404: DISEASES OF THE PERICARDIUM. 



already dwelt upon the significant fact that, notwithstanding the ex- 

 tent of the dulness, the heart-tones are low, and the beat feeble and 

 inaudible when the patient lies down. If the dulness commence at 

 the second rib, we must take notice whether or not the diaphragm and 

 heart be pushed upward. If so, it will be impossible to form any- 

 positive conclusion as to the presence of liquid in the pericardium. 

 The possibility of the existence of aneurism of the aorta, of excessive 

 dilatation of the right auricle, of infiltration of the anterior edges of 

 the lung, and of retraction of the lung, which allows a larger portion 

 of the pericardium to come into contact with the thoracic wall, must 

 also be excluded ere the diagnosis of pericardial effusion can be re- 

 garded as established. Sometimes, notwithstanding the existence of 

 a very large effusion, the cardiac dulness is not increased, although in 

 the vicinity of the area of dulness the percussion-sound is somewhat flat. 

 In these cases the anterior edge of the lung has become immovable, 

 owing to adhesion of the pulmonary and costal pleurae. 



3. The murmurs heard in the heart usually permit of a conclu- 

 sion as to the nature of the existing disease. In the first place, their 

 quality affords some information. Not only the pericardial sounds, but 

 many of those arising in the heart are friction-sounds. In the one 

 case, the roughened surfaces of the pericardium rub together ; in the 

 other, the roughened endocardial surface is rubbed by the current of 

 the blood ; but, in many instances, the sounds are so distinctly those 

 of scraping or scratching, that we can have no doubt but that they 

 proceed from the pericardium. The points at which they are best 

 audible is of more importance. As it is mainly the right side of the 

 heart which lies in contact with the side of the chest, and rubs against 

 it during its diastole and systole, pericardial sounds are very often 

 heard over the right ventricle, where endocarditis and valvular disease 

 are very rare. The time at which the sounds are heard is of great mo- 

 ment. In endocarditis, they are isochronic with the heart-sounds, and 

 supplant them. In pericarditis they precede the normal sounds, or 

 come after them. When the beat of the heart is very rapid, it is hard 

 to say if the false sounds be isochronic with the normal ones or not. 



The extension of the sounds exhibits a further difference (Bain- 

 b&rger). In pericarditis they are sometimes confined to a very small 

 spot; in endocarditis they are transmitted along the current of the 

 blood. Lastly, as the heart rises and falls in the liquid around it, 

 pericardial sounds are much more liable to change with alteration of 

 attitude in the patient than the endocardial murmurs. 



Rhythmical friction-sound of the pleura may arise in consequence 

 of inflammation of that portion of the pleura which overlies the peri- 

 cardium, the roughened costal pleura being made to rub against the 



