The Roentgen Diagnosis of Pericardial Effusion

Abstract

There is no single roentgenologic sign of pericardial effusion. Such errors in diagnosis as are frequently encountered are most often the result of an impression gained by inspection of the film alone, and a conclusion that the heart shadow resembles a “water-bottle.” Since the contour of an enlarged heart may, in some cases, simulate the outline of a pericardial effusion, every bit of available evidence must be sought and weighed. Observations by various investigators have contributed substantially toward the diagnosis of pericardial effusion since the report of Camp and White (1) in 1932, which stated that in only one of 49 patients studied roentgenologically was the diagnosis of pericardial effusion established antemortem. The purpose of this paper is to summarize the most useful signs commonly employed and to present our own observations as to the diagnosis and differential diagnosis of pericardial effusion. The pericardium is a membranous sac containing elastic fibers and consisting of a visceral and a parietal layer. While the visceral layer is more or less intimately adherent to the surface of the heart, the parietal layer is loosely applied. This creates an actual space between the two layers, which normally contains 15–20 c.c. of clear, straw-colored fluid. After rounding the inferior borders and surface of the heart, the pericardium becomes firmly attached to the central tendon of the diaphragm (Fig.1). Superiorly, the pericardium is reflected onto the coats of the great vessels, with which it blends intimately. Anteriorly, the outer layer is loosely attached to the pleura by fibre-areolar tissue—the pleuro-pericardial membrane. At times, however, this membrane may consist of firm, dense, fibrous tissue. Attachment to the sternum is by the superior and inferior sterno-pericardial ligaments. The superior and inferior venae cavae pierce the pericardium posteriorly, as do also the four pulmonary veins. The ligamentum arteriosum is usually enclosed by pericardium, though occasionally it lies outside the attachment of the pericardial sac to the great vessels. While fluid in the pericardium may, under certain circumstances, accumulate with startling rapidity, as for example in the case of trauma, the process is usually subacute or chronic, and it is with these forms that this paper is chiefly concerned. Fluid naturally gravitates to the most dependent portions of the sac. Most observers (2, 3) agree that amounts less than 250 to 300 c.c. may not be recognized roentgenologically. This may be due to the fact that the normal heart is subject to considerable variation in size before it may be considered enlarged, and unless a patient has been under roentgen observation for a sufficiently long period to show progressive increase in the size of the heart shadow, it may not be possible to tell, from a single examination, whether or not the shadow is abnormal.