Echocardiographic observation of ventricular volume changes and swinging septal position in massive pericardial effusion.

Swinging interventricular septal position and ventricular volume changes associated with respiration were studied in a patient with massive uremic pericardial effusion and pulsus paradoxus. Inspiration was regularly associated with a posterior swinging septal position which dramatically increased right ventricular (RV) volume with a lesser change in left ventricular (LV) volume. Expiration was consistently accompanied by an anterior swing of septal position which nearly obliterated the RV with slight enlargement of the LV. The above changes produced a pendulum-like motion of the septal position as the patient breathed. This may reflect the ventricular volume changes that accompany respiration in severe pericardial effusion association with pulsus paradoxus.