A new cross sectional echocardiographic method for estimating the volume of large pericardial effusions.

OBJECTIVE: To evaluate a new cross sectional echocardiographic method for estimating the volume of pericardial effusions. DESIGN: The volume of pericardial fluid removed by surgical drainage or paracentesis was compared with the volume estimated by the echocardiographic method. The pericardial sac volume and cardiac volume were calculated by applying the formula for the volume of a prolate ellipse (pi x 4/3 x L/2 x D1/2 x D2/2) where L is the major axis and D1 and D2 are the minor axes. The pericardial fluid volume was calculated as the pericardial sac volume minus the cardiac volume. PATIENTS: 13 patients with 14 large pericardial effusions (one recurrence) all of whom had tamponade and cross sectional echocardiography just before therapeutic full drainage of the effusion. RESULTS: The volumes of pericardial fluid drained ranged from 0.5 to 2.11. The correlation between these actual volumes and the volumes estimated by echocardiography was excellent (r = 0.97); the correlation was good in four patients with intrapericardial adhesions. CONCLUSIONS: Because of certain approximations in measuring quantity of pericardial fluid drained, the echocardiographic estimations cannot be claimed to be definite. The data, however, indicate that the echocardiographic method is sufficiently reliable to provide useful estimates for practical clinical purposes.