The right pericardial fat pad.

Abstract

It is generally recognized that on a chest roentgenogram the pericardial fat pad often produces a shadow at the left apical border of the heart (3). It was our good fortune to observe two interesting autopsies on extremely obese white males. Upon opening the thoracic cage it was noted that the pericardial fat was markedly increased (Fig. 1). More significant was an unusually thick pericardial fat pad which covered the anterior and right lateral surface of the right auricle and superior vena cava. The question then presented itself: Would this fat pad produce a shadow on a postero-anterior roentgenogram of the chest similar to the shadow seen at the left border of the heart? It may be recalled that on routine postero-anterior chest films of obese persons the mid portion of the mediastinum at times appears broadened. This is usually explained by the elevated diaphragm and the transverse position of the heart. It is the purpose of this paper to present findings in gross pathological specimen, and on x-ray films, to show (a) that there is a right pericardial fat pad at the level of right auricle and superior vena cava, (b) that this is possibly related to generalized obesity, and (c) that, when present, it can produce a shadow on the posteroanterior chest film. Our cases are of course far too few to be significant for statistical purposes. Case I (Figs. 1–4): A markedly obese white male died of cirrhosis of the liver. At autopsy a thick right pericardial fat pad was found. Case II: A markedly obese white male died of carcinoma of the stomach. At autopsy a right pericardial fat pad with the same anatomical relations as in the previous case was found. It is realized that there is considerable distortion of the normal anatomy after death and particularly after autopsy. In order to prove that the fat pad seen on the right was not due to postmortem distortion but actually lay lateral to the superior vena cava, a finger was placed in the superior vena cava and the thumb placed completely laterally. Approximately 1.5 cm. of pericardial fat was interposed between the fingers. Roentgenograms of the specimen were taken (Fig. 2) with a metallic object completely filling the superior vena cava and extending into the right auricle. In these the right fat pad can be clearly seen. This fat was then dissected off the right auricle and superior vena cava and another picture was taken (Fig. 3) to show these relations more clearly. It is felt that the knowledge that this structure is occasionally present may aid in explaining a prominence of the upper part of the cardiovascular shadow which otherwise might be interpreted as a dilated superior vena cava. A search of the English literature reveals very little on the subject of pericardial fat pad. Hugo Roesler mentions its presence on the right side of the heart and the front of the aorta (1). Master related the left pericardial fat pad to obesity (2).