An unusual precordial pulse and sound assoicated with large pericardial effusion.

An unusual, high-pitched, early diastolic sound coinciding with a prominent, sharp precordial pulse was observed in a patient with a large chronic pericardial effusion. The pulse and sound coincided exactly with the anterior excursion of the heart within the fluid-filled pericardial sac, suggesting that the sound and pulse result from the ballistic effect of the heart striking the anterior pericardium and chest wall. This finding may be specific for large pericardial effusion with a "swinging heart."