hemodynamic repercussion. Mild pericardial effusion (sum of echo-free spaces in the anterior and posterior pericardial sac of less than 10 mm) is a relatively frequent finding, especially in elderly women[1
]. In fact, this finding does not always correspond to true effusion, but to pericardial fat. In these cases, computed tomography (CT) is a reliable method to precisely identify the nature of this echocardiographic finding[2
Although echocardiography is the standard and most available method for the evaluation of pericardial effusion, CT[2
] and magnetic resonance imaging (MRI) can offer some advantages. These imaging techniques allow assessment of the entire chest and detection of associated abnormalities in the mediastinum, lungs and adjacent structures. CT and MRI are also less operator dependent and delineate more precisely the spacial distribution of pericardial effusion in complex pericardial collections. In addition, multidetector CT scanners and MRI may provide valuable information about the function and dynamics of the heart and pericardium. Some of the reported limitations of echocardiography are generally not present with CT, including the possibility of false-positive findings due to adjacent pathologic conditions that may simulate pericardial effusion. Another advantage of CT and MRI is the possibility of identifying hemorrhagic effusions or clots within the pericardium.
The aim of this article is to give a comprehensive review of the etiology, hemodynamic repercussion, and management of moderate (sum of echo-free spaces in anterior and posterior pericardial sac between 10 and 20 mm) and severe (more than 20 mm) pericardial effusion.
CLINICAL APPROACH TO ETIOLOGIC DIAGNOSIS
When a clinician is faced with a patient who presents with a pericardial effusion, the first challenge is to identify its etiology. In some instances, it can be easily related to an associated condition or medical procedure (Table ). This happens, for example, in patients who develop pericardial effusion in the course of acute myocardial infarction[3
], in patients with end-stage renal failure, in patients receiving chest radiation, or in patients recently submitted to an invasive cardiac procedure with endocavitary catheters. However, even in these contexts, the possibility of unrelated etiologies should be considered. The finding of a pericardial effusion in patients with underlying malignancy creates a more complex dilemma, as not infrequently pericardial effusion is due to alternative causes and not to direct neoplastic pericardial involvement. In Posner’s series[5
] malignant pericardial disease was diagnosed in 18 (58%) of 31 patients with underlying cancer and pericarditis, while 32% of the patients had idiopathic pericarditis and 10% had radiation induced pericarditis. Porte et al[6
] studied 114 patients with recent or remote history of cancer and a pericardial effusion of unknown origin requiring drainage for diagnostic or therapeutic purposes. Pericardioscopy was performed in 112 patients with pericardial fluid analysis and biopsy of abnormal structures or deposits under direct visual control. Malignant pericardial disease was found in 44 (38%) patients, while 70 (61%) patients had non-malignant pericardial effusions (idiopathic in 33 patients, radiation-induced in 20 patients, infectious effusion in 10 patients, and hemopericardium as a result of coagulation disorders in 8 patients). These studies are important since they show that, in more than half of the patients with underlying cancer, a pericardial effusion is due to causes different than direct neoplastic involvement. Therefore, the precise etiology of these effusions needs to be clarified, as obvious prognostic and therapeutic consequences ensue. Pericardioscopy may be helpful in selected cases[7
]. Imaging techniques such as CT, MRI and positron emission tomography may also be very useful in the investigation of the presence and extension of neoplastic disease.
Causes of pericardial effusion
In many patients the etiology is initially difficult to establish as no apparent cause is present at the time a pericardial effusion is first identified. Although the final diagnosis of the cause of a pericardial effusion should be based on specific data, some simple clinical indicators may be useful in suggesting a likely etiologic category. Agner et al[9
], in a retrospective series of 133 patients, observed that hemodynamic compromise, cardiomegaly, pleural effusion, and a large pericardial effusion were more common in patients with tuberculous or malignant pericardial disease than in patients with idiopathic pericarditis. Hemorrhagic pericardial effusion has been associated with neoplasia in some studies[10
], but hemorrhagic effusions can also be seen in patients with idiopathic pericarditis. In fact, the predictive value of these different clinical findings for assessing the etiology of pericardial effusions has not been established. We hypothesized that some simple clinical findings such as the presence of underlying disease, development of cardiac tamponade, and presence or absence of inflammatory signs (typical pericarditic chest pain, fever, pericardial friction rub), might be helpful in classifying the patients into a major etiologic diagnostic category. We prospectively studied 322 patients with moderate and severe pericardial effusion[11
]. In 60% of these patients a known previous condition that could cause pericardial effusion was present. The pericardial effusion was demonstrated to be related to the underlying disease in all but 7 of these patients. In the patients with no apparent cause of pericardial effusion at the time of diagnosis (40%) we found that the presence of inflammatory signs (characteristic chest pain, pericardial friction rub, fever or typical electrocardiographic changes) was predictive for acute idiopathic pericarditis (P
< 0.001, likelihood ratio 5.4), irrespective of the size of the effusion and the presence or absence of tamponade. Furthermore, severe effusion with absence of inflammatory signs and absence of tamponade was predictive for chronic idiopathic pericardial effusion (P
< 0.001, likelihood ratio 20), and tamponade without inflammatory signs for neoplastic pericardial effusion (P
< 0.001, likelihood ratio 2.9). The search for evidence of previous chronic effusion can be particularly helpful, as it may make it possible to distinguish neoplastic disease from chronic idiopathic pericardial effusion, which sometimes presents with tamponade. Therefore, although the final etiologic diagnosis should certainly be based on specific clinical data in individual patients, we think that the data afforded by this study may be helpful in the initial assessment and in the decision to perform invasive pericardial studies. Tuberculous pericarditis deserves special attention. Most patients with acute pericarditis will be finally diagnosed with idiopathic pericarditis, but a few cases will correspond to tuberculous pericarditis. Identification of these cases is important due to obvious therapeutic implications. The diagnosis can be established through general examination, including the search of tubercle bacilli in sputum or gastric aspirate or by means of pericardial fluid or pericardial tissue examination (indicated in patients with tamponade or with persistent active illness for more than 3 wk).