Cardiomegaly and Paradoxical Pulse

A middle-aged man with a history of surgery for bronchogenic carcinoma was initially seen at the emergency room with weakness. Physical examination disclosed a paradoxical pulse of 15 mm Hg and on a chest roentgenogram, the cardiac silhouette was greatly enlarged. The ECG was abnormal; the echocardiogram is shown (Fig 1). What is your diagnosis?

Diagnosis.—Massive Pericardial Effusion  The echocardiogram shows a large pericardial effusion in front of and behind the heart. Swinging of the heart with every other cardiac cycle results in the electrical alternans seen in the accompanying ECG. Cardiac oscillation within a large pericardial effusion most commonly occurs with every cardiac cycle rather than with alternate cycles, as in this case. This swinging distorts valvular motion and can mimic, for example, mitral prolapse. In pericardial tamponade, notching of right ventricular epicardial motion shortly after the QRS (seen in Fig 1) has been noted along with decreased