Loculated pericardial effusion in acute pericarditis: diagnosis by combined echocardiographic and radioisotopic techniques.

A young man with a typical clinical presentation of acute pericarditis, on M-mode echocardiography, was repeatedly found to have a relatively echo-free area posterosuperior to the left ventricle, disappearing as the left ventricular apex was scanned. A radioisotopic "pericardial scan" revealed pericardial fluid lateral and inferior to the heart but not at the apex. This represents an additional type of M-mode echocardiographic presentation of loculated pericardial effusion.