Usually pericardial effusion(PE) is not found behind the left atrium,because the pericardial attachments are refleted onto the pulmonary veins.Somtimes,PE can be visualized in the oblique sinus,which is located behind the LA. A PE is anterior to the descending aorta,whereas a pleural effusion(PL) is posterior to the aorta.

 Echo Features of Tamponade

Echo Features of Tamponade: 1) Large volume pericardial effusion; 2) RA and/or Rv diastolic collapse; 3) Doppler features are of exaggerated changes in transmitral and transtricuspid flows and changes in flow patterns of the superior vena cava.