Pericardial fluid may remain undiagnosed if history and physical examination fail to detect it or to differentiate between it and an enlarged heart. Plain chest films or fluoroscopic screening are not always helpful. Even a diagnostic tap may fail when the amount of fluid is too small. Other methods must often be resorted to for confirmation of diagnosis.
Best known of these diagnostic aids is angiocardiography. Utilizing a contrast medium to fill the cardiac chambers, this technique permits measurement of the interval between the outlined inner myocardial border and the outer rim of the pericardium. If the interval grossly exceeds the normal thickness of the myocardium, the suspected diagnosis of pericardial fiuid becomes almost a certainty.
Either a radiopaque dye or carbon dioxide gas may be used as a contrast medium in the angiocardiographic study. Shuford et al1 compared the two media in 31 patients with pericardial effusion, using