PERICARDITIS. 403 



Extension of the dulness to the left, beyond the point at which the 

 apex beats, is a positive sign of the existence of a collection of liquid 

 in the pericardium. Gertiardt has pointed out that pericardial effusion 

 forms an important exception to the rule according to which cardiac 

 dulness remains the same, whether the attitude be erect or recum- 

 bent, as in the latter case its limits become from one-third to one-half 

 larger. 



Upon auscultation, unless the heart be hypertrophied, or in violent 

 action, its sounds are remarkably feeble, and often nearly inaudible. 

 The disproportion between the extensive dulness and the feeble im- 

 pulse and lowness of the heart-sounds is an important indication of pe- 

 ricardial effusion. In addition to this, there are, in most cases, friction- 

 sounds which suggest the idea of scraping, rubbing, and scratching. 

 These friction-sounds are unlike those of pleuritis, which are only audi- 

 ble before the pleural surfaces are separated by the liquid, or after the 

 liquid part of the effusion has been absorbed, as they sometimes may 

 be heard when there is a great deal of water in the pericardial sac. 

 As the sounds are produced both by the rubbing up and down of the 

 heart against the thoracic wall and its rotation upon its long axis, 

 after the opposing surfaces have lost their primitive smoothness, and 

 as the movements of the heart are of far longer duration than the nor- 

 mal sounds which it causes, these friction-sounds, although rhythmical, 

 are hardly ever isochronic with the normal cardiac tones, but outlast 

 them, making a prolongation, or sometimes preceding them. 



About the lower lobe of the left, lung the percussion-sound is often 

 flat, from pressure, and we must beware of mistaking it for pleuritis. 

 The presence of pectoral fremitus will guard against error. 



DIAGNOSIS. Pericarditis is most apt to be mistaken for endocar- 

 ditis. The functional disturbances, when they occur, are very much 

 alike in the two diseases, although pain about the heart is far more 

 common in pericarditis, as is also the case with dyspnoea and the cyano- 

 sis. As it often happens, however, that neither of them furnishes any 

 subjective symptoms whatever, differential diagnosis must mainly de- 

 pend upon physical exploration : 1. In the first place, in endocarditis, 

 we never find prominence of the cardiac region, which, although not 

 common, does sometimes appear in pericarditis. 2. The form of the 

 tract of abnormal dulness affords an important clew. In endocarditis 

 the dulness may become abnormally widened in a few days, as when 

 dilatation of the right ventricle occurs early. In pericarditis the dul- 

 ness almost always begins in the vicinity of the great vessels, and 

 afterward assumes a triangular form. If the left border of the dul- 

 ness reach beyond the apex, the right considerably surpassing the 

 right edge of the sternum, effusion is present in the sac. We have 



