PERICARDITIS

IT is not widely realized that pericarditis is found twice as commonly at necropsy as it is in life. Many clinical cases of pericarditis are therefore being missed. A review of the clinical findings suggests that the only true diagnostic sign is the friction rub, and this, at times, may be transient, hard to hear, or misleading. The rub may have three components in the cardiac cycle, these being caused by atrial systole, ventricular systole and ventricular diastole, each moving the heart within the pericardial sac. However, only two components may be heard, and sometimes only one, and then the rub is diIDcult to distinguish from common systolic murmurs. Another feature of importance in the diagnosis of 'pericarditis is the presence of chest pain. This is common, often aggravated by movement of the chest, by lying flat, or by swallowing, and rarely radiates to the arms. (1) These features serve to distinguish it from the pain of myocardial infarction. The electrocardiographic signs of pericarditis are characteristically widespread throughout many leads. The early signs are of B·T segment elevation, but this may not occur for a day or two after the friction rub first appears and, indeed, may not occur at all. In a later phase the T waves may become inverted and the electrocardiogram then suggests widespread myocardial damage, but of an entirely non-speciflc kind. Serial electrocardiograms in these cases may be helpful. The presence of a significant effusion may aid considerably in diagnosis. Increase of heart size, either clinical or radiographic, even if transient, suggests the diagnosis. However, whilst effusion is frequent in pericarditis, collections of less than 300 ml need not distort the cardiac outline. With the development of an effusion, heart sounds often become less distinct and a rub, if present previously, may diminish or disappear, but this is not always so, as D. H. Spodick(l) has emphasized in a recent review of acoustic phenomena in pericardial disease. Several effective methods are now available for detecting pericardial effusions. Blood pool scanning of the heart by the use of radio-active indium (118m In) will distinguish effusions of moderate size from cardiac enlargement. The scan shows the heart blood pool separated from the liver blood pool by the pericardial fluid. (S) The procedure is simple and safe. Echocardiography affords a completely atraumatic method of demonstrating the fluid layer by making use of refiected ultrasound. The injection of radioopaque contrast medium or carbon dioxide into the right atrium through a cardiac catheter gives a good indication of pericardial fluid or thickening. Sometimes pericardial paracentesis may be necessary to obtain a sample of fluid or to relieve tamponade. If this is merely carried out with a needle