Echocardiography in the Diagnosis of Pericardial Effusion

Abstract

The diagnosis of pericardial effusion by reflected ultrasound, as described by Feigenbaum and his associates (1), promises to be a technic superior to presently used modalities with respect to safety and ease of performance and equivalent to them in accuracy. Differentiating a pericardial effusion from a large, dilated heart is a familiar problem to radiologists. Radioisotope scanning (2) as well as various radiographic procedures from simple decubitus films to angiocardiography and intravenous CO2 (3–5) are used to aid in this distinction. The latter has proved the most satisfactory in our hands and is virtually without morbidity. However, all these technics generally require in excess of thirty minutes. In addition, they involve the use of elaborate equipment and necessitate transport of the patient. These factors, plus positional requirements, prohibit examination of the very ill patient—often the one in whom correct diagnosis is most urgent. In contrast, echocardiograms can be obtained with commercially available ultra- sonoscopes readily mounted on a stand that can be wheeled to the patient's bedside if necessary. The procedure takes about five minutes, can be performed with the patient supine or sitting, and involves no x-ray exposure. Even patients in O2 tents can be examined. The diagnosis of pericardial effusion is based on identification of an echo from the pericardium separate and distinct from the echo of the posterior heart wall (Fig. 1). Technic With signals pulsed at 200 cycles∕second, a 2.5 megacycle transducer of 1.9 cm diameter is applied parasternally in the left fourth or fifth intercostal space and directed posteriorly. Lubricant jelly is used to assure good contact. If the patient is so thin that intercostal areas are concave, a water-filled finger-cot can be placed between skin and transducer. Occasionally, difficulty is encountered in an emphysematous chest with vertical heart “hidden” behind overexpanded lung or sternum. In such cases a better record may be obtained by placing the transducer just below the xiphoid, directing it cephalad, posteriorly and to the left. The posterior wall echo is readily identified as a strong signal 8–14 cm from the transducer, having distinct pulsatile motion with the cardiac cycle (seen on the oscilloscope as horizontal motion). In the absence of pericardial effusion, no strong echo is identified posterior to this pulsatile signal. In the presence of effusion, an abnormal interface is introduced, giving rise to a second strong echo from the posterior pericardium. This echo does not move appreciably with the cardiac cycle but does move with respiration. (Echoes from the anterior heart wall are deliberately eliminated on the oscilloscope in this technic.)