ECHOCARDIOGRAPHY Hydrodynamic compression of the right atrium : a new echocardiographic sign of cardiac tamponade

The relationship of right atrial inversion, a previously undescribed cross-sectional echocardiographic sign, to the presence of cardiac tamponade was examined. We studied 127 patients with moderate or large pericardial effusions. Cardiac tamponade was present in 19 and absent in 104. Four patients with equivocal tamponade were excluded from analysis. Right atrial inversion was present in 19 of 19 patients with cardiac tamponade and 19 of 104 without cardiac tamponade (sensitivity, 100%; specificity, 82%; predictive value, 50%). The degree of inversion as quantitated by the area-corrected curvature did not improve the ability to discriminate between patients with and without cardiac tamponade. However, consideration of the duration of inversion by the right atrial inversion time index (duration of inversion/cardiac cycle length) and an empirically derived cut-off of 0.34 did improve the specificity and predictive value (100% and 100%, respectively) without a significant loss of sensitivity (94%). We conclude that right atrial inversion, particularly if prolonged, is a useful echocardiographic marker of cardiac tamponade that may be of particular diagnostic value when the clinical picture is unclear. Circulation 68, No. 2, 294-301, 1983. THE ROLE of echocardiography in the diagnosis of pericardial effusion is now well established. 1 2 Unfortunately, the echocardiographic differentiation of hemodynamically insignificant effusion from that associated with cardiac tamponade remains difficult. Previous M mode studies have identified a number of abnormalities in patients with cardiac tamponade. The majority of these signs reflect exaggerated respiratory variation in ventricular filling and cardiac output due to the inability of the heart to expand normally within the tense fluid-filled pericardium. These signs include right ventricular expiratory end-diastolic compression,3 pronounced reciprocal respiratory variation in right and left ventricular size,' both absolute and inspiratory reductions in mitral D-E excursion4 I and E-F slope,4 I and inspiratory reduction in the area of the aortic valve opening and left ventricular ejection time.4 Abnormal motion of the right ventricular wall in the form of systolic notching7 and collapse during isovolumetric relaxation and early diastole' has also been From the Cardiac Unit, Massachusetts General Hospital, Boston. Address for correspondence: Arthur E. Weyman. M.D., Massachusetts General Hospital, Director of Non-invasive Cardiology Laboratory, Fruit St., Boston, MA 02114. Received Nov. 9, 1982; revision accepted April 25, 1983. Dr. Gillam is a fellow of the Canadian Heart Foundation. Presented at the 31st Annual Scientific Session of the American College of Cardiology, April 1982, Atlanta. 294 noted in patients with hemodynamic compromise due to pericardial effusion. Unfortunately, however, the sensitivity and specificity of any of these signs in the identification of cardiac tamponade remain in question, and no single or group of signs has emerged as an unequivocal marker of this potentially life-threatening complication. More recently, the improved visualization of the right heart afforded by cross-sectional echocardiography has allowed better definition of right ventricular structure and function and has permitted a better understanding of the abnormalities noted on M mode studies. Armstrong et al.,9 expanding on the earlier M mode work of Shiina et al. ,8 have noted right ventricular diastolic collapse to be a sensitive and specific marker for cardiac tamponade. During our cross-sectional echocardiographic examination of patients with pericardial effusion, we have noted striking late diastolic inversion of the right atrial free wall, a previously undescribed abnormality that appeared most obvious in patients with cardiac tamponade. The purpose of this study, therefore, was to define this invagination of the right atrial free wall qualitatively and quantitatively and to examine its relationship to the presence of hemodynamically signifi-