Nonmalignant causes of pericardial effusion include pericarditis, myocardial infarction, uremia, hypothyroidism, systemic lupus erythematosus, trauma, postsurgical pericardotomy syndrome, and intrapericardial hematomas.[14,15,16] AIDS may also cause pericardial effusion with pericarditis. Radiation therapy or chemotherapy drugs can cause pericarditis without metastatic involvement of the pericardium. Radiation pericarditis is usually associated with radiation doses to the cardiac window exceeding 3,000 cGy  and occurs most frequently in patients who have received mediastinal radiation for Hodgkin disease or breast cancer. Doxorubicin and cyclophosphamide have been associated with the development of acute pericarditis with effusions.[11,12] Other drugs that may cause acute pericarditis include procainamide, hydralazine, isoniazid, methysergide, phenytoin, and anticoagulants.
Pericardial tamponade results from progressive fluid accumulation in the pericardial sac, causing elevated intrapericardial pressure, diminished stroke volume, decreased cardiac output, progressive decrease in cardiac diastolic filling, and hemodynamic compromise resulting in death if not treated. Hemodynamic compromise occurs when the normal amount of pericardial fluid (approximately 15-50 cc) increases to 200 cc to 1,800 cc.[15,18] When fluid accumulates rapidly, as little as 250 cc of fluid can result in tamponade.[11,19]
Dyspnea occurs in 93% of patients with pericardial effusions. Cough, chest pain, and orthopnea (discomfort with breathing while lying flat) are common symptoms. Other symptoms of pericardial effusion include upper abdominal distention or pressure due to downward hepatic distention, hiccups due to pressure on the diaphragm, or pleuritic pain due to stretching of the pericardium (especially when lying flat). Signs of effusion include Kussmaul's sign (increased distention of jugular veins with inspiration), Freidreich's sign (rapid diastolic descent of the venous pulse), and pulsus paradoxus (decrease of more than 10 mm Hg in the diastolic pressure on inspiration). Pericardial friction rubs and fever are more commonly associated with nonmalignant causes of pericardial effusions than malignant etiologies.
Signs of pericardial tamponade include tachycardia, pulsus paradoxus, elevated jugular venous pressure, and hypotension; however, some patients may develop tamponade without this clinical pattern.
Chest radiography may show widening of the cardiac silhouette  if the amount of pericardial fluid collection exceeds 250 cc. Chest x-ray cannot determine the degree of cardiac dysfunction or tamponade. Loculated pericardial effusions may not be apparent on standard posterior/anterior or lateral chest radiographic views.
Transthoracic echocardiography using apical, subxiphoid, and parasternal views can evaluate the presence, quantity, and quality of suspected pericardial effusions as well as associated pericardial masses and inflammation. Moderate effusions on echocardiography show an echo-free space of 10 mm to 20 mm during diastole in M-mode or 2-dimensional echocardiography, whereas severe effusions have an echo-free space exceeding 20 mm.[21,22] Echocardiography can also determine right and left ventricular function and the possibility of right ventricular or atrial diastolic collapse. Left ventricular collapse due to large pleural effusion without clinically significant pericardial effusions has been reported;[4,16,23,24] however, transesophageal echocardiography may be useful for loculated effusions due to adhesions adjacent to the atria, where the thinness of the atrial wall may not be well visualized on transthoracic echocardiography.[4,16]