Right ventricular compression as a sign of cardiac tamponade: an analysis of echocardiographic ventricular dimensions and their clinical implications.

We have identified pericardial effusion by echocardiography in 174 patients. Seventeen had cardiac tamponade which was not always clinically obvious. Right ventricular narrowing or compression, occurring in the minor axis at end diastole and end expiration, to 7 +/- 2 mm or less, was strongly associated with tamponade in patients with effusion. Right ventricular compression and signs of tamponade abated with pericardiocentesis. One patient was in tamponade without obvious right ventricular narrowing. Nonetheless, he demonstrated serial increases in right ventricular dimensions which paralleled hemodynamic improvement. Diminished left ventricular end-diastolic dimension, "swinging heart," electrical alternans, reciprocal respiratory variations in right and left ventricular end-diastolic dimensions and variation in amplitude of the mitral D-E slope were nonspecific for tamponade. Evaluation of right ventricular dimensions may be clinically useful to diagnose and monitor cardiac tamponade.