Can Cardiac Tamponade be Diagnosed by Echocardiography? Experimental Studies

SUMMARY The purpose of this study was to determine if respiratory variation and/or absolute size of echocardiographically measured right or left ventricular internal dimension at end-diastole (RVIDd or LVIDd) are accurate indicators of the presence or severity of cardiac tamponade. We measured RVIDd or LVIDd by echocardiography in nine closed-chest, spontaneously breathing dogs in control and during hypoten-sive tamponade. With tamponade, the end-expiratory RVIDd and LVIDd were significantly smaller than con-trol. Inspiratory increases in RVIDd and decreases in LVIDd were exaggerated during tamponade. Because of the wide range and overlap of RVIDd and LVIDd, no single expiratory value or amount of respiratory change indicated the presence or severity of tamponade. We conclude that if serial echocardiograms show a pericar-dial effusion, a decreasing end-expiratory RVIDd and LVIDd and an increasing percentage change in ven-tricular diameter with inspiration, a progressive degree of tamponade should be suspected. However, a single echocardiogram cannot accurately predict the presence or severity of tamponade. THE ECHOCARDIOGRAM is a sensitive and ac-curate tool for diagnosing pericardial effusion. ' 2 Re-cent studies in patients with pericardial effusion have suggested that changes in ventricular diameter with respiration3 or right ventricular compression5 are echocardiographic findings that may indicate pericar-dial tamponade. However, such changes may not be specific for or predictive of cardiac tamponade.4 6, 7 The purpose of this study was to determine if echocar-diography could be used to predict the presence and/or severity of cardiac tamponade in an ex-perimental model